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03349 Applications of thermal energy storage in Saudi Arabia
13
99lQ3346 Removing coke flour from effluent of processing plant by ceramic membrane Xing, W. et al. Nanjing Huagong Daxue Xuebao, 1998, 20, (3), 10-13. (In Chinese) The paper examines the micro-filtration of wastewater containing coke flour by ceramic membranes. The ZrOl membranes with pore diameter of 0.2 pm and 1.0 pm pore A1203 membranes were used. The cleaned water was obtained by the 0.2 pm Zr02 membrane and by 1.0 pm A1203 membrane with flocculation pre-treatment. Back-flushing condition and membrane cleaning method were also studied.
13
SPACE HEATING COOLING Applications
of thermal
AND
energy storage
in Saudi
Hasnain, S. M. et al. Int. J. Energy Res., 1999, 23, (2), 117-124. Sixty-five per cent of the total electrical energy consumption in buildings in Saudi Arabia comes from the heating, ventilating and air conditioning (HVAC) system. This is due to a very high ambient temperature which persists for a long period during the summer. Moreover, gas turbines efficiency also decrease with the high ambient temperatures. In the HVAC industry cool storage, commonly known as thermal energy storage (TES) is the most preferred demand-side management (DSM) technology for shifting cooling electrical demand from peak daytime periods to off-peak night-time. The most popular and well-suited TES concept for Saudi Arabia is either chilled water or ice storage system, depending upon the applications and the required storage capacity. This paper shows how TES offers a means of reducing the electrical demand in large commercial buildings. This paper also discusses favouring conditions and other aspects of cool storage applications in Saudi Arabia. TES economics are considered and a cost analysis is presented to illustrate the potential savings that can be achieved by the use of TES in Saudi Arabia. 99lQ3350 Case study: Practical application of enhancement device in an ammonia flooded evaporator Ayub, Z. Enhanced Heat Transfer, 1999, 6, (l), 31-35. An ammonia flooded evaporator was to cool 40% by weight propylene glycol from 50 to 34°F. The double enhanced tubes lacked desired enhancement on the internal surface of tubes. It was decided to incorporate twisted tape inserts into each tube to overcome the capacity shortage. Energy management method for fuel saving in 99m3351 central heating installations Bakos, G. C. et al. Energy and Buildings, 1999, 29, (2), 135-139. A method is described for the energy management of the central heating installations of residences and other buildings. In particular, it refers to the optimum exploitation of thermal inertia of the building with optimization of the daily operation cycle of heating. The span and desired temperatures are defined by the user within some acceptable limits, whereas their sequence of alteration based on the desired interior temperature depends on the outdoor temperature. A microprocessor is used to analyse the readings of various sensors, placed at different points of the heating installation and to control the overall system operation. 99103352 Energy tariff and thermal comfort in public houses Bond, M. A. and Probert, S. D. Applied Energy, 1999, 62, (l), l-65. To contribute to achieving improved energy-effectiveness of future designs of public houses and the equipment employed therein, energy usage and wastages have been examined for two pubs, one of modern and the other of traditional construction. The use of pertinent energy-consuming equipment was surveyed and the associated patterns of operation assessed. Energy tariffs in force are analysed with respect to their influence upon demands. Thermal conditions within the public areas of the public houses were also monitored and the proportion of energy used for space heating determined. Refrigeration equipment was particularly energy consuming, owing to the conditions under which it was required to operate. Despite the availability of more efficient alternatives, tungsten lighting is still in common use in bars and accounted for up to a quarter of the electricity used in the public houses considered. There, controls for the heating systems are basic but illdevised, so leading to extreme thermal conditions in some areas of the pubs: consequently there are significant opportunities for savings. Ventilation controls were overlooked, so large rates of heat loss occurred via the exhaust air. The potential for achieving significant energy-savings through the introduction of waste-heat recovery equipment is hampered by (i) the brewery’s requirement for a payback period for such investments of 1 year or less and (ii) the reality that energy bills amount only to 3% of turnover at present unit-energy prices and are therefore of less importance than customer comfort. Values of the recommended ‘energy indices’ are calculated in order to assess the pubs’ overall performances: according to these nationally-accepted benchmarks for these concepts, both assessed pubs are classified as ‘good’, despite the shortcomings of each enterprise identified in the research.
Space heating and cooling
99103353 An evaluation of models for condensation heat transfer on low-finned tubes Briggs, A. and Rose, J. W. Enhanced Heat Transfer, 1999, 6, (1). 51-60. Several theoretical models for calculating heat-transfer coefficients during condensation on horizontal low-finned tubes have been examined. In this paper these are discussed and compared with recent experimental data considered to be reliable. It is evident that the effect of both gravity and surface tension-induced pressure gradient must he accounted for when calculating the condensate film thickness and hence the heat flux on the various parts of the fin and tube surface. Of critical importance also is capillary retention, which causes condensate to be held between the tins on the lower part of the surface. Except when the thermal conductivity of the tube material is high, it is also necessary to take account of the temperature drop arising from conduction in the fin. The experimental data used for the comparisons cover a range of fin geometric variables (height, thickness and space between fins) and tube diameter as well as different tube materials and condensing fluids. In one of the two most successful models the condensate flow and heat transfer over the various surfaces are analysed in a quite rigorous manner, but this model necessarily incorporates certain simplifying assumptions to obtain a fourth order differential equation for the condensate film thickness profile along the fin surface. The second successful theory uses dimensional analysis to treat surface tension-induced condensate drainage. In this case recourse to experimental data is needed to determine two constants. These are both of order unity and the final result is in the form of algebraic equations which may readily be used in design and optimization.
99m3354 Experimental evaluation of night ventilation phenomena Geros, V. et al. Energy and Buildings, 1999, 29, (2), 141-154. A systematic investigation, using both experimental and theoretical tools, was carried out on the potential of night ventilation techniques when applied to full-scale buildings, under different structure, design, ventilation and climatic characteristics. In addition, the paper aims to investigate the impact and the limitations of night ventilation techniques regarding the thermal behaviour of various types of buildings. Real-scale measurements in three buildings operating under free-floating and air conditioning conditions have been performed. The cooling potential of night ventilation techniques applied to buildings operating under different conditions and with variable air flow rates, has been experimentally and theoretically studied. Additionally, sensitivity analysis on the impact of the major parameters determining the phenomena has also been carried out. Practical considerations on the impact of the main parameters are given.
99103355 A feasibility study of a solar desiccant airconditioning system-Part II: transient simulation and economics Davanagere, B. S. et al. Int. .I. Energy Res., 1999, 23, (2), 103-116. A solid desiccant cooling system with a backup vapour compression system has been simulated using TRNSYS. The performance of the system was evaluated in four cities in the US with different climates. In order to assess the feasibility of these systems and to determine the relevant economic parameters such as life cycle costs, life cycle savings and payback periods, economic analysis was carried out. Results show that the system has higher COP values for the locations with more latent loads. The air conditioner was able to meet the cooling demand in all four regions, but it needed more auxiliary energy in the eastern and mountain regions than in the central region, because of the higher solar fraction in the central region. The simulation also showed that the desiccant cooling system by itself was capable of meeting the cooling demand and hence the requirement of a backup system may be eliminated. Thermal and economic parameters were analysed for varying solar subsystem sizes which proved helpful in optimizing the design of the solar system. Recommendations for minimizing the auxiliary energy costs using different methods for supplying the thermal energy for desiccant regeneration are described.
99103356 Friction and wear characteristics of polyvinyl ether (PVE) as a lubricant for alternative refrigerant Yamamoto, Y. et al. Nippon Kikai Gakkai Ronbunshu, C-hen, 1998, 64, (624), 3179-3184. (In Japanese) The paper studied the tribological characteristics of a synthetic lubricating oil of polyvinyl ether (PVE) for an alternative refrigerant. Three different testers were used with polyesters (POE), polypropylene glycols (PPG) and hydrogenated coal-tar oil traction oil. In the boundary lubrication regime, PVE gave higher friction coefficient and lower wear amount than POE and PPG. The high friction and low wear of PVE with high viscosity-pressure coefficient were attributed to a solidified film formed in a conjunction zone of high contact pressure. Although the solidified film had a high shear strength leading to a high coefficient of friction, it had a high ability to prevent the direct contact between rubbing surfaces compared with a boundary film consisting mainly of the absorbed molecules of POE. The tribological characteristics in boundary lubrication are effected by two kinds of boundary films, adsorbed film and solidified film.
Fuel and Energy Abstracts
September
1999
351
99lQ3346 Removing coke flour from effluent of processing plant by ceramic membrane Xing, W. et al. Nanjing Huagong Daxue Xuebao, 1998, 20, (3), 10-13. (In Chinese) The paper examines the micro-filtration of wastewater containing coke flour by ceramic membranes. The ZrOl membranes with pore diameter of 0.2 pm and 1.0 pm pore A1203 membranes were used. The cleaned water was obtained by the 0.2 pm Zr02 membrane and by 1.0 pm A1203 membrane with flocculation pre-treatment. Back-flushing condition and membrane cleaning method were also studied.
13
SPACE HEATING COOLING Applications
of thermal
AND
energy storage
in Saudi
Hasnain, S. M. et al. Int. J. Energy Res., 1999, 23, (2), 117-124. Sixty-five per cent of the total electrical energy consumption in buildings in Saudi Arabia comes from the heating, ventilating and air conditioning (HVAC) system. This is due to a very high ambient temperature which persists for a long period during the summer. Moreover, gas turbines efficiency also decrease with the high ambient temperatures. In the HVAC industry cool storage, commonly known as thermal energy storage (TES) is the most preferred demand-side management (DSM) technology for shifting cooling electrical demand from peak daytime periods to off-peak night-time. The most popular and well-suited TES concept for Saudi Arabia is either chilled water or ice storage system, depending upon the applications and the required storage capacity. This paper shows how TES offers a means of reducing the electrical demand in large commercial buildings. This paper also discusses favouring conditions and other aspects of cool storage applications in Saudi Arabia. TES economics are considered and a cost analysis is presented to illustrate the potential savings that can be achieved by the use of TES in Saudi Arabia. 99lQ3350 Case study: Practical application of enhancement device in an ammonia flooded evaporator Ayub, Z. Enhanced Heat Transfer, 1999, 6, (l), 31-35. An ammonia flooded evaporator was to cool 40% by weight propylene glycol from 50 to 34°F. The double enhanced tubes lacked desired enhancement on the internal surface of tubes. It was decided to incorporate twisted tape inserts into each tube to overcome the capacity shortage. Energy management method for fuel saving in 99m3351 central heating installations Bakos, G. C. et al. Energy and Buildings, 1999, 29, (2), 135-139. A method is described for the energy management of the central heating installations of residences and other buildings. In particular, it refers to the optimum exploitation of thermal inertia of the building with optimization of the daily operation cycle of heating. The span and desired temperatures are defined by the user within some acceptable limits, whereas their sequence of alteration based on the desired interior temperature depends on the outdoor temperature. A microprocessor is used to analyse the readings of various sensors, placed at different points of the heating installation and to control the overall system operation. 99103352 Energy tariff and thermal comfort in public houses Bond, M. A. and Probert, S. D. Applied Energy, 1999, 62, (l), l-65. To contribute to achieving improved energy-effectiveness of future designs of public houses and the equipment employed therein, energy usage and wastages have been examined for two pubs, one of modern and the other of traditional construction. The use of pertinent energy-consuming equipment was surveyed and the associated patterns of operation assessed. Energy tariffs in force are analysed with respect to their influence upon demands. Thermal conditions within the public areas of the public houses were also monitored and the proportion of energy used for space heating determined. Refrigeration equipment was particularly energy consuming, owing to the conditions under which it was required to operate. Despite the availability of more efficient alternatives, tungsten lighting is still in common use in bars and accounted for up to a quarter of the electricity used in the public houses considered. There, controls for the heating systems are basic but illdevised, so leading to extreme thermal conditions in some areas of the pubs: consequently there are significant opportunities for savings. Ventilation controls were overlooked, so large rates of heat loss occurred via the exhaust air. The potential for achieving significant energy-savings through the introduction of waste-heat recovery equipment is hampered by (i) the brewery’s requirement for a payback period for such investments of 1 year or less and (ii) the reality that energy bills amount only to 3% of turnover at present unit-energy prices and are therefore of less importance than customer comfort. Values of the recommended ‘energy indices’ are calculated in order to assess the pubs’ overall performances: according to these nationally-accepted benchmarks for these concepts, both assessed pubs are classified as ‘good’, despite the shortcomings of each enterprise identified in the research.
Space heating and cooling
99103353 An evaluation of models for condensation heat transfer on low-finned tubes Briggs, A. and Rose, J. W. Enhanced Heat Transfer, 1999, 6, (1). 51-60. Several theoretical models for calculating heat-transfer coefficients during condensation on horizontal low-finned tubes have been examined. In this paper these are discussed and compared with recent experimental data considered to be reliable. It is evident that the effect of both gravity and surface tension-induced pressure gradient must he accounted for when calculating the condensate film thickness and hence the heat flux on the various parts of the fin and tube surface. Of critical importance also is capillary retention, which causes condensate to be held between the tins on the lower part of the surface. Except when the thermal conductivity of the tube material is high, it is also necessary to take account of the temperature drop arising from conduction in the fin. The experimental data used for the comparisons cover a range of fin geometric variables (height, thickness and space between fins) and tube diameter as well as different tube materials and condensing fluids. In one of the two most successful models the condensate flow and heat transfer over the various surfaces are analysed in a quite rigorous manner, but this model necessarily incorporates certain simplifying assumptions to obtain a fourth order differential equation for the condensate film thickness profile along the fin surface. The second successful theory uses dimensional analysis to treat surface tension-induced condensate drainage. In this case recourse to experimental data is needed to determine two constants. These are both of order unity and the final result is in the form of algebraic equations which may readily be used in design and optimization.
99m3354 Experimental evaluation of night ventilation phenomena Geros, V. et al. Energy and Buildings, 1999, 29, (2), 141-154. A systematic investigation, using both experimental and theoretical tools, was carried out on the potential of night ventilation techniques when applied to full-scale buildings, under different structure, design, ventilation and climatic characteristics. In addition, the paper aims to investigate the impact and the limitations of night ventilation techniques regarding the thermal behaviour of various types of buildings. Real-scale measurements in three buildings operating under free-floating and air conditioning conditions have been performed. The cooling potential of night ventilation techniques applied to buildings operating under different conditions and with variable air flow rates, has been experimentally and theoretically studied. Additionally, sensitivity analysis on the impact of the major parameters determining the phenomena has also been carried out. Practical considerations on the impact of the main parameters are given.
99103355 A feasibility study of a solar desiccant airconditioning system-Part II: transient simulation and economics Davanagere, B. S. et al. Int. .I. Energy Res., 1999, 23, (2), 103-116. A solid desiccant cooling system with a backup vapour compression system has been simulated using TRNSYS. The performance of the system was evaluated in four cities in the US with different climates. In order to assess the feasibility of these systems and to determine the relevant economic parameters such as life cycle costs, life cycle savings and payback periods, economic analysis was carried out. Results show that the system has higher COP values for the locations with more latent loads. The air conditioner was able to meet the cooling demand in all four regions, but it needed more auxiliary energy in the eastern and mountain regions than in the central region, because of the higher solar fraction in the central region. The simulation also showed that the desiccant cooling system by itself was capable of meeting the cooling demand and hence the requirement of a backup system may be eliminated. Thermal and economic parameters were analysed for varying solar subsystem sizes which proved helpful in optimizing the design of the solar system. Recommendations for minimizing the auxiliary energy costs using different methods for supplying the thermal energy for desiccant regeneration are described.
99103356 Friction and wear characteristics of polyvinyl ether (PVE) as a lubricant for alternative refrigerant Yamamoto, Y. et al. Nippon Kikai Gakkai Ronbunshu, C-hen, 1998, 64, (624), 3179-3184. (In Japanese) The paper studied the tribological characteristics of a synthetic lubricating oil of polyvinyl ether (PVE) for an alternative refrigerant. Three different testers were used with polyesters (POE), polypropylene glycols (PPG) and hydrogenated coal-tar oil traction oil. In the boundary lubrication regime, PVE gave higher friction coefficient and lower wear amount than POE and PPG. The high friction and low wear of PVE with high viscosity-pressure coefficient were attributed to a solidified film formed in a conjunction zone of high contact pressure. Although the solidified film had a high shear strength leading to a high coefficient of friction, it had a high ability to prevent the direct contact between rubbing surfaces compared with a boundary film consisting mainly of the absorbed molecules of POE. The tribological characteristics in boundary lubrication are effected by two kinds of boundary films, adsorbed film and solidified film.
Fuel and Energy Abstracts
September
1999
351