Power plants with a vehicle-borne hydrogen generator

Inr J. Hydrogen Energy Vol. 21, No. 9, pp. 801 805, 1996 Copyright (Q 1996 International Association for Hydrogen Energy Elsevier Science Ltd Printed in Great Britam. All rights reserved PII: SO360-3199(96)00001-8 036&3199/96 $15.00+ 0.00

Pergamon

POWER PLANTS

WITH

A VEHICLE-BORNE

HYDROGEN

GENERATOR

I. L. KOLBENEV* St IPetersburg State Agrarian University,

Tsarskoye Selo, St Petersburg 189620, Russia

(Receiaed for publication 2 January 1996) Abstract-Vehicles operating on hydrogen which can take the place of petrol and diesel fuel have with increasing frequency come into the focus of attention. The present paper discusses the efficiency of a vehicle-borne automobile-tractor hydrogen generator (ATHG), qualitative indices and designs of low-toxicity power plants with internal combustion engines (ICES) and zero-emission plants based on a battery of hydrogen fuel elements (FEs) and an ATHG. The design of a power plant for a tractor with FEs and an ATHG can be a scenario for the development of electric automobiles and tractors. Copyright @ 1996 International Association for Hydrogen Energy

NOMENCLATURE n c C, c0 D

T,

Thermal conductivity Concentration of the combustion mixture of power particles Concentration of the active component of the power carrier on the jet axis Concentration of the active component of the power carrier at the initial cross-section of the jet Diffusion coeflicient of the active component of the power carrier in fluid l’il k$R,d

D,

DamkGhler number, D, =

d K

Diameter of the reacting mixture flow (mm) Constant of the chemical reaction rate Specific parameter of hydrogen (kg/kg) Mass flow the power carrier Index characterizing medium dispersity Mass of hydrogen fed to the engine (kg) Theoretical mass of the hydrogen generator (kg) Index of the non-Newtonian liquid Constant of the chemical reaction Effective power of the internal combustion engine (W Effective power of the internal combustion engine under nominal conditions (W) Thermal effect of the reaction Reynolds number, Re = uf mNdNJm Dispersion composition of the power carrier (mm) Starting reaction temperature (“C)

KH> MO m mH *J mH,

N

:e

P .Z” Q Re r T

*Address: Russia.

u, v

Temperature of the active component of the power carrier on the jet axis (“C) Longitudinal, lateral components of the combustible mixture rate Maximum volume of hydrogen released for the total reaction time (dm3) Volume of hydrogen released for time z (dm3) Chemical reaction rate Power carrier momentum flow, J, = apzd2uz Longitudinal, lateral coordinates Oxidant-excess coefficient Relative heat flow, & = 9

?i,,R,pC,J,

Time-averaged mixture density Total heat flow, 4 = 4, + 4ch Heat flow due to convection, 4, = &nd2u,T, Heat flow due to the chemical reaction, bch

=

MoQ

Time (s), (h) Chemical reaction time (s) Hydrodynamic time (s) Net efficiency of auxiliary systems Net efficiency of the gas generator Net efficiency of the petrol-hydrogen engine Thermodynamic efficiency of a FE Net efficiency of a FE battery Net efficiency of the power plant with a FE battery

1. INTRODUCTION In recent years, reassuring results of conducted research, engineering developments and demonstration projects have been obtained. Predictions suggest that at the end

79 Basseynaya St, Apt 100, St Petersburg 196211

801

802

I. L. KOLBENEV

of the century vehicles on alternative fuels will be able to satisfy the world’s increasing needs for power with no environmental pollution and become a multi-million business [l, 21. Two schemes of hydrogen generation and use in vehicles are known: centralized and vehicle-borne [3]. The first one involves production of hydrogen in an industrial gas generator and its accumulation aboard a vehicle. An experimental design of German Lloyd can serve as an illustration of the first scheme 141. The second scheme is oriented towards hydrogen production in a vehicle-borne gas generator which forms a part of a vehicle power plant [S]. According to the assessment of American specialists, it is natural-gas catalytic conversion that will give cheap hydrogen before 1996, but later on the process of gasification of coal is believed to have the best prospects, the coal portion increasing in the balance of primary power sources [S]. Reduced oxides of Si, Al, Fe and their compounds produced from the mineral fraction of coal or ash and slag wastes of thermal power plants, ferrosilicon and by-products of the aluminium and magnesium industry can become a power carrier for ATHGs [6]. Power carrier in the form of pellets, powder or paste is convenient for transportation to the consumer. The economic assessment of hydrogen production from water by the action of a power carrier turned out to be rather reassuring [7]. Limited possibilities of metal-hydride accumulators also favour the new power carrier. At any rate, the opinion of specialists from the U.S.A., Germany and the Ukraine reduces to the fact that no hydrogen sorptive capacity above 1.2 mass % can be obtained in real automobile systems [S]. The present paper discusses the ATHG efficiency, qualitative indices and designs of low-toxicity power plants with an ICE and tractor plants with zero emission. 2. ATHG

is limited to qhe.= 0.14 -0.48 [lo]. Muthmutiral

(3)

Boundary conditions (symmetry on the axis and asymptotic tending to zero of desired functions at infinity):

au aT ac v=-=-=oo; ay ay aY=

-4 = 1 - exp( -kt”a). %

(1)

The rate of hydrogen generation is limited by slow diffusion of power-carrier particles and water through a layer of slag to the reaction area and determined by the reaction surface which is characterized by r, power-carrier properties, T, and c(,. In batch-operated hydrogen generators, where solid phase reaction products are accumulated in the device, efficiency

c+o;

y=o;

T+ T,; u+o;

y+cc.

(4)

Solution of system (3) with boundary conditions (4) found by the method of limited similitude in the form specific for jet flows [l l] of the nondimensional kind looks as follows:

N+l 2(2N-1) 1 X-2N-1;

EFFICIENCY

Hydrogen generation methods according to the new ATHG technology are described elsewhere [9]. The reaction of a finely milled power carrier with water is a heterogeneous process:

model of the A THG working process

We (together with A. V. Soldatkin) have proposed a mathematical model of the ATHG working process. The ATHG employs jet mixing of reagents and continuous removal of reaction products. Initial data from the mathematical model equation (transport of momentum, heat and diffusion of power-carrier particles in fluid) within the scope of the boundary-layer theory [Ill]:

2-N 6(x)= (&J,)rn

L

x2NI

FCY,N -A T,(x) = T x

1.1

c,(x) = 7F(Y~N)x -& 2

;

/I, eDa”

PO+ eDa” - 1’ PO /I, + eDa” - 1

Numerical values of constants are taken with no chemical reaction at N = 1[12], i., = i., = 4/5, y1 = 4/3, i. = 417.

The efficiency of reagent jet mixing is achieved through maintaining 7: and ~~~values. Figure 1 presents c, and T, dependences at distance X = 2x/dRe (the sign of making a quantity nondimensional is omitted) from the nozzle. For r,* assessment the

A VEHICLE-BORNE

HYDROGEN

803

GENERATOR

2-

cm Tm

_

4

’ I

v& 3

0

2

5 I 1

I 2

I 3

x

Fig. 1. Change of concentration and temperature of the power carrier along the axis of symmetry. (1) N = 1; D, = 0, fl, = 1; (2) N = 1, D, = 2, &, = 1.5; (3) N = I, D, = 1.5, & = 1.5; (4) N = 1, D, = 2, & = 2.5;(5) N = 1, D, = 1, /j’, = 1.5.

dependences in Fig. 1 are used and change U, the first equation of system (5). Figure 2 is a distribution of the hydrogen release rate in reaction time for lg activated power carrier. Here r,,, = 20-30 s, the ATHG operates with the greatest efficiency when z,* > z,~ and qhg = 0.95, $ = 58 s, N = 1.5, x = 4, D, = 2 and p, = 1.5. Figure 3 shows an ATHG prototype with ylh,.= 0.9-0.95.

3. ATHG

IN PLANTS

WITH

AN ICE

Fig. 3. Automobile-tractor hydrogen generator. 1, reactor unit; 2, power carrier and control unit; 3, power carrier proportioning pump; 4, slag removal mechanism; 5, raw material tank; 6, branch pipe for feeding the steam-hydrogen mixture and 7, branch pipe for slag.

second capsule similar in arrangement. When filled, it closes. Figure 5 demonstrates the world’s first hydrogendiesel tractor VDT-01 based on the tractor T-16M. In operation conditions at (4.0-5.5% consumption of hydrogen with respect to diesel fuel and the 5-fold consumption of steam with respect to the hydrogen consumption, the consumption of diesel fuel reduces by 8-l 3 %, smoking by a factor of 2.1-2.8, emissions of nitric

Engineering-development designs have been developed and discussed for power plants with hydrogen, petrolhydrogen and hydrogen-diesel engines and an ATHG u31.

Figure 4 is a diagram of a power plant with an ATHG. Reservoir 4 with the power raw material is made like a tin of instant coffee. You mount it on reactor unit 3, the cover is broken through and the tin contents enter engine 9. The waste slag fills sump 11 gradually, which is the

/ I

M

3 A 5

I 10

4

Fig. 2.

Distribution of hydrogen release rate in reaction time. (l),(2) T, = 40, 60°C.

11

1

2

Fig. 4. Diagram of a power plant with an automobile-tractor hydrogen generator. 1, 5 pumps; 2, water tank; 3, reactor unit; 4, power carrier reservoir; 6, power carrier hatcher; 7, condenser; 8, hydrogen feed regulator; 9, engine; 10,slag removal mechanism and 11. suma. 1

I. L. KOLBENEV

804

Fig. 5. Hydrogen-diesel tractor with a vehicle-borne hydrogen generator. 1, internal combustion engine; 2, hydrogen generator; 3, raw material tank; 4, sump.

oxide, carbon monoxide and hydrocarbons decrease by a factor of 2.0-2.5, 9-10 and 1.4-1.6, respectively, as compared to the basic tractor T-16M. When using hydrogen as an auxiliary fuel for petrol, mixed control of the engine power is effected. For P P,” = 0.2, VICE= 0.2 is obtained. For PJP,, = 0.7, q$! = 0.31 is rt%hed [6]. 4. TRACTOR

WITH

FES AND AN ATHG

A variant of installing a FE battery on the tractor VDT-01 is discussed. Electric tractors can find application with the highest efficiencv in nlaces of limited air exchange with no sources of harmful emissions, noise and vibrations. Figure 6 presents a diagram of a power plant for a tractor with FEs and an ATHG. In device 8 impurities are removed from hydrogen and then the latter is fed to FE battery 9. Net efficiency of a FE battery: VFCB

=

VTVVY~CV,,

(6)

where qv, is the voltage efficiency, qc the current efficiency, q,, the current leakage. I]~,-~ = 0.8-0.9 is to be expected

C61.

Quality index of the power plant: ECG VPP

=

~FCB~hg~as’

(7)

The efficiency of power conversion in ATHG and systems qhgqas= 0.7-0.86. Therefore, a&liary = 0.6-0.8, which is comparable to the efficiency of VPP the existing power plants for vehicles with FEs [14]. Electric tractor parameters The effective range at the complete store of a power carrier is 300 km. The power carrier store at K,> = 0.28 kg/kg is 20 kg in three “coffee tins”. The water store is obtained from the FE battery. Mean speed 14 km/h. Operation mass = 1810 kg. Mass of carried freight = 900 kg. Operation power P, = 0.75W, P,, = 15 kW [133.

A VEHICLE-BORNE

HYDROGEN GENERATOR

805

The developments have been registered at the State Patent Office of Russia. The author plans to take out a license for the vehicle-borne hydrogen generator to be used in industry, automobiles and tractors serving various objectives. For this purpose international cooperation is proposed. REFERENCES

h-

5

3 I P10

I

I

Fig. 6. Diagram of a power plant for a tractor with a FE battery and an ATHG. 1, 5 pumps; 2, water tank; 3, reactor unit; 4, power carrier reservoir,, 6, power carrier hatcher; 7, condenser; 8, steam-gas mixture desiccator; 9, FE battery; 10,slag removal mechanism; 11, sump; 12, compressor and 13, air outlet.

FE battery

parameters

Tentatively taken to be similar to LASERCELL, 34 kg, hydrogen demand 2.3 kg.

mass

A THG parameters

The mass is 29 kg, the capacity is controlled by changing the power carrier supply to the reactor at cc, = 2-5. The design of a tractor power plant with zero emission based on a FE battery and an ATHG can be a scenario for the development of electric automobiles and tractors.

1. T. N. Veziroglu and F. Barbir, Hydrogen: the wonder fuel. Int. J. Hydrogen Energy 17, 391404 (1992). 2. J. S. Cannon, Hydrogen-powered automative programs in the U.S.A. New Energy Systemsand Conversions. Proc. 1st Internationnl Conference Jokohama, 1077112(1993). 3. I. L. Kolbenev, Improvement of the energy-and-ecology indices of automobile-tractor diesels.Dcigatelestroyeniye 12, 53-56 (1987). 4. G. Fischer, Derzeitige Moglichkeiten von Wasserstohbetrieb. Seewirtschaff 7, 56-61 (1990). 5. I. L. Kolbenev, Expansion of fuel and power resources by the useof non-conventional power. Inf. J. Renewable Energy 2, 445449 (1992). 6. I. L. Kolbenev, A non-traditional energy carrier: the efficiency of usein power plants with a hydrogen generator. Int. J. Renewable Energy 3, 221-233 (1993). 7. V. A. Troshen’kin, A. I. Blinov and I. E. Klevan, Prospects for the economy of hydrogen production from water using power-accumulating substances.Atomnooodorodnoya energetika i tekhnolgiyu 3( 19) 36-38 (1984). 8. A. I. Mischenko, Scientific-and-technical problems of using hydrogen as a fuel for automobile engines. Problemy Mashino>troyeniyu 31, 79984 (1989). 9. I. L. Kolbenev, Vehicle-borne hydrogen generators: A new technology. New Energy Systems and Conversions. Proc. 1st International Conference, Jokohama. loll106 (1993). 10. I. L. Varshavskii (ed.), Energy-accumulating substances and their use. Naukova Dumka, Kiev (1980). 11. G. Shlikhting (ed.),Boundary-layer theory. Nauka, Moscow ( 1974). 12. 1. L. Kolbenev and A. V. Soldatkin, Operating-condition peculiarities of a hydrogen generator for low-toxicity engines. Dvigatelestroyeniye 8, 54-55, 62 (1986). 13. I. L. Kolbenev, Hydrogen fuel in automobiles and tractors. Int. J. Hydrogen Energy 18, 409420 (1993). 14. I. L. Kolbenev (ed.),Electrochemical generutors in submurine apparatus:. Voyenizdat, Moscow (1980).