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Heat pipe research and development in east european countries
Heat Recovery Systems & CHP Vol. 9, No. 1, pp. 3-17, 1989 Printed in Great Britain
0890-4332/89 $3.00+ .00 Pergamon Press plc
HEAT PIPE RESEARCH AND DEVELOPMENT EUROPEAN COUNTRIES
IN EAST
F. POL~,gEK National Research Institute for Machine Design, SVOSS, 19011 Praha 9-B6chovice, Czechoslovakia Abstract--The paper presents a review, made on the basis of available publications, of the research, development and application of heat pipes and closed two-phase thermosyphons in East European countries, i.e. Bulgaria, Czechoslovakia, German Democratic Republic, Hungary, Poland, Rumania and Yugoslavia from 1984 to 1986.
NOMENCLATURE d J L q R t u W
diameter (m, mm) mass flow rate (kg s- i ) length (m, ram) heat performance (W) heat flux (Wm -2) thermal resistance (K W - ') temperature (°C) pitch (m, mm) heat capacity (3V K - ~)
Greek symbols heat transfer coefficient (W m-2 K - ~) A difference 6 thickness (m, mm) ~t' tilt angle from the horizontal position (°) rl thermal efficiency T time (s) Subscripts A warm stream B cold stream F fin e external ef effective i internal K condensation part O start V evaporation part W environment 1 inlet 2 outlet I first stage 11 second stage INTRODUCTION
An exhaustive survey about the state of research and development of heat pipes in the countries of Eastern Europe up to the end of 1983 was given at the 5th International Heat Pipe Conference in Tsukuba in 1984 [1]. This survey is now supplemented, on the request of the 6th IHPC organizers, with publications from the period of 1984-1986. ANALYSIS
OF THE
HEAT
PIPE OPERATION
Since the 5th IHPC in 1984, the activities in the field of the heat pipes in the East European countries have concentrated, particularly, on effective application of the heat pipes and heat pipe systems in industry and agriculture. 3
F, POLA~EK
4
The aim of both theoretical and experimental research was especially the investigation of transport phenomena in closed two-phase thermosyphons [B2], [F2], IF3], IF4], IF7], [H4]. ILl]. [R2], [R3], [R4], [$3], [$4] numerical assessment of unsteady state temperature fields in solid bodies with built-heat pipes by means of the finite elements and differences methods [DI], [Z7], the determination of heat transfer coefficients and critical heat fluxes in the evaporating and boiling of liquids from capillary porous materials, dealt with in the 6th IHPC paper [2] and material compatibility of heat pipes IN2], IN3]. A computing program has been designed to study the behaviour of a heterogeneous system consisting of a cast, chill, high temperature sodium heat pipe and sand mould. The computation algorithm is based on the application of the finite differences method to solve heat conduction equations. Solidification (melting) is solved by heat sources or heat sinks in the nods. The heat pipe is simulated by the entry of heat flux in the nods appertaining to its presupposed location. For this purpose an understeady state double-capacity heat pipe model has been designed and tested, separately, respecting the impact of the heat capacities of the evaporation and condensation part. For the opening stage of the unsteady state process, while the pipe is being heated without internal mass transfer into the condensation part, the heat flow is defined as:
_ dtv Q,=Wv-~r;
for
tv
(1)
The second stage with the condensation part already operating, is described as:
Q,, = Wv dtv Wx dtx dr + ~ + ~(tx - tw).
(2)
For the purpose of the program, the relationship (2) has been formally modified, like in [3], into:
dtv q = C, ~ + C2(tv- tel),
(3)
Ci, C2, te/ being complex constants. The computation results have produced some fresh information, helping establish the priorities for further research. To give an example, the computations have proved that the cooling of steel casts can be externally controlled [Z9]. The heat performance of the water-filled steel heat pipes is not stable because of the non-condensing gas which develops inside the pipes as a result of electro-chemical corrosion. The main objective of the measures taken at SVOSS was to curb the development of the gas. For this purpose, 3 methods have been used [N3]: (1) passivating the inner heat pipe surface with magnetite (Fe~O4) layer; (2) adding inhibition substance to the working fluid; (3) covering the pipe surface with Fe304 layer plus adding the inhibitor to the working fluid. To be able to compare the methods, all heat pipes were manufactured of mild carbon steel. To produce the FesO4 layer an oxidation method was applied using preheated water vapour or water vapour with an oxidation catalysator (NH4)2 MOO4. The basis of the inhibitor were the chromates, such as K2 CrO4. The life tests checked the temperature profile along the pipes condensation part with a contact thermometer, or contactless temperature measurements were undertaken with the aid of thermovision AGA. After 6000 working hours assessment was made on the grounds of the temperature profile measuring results, the non-condensing gas, the working charge and the internal heat pipe surface analysis. The lowest level of hydrogen development in the steel pipes was observed while using the third method, which is more costly than the second method that showed rather good results as well, as can be seen in Table 1. The corrosion of the external surface of the fin aluminium and steel pipes was tested on 5-row HPHE consisting of water-filled bimetallic Al/steel finned tubes: 56/28/25/21-3 (0.75), finned pipe markings of--bimetallic pipes:
d,,Id'
H e a t pipe research a n d d e v e l o p m e n t in E a s t E u r o p e a n c o u n t r i e s Table I. Results of steel-water heat pipe life tests Heat pipe Method no.
I 2 3
Surface treatment
Results after 6000 h life test Working fluid
At (°C)
Content of H2 in inert gases
Composition of inner surface layer--X-ray analysis
H20 H:O
32 l0
maximum traces
,, Fe; slightly Fe~O4 strongly Fe~O£ strongly Fe
H20 + inhibitor
6
traces
a Fe; Implication (Fe, Cr)304
H20 + inhibitor
3
~
,, Fe; F~O4 slightly (Fe, Cr)203
Oxidation by vapour at temperature 550°C Oxidation by vapour at temperature 550°C
At: temperature difference along condensation part of heat pipe. Inhibitor: 0.5% water solution of K:CrO 4 (pH = 7.87).
extruded pipes:
The verifying tests of these exchangers, performed since 1985 in a brick factory using as a heat source that sort of equipment fuelled by heavy oil with high content of corrosive SO: in its flue gases, have proved that from the point of view of corrosive effects these exchangers are quite satisfactory. They work within the temperature range 180-280°C of flue gases coming into the evaporation section, and at 20-30°C of the inlet fresh air, which with thermal efficiency of 48%, will secure the preheating of the inlet air at 87-150°C. Deliberately omitting to clean the heat exchanging surface in the flue gases chamber of dust particles will reduce, according to the tests made over 42 days, the flue gases flow to 18% of the original value and, as a result, the thermal efficiency will drop from 48 to 15%, although the corrosion of both the aluminium and steel surface was, in terms of metallurgical analysis, minimal. As shown in Fig. 1, the main problem is the fouling of the heat exchanging surface by the flue gases of heavy fuel oil and not the corrosive effects of the sulphur oxides. In order to examine the corrosion of aluminium fins caused by flue gases we used an X-ray qualitative surface analysis. On the fin surface a marked continuous carbon layer is developed in
,, .~ ........
Fig. I.
~i ¸ ,
~ ~
• ~,
F o u l i n g o f the H P H E after o p e r a t i o n in flue gases.
6
[:. POL,&~EK
sharp contrast to the metal surface on which it occurs. The X-ray microanalyser revealed that the layer consisted largely of sulphur. The diffusion of sulphur into the metal fundament was not observed (Fig. 2a-2c, enlarged 800 times). The aluminium traces found in the sediment layer and in Wood's metal, in which the fin was sealed, are the result of the aluminium fin grinding preparation. This evaluation of the corrosion was studied in test samples exposed for over 6000 hours to heavy fuel oil flue gases at a temperature of about 160°C [N3]. A P P L I C A T I O N OF H E A T PIPES IN T H E C O U N T R I E S OF E A S T E R N E U R O P E So far the widest application of heat pipes in East European countries can be found in waste heat recovery in power programs, in electrical and mechanical engineering and in the chemical
a. An aluminium fin surface laycrl
b. Surface distribution of S in am Al-fin layer (X-rays S, K,).
Heat pipe research and development in East European countries
7
c. Surface distribution of AI in an Al-fin surface layer (X-rays AI, K~). Fig. 2. Corrosion of aluminium fins caused by flue gases (enlarged 800 x ).
industry. Select heat pipe applications in Czechoslovakia have been discussed in a separate paper of the 6th IHPC [4].
Waste heat recovery through heat pipe exchangers As a result of the energetic crisis in the 1970s, a considerable cut in fossil fuel consumption had to be made in the entire CMEA community, particularly in agricultural establishments, where the production of I 1 of milk required as much as 0.4 1 of oil. This effort led to organizing the so called 'integrated energetic systems', which employ, to supply the agricultural buildings with heat and heat the service water, not only standard but also secondary heat resources such as solar collectors, heat pumps, biogas, heat accumulators and especially waste heat recovery systems, e.g. heat pipe heat exchangers (HPHE). To obtain the optimum operation of all these devices, automatic systems are established controlled by microcomputers. The recovery of waste heat from technical resources and biological warm of the animals is of fundamental importance for agricultural mass production. In Czechoslovak conditions, the installation of as many as 20,000 HPHE units is expected within the next few years. The waste heat recovery from air, flue gases and liquids to preheat fresh cool air, to warm water or to produce low pressure steam is widely utilized in the CMEA countries, as already discussed in our earlier paper [5]. Apart from the main goal to economize on energy, the waste heat recovery in agricultural establishments has also important side effects in creating a more favourable environment for livestock, improving their health conditions, increasing their increments and, last but not least, raising the durability of buildings and technological equipment. It can be expected that these additional features will soon become, after installing complex energetic and airconditioning systems in agricultural mass production plants, economically more significant than the initial energy economizing aims. Even now, after the introduction of 1200 HPHE units into the agricultural and industrial establishments in Czechoslovakia it has been found that, for instance, weight increments in calf rearing have grown by as much as 10% as a result of a better ventilation system improved with heat recovery. A similar favourable outcome has been registered in large poultry farms where, besides weight increment, considerable improvement in the health of the fowls and a drop in the death rate has been observed. Out of the four, tested heat exchanger types for recuperating waste heat in agricultural plants, only the HPHE with 60-80% thermal efficiency and, inspite of their lower performance (up to 50%) the plate exchangers have been recommended, as long as plate
8
F. POLA~EK
design allows for the easy removal of deposits from heat exchanging areas. Run around coil types of heat exchangers are not convenient from operation and investment viewpoints, and rotational regenerators are not permissible for veterinary reasons. Outside Czechoslovakia waste heat recovery through HPHEs is also intensively studied in other Eastern European countries, [B1], [B4], [BS], [Eli, [F5], [G1], [K2], [Pl], [RI], [Anl0], [Anl4], [An l S]. To give some examples: The Research Institute of Power Engineering (VEIKI), Budapest designed and put into operation several HPHEs consisting of water-fiUed steel gravitation heat pipes to preheat fresh air in boilers and ovens by using flue gas heat. The HPHE installed in the petrochemical plant of Dunai K6olajfinomit6 is made up to 1530 heat pipes (~b 22/2 mm: length 2750 mm) to preheat air with flow rate JB = 2.7 Kgs -~ by as much as 180 K through flue gas heat (JA = 2.9 Kg s-~, tA~ = 310°C). At the HPHE maximum heat performance of 8140 kW the efficiency of the oven rose by 7.4% [B4], [B5], [Eli. An establishment producing air-conditioning devices in Budapest (FI~ITOBER) manufactures HPHE made of freon or ammonia-filled aluminium finned pipes and of water-filled copper pipes to recover waste heat in air conditioning and air exchange [Anl0]. University of Brasov, jointly with a producer of air-conditioning equipments, put into operation an HPHE made up of radially extruded aluminium finned pipes [~b 40/23/19-3.55(1), length 2100 mm] with acetone charge to recover oven waste heat in paint and enamel shops [FS]. A steel heat pipe (~b 23/3 mm) heat exchanger is employed by the Industrial Energetic Plant in Bulgaria to warm service water with flue gas waste heat (150°C) at total thermal output 21 kW [PI]. Also the KOSORA Plant in the G.D.R. uses a bundle of steel gravitation heat pipes to warm water with flue gas waste heat (120°C) [AnlS]. For purposes of air exchange and conditioning in farming establishments, the D.D.R. enterprise W/irmetechnik und Liiftungsbau, Gotha, manufactures HPHEs consisting of ammonia-filled bimetallic A l/steel finned pipes [An 14]. Table 2 compares calculations of financial pay-back in four types of heat exchangers recovering waste heat from broiler fast feeding farms. The comparison has revealed the convenience of using HPHEs in this type of establishment [ZS]. The problems of waste heat recovery through HPHEs have also been treated by the Universities of Gdafisk and Wroclaw in Poland [R l l, [1], University of Ljubljana in Yugoslavia [G1], University YASI in Roumania Ill, University Karl-Marx-Stadt in D.D.R. [K2] and Bauakademie Berlin [l]. The maintenance of the necessary microclimate in public buildings and premises requires, among other things, the exchange of deteriorated air. Exchanging the air by HPHE reduces thermal losses caused by ventilation. Sub-window ventilating unit with a small inbuilt HPHE was tested [.t2]. Heat pipe solar collectors and heat accumulators
The technical and economic research of solar collectors, heat pumps and heat accumulators in the CMEA community has shown that in most countries the pay-back of the investment funds does exceed five years and, consequently, their application in solving energetic problems can be allowed only in certain instances. In Czechoslovak conditions, for example, in view of the intensity of solar radiation only service water heating solar systems can be technically and economically justified. Of technical interest is the solar collector designed jointly with water heating and heat storage as shown in Fig. 3 [D2]. An axially finned heat pipe is mounted in a glass cylinder, while its smooth condensation part runs first through a heat storage filling, then through a water heating reservoir. Some other designs
Table 2. Calculation comparison of various type of heat exchangers to recovery waste heat in broiler farms Thermal
I 2 3 4 5
Type of heat
efficiency
exchanger
t/
Saving of city gas [m3 year- I]
0.78 0.67
126 538 108 546
3.4 3.4
0.67 0.50 0.39
108 546 81 112 63 600
3.8 4.4 4
Rotary type (rotor diameter 2.5 m) HPHE; tubes ~ 38/35/15-3.5 (0.85); NH~ Filling Rotary type (rotor diameter 2 m) Cross flow plate exchanger Ran around coil
~
Pay-back [years]
Heat pipe research and development in East European countries
2
~
2
1
9
/,
3
2
1
3 Fig. 3. Solar collector with heat storage l--heat pipe 2--evaporation part 3--absorber 4--glass tube 5--heat storage part 6--condensationpart 7--water.
Fig. 4. Heat pipe cooler of potentiailess modules l---Cu/water heat pipe 2--fins 3--AI block 4--potentialless modules.
of independent solar collectors and heat storages based on heat pipe principles are being investigated, as well as the heat pipe systems to utilize the warm mineral springs which are frequently found not only in Czechoslovakia, but in Bulga/ia, Hungary and other countries as well.
Heat pipe applications in electrical engineering Apart from the HPHEs, the largest application of the heat pipes in the East European countries has been found in cooling equipment and machinery in electrical engineering. In power electrical engineering, they are especially used as: coolers to cool power semi-conductor elements IF 1], [H 12], [I413], [PS], [$1], [$2]; switch and circuit-breaker devices [B3], [M4]; components of reproduction technique; bus-bars [B3], [M4]; plasma cathodes [H10]; etc. In electronics they are particularly used as coolers of elements in microelectronics [Z1-Z3]. Some applications are dealt with in a separate 6th IHPC paper [4]. The life time of accumulator batteries to drive e.g. mine locomotives, depends considerably on electrolyte overheating while recharging the battery. If, instead of a plug on top of the accumulator, we use a freon-filled heat pipe with its smooth evaporation part plunged in the electrolyte and the finned condensation part cooled either by free or forced air convection, the life time of the battery will be increased by 50-100% as proved in the mine battery locomotive operation tests [D3]. To cool power semiconductor elements of the pellet type with contact surface diameter 30, 40 and 60 mm, special capillary heat pipes with face heating and gravitational loop-shaped heat pipes have been developed. More particular information is given in a separate 6th IHPC paper [4]. To cool potentialless modules, special coolers have been developed from copper heat pipes with sintered capillary system and water filling, whose evaporation parts are inserted into an aluminium block with three attached potentiaUess 431-type modules (Fig. 4). For the heat pipe parameters quoted in Fig. 5 we also indicate the dependence of the cooler's thermal resistance on its position (heat performance 500 W and cooling air velocity between the fins 6 m s- ' ). This design allows for cooling of even most efficient modules under maximum power loading [S1], [$2]. To cool pellet power transistors with a contact surface diameter of 30 mm, apart from the capillary heat pipes with face heating also closed two phase thermos)phons have been developed as shown in the Fig. 6 [$2]. According to the calculations and data design of SVOSS two Czechoslovak manufacturers have been producing heat pipe heat exchangers to cool enclosed boxes containing electronic control elements. For heat performance from 100-500 W the plant KOH-I-NOOR, Prague is producing small units equipped with fans of a mezaxial type at a maximum volume flow rate of 200 m 3 hand maximum pressure difference of 80 Pa [An 16]. The medium size compact heat exchangers with A1 extended surface and Cu/freons or Cu/water heat pipes for heat performance from 300 to 3000 W have been produced by the plant V, Nov6
F. POLA~EK
10
5
V-IlII 0.5
t___lill
a
~-3
KW"I
IIII
.,2 t111~1
0,,3 02
°goo
4 6
o-G- ty ,..~o °
Fig. 5. Dependence of thermal resistance of the heat pipe cooler of potentialless modules on tilt angle.
Fig. 6. Heat pipe cooler of power transistor P30 1---evaporation part 2---condensation part 3--fins 4--sintered capillary structure 5----contact area with a power transistor 6--power supply.
Mesto nad Vhhom [An 4]. As you can see from Fig. 7 these HPHE are particularly suitable for cleaner working conditions, e.g. computing centres. Figure 8 shows a printed wiring board with flat copper water heat pipes with screen capillary systems. The condensation parts 30 mm in length.were provided with copper fins. With cooling air velocity 2.5 m s -~ in front of the fins and with evaporation part temperature 60°C, the heat performance of each heat pipe in horizontal position is 10 W [ZI], [Z2]. Heat treating equipment for wires and bands in cable works using an accelerated electron beam is plotted in Fig. 9. The processed wire is drawn over the suction forechambers into the proper vacuum chamber. Here, it is heated by secondary electrons emitted and concentrated by the mirror and by electrons discharged by the screening. The heat from the plasma cathode generated mainly by the ion incidence in glow discharge is taken away to the cooling air through a heat pipe installed in the cathode body. The cathode body serves at the same time as a high voltage power supply from the external line to the emitting surface. The solution not only guarantees the withdrawal of high heat performances, but the tightness of the vacuum chamber as well. The equipment for dry treating
Fig. 7. Heat pipe heat exchanger for cooling of enclosed boxes [An4].
Heat pipe research and development in East European countries
Fig. 8. Cooling of ICs on printed wiring board 1--IC 2--board 3--heat pipe 4--condensation part with fins.
the wires was installed and tested in cooperation of the SVUSS and the Institute o f Power Electrical Engineering Prague in the cable manufacturing works. The withdrawn loss performance from one cathode ~b 80 mm moved round 3 kW [Hl0]. The Research Institute o f the Electrical Industry in Budapest used copper heat pipes (~b 8/1 mm) with water as a working fluid for cooling on the cold side o f the thermoelectric generator. As a heat source for the hot side of the generator natural gas was used. They also used copper heat pipes to cool the stator o f linear motor and the unreliable water cooling system was changed to the effective heat pipe forced air cooling. To use waste heat, metallurgy thermoelectric generators with heat pipes were used. Electric current from generators was employed for supplying control and regulation devices. The research group at the Institute of Physics o f Zagreb University, in cooperation with the National Bureau of Standards, Washington D.C. and the Alexander yon Humboldt Stiftung have
6
is Fig. 9. Cooling of plasma cathode by a heat pipe I--plasma cathode as a heat pipe 2--vacuum chamber 3--evacuated adjacent chamber 4---annealed wire or band 5--cooling air 6--current supply 7---emission of electrons 8--screening under target.
12
F. POLASEK
been employing a heat pipe oven for the absorption measurements as a reservoir of liquid metal, in thermal equilibrium with its vapour, for spectroscopic measurements [M2], [M3], [VI]. In their last design [M2] they used a heat pipe oven as a reservoir of liquid metal, in thermal equilibrium with its vapour, for supplying the inner chamber with the metal vapour. In such a way the vapour temperature and pressure can be independently changed, permitting temperature variation measurements of the absorption coefficient at high vapour pressures. The research group at the Polytechnic Institute Ilmenau in the D.D.R. used copper/water heat pipes for the cooling of a high frequency A.C. electric motor 400 kW [B8]. Rotating heat pipes were used to cool the twin aircoil blade of a gas turbine [Ml]. Heat pipe applications in other industries
The heat pipes can be employed in different industrial plants with the main objective to intensify cooling or heating and simultaneously, to prevent undesirable substances from penetrating into the surroundings; the HPHE for instance, applied in wet waste gas desulphurization [6] has already proved its merits. The HPHE, which perfectly separates the warm and cold streams, prevents the injurants from spreading outside the working area. For reasons of environmental protection, many a production process has been changed into a closed cycle, in respect of cooling water circulation which serves to cool heat stressed machinery and equipment. The installation of two cooling circuits linked over a heat exchanger makes it possible to fill the interior circuit with clean water.- (or another convenient heat conducting liquid)
a.
I
01 5
10
I
15 K hi tad b.
I 20
Fig. 10. Heat pipe heat exchanger: type water-water. a. Scheme of HPHE. b. Dependence of the heat performance on the difference of inlet warm and inlet cold streams; Row rate of warm water 0.67 kgs-‘; Row rate of cold water 0.1 kg s-‘.
temperature
H e a t pipe research and development in East European countries
13
Fig. 11. Vapour-chamber for texturing of artificial fibres l--electric resistance heater 2--guide grooves for contact fibres with isothermal chamber surface 3--filling tube 4--insulated condensation part of the chamber.
without the risk of fouling or corroding the active heat exchanging surfaces and to use, in the exterior circuit, service water without modifications. On the other hand, with two cooling circuits the cooling water from the machines does not convey any noxious or other undesirable substances into the waste. To meet this requirement, the heat exchanger design must allow for quick and easy cleaning of the heat exchanging surfaces that lie in contact with service water. The answer to this problem is the HPHE whose diagram is plotted in Fig. 10. It consists, e.g. of a bundle of smooth copper pipes (~b 14/0.5 mm, length 200mm) with methylalcohol filling. For an exchanger comprising 14 heat pipes, Fig 10 shows the dependence of heat performance on the difference of the inlet temperatures of both water streams with preselected mass flow rates. Computing a comparison with a variant of a standard twin-draught cross-current heat exchanger has proved that although the built in volume of both exchangers is approximately the same, the HPHE is simpler, particularly in respect of the cleanability of its heat exchanging surface. The HPHE were used to cool the warm, clean inner water of the plastic moulds by service water in a chemical plant. In this plant individual copper/water heat pipes have found wide application, especially in cooling injection moulds for thin, long profiles, where no cooling water channels can be conveniently designed [HI0], [P7], [Pg]. At "controlled cast aluminium and its alloys solidification" the heat pipes allow for cooling of critical points of the mould, thus reducing the H.R.$. 9/I--B
14
F. POLIX~EK
Fig. 12. Sodium distillation unit with variable conductance steel/water heat pipes l-heat pipes; 2-boiler of the unit.
casting period and improving the mechanical properties of the metal. For example when steel/mercury heat pipes were used the solidification time of the flange was cut by 35% [HI0]. To produce isothermic surfaces of an even larger size, needed in technological operations such as heat processing of artificial fibres, special vapour chambers are designed consisting of heat pipes, usually with a rectangular cross-section, and isothermic furnaces usually shaped as cylindrical annuli. When heating the evaporation part by, say, a built in electric resistance heater, the whole space of the vapour chamber is filled with steam of almost equal temperature. If the external surface of the vapour chamber is insulated, thermal losses to the surroundings are minimal and the evaporation part input only makes up for these thermal losses. Figure I 1 shows a vapour chamber of 2 m in height designed to maintain the surface temperature of six grooves at 230°C + I°C while processing artificial fibres. Figure 12 shows a sodium distillation plant with variable conductance steel/water heat pipes for temperature control during the condensation of clean sodium vapour.
CONCLUSION According to the available literature there are over 40 institutes and establishments engaged in the research and development of heat pipes in the countries of Eastern Europe. The main applications are aimed at utilizing air and flue gas waste heat and at intensified cooling, especially in electrical engineering.
Heat pipe research and development in East European countries
15
Many countries of Eastern!!E~irope (CZeehosl0vakia;': Bulgaria, Hu~igary) possess considerable heat resources in the form of mineral springs. At present, their exploitation is rather low. Now a technical and economic investigation is on the way, on how to apply heat pipe systems in the exploitation of geothermal energy, not only in agriculture and industry, but even in households, for one can expect that in this area heat pipes would be very useful. Acknowledgements--The author expresses his deep gratitude to all people who supplied valuable information for this paper. Apart from my colleagues in the National Research Institute for Machine Design, Prague---B~hovice, special thanks go to Dr J. Bielik, Dr H. Biesenack, Ing. H. Berger, Ing. J. Erdei, Dr D. Fetcu, lng. F. Jelinek, Ing. L. Kolev, Dr Milo~evi~:, Prof. D. Nebel, Dr P6tsehke, Dr H. Rokicki, Ing. K. Smr~ek, Dr T. TSrSk, Mrs I. Tusarov~i and Dr V. Zbofil.
REFERENCES 1. F. Pol~i~ek, Heat pipe research and development in East European countries, Proceedings of the 5th International Heat Pipe Conference, Vol. 2, pp. 15-51. Tsukuba, May 14-18 (1984). 2. V. Hlava~ka, L. Horv/tth, J. Kabi~ek, F. Kupec and F. Pol~i~ek, Heat transfer and critical heat fluxes at boiling on heating surfaces covered by capiliary porous structures, Proceedings of the 6th International Heat Pipe Conference. Grenoble, May 25-29 (1987). 3. G. T. Colwell, K. J. Wells and J. T. Berry, Theoretical study of the use of heat pipes in metal casting, Proceedings of the 5th International Heat Pipe Conference, Vol. 1, pp. 220-224. Tsukuba, May 14-18 (1984). 4. A. Ger~k, L. Horv/tth, F. Jelinek, P. [;tulc and L. Zbofil, Examples of heat pipe application in chemical, electrical and other industries, Proceedings of the 6th International Heat Pipe Conference. Grenoble, May 25-29 (1987). 5. J. Bielik, M. Cagala, V. Hlava~ka, V. G. Kiselev, F. Pol~iek, P. ~tulc, L. L. Vasiliev and J. Zemfi.nek, Experience from heat pipe heat exchanger operations in connection with fouling, freezing and other operation conditions, Proceedings of the 6th International Heat Pipe Conference. Grenoble, May 25-29, (1987). 6. J. Niekawa, K. Matsumoto, H. Noda and T. Koizumi, Large scale heat pipe heat exchanger for flue gas desulfurizing systems, Proceedings of the 5th International Heat Pipe Conference, Vol. 2, pp. 147-152. Tsukuba, May 14--18 (1984). Reference is also made to the following cumulative supplement of heat pipe publications to reference [1] from East European Countries for period 1984-1986. BI. G. Bacanu, V. Hoffmann and P. Oarcea, A study of heat pipe heat exchanger performance (in Rumanian), Proceedings of the Lucrdrile Conferintei de Transmiterea C~ldurii si Optimizerea Utilizrrii Energici Termice, Vol. 1, pp. 80-85. Brasov, October 30-31 (1986). B2. M. Balask6, S. Konczol and F. Svfib, Neutron radiography study of pulsed boiling in a water-filled heat pipe, Int. J. Refrigeration 9, 80-83 (1986). B3. M. Bartfik, P. Moser, F. Pol/L~k and O. Otlej~ek, Cooling of electric machines and electrical devices by heat pipes (in Czech), Elektrovfzkum 2, 104-115 (1984). B4. I. Bereznay and J. Erdei, Heat pipe waste heat utilizer for boilers and industrial furnaces (in Hungarian), Veiki K0zlembnyek, 13-17 (1985). B5. I. Bereznay and J. Erdei, Waste heat recovery of flue gases by heat pipe and hybrid heat exchangers (in German), Report VEIKI, Budapest (1986). B6. M. Brfit, Heat recovery by means of heat pipe heat exchanger (in Czech), Teplo 4, 19-21 (1985). B7. V. F. Bukreev, F. Polfitek, J. Zemfinek, P. Stulc, G. Hanzfilek and K. Ko~aL Air-to-air thermal recovery units, J. Heat Recovery Systems 5, 451-461 (1985). B8. H. Biesenack and R. Neundorf, Problems with heat pipe application in high frequency A.C. electric motors (in German), Elektrie 39, 169-170 (1985). DI. J. DobifiL L. Horvfith and I. Davidovi~, Heat conduction in solid with heat pipes by FEM, Proceedings of the 4th International Conference, on Numerical Methods in Thermal Problems, Vol. 1, pp. 122-131. Swansea, July 15-18, (1985). D2. J. Drnec, F. Pol~ek and P. gtulc, A study of the heat pipe and cold storage systems (in Czech), Elektrotechnickp obzor 76 (1987). D3. I. l)rm~enkov~t, Coolers increase life time of accumulators (in Czech), V~da a technika v SSSR 14, 28 (1986). El. J. Erdei and I. Bereznay, Waste heat recovery to preheating of air in power stations, Energiewirtschaft 24, 559-561 (1985). FI. K. Fejfar, Cooling of power transistor KD 503 in narrow space conditions (in Czech), Sd~lovacl technika 34, 386-387 (1986). F2. D. Fetcu, V. Hoffmann, M. Muresan and V. Ungureanu, Heat performance of an acetone heat pipe (in Rumanian), Proceedings of the Lucr~rile Conferintei de Transmiterea C~ddurii si Optimizarea Utiliz,lrii Energici Termice, Vol. 1, pp. 63-72. Brasov, October 30-31 (1986). F3. D. Fetcu, V. Hoffmann and V. Ungureanu, Theoretical and experimental study of wickless heat pipes (in Rumanian), Proceedings of the Lucrdrile Conferintei de Transmiterea Chldurii si Optimizarea Utilizbrii Energici Termice, Vol. !, pp. 55-62. Brasov, October 30-31 (1986). F4. D. Fetcu, V. Hoffmann and V. Ungureanu, A method of gravitational heat pipe design based on temperature difference (in Rumanian), Proceedings of the Lucr,lrile Conferintei de Transmiterea C~ldurii si Optimizarea Utiliz~rii Energici Termice, Vol. 1, pp. 72-79. Brasov, October 30-31 (1986). F5. D. Fetcu, V. Hoffmann and V. Ungureanu, Possibility of using acetone heat pipes to construction of recuperative heat exchangers (in French), Buletinul Universiultii din Brasov 27, 71-74 (1985). F6. D. Fetcu, V. Hoffmann and V. Ungureanu, Certain aspects of using water as a working fluid of carbon steel heat pipes (in French), Buletinul Universitrtii din Brasov 27, 75-78 (1985).
16
F. POL,~EK
F7. D. Fetcu, V. Hoffmann and V. Ungureanu, A study of tilt angle inclination on heat performance of acetone and freon gravitational heat pipes (in French), Buletinal Unh~ersitdtii din Brasoc 27, 65-70 (1985). G1. B. Gagpergi~, I. Golovi6 and I. Nemec, Investigation of heat pipe (two-phase thermosyphon) heat exchangers, Proceedings of the XII ICHMT International Symposium on High Temperature Heat Exchangers, pp. 1~ . Dubrovnik, August 26-30, (1985). HI. Z. Havlin, Application of heat pipe heat exchangers in dust environment (in Czech), Proceedings of the Svmpostum on Heat Recot,erym Agriculture, pp. 16-25. Prague, May 15-18 (1984). H2. L. Hag, Experience from using secondary energy sources in agriculture (in Czech), Proceedings of the Seminar on Secondary Energy Sources, pp. 99-108. Ostrava, October I0 (1985). H3. V. Hlava(:ka, Some speciality of calculation of heat pipe exchangers (in Czech), Proceedings o["the 3rd Heat Pipe Seminar, pp. 38-41. Prague, November 7, (1985). H4. V. Hlava~ka, R. Ledeck~, and J. N. ~ev~uk, Experimental study of heat performance of sodium heat pipes (in Russian), Proceedings of the 7th Heat and Mass Transfer Conference, Vol. 8, pp. 64-71. Minsk, May 21-25 (1984). H5. V. Hlava~ka, F. Pol/tgek and P. ~tulc, Heat Pipe Heat Exchangersfor Heat Recovery (in Russian). ITMO AN BSSR, Minsk (1987). H6. V. Hlava~ka, P. ~tulc, J. Zemfinek, K. Jilek and M. Barnik, Observation of heat pipe heat exchangers in working conditions (in Czech), Proceedings of the 3rd Heat Pipe Seminar, pp. 30-35. Prague, November 7 (1985). H7. V. Hlava~ka, P. fltulc, J. Zemfinek, K. Jilek and M. Bart~ik, Heat pipe heat exchanger operating experience (in Czech), Zdravotnl technika a czduchotechnika 29, 81-88 (1986). H8. V. Hlava(~ka, ~tulc P. and A. Zuzafi:ik, Two-phase closed thermosyphons for heat exchangers (in Czech), Strojirenstvi 36, 391-395 (1986). H9. J. Hofman, Heat recovery in agriculture (in Czech), Proceedings of the Symposium on Heat Recover)" Devices, pp. 89-97. Klatovy, November 13 (1985). H10. L. Horv~ith and F. Polh~,ek, Survey of choice heat pipe applications (in Czech), Proceedings of the 3rd Heat Pipe Seminar, pp. 7-15. Prague, November 7 (1985). HI1. L. Horv~ith and F. Polfigek, Possibility of application of heat pipes in industry (in Czech), lnformace Potravinoprojektu 4, 74--93 (1985). H 12. L. H orv~th, F. Pol~ek, A. First and L. Netolick~, The cooling of the power semiconductor elements of the traction driving mechanism by heat pipes (in Czech), Proceedings of the 3rd Heat Pipe Seminar, pp. 42-52. Prague, November 7 (1985). HI3. L. Horv~ith, F. Pol~i~ek, L. Netolick~ and A. First, Cooling of power semiconductor devices of traction converters by heat pipes (in Czech), Technickk zpr~vy ~KD 19, 1-8, (1985). J1. J. Jakeg, O. O~lej~ek and L. Horv~ith, High performance heat pipes (in Czech), Proceedings of the 2nd Symposium on Cooling of Microelectronic Devices, pp. 6-12. Pardubice, December 5-6 (1984). J2. F. Jelinek, J. Tuhh~ek and J. Pilous, Low temperature heat pipes for application in industry (in Czech), Proceedings of the Symposium on Heat Recovery Devices, pp. 64-88. Klatovy, November 13 (1985). KI. J. Kfira, J. Zem/mek and L. Ha~, Operation testing of heat pipe heat exchangers (in Czech), Proceedings of the Symposium on Heat Recovery in Agriculture, pp. 26-29. Prague, May 15--18 (1984). K2. D. Keller and A. Thieme, Heat recovery by heat pipe heat exchangers during drying (in German), Proceedings of the lOth Wiirmetechnische Tagung, pp. 17. Trocknung, Karl-Marx-Stadt, December 3-4 (1985). K3. S. V. Konev, F. Polh~k and L. Horvfith, Heat transfer at boiling in capillary-porous materials (in Russian), Proceedings of the 7th Heat and Mass Transfer Conference, Vol. 6, pp. 15--19. Minsk, May 21-25 (1984). LI. R. Ledeck~, Tilt angle influence on heat performance (in Czech), Proceedings of the 3rd Heat Pipe Seminar, pp. 36-37. Prague, November 7 (1985). L2. R. Ledeck~,, Heat exchangers made of variable conductance heat pipes (in Czech), Proceedings of the 3rd Heat Pipe Seminar, pp. 36-37. Prague, November 7, (1985). M 1. M. Majcen and N. garunac, Heat pipe cooled twin aircoil blade as an element for higher efficiency of tonglife gas turbine, Proceedings of the Heat and Mass Transfer in Rotating Machinery Symposium, pp. 112-116. Dubrovnlk, September 1-3 (1982). M2. S. Milogevi~, R. Beuck and G. Pichler, Superheating in the heat pipe oven, Applied Physics 641, 235-239. M3. S. Milo~evi~ and G. Pichler, A study of Naz diffuse bands in voilet by the excitation through self-broadened D-lines, Zeischrift fiir Physik D, Atoms, Molecules and Elasters 1, 223-229 (1986). NI. S. Nevenkin, M. Kibarova and V. Georgiev, Heat transfer characteristics of low temperature heat pipes with metal fibre and bronze sintered wicks (in Bulgarian), Proceedingsof the Conference na energ(ie-metodi, technotogija, izolelija i modernizacii 2, 327-332. Varna (1985). N2. I. Novotna, Compatibility of aluminium and steel heat pipes with flue gases (in Czech), Strojirenskf zpravodaj 3, 6 (1987). N3. I. Novotnfi and V. Sokolikov~, Contribution to heat pipe compatibility (in Czech), Proceedings of the 3rd Heat Pipe Seminar, pp. 60-64. Prague, November 7 (1985). PI. P. Penchev, Heat utilization system with heat pipes (in Bulgarian), Energetika 6, 24-26 (1986). P2. B. Pokorn~, and F. Pol~ek, Heat pipes and their applications in industry (in Czech), Proceedings of the Symposium on Heat Recover)' Devices, pp. 44-63. Ktatovy, November 13 (1985). P3. F. Pol~igek, Designer routing at design and calculation of heat pipes (in Czech), Proceedings of the 3rd Heat Pipe Seminar, pp. 65--92. Prague, November 7 (1985). P4. F. Polfigek, Heat pipe research and development in COMECON countries (in Russian), Report, No. 9 and 10, ITMO AN BSSR Minsk (1985). P5. F. Polfigek, Cyrogenic heat pipes in cryogenic devices (in Czech), Proceedings of the Kryogenika 1986International Conference, pp. 86-93. Prague, April 15-17 (1986). P6. F. Polfi~ek, Heat pipe heat exchangers for waste heat recovery (in Czech), Zdrat,otni technika a t,zduchotechnika 29, 180-181 (1986). P7. F. Polfigek, A. Gerfik and F. Jelinek, Heat pipes for cooling and temperature stabilization of plastic processing equipments (in Russian), Proceedings of the scientific papers on Heat Pipes and Heat Pipes Heat Exchangers, pp. 74-86. ITMO AN BSSR, Minsk (1986).
Heat pipe research and development in East European countries
17
PS. F. Pol~i~ek and L. Horv~th, C0oiing of power semiconductor devices of traction converters by heat pipes (in Russian), Report, No. II, ITMO AN BSSR, Minsk (1985). P9. F. Polfi.~ek and F. Jelinck, Application of heat pipes to cooling and thermal control of plastics mould casting (in Czech), Plasty a kauduk 22, 231-236 0985). P10. F. Pol/L~k and P. gtulc, Heat pipe heat exchangers (in Czech). Techniky, Prague 0986). Pl 1. F. Polfi!ick, P. ~tulc, J. Nassler and J. Biclck, Heat pipe heat exchangers for heat recovery in chemical industry (in Czech), Proceedings of the Innovations in Chemical Industry Symposium, pp. 154-164. Stfivnick6 Bane, May 14-16, 1986. Rl. H, Rokicki, Study of heat pipe application to recovery of waste heat of flue gases of boilers (in Polish), Ph. D, Thesis, Politechnika Gdafiska, (1981). R2. H. Rokicki, Two-phase closed thermosyphon (in Polish), Gospodarka paliwami i energkT, 31, 16-18 (1983). R3. H, Rokicki, A mathematical analysis of the thermal processes in a heat pipe (in Polish), Zeszyty naukowe Politechniki Gdattskiej 44, 3-13 (1983), R4. H. Rokicki, Influence of the working fluid filling on the heat performance of heat pipe (in Polish), Gospodarka paliwami i energia 33, 7-10 (1985). Sl. K. Smr~ek, Heat pipes---efficient cooling element (in Czech), Elektrotechnika 40, 226-230 (1985). $2. K. Smr6ek, Heat pipe research in ~KD Polovodi(:e plant (in Czech), Elecktrotechnika 41, 306-312 (1986). $3. P. gtulc, M. Bart/tk and K. Jilck, Inner thermal resistance of two-phase closed thermosyphons (in Czech), Proceedings of the 3rd Heat Pipe Seminar, pp. 16-26. Prague, November 7 (1985). $4. P. gtulc, V. G. Kiselev and J. N. Matveyev, Heat pipe heat exchangers for low-potential heat utilization (in Russian), Proceedings of the 7th Heat and Mass Transfer Conference, Vol. 8, pp. 169-174. Minsk, May 21-25 0984). Vl. D. Ve~a, S. Milo/ievi~ and G. Pichler, Discharge studied of the lithium dimer diffuse bands, Optics Communications 56, 172-178 (1985). V2. Z. Viktorin, K. Hou~,ka and A. Gerfik, Technical and economical evaluation of the heat recovery in convective drying (in German), Proceedings of the lOth Wiirmetechnische Tagung--Trocknung, pp. 43-47. Karl-Marx-Stadt, December 3-4, (1985). " V3. Z. Viktorin, K. Houf,ka and A. Ger/~k, technical and economical evaluation of the heat recovery in convective drying (in Czech), Zdravomi technika a vzduchotechnika 29, 163-171 (1986). ZI. V. Zbofil, J. Je~ek and M. Tyburec, Electronics cooling in automatic and computer technics (in Czech), Proceedings of the Seminar on Mini-calculators 1986, Prague, October 6-7 (1986). Z2. V. Zbofil and M. Tyburec, Computer elements cooling (in Czech), Automatizace v)podetni techniky 57, 14-27 (1986). Z3. V. Zbofil, M, Tyburec and P. gtulc, Heat pipes for cooling of electronic elements and devices (in Czech), Proceedings of the 2rid Symposium on Cooling in Microelectronics Devices, pp. 13-15. Pardubice, December 5-6 (1984). 7_,4. J. Zemfinek, Research development and application of heat pipe exchangers (in German), Proceedings of the llth Int. Conference on Industrial Energy Management, pp. 24-29. Berlin (1984). ZS. J. Zemfi.nek, Energy reduction of poultry farmings and fattening stations (in Czech), Proceedings of the llth Conference on Heating, Ventilation and Air Conditioning, pp. 1-7. Nitra, August 25-27 0986). Z6. J. Zcm/mek, Recuperative heat pipe heat exchangers (in Czech), Technickd informace STS 3, 1985, pp. 41-44. ZT. M. Zemfinek, Heat recovery efficiency of recuperative heat exchangers (in Czech), Teplo 2, pp. 15-17 (1986). Z8. M. Zcmfi.nek, F. Huk and J. Chysk~, Heat recovery in agriculture by means of plate heat exhangers (in Czech), Zdravomi technika a vzduchotechnika 28, 231-237 (1985). Z9. A. Zuzafifik, Contribution to study of steel cast cooling by heat pipes (in Czech), Proceedings of the 3rd Heat Pipe Seminar, pp. 57-59, Prague, November 7 0985). Anl. Heat pipe heat exchangers--type N, W (in Czech), Prospectus of the Vzduchotechnika, Novb Mesto n. Vdhom (1984). An2. Heat pipe heat exchangers--type R (in Czech), Prospectus t~f the Vzduchotechnika, Novb Mesto n. V,ihom (1984). An3. Heat pipe heat exchangers--capillary type KTN (in Czech), Prospectus of the Vzduchotechnika, Novd Mesto n. Vdhom (1986). An4. Heat pipes coolers of closed boxes (in Czech), Prospectus of the Vzduchotechnika, Novd Mesto n. Vdhom (1986). An5. Heat pipe coolers of power semi-conductor devices--type CHVPS 65 (in Czech), Prospectus of the Vzduchotechnika, Novd Mesto n. VfThom (1986). An6. Heat pipes--type G (in Czech), Prospectus of the JZD, MrAkov (1984). An7. Heat pipe heat exchangers--type ZV 3-025... 033 (in Czech), Prospectus of the JZD, Mr/tkov (1984). An8. Heat pipe heat exchangers--type RSA (in Czech), Prospectus of STS, Mimofi (1984). An9. Heat pipes (in Czech), Prospectus of the KOH-I-NOOR, Prague (1984). Ani0. Heat pipe heat exchangers (in Hungarian), Prospectus of the FOTOBER, Budapest (1986). Anl 1. Conditioning unit with heat recovery-type UT-F-12 (in Russian), Prospectus of the GSKB Brest (1985). Anl2. New cooling method of batteries (in Czech), Technika v SSSR 6, 121 (1986). Ant3. 40 years anniversary of the National Research Institute for Machine Design (in Czech), Revue obchodu, pr~mysm, hospodd~stvi 11, 17-48 (1986). Anl4. Heat pipe heat exchangers--type WR 25 (in German), Prospectus of Wiirmetechnik und Liiftungbau, Gotha (1985). AnlS. Heat pipes for heat recovery in glass industry (in German), Prospectus of VEB Rohrleitungs und Heizungsmontagen, Dresden. Kosora, Dresden (1986). Anl6. Heat pipe coolers of closed boxes (in Czech), Prospectus of the KOH-I-NOOR, Prague (1987).
0890-4332/89 $3.00+ .00 Pergamon Press plc
HEAT PIPE RESEARCH AND DEVELOPMENT EUROPEAN COUNTRIES
IN EAST
F. POL~,gEK National Research Institute for Machine Design, SVOSS, 19011 Praha 9-B6chovice, Czechoslovakia Abstract--The paper presents a review, made on the basis of available publications, of the research, development and application of heat pipes and closed two-phase thermosyphons in East European countries, i.e. Bulgaria, Czechoslovakia, German Democratic Republic, Hungary, Poland, Rumania and Yugoslavia from 1984 to 1986.
NOMENCLATURE d J L q R t u W
diameter (m, mm) mass flow rate (kg s- i ) length (m, ram) heat performance (W) heat flux (Wm -2) thermal resistance (K W - ') temperature (°C) pitch (m, mm) heat capacity (3V K - ~)
Greek symbols heat transfer coefficient (W m-2 K - ~) A difference 6 thickness (m, mm) ~t' tilt angle from the horizontal position (°) rl thermal efficiency T time (s) Subscripts A warm stream B cold stream F fin e external ef effective i internal K condensation part O start V evaporation part W environment 1 inlet 2 outlet I first stage 11 second stage INTRODUCTION
An exhaustive survey about the state of research and development of heat pipes in the countries of Eastern Europe up to the end of 1983 was given at the 5th International Heat Pipe Conference in Tsukuba in 1984 [1]. This survey is now supplemented, on the request of the 6th IHPC organizers, with publications from the period of 1984-1986. ANALYSIS
OF THE
HEAT
PIPE OPERATION
Since the 5th IHPC in 1984, the activities in the field of the heat pipes in the East European countries have concentrated, particularly, on effective application of the heat pipes and heat pipe systems in industry and agriculture. 3
F, POLA~EK
4
The aim of both theoretical and experimental research was especially the investigation of transport phenomena in closed two-phase thermosyphons [B2], [F2], IF3], IF4], IF7], [H4]. ILl]. [R2], [R3], [R4], [$3], [$4] numerical assessment of unsteady state temperature fields in solid bodies with built-heat pipes by means of the finite elements and differences methods [DI], [Z7], the determination of heat transfer coefficients and critical heat fluxes in the evaporating and boiling of liquids from capillary porous materials, dealt with in the 6th IHPC paper [2] and material compatibility of heat pipes IN2], IN3]. A computing program has been designed to study the behaviour of a heterogeneous system consisting of a cast, chill, high temperature sodium heat pipe and sand mould. The computation algorithm is based on the application of the finite differences method to solve heat conduction equations. Solidification (melting) is solved by heat sources or heat sinks in the nods. The heat pipe is simulated by the entry of heat flux in the nods appertaining to its presupposed location. For this purpose an understeady state double-capacity heat pipe model has been designed and tested, separately, respecting the impact of the heat capacities of the evaporation and condensation part. For the opening stage of the unsteady state process, while the pipe is being heated without internal mass transfer into the condensation part, the heat flow is defined as:
_ dtv Q,=Wv-~r;
for
tv
(1)
The second stage with the condensation part already operating, is described as:
Q,, = Wv dtv Wx dtx dr + ~ + ~(tx - tw).
(2)
For the purpose of the program, the relationship (2) has been formally modified, like in [3], into:
dtv q = C, ~ + C2(tv- tel),
(3)
Ci, C2, te/ being complex constants. The computation results have produced some fresh information, helping establish the priorities for further research. To give an example, the computations have proved that the cooling of steel casts can be externally controlled [Z9]. The heat performance of the water-filled steel heat pipes is not stable because of the non-condensing gas which develops inside the pipes as a result of electro-chemical corrosion. The main objective of the measures taken at SVOSS was to curb the development of the gas. For this purpose, 3 methods have been used [N3]: (1) passivating the inner heat pipe surface with magnetite (Fe~O4) layer; (2) adding inhibition substance to the working fluid; (3) covering the pipe surface with Fe304 layer plus adding the inhibitor to the working fluid. To be able to compare the methods, all heat pipes were manufactured of mild carbon steel. To produce the FesO4 layer an oxidation method was applied using preheated water vapour or water vapour with an oxidation catalysator (NH4)2 MOO4. The basis of the inhibitor were the chromates, such as K2 CrO4. The life tests checked the temperature profile along the pipes condensation part with a contact thermometer, or contactless temperature measurements were undertaken with the aid of thermovision AGA. After 6000 working hours assessment was made on the grounds of the temperature profile measuring results, the non-condensing gas, the working charge and the internal heat pipe surface analysis. The lowest level of hydrogen development in the steel pipes was observed while using the third method, which is more costly than the second method that showed rather good results as well, as can be seen in Table 1. The corrosion of the external surface of the fin aluminium and steel pipes was tested on 5-row HPHE consisting of water-filled bimetallic Al/steel finned tubes: 56/28/25/21-3 (0.75), finned pipe markings of--bimetallic pipes:
d,,Id'
H e a t pipe research a n d d e v e l o p m e n t in E a s t E u r o p e a n c o u n t r i e s Table I. Results of steel-water heat pipe life tests Heat pipe Method no.
I 2 3
Surface treatment
Results after 6000 h life test Working fluid
At (°C)
Content of H2 in inert gases
Composition of inner surface layer--X-ray analysis
H20 H:O
32 l0
maximum traces
,, Fe; slightly Fe~O4 strongly Fe~O£ strongly Fe
H20 + inhibitor
6
traces
a Fe; Implication (Fe, Cr)304
H20 + inhibitor
3
~
,, Fe; F~O4 slightly (Fe, Cr)203
Oxidation by vapour at temperature 550°C Oxidation by vapour at temperature 550°C
At: temperature difference along condensation part of heat pipe. Inhibitor: 0.5% water solution of K:CrO 4 (pH = 7.87).
extruded pipes:
The verifying tests of these exchangers, performed since 1985 in a brick factory using as a heat source that sort of equipment fuelled by heavy oil with high content of corrosive SO: in its flue gases, have proved that from the point of view of corrosive effects these exchangers are quite satisfactory. They work within the temperature range 180-280°C of flue gases coming into the evaporation section, and at 20-30°C of the inlet fresh air, which with thermal efficiency of 48%, will secure the preheating of the inlet air at 87-150°C. Deliberately omitting to clean the heat exchanging surface in the flue gases chamber of dust particles will reduce, according to the tests made over 42 days, the flue gases flow to 18% of the original value and, as a result, the thermal efficiency will drop from 48 to 15%, although the corrosion of both the aluminium and steel surface was, in terms of metallurgical analysis, minimal. As shown in Fig. 1, the main problem is the fouling of the heat exchanging surface by the flue gases of heavy fuel oil and not the corrosive effects of the sulphur oxides. In order to examine the corrosion of aluminium fins caused by flue gases we used an X-ray qualitative surface analysis. On the fin surface a marked continuous carbon layer is developed in
,, .~ ........
Fig. I.
~i ¸ ,
~ ~
• ~,
F o u l i n g o f the H P H E after o p e r a t i o n in flue gases.
6
[:. POL,&~EK
sharp contrast to the metal surface on which it occurs. The X-ray microanalyser revealed that the layer consisted largely of sulphur. The diffusion of sulphur into the metal fundament was not observed (Fig. 2a-2c, enlarged 800 times). The aluminium traces found in the sediment layer and in Wood's metal, in which the fin was sealed, are the result of the aluminium fin grinding preparation. This evaluation of the corrosion was studied in test samples exposed for over 6000 hours to heavy fuel oil flue gases at a temperature of about 160°C [N3]. A P P L I C A T I O N OF H E A T PIPES IN T H E C O U N T R I E S OF E A S T E R N E U R O P E So far the widest application of heat pipes in East European countries can be found in waste heat recovery in power programs, in electrical and mechanical engineering and in the chemical
a. An aluminium fin surface laycrl
b. Surface distribution of S in am Al-fin layer (X-rays S, K,).
Heat pipe research and development in East European countries
7
c. Surface distribution of AI in an Al-fin surface layer (X-rays AI, K~). Fig. 2. Corrosion of aluminium fins caused by flue gases (enlarged 800 x ).
industry. Select heat pipe applications in Czechoslovakia have been discussed in a separate paper of the 6th IHPC [4].
Waste heat recovery through heat pipe exchangers As a result of the energetic crisis in the 1970s, a considerable cut in fossil fuel consumption had to be made in the entire CMEA community, particularly in agricultural establishments, where the production of I 1 of milk required as much as 0.4 1 of oil. This effort led to organizing the so called 'integrated energetic systems', which employ, to supply the agricultural buildings with heat and heat the service water, not only standard but also secondary heat resources such as solar collectors, heat pumps, biogas, heat accumulators and especially waste heat recovery systems, e.g. heat pipe heat exchangers (HPHE). To obtain the optimum operation of all these devices, automatic systems are established controlled by microcomputers. The recovery of waste heat from technical resources and biological warm of the animals is of fundamental importance for agricultural mass production. In Czechoslovak conditions, the installation of as many as 20,000 HPHE units is expected within the next few years. The waste heat recovery from air, flue gases and liquids to preheat fresh cool air, to warm water or to produce low pressure steam is widely utilized in the CMEA countries, as already discussed in our earlier paper [5]. Apart from the main goal to economize on energy, the waste heat recovery in agricultural establishments has also important side effects in creating a more favourable environment for livestock, improving their health conditions, increasing their increments and, last but not least, raising the durability of buildings and technological equipment. It can be expected that these additional features will soon become, after installing complex energetic and airconditioning systems in agricultural mass production plants, economically more significant than the initial energy economizing aims. Even now, after the introduction of 1200 HPHE units into the agricultural and industrial establishments in Czechoslovakia it has been found that, for instance, weight increments in calf rearing have grown by as much as 10% as a result of a better ventilation system improved with heat recovery. A similar favourable outcome has been registered in large poultry farms where, besides weight increment, considerable improvement in the health of the fowls and a drop in the death rate has been observed. Out of the four, tested heat exchanger types for recuperating waste heat in agricultural plants, only the HPHE with 60-80% thermal efficiency and, inspite of their lower performance (up to 50%) the plate exchangers have been recommended, as long as plate
8
F. POLA~EK
design allows for the easy removal of deposits from heat exchanging areas. Run around coil types of heat exchangers are not convenient from operation and investment viewpoints, and rotational regenerators are not permissible for veterinary reasons. Outside Czechoslovakia waste heat recovery through HPHEs is also intensively studied in other Eastern European countries, [B1], [B4], [BS], [Eli, [F5], [G1], [K2], [Pl], [RI], [Anl0], [Anl4], [An l S]. To give some examples: The Research Institute of Power Engineering (VEIKI), Budapest designed and put into operation several HPHEs consisting of water-fiUed steel gravitation heat pipes to preheat fresh air in boilers and ovens by using flue gas heat. The HPHE installed in the petrochemical plant of Dunai K6olajfinomit6 is made up to 1530 heat pipes (~b 22/2 mm: length 2750 mm) to preheat air with flow rate JB = 2.7 Kgs -~ by as much as 180 K through flue gas heat (JA = 2.9 Kg s-~, tA~ = 310°C). At the HPHE maximum heat performance of 8140 kW the efficiency of the oven rose by 7.4% [B4], [B5], [Eli. An establishment producing air-conditioning devices in Budapest (FI~ITOBER) manufactures HPHE made of freon or ammonia-filled aluminium finned pipes and of water-filled copper pipes to recover waste heat in air conditioning and air exchange [Anl0]. University of Brasov, jointly with a producer of air-conditioning equipments, put into operation an HPHE made up of radially extruded aluminium finned pipes [~b 40/23/19-3.55(1), length 2100 mm] with acetone charge to recover oven waste heat in paint and enamel shops [FS]. A steel heat pipe (~b 23/3 mm) heat exchanger is employed by the Industrial Energetic Plant in Bulgaria to warm service water with flue gas waste heat (150°C) at total thermal output 21 kW [PI]. Also the KOSORA Plant in the G.D.R. uses a bundle of steel gravitation heat pipes to warm water with flue gas waste heat (120°C) [AnlS]. For purposes of air exchange and conditioning in farming establishments, the D.D.R. enterprise W/irmetechnik und Liiftungsbau, Gotha, manufactures HPHEs consisting of ammonia-filled bimetallic A l/steel finned pipes [An 14]. Table 2 compares calculations of financial pay-back in four types of heat exchangers recovering waste heat from broiler fast feeding farms. The comparison has revealed the convenience of using HPHEs in this type of establishment [ZS]. The problems of waste heat recovery through HPHEs have also been treated by the Universities of Gdafisk and Wroclaw in Poland [R l l, [1], University of Ljubljana in Yugoslavia [G1], University YASI in Roumania Ill, University Karl-Marx-Stadt in D.D.R. [K2] and Bauakademie Berlin [l]. The maintenance of the necessary microclimate in public buildings and premises requires, among other things, the exchange of deteriorated air. Exchanging the air by HPHE reduces thermal losses caused by ventilation. Sub-window ventilating unit with a small inbuilt HPHE was tested [.t2]. Heat pipe solar collectors and heat accumulators
The technical and economic research of solar collectors, heat pumps and heat accumulators in the CMEA community has shown that in most countries the pay-back of the investment funds does exceed five years and, consequently, their application in solving energetic problems can be allowed only in certain instances. In Czechoslovak conditions, for example, in view of the intensity of solar radiation only service water heating solar systems can be technically and economically justified. Of technical interest is the solar collector designed jointly with water heating and heat storage as shown in Fig. 3 [D2]. An axially finned heat pipe is mounted in a glass cylinder, while its smooth condensation part runs first through a heat storage filling, then through a water heating reservoir. Some other designs
Table 2. Calculation comparison of various type of heat exchangers to recovery waste heat in broiler farms Thermal
I 2 3 4 5
Type of heat
efficiency
exchanger
t/
Saving of city gas [m3 year- I]
0.78 0.67
126 538 108 546
3.4 3.4
0.67 0.50 0.39
108 546 81 112 63 600
3.8 4.4 4
Rotary type (rotor diameter 2.5 m) HPHE; tubes ~ 38/35/15-3.5 (0.85); NH~ Filling Rotary type (rotor diameter 2 m) Cross flow plate exchanger Ran around coil
~
Pay-back [years]
Heat pipe research and development in East European countries
2
~
2
1
9
/,
3
2
1
3 Fig. 3. Solar collector with heat storage l--heat pipe 2--evaporation part 3--absorber 4--glass tube 5--heat storage part 6--condensationpart 7--water.
Fig. 4. Heat pipe cooler of potentiailess modules l---Cu/water heat pipe 2--fins 3--AI block 4--potentialless modules.
of independent solar collectors and heat storages based on heat pipe principles are being investigated, as well as the heat pipe systems to utilize the warm mineral springs which are frequently found not only in Czechoslovakia, but in Bulga/ia, Hungary and other countries as well.
Heat pipe applications in electrical engineering Apart from the HPHEs, the largest application of the heat pipes in the East European countries has been found in cooling equipment and machinery in electrical engineering. In power electrical engineering, they are especially used as: coolers to cool power semi-conductor elements IF 1], [H 12], [I413], [PS], [$1], [$2]; switch and circuit-breaker devices [B3], [M4]; components of reproduction technique; bus-bars [B3], [M4]; plasma cathodes [H10]; etc. In electronics they are particularly used as coolers of elements in microelectronics [Z1-Z3]. Some applications are dealt with in a separate 6th IHPC paper [4]. The life time of accumulator batteries to drive e.g. mine locomotives, depends considerably on electrolyte overheating while recharging the battery. If, instead of a plug on top of the accumulator, we use a freon-filled heat pipe with its smooth evaporation part plunged in the electrolyte and the finned condensation part cooled either by free or forced air convection, the life time of the battery will be increased by 50-100% as proved in the mine battery locomotive operation tests [D3]. To cool power semiconductor elements of the pellet type with contact surface diameter 30, 40 and 60 mm, special capillary heat pipes with face heating and gravitational loop-shaped heat pipes have been developed. More particular information is given in a separate 6th IHPC paper [4]. To cool potentialless modules, special coolers have been developed from copper heat pipes with sintered capillary system and water filling, whose evaporation parts are inserted into an aluminium block with three attached potentiaUess 431-type modules (Fig. 4). For the heat pipe parameters quoted in Fig. 5 we also indicate the dependence of the cooler's thermal resistance on its position (heat performance 500 W and cooling air velocity between the fins 6 m s- ' ). This design allows for cooling of even most efficient modules under maximum power loading [S1], [$2]. To cool pellet power transistors with a contact surface diameter of 30 mm, apart from the capillary heat pipes with face heating also closed two phase thermos)phons have been developed as shown in the Fig. 6 [$2]. According to the calculations and data design of SVOSS two Czechoslovak manufacturers have been producing heat pipe heat exchangers to cool enclosed boxes containing electronic control elements. For heat performance from 100-500 W the plant KOH-I-NOOR, Prague is producing small units equipped with fans of a mezaxial type at a maximum volume flow rate of 200 m 3 hand maximum pressure difference of 80 Pa [An 16]. The medium size compact heat exchangers with A1 extended surface and Cu/freons or Cu/water heat pipes for heat performance from 300 to 3000 W have been produced by the plant V, Nov6
F. POLA~EK
10
5
V-IlII 0.5
t___lill
a
~-3
KW"I
IIII
.,2 t111~1
0,,3 02
°goo
4 6
o-G- ty ,..~o °
Fig. 5. Dependence of thermal resistance of the heat pipe cooler of potentialless modules on tilt angle.
Fig. 6. Heat pipe cooler of power transistor P30 1---evaporation part 2---condensation part 3--fins 4--sintered capillary structure 5----contact area with a power transistor 6--power supply.
Mesto nad Vhhom [An 4]. As you can see from Fig. 7 these HPHE are particularly suitable for cleaner working conditions, e.g. computing centres. Figure 8 shows a printed wiring board with flat copper water heat pipes with screen capillary systems. The condensation parts 30 mm in length.were provided with copper fins. With cooling air velocity 2.5 m s -~ in front of the fins and with evaporation part temperature 60°C, the heat performance of each heat pipe in horizontal position is 10 W [ZI], [Z2]. Heat treating equipment for wires and bands in cable works using an accelerated electron beam is plotted in Fig. 9. The processed wire is drawn over the suction forechambers into the proper vacuum chamber. Here, it is heated by secondary electrons emitted and concentrated by the mirror and by electrons discharged by the screening. The heat from the plasma cathode generated mainly by the ion incidence in glow discharge is taken away to the cooling air through a heat pipe installed in the cathode body. The cathode body serves at the same time as a high voltage power supply from the external line to the emitting surface. The solution not only guarantees the withdrawal of high heat performances, but the tightness of the vacuum chamber as well. The equipment for dry treating
Fig. 7. Heat pipe heat exchanger for cooling of enclosed boxes [An4].
Heat pipe research and development in East European countries
Fig. 8. Cooling of ICs on printed wiring board 1--IC 2--board 3--heat pipe 4--condensation part with fins.
the wires was installed and tested in cooperation of the SVUSS and the Institute o f Power Electrical Engineering Prague in the cable manufacturing works. The withdrawn loss performance from one cathode ~b 80 mm moved round 3 kW [Hl0]. The Research Institute o f the Electrical Industry in Budapest used copper heat pipes (~b 8/1 mm) with water as a working fluid for cooling on the cold side o f the thermoelectric generator. As a heat source for the hot side of the generator natural gas was used. They also used copper heat pipes to cool the stator o f linear motor and the unreliable water cooling system was changed to the effective heat pipe forced air cooling. To use waste heat, metallurgy thermoelectric generators with heat pipes were used. Electric current from generators was employed for supplying control and regulation devices. The research group at the Institute of Physics o f Zagreb University, in cooperation with the National Bureau of Standards, Washington D.C. and the Alexander yon Humboldt Stiftung have
6
is Fig. 9. Cooling of plasma cathode by a heat pipe I--plasma cathode as a heat pipe 2--vacuum chamber 3--evacuated adjacent chamber 4---annealed wire or band 5--cooling air 6--current supply 7---emission of electrons 8--screening under target.
12
F. POLASEK
been employing a heat pipe oven for the absorption measurements as a reservoir of liquid metal, in thermal equilibrium with its vapour, for spectroscopic measurements [M2], [M3], [VI]. In their last design [M2] they used a heat pipe oven as a reservoir of liquid metal, in thermal equilibrium with its vapour, for supplying the inner chamber with the metal vapour. In such a way the vapour temperature and pressure can be independently changed, permitting temperature variation measurements of the absorption coefficient at high vapour pressures. The research group at the Polytechnic Institute Ilmenau in the D.D.R. used copper/water heat pipes for the cooling of a high frequency A.C. electric motor 400 kW [B8]. Rotating heat pipes were used to cool the twin aircoil blade of a gas turbine [Ml]. Heat pipe applications in other industries
The heat pipes can be employed in different industrial plants with the main objective to intensify cooling or heating and simultaneously, to prevent undesirable substances from penetrating into the surroundings; the HPHE for instance, applied in wet waste gas desulphurization [6] has already proved its merits. The HPHE, which perfectly separates the warm and cold streams, prevents the injurants from spreading outside the working area. For reasons of environmental protection, many a production process has been changed into a closed cycle, in respect of cooling water circulation which serves to cool heat stressed machinery and equipment. The installation of two cooling circuits linked over a heat exchanger makes it possible to fill the interior circuit with clean water.- (or another convenient heat conducting liquid)
a.
I
01 5
10
I
15 K hi tad b.
I 20
Fig. 10. Heat pipe heat exchanger: type water-water. a. Scheme of HPHE. b. Dependence of the heat performance on the difference of inlet warm and inlet cold streams; Row rate of warm water 0.67 kgs-‘; Row rate of cold water 0.1 kg s-‘.
temperature
H e a t pipe research and development in East European countries
13
Fig. 11. Vapour-chamber for texturing of artificial fibres l--electric resistance heater 2--guide grooves for contact fibres with isothermal chamber surface 3--filling tube 4--insulated condensation part of the chamber.
without the risk of fouling or corroding the active heat exchanging surfaces and to use, in the exterior circuit, service water without modifications. On the other hand, with two cooling circuits the cooling water from the machines does not convey any noxious or other undesirable substances into the waste. To meet this requirement, the heat exchanger design must allow for quick and easy cleaning of the heat exchanging surfaces that lie in contact with service water. The answer to this problem is the HPHE whose diagram is plotted in Fig. 10. It consists, e.g. of a bundle of smooth copper pipes (~b 14/0.5 mm, length 200mm) with methylalcohol filling. For an exchanger comprising 14 heat pipes, Fig 10 shows the dependence of heat performance on the difference of the inlet temperatures of both water streams with preselected mass flow rates. Computing a comparison with a variant of a standard twin-draught cross-current heat exchanger has proved that although the built in volume of both exchangers is approximately the same, the HPHE is simpler, particularly in respect of the cleanability of its heat exchanging surface. The HPHE were used to cool the warm, clean inner water of the plastic moulds by service water in a chemical plant. In this plant individual copper/water heat pipes have found wide application, especially in cooling injection moulds for thin, long profiles, where no cooling water channels can be conveniently designed [HI0], [P7], [Pg]. At "controlled cast aluminium and its alloys solidification" the heat pipes allow for cooling of critical points of the mould, thus reducing the H.R.$. 9/I--B
14
F. POLIX~EK
Fig. 12. Sodium distillation unit with variable conductance steel/water heat pipes l-heat pipes; 2-boiler of the unit.
casting period and improving the mechanical properties of the metal. For example when steel/mercury heat pipes were used the solidification time of the flange was cut by 35% [HI0]. To produce isothermic surfaces of an even larger size, needed in technological operations such as heat processing of artificial fibres, special vapour chambers are designed consisting of heat pipes, usually with a rectangular cross-section, and isothermic furnaces usually shaped as cylindrical annuli. When heating the evaporation part by, say, a built in electric resistance heater, the whole space of the vapour chamber is filled with steam of almost equal temperature. If the external surface of the vapour chamber is insulated, thermal losses to the surroundings are minimal and the evaporation part input only makes up for these thermal losses. Figure I 1 shows a vapour chamber of 2 m in height designed to maintain the surface temperature of six grooves at 230°C + I°C while processing artificial fibres. Figure 12 shows a sodium distillation plant with variable conductance steel/water heat pipes for temperature control during the condensation of clean sodium vapour.
CONCLUSION According to the available literature there are over 40 institutes and establishments engaged in the research and development of heat pipes in the countries of Eastern Europe. The main applications are aimed at utilizing air and flue gas waste heat and at intensified cooling, especially in electrical engineering.
Heat pipe research and development in East European countries
15
Many countries of Eastern!!E~irope (CZeehosl0vakia;': Bulgaria, Hu~igary) possess considerable heat resources in the form of mineral springs. At present, their exploitation is rather low. Now a technical and economic investigation is on the way, on how to apply heat pipe systems in the exploitation of geothermal energy, not only in agriculture and industry, but even in households, for one can expect that in this area heat pipes would be very useful. Acknowledgements--The author expresses his deep gratitude to all people who supplied valuable information for this paper. Apart from my colleagues in the National Research Institute for Machine Design, Prague---B~hovice, special thanks go to Dr J. Bielik, Dr H. Biesenack, Ing. H. Berger, Ing. J. Erdei, Dr D. Fetcu, lng. F. Jelinek, Ing. L. Kolev, Dr Milo~evi~:, Prof. D. Nebel, Dr P6tsehke, Dr H. Rokicki, Ing. K. Smr~ek, Dr T. TSrSk, Mrs I. Tusarov~i and Dr V. Zbofil.
REFERENCES 1. F. Pol~i~ek, Heat pipe research and development in East European countries, Proceedings of the 5th International Heat Pipe Conference, Vol. 2, pp. 15-51. Tsukuba, May 14-18 (1984). 2. V. Hlava~ka, L. Horv/tth, J. Kabi~ek, F. Kupec and F. Pol~i~ek, Heat transfer and critical heat fluxes at boiling on heating surfaces covered by capiliary porous structures, Proceedings of the 6th International Heat Pipe Conference. Grenoble, May 25-29 (1987). 3. G. T. Colwell, K. J. Wells and J. T. Berry, Theoretical study of the use of heat pipes in metal casting, Proceedings of the 5th International Heat Pipe Conference, Vol. 1, pp. 220-224. Tsukuba, May 14-18 (1984). 4. A. Ger~k, L. Horv/tth, F. Jelinek, P. [;tulc and L. Zbofil, Examples of heat pipe application in chemical, electrical and other industries, Proceedings of the 6th International Heat Pipe Conference. Grenoble, May 25-29 (1987). 5. J. Bielik, M. Cagala, V. Hlava~ka, V. G. Kiselev, F. Pol~iek, P. ~tulc, L. L. Vasiliev and J. Zemfi.nek, Experience from heat pipe heat exchanger operations in connection with fouling, freezing and other operation conditions, Proceedings of the 6th International Heat Pipe Conference. Grenoble, May 25-29, (1987). 6. J. Niekawa, K. Matsumoto, H. Noda and T. Koizumi, Large scale heat pipe heat exchanger for flue gas desulfurizing systems, Proceedings of the 5th International Heat Pipe Conference, Vol. 2, pp. 147-152. Tsukuba, May 14--18 (1984). Reference is also made to the following cumulative supplement of heat pipe publications to reference [1] from East European Countries for period 1984-1986. BI. G. Bacanu, V. Hoffmann and P. Oarcea, A study of heat pipe heat exchanger performance (in Rumanian), Proceedings of the Lucrdrile Conferintei de Transmiterea C~ldurii si Optimizerea Utilizrrii Energici Termice, Vol. 1, pp. 80-85. Brasov, October 30-31 (1986). B2. M. Balask6, S. Konczol and F. Svfib, Neutron radiography study of pulsed boiling in a water-filled heat pipe, Int. J. Refrigeration 9, 80-83 (1986). B3. M. Bartfik, P. Moser, F. Pol/L~k and O. Otlej~ek, Cooling of electric machines and electrical devices by heat pipes (in Czech), Elektrovfzkum 2, 104-115 (1984). B4. I. Bereznay and J. Erdei, Heat pipe waste heat utilizer for boilers and industrial furnaces (in Hungarian), Veiki K0zlembnyek, 13-17 (1985). B5. I. Bereznay and J. Erdei, Waste heat recovery of flue gases by heat pipe and hybrid heat exchangers (in German), Report VEIKI, Budapest (1986). B6. M. Brfit, Heat recovery by means of heat pipe heat exchanger (in Czech), Teplo 4, 19-21 (1985). B7. V. F. Bukreev, F. Polfitek, J. Zemfinek, P. Stulc, G. Hanzfilek and K. Ko~aL Air-to-air thermal recovery units, J. Heat Recovery Systems 5, 451-461 (1985). B8. H. Biesenack and R. Neundorf, Problems with heat pipe application in high frequency A.C. electric motors (in German), Elektrie 39, 169-170 (1985). DI. J. DobifiL L. Horvfith and I. Davidovi~, Heat conduction in solid with heat pipes by FEM, Proceedings of the 4th International Conference, on Numerical Methods in Thermal Problems, Vol. 1, pp. 122-131. Swansea, July 15-18, (1985). D2. J. Drnec, F. Pol~ek and P. gtulc, A study of the heat pipe and cold storage systems (in Czech), Elektrotechnickp obzor 76 (1987). D3. I. l)rm~enkov~t, Coolers increase life time of accumulators (in Czech), V~da a technika v SSSR 14, 28 (1986). El. J. Erdei and I. Bereznay, Waste heat recovery to preheating of air in power stations, Energiewirtschaft 24, 559-561 (1985). FI. K. Fejfar, Cooling of power transistor KD 503 in narrow space conditions (in Czech), Sd~lovacl technika 34, 386-387 (1986). F2. D. Fetcu, V. Hoffmann, M. Muresan and V. Ungureanu, Heat performance of an acetone heat pipe (in Rumanian), Proceedings of the Lucr~rile Conferintei de Transmiterea C~ddurii si Optimizarea Utiliz,lrii Energici Termice, Vol. 1, pp. 63-72. Brasov, October 30-31 (1986). F3. D. Fetcu, V. Hoffmann and V. Ungureanu, Theoretical and experimental study of wickless heat pipes (in Rumanian), Proceedings of the Lucrdrile Conferintei de Transmiterea Chldurii si Optimizarea Utilizbrii Energici Termice, Vol. !, pp. 55-62. Brasov, October 30-31 (1986). F4. D. Fetcu, V. Hoffmann and V. Ungureanu, A method of gravitational heat pipe design based on temperature difference (in Rumanian), Proceedings of the Lucr,lrile Conferintei de Transmiterea C~ldurii si Optimizarea Utiliz~rii Energici Termice, Vol. 1, pp. 72-79. Brasov, October 30-31 (1986). F5. D. Fetcu, V. Hoffmann and V. Ungureanu, Possibility of using acetone heat pipes to construction of recuperative heat exchangers (in French), Buletinul Universiultii din Brasov 27, 71-74 (1985). F6. D. Fetcu, V. Hoffmann and V. Ungureanu, Certain aspects of using water as a working fluid of carbon steel heat pipes (in French), Buletinul Universitrtii din Brasov 27, 75-78 (1985).
16
F. POL,~EK
F7. D. Fetcu, V. Hoffmann and V. Ungureanu, A study of tilt angle inclination on heat performance of acetone and freon gravitational heat pipes (in French), Buletinal Unh~ersitdtii din Brasoc 27, 65-70 (1985). G1. B. Gagpergi~, I. Golovi6 and I. Nemec, Investigation of heat pipe (two-phase thermosyphon) heat exchangers, Proceedings of the XII ICHMT International Symposium on High Temperature Heat Exchangers, pp. 1~ . Dubrovnik, August 26-30, (1985). HI. Z. Havlin, Application of heat pipe heat exchangers in dust environment (in Czech), Proceedings of the Svmpostum on Heat Recot,erym Agriculture, pp. 16-25. Prague, May 15-18 (1984). H2. L. Hag, Experience from using secondary energy sources in agriculture (in Czech), Proceedings of the Seminar on Secondary Energy Sources, pp. 99-108. Ostrava, October I0 (1985). H3. V. Hlava(:ka, Some speciality of calculation of heat pipe exchangers (in Czech), Proceedings o["the 3rd Heat Pipe Seminar, pp. 38-41. Prague, November 7, (1985). H4. V. Hlava~ka, R. Ledeck~, and J. N. ~ev~uk, Experimental study of heat performance of sodium heat pipes (in Russian), Proceedings of the 7th Heat and Mass Transfer Conference, Vol. 8, pp. 64-71. Minsk, May 21-25 (1984). H5. V. Hlava~ka, F. Pol/tgek and P. ~tulc, Heat Pipe Heat Exchangersfor Heat Recovery (in Russian). ITMO AN BSSR, Minsk (1987). H6. V. Hlava~ka, P. ~tulc, J. Zemfinek, K. Jilek and M. Barnik, Observation of heat pipe heat exchangers in working conditions (in Czech), Proceedings of the 3rd Heat Pipe Seminar, pp. 30-35. Prague, November 7 (1985). H7. V. Hlava~ka, P. fltulc, J. Zemfinek, K. Jilek and M. Bart~ik, Heat pipe heat exchanger operating experience (in Czech), Zdravotnl technika a czduchotechnika 29, 81-88 (1986). H8. V. Hlava(~ka, ~tulc P. and A. Zuzafi:ik, Two-phase closed thermosyphons for heat exchangers (in Czech), Strojirenstvi 36, 391-395 (1986). H9. J. Hofman, Heat recovery in agriculture (in Czech), Proceedings of the Symposium on Heat Recover)" Devices, pp. 89-97. Klatovy, November 13 (1985). H10. L. Horv~ith and F. Polh~,ek, Survey of choice heat pipe applications (in Czech), Proceedings of the 3rd Heat Pipe Seminar, pp. 7-15. Prague, November 7 (1985). HI1. L. Horv~ith and F. Polfigek, Possibility of application of heat pipes in industry (in Czech), lnformace Potravinoprojektu 4, 74--93 (1985). H 12. L. H orv~th, F. Pol~ek, A. First and L. Netolick~, The cooling of the power semiconductor elements of the traction driving mechanism by heat pipes (in Czech), Proceedings of the 3rd Heat Pipe Seminar, pp. 42-52. Prague, November 7 (1985). HI3. L. Horv~ith, F. Pol~i~ek, L. Netolick~ and A. First, Cooling of power semiconductor devices of traction converters by heat pipes (in Czech), Technickk zpr~vy ~KD 19, 1-8, (1985). J1. J. Jakeg, O. O~lej~ek and L. Horv~ith, High performance heat pipes (in Czech), Proceedings of the 2nd Symposium on Cooling of Microelectronic Devices, pp. 6-12. Pardubice, December 5-6 (1984). J2. F. Jelinek, J. Tuhh~ek and J. Pilous, Low temperature heat pipes for application in industry (in Czech), Proceedings of the Symposium on Heat Recovery Devices, pp. 64-88. Klatovy, November 13 (1985). KI. J. Kfira, J. Zem/mek and L. Ha~, Operation testing of heat pipe heat exchangers (in Czech), Proceedings of the Symposium on Heat Recovery in Agriculture, pp. 26-29. Prague, May 15--18 (1984). K2. D. Keller and A. Thieme, Heat recovery by heat pipe heat exchangers during drying (in German), Proceedings of the lOth Wiirmetechnische Tagung, pp. 17. Trocknung, Karl-Marx-Stadt, December 3-4 (1985). K3. S. V. Konev, F. Polh~k and L. Horvfith, Heat transfer at boiling in capillary-porous materials (in Russian), Proceedings of the 7th Heat and Mass Transfer Conference, Vol. 6, pp. 15--19. Minsk, May 21-25 (1984). LI. R. Ledeck~, Tilt angle influence on heat performance (in Czech), Proceedings of the 3rd Heat Pipe Seminar, pp. 36-37. Prague, November 7 (1985). L2. R. Ledeck~,, Heat exchangers made of variable conductance heat pipes (in Czech), Proceedings of the 3rd Heat Pipe Seminar, pp. 36-37. Prague, November 7, (1985). M 1. M. Majcen and N. garunac, Heat pipe cooled twin aircoil blade as an element for higher efficiency of tonglife gas turbine, Proceedings of the Heat and Mass Transfer in Rotating Machinery Symposium, pp. 112-116. Dubrovnlk, September 1-3 (1982). M2. S. Milogevi~, R. Beuck and G. Pichler, Superheating in the heat pipe oven, Applied Physics 641, 235-239. M3. S. Milo~evi~ and G. Pichler, A study of Naz diffuse bands in voilet by the excitation through self-broadened D-lines, Zeischrift fiir Physik D, Atoms, Molecules and Elasters 1, 223-229 (1986). NI. S. Nevenkin, M. Kibarova and V. Georgiev, Heat transfer characteristics of low temperature heat pipes with metal fibre and bronze sintered wicks (in Bulgarian), Proceedingsof the Conference na energ(ie-metodi, technotogija, izolelija i modernizacii 2, 327-332. Varna (1985). N2. I. Novotna, Compatibility of aluminium and steel heat pipes with flue gases (in Czech), Strojirenskf zpravodaj 3, 6 (1987). N3. I. Novotnfi and V. Sokolikov~, Contribution to heat pipe compatibility (in Czech), Proceedings of the 3rd Heat Pipe Seminar, pp. 60-64. Prague, November 7 (1985). PI. P. Penchev, Heat utilization system with heat pipes (in Bulgarian), Energetika 6, 24-26 (1986). P2. B. Pokorn~, and F. Pol~ek, Heat pipes and their applications in industry (in Czech), Proceedings of the Symposium on Heat Recover)' Devices, pp. 44-63. Ktatovy, November 13 (1985). P3. F. Pol~igek, Designer routing at design and calculation of heat pipes (in Czech), Proceedings of the 3rd Heat Pipe Seminar, pp. 65--92. Prague, November 7 (1985). P4. F. Polfigek, Heat pipe research and development in COMECON countries (in Russian), Report, No. 9 and 10, ITMO AN BSSR Minsk (1985). P5. F. Polfigek, Cyrogenic heat pipes in cryogenic devices (in Czech), Proceedings of the Kryogenika 1986International Conference, pp. 86-93. Prague, April 15-17 (1986). P6. F. Polfi~ek, Heat pipe heat exchangers for waste heat recovery (in Czech), Zdrat,otni technika a t,zduchotechnika 29, 180-181 (1986). P7. F. Polfigek, A. Gerfik and F. Jelinek, Heat pipes for cooling and temperature stabilization of plastic processing equipments (in Russian), Proceedings of the scientific papers on Heat Pipes and Heat Pipes Heat Exchangers, pp. 74-86. ITMO AN BSSR, Minsk (1986).
Heat pipe research and development in East European countries
17
PS. F. Pol~i~ek and L. Horv~th, C0oiing of power semiconductor devices of traction converters by heat pipes (in Russian), Report, No. II, ITMO AN BSSR, Minsk (1985). P9. F. Polfi.~ek and F. Jelinck, Application of heat pipes to cooling and thermal control of plastics mould casting (in Czech), Plasty a kauduk 22, 231-236 0985). P10. F. Pol/L~k and P. gtulc, Heat pipe heat exchangers (in Czech). Techniky, Prague 0986). Pl 1. F. Polfi!ick, P. ~tulc, J. Nassler and J. Biclck, Heat pipe heat exchangers for heat recovery in chemical industry (in Czech), Proceedings of the Innovations in Chemical Industry Symposium, pp. 154-164. Stfivnick6 Bane, May 14-16, 1986. Rl. H, Rokicki, Study of heat pipe application to recovery of waste heat of flue gases of boilers (in Polish), Ph. D, Thesis, Politechnika Gdafiska, (1981). R2. H. Rokicki, Two-phase closed thermosyphon (in Polish), Gospodarka paliwami i energkT, 31, 16-18 (1983). R3. H, Rokicki, A mathematical analysis of the thermal processes in a heat pipe (in Polish), Zeszyty naukowe Politechniki Gdattskiej 44, 3-13 (1983), R4. H. Rokicki, Influence of the working fluid filling on the heat performance of heat pipe (in Polish), Gospodarka paliwami i energia 33, 7-10 (1985). Sl. K. Smr~ek, Heat pipes---efficient cooling element (in Czech), Elektrotechnika 40, 226-230 (1985). $2. K. Smr6ek, Heat pipe research in ~KD Polovodi(:e plant (in Czech), Elecktrotechnika 41, 306-312 (1986). $3. P. gtulc, M. Bart/tk and K. Jilck, Inner thermal resistance of two-phase closed thermosyphons (in Czech), Proceedings of the 3rd Heat Pipe Seminar, pp. 16-26. Prague, November 7 (1985). $4. P. gtulc, V. G. Kiselev and J. N. Matveyev, Heat pipe heat exchangers for low-potential heat utilization (in Russian), Proceedings of the 7th Heat and Mass Transfer Conference, Vol. 8, pp. 169-174. Minsk, May 21-25 0984). Vl. D. Ve~a, S. Milo/ievi~ and G. Pichler, Discharge studied of the lithium dimer diffuse bands, Optics Communications 56, 172-178 (1985). V2. Z. Viktorin, K. Hou~,ka and A. Gerfik, Technical and economical evaluation of the heat recovery in convective drying (in German), Proceedings of the lOth Wiirmetechnische Tagung--Trocknung, pp. 43-47. Karl-Marx-Stadt, December 3-4, (1985). " V3. Z. Viktorin, K. Houf,ka and A. Ger/~k, technical and economical evaluation of the heat recovery in convective drying (in Czech), Zdravomi technika a vzduchotechnika 29, 163-171 (1986). ZI. V. Zbofil, J. Je~ek and M. Tyburec, Electronics cooling in automatic and computer technics (in Czech), Proceedings of the Seminar on Mini-calculators 1986, Prague, October 6-7 (1986). Z2. V. Zbofil and M. Tyburec, Computer elements cooling (in Czech), Automatizace v)podetni techniky 57, 14-27 (1986). Z3. V. Zbofil, M, Tyburec and P. gtulc, Heat pipes for cooling of electronic elements and devices (in Czech), Proceedings of the 2rid Symposium on Cooling in Microelectronics Devices, pp. 13-15. Pardubice, December 5-6 (1984). 7_,4. J. Zemfinek, Research development and application of heat pipe exchangers (in German), Proceedings of the llth Int. Conference on Industrial Energy Management, pp. 24-29. Berlin (1984). ZS. J. Zemfi.nek, Energy reduction of poultry farmings and fattening stations (in Czech), Proceedings of the llth Conference on Heating, Ventilation and Air Conditioning, pp. 1-7. Nitra, August 25-27 0986). Z6. J. Zcm/mek, Recuperative heat pipe heat exchangers (in Czech), Technickd informace STS 3, 1985, pp. 41-44. ZT. M. Zemfinek, Heat recovery efficiency of recuperative heat exchangers (in Czech), Teplo 2, pp. 15-17 (1986). Z8. M. Zcmfi.nek, F. Huk and J. Chysk~, Heat recovery in agriculture by means of plate heat exhangers (in Czech), Zdravomi technika a vzduchotechnika 28, 231-237 (1985). Z9. A. Zuzafifik, Contribution to study of steel cast cooling by heat pipes (in Czech), Proceedings of the 3rd Heat Pipe Seminar, pp. 57-59, Prague, November 7 0985). Anl. Heat pipe heat exchangers--type N, W (in Czech), Prospectus of the Vzduchotechnika, Novb Mesto n. Vdhom (1984). An2. Heat pipe heat exchangers--type R (in Czech), Prospectus t~f the Vzduchotechnika, Novb Mesto n. V,ihom (1984). An3. Heat pipe heat exchangers--capillary type KTN (in Czech), Prospectus of the Vzduchotechnika, Novd Mesto n. Vdhom (1986). An4. Heat pipes coolers of closed boxes (in Czech), Prospectus of the Vzduchotechnika, Novd Mesto n. Vdhom (1986). An5. Heat pipe coolers of power semi-conductor devices--type CHVPS 65 (in Czech), Prospectus of the Vzduchotechnika, Novd Mesto n. VfThom (1986). An6. Heat pipes--type G (in Czech), Prospectus of the JZD, MrAkov (1984). An7. Heat pipe heat exchangers--type ZV 3-025... 033 (in Czech), Prospectus of the JZD, Mr/tkov (1984). An8. Heat pipe heat exchangers--type RSA (in Czech), Prospectus of STS, Mimofi (1984). An9. Heat pipes (in Czech), Prospectus of the KOH-I-NOOR, Prague (1984). Ani0. Heat pipe heat exchangers (in Hungarian), Prospectus of the FOTOBER, Budapest (1986). Anl 1. Conditioning unit with heat recovery-type UT-F-12 (in Russian), Prospectus of the GSKB Brest (1985). Anl2. New cooling method of batteries (in Czech), Technika v SSSR 6, 121 (1986). Ant3. 40 years anniversary of the National Research Institute for Machine Design (in Czech), Revue obchodu, pr~mysm, hospodd~stvi 11, 17-48 (1986). Anl4. Heat pipe heat exchangers--type WR 25 (in German), Prospectus of Wiirmetechnik und Liiftungbau, Gotha (1985). AnlS. Heat pipes for heat recovery in glass industry (in German), Prospectus of VEB Rohrleitungs und Heizungsmontagen, Dresden. Kosora, Dresden (1986). Anl6. Heat pipe coolers of closed boxes (in Czech), Prospectus of the KOH-I-NOOR, Prague (1987).