摘要:

AbstractDrying is one of the most energy intensive unit operations. In many applications the drying temperatures required are low enough to make the inclusion of a heat pump in the system worthy of consideration. Five drying/dehumidification systems, including three with heat pumps, have been compared theoretically on the basis of specific power consumption (SPC), (i.e. the energy supplied per unit of moisture condensed) and primary energy consumption (PEC) which is (SPC) divided by the efficiency of primary energy conversion. The efficiency of each system is improved as the relative humidity of the air leaving the dryer is increased. The optimum is, however, very flat and a heat pump should be advantageous when a minimum relative humidity of 30 per cent is acceptable within the drying chamber. A closed cycle dryer is shown to be the most advantageous but requires careful matching.

ISSN:0363-907X    

DOI:10.1002/er.4440060402

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractAn experimental heat pump dehumidifier is described. Actual coefficients of performance (COP)Aare plotted against the gross temperature lift (TCO‐ TEV) for various bypass ratios and air velocities. Interpolated values of (COP)Afor a specified temperature lift were obtained by fitting each set for various dry bulb temperatures of air leaving the humidifier using a linear equation. These values of (COP)Aare plotted against the linear velocity of the air stream approaching the evaporator at different dry bulb temperatures. The curves show a maximum of (COP)Aat approach velocities in the region of 1·6 ms

ISSN:0363-907X    

DOI:10.1002/er.4440060403

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractExperimental data from the heat pump dehumidifier described in Part II (Taiet al, 1982) are presented in terms of the specific power consumption (SPC). Plots are presented of (SPC) against superheat at the exit of the evaporator for various air bypass ratios and (SPC) against approach velocity of air to the evaporator for various dry bulb temperatures. These all show a minimum value of (SPC). A plot of (SPC) and (COP)Aagainst the superheat at the exit of the evaporator shows that the minimum value of (SPC) coincides with the maximum value of (COP)A.

ISSN:0363-907X    

DOI:10.1002/er.4440060404

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractTo calculate the energy performance of buildings, one must know the heat‐transfer characteristics of the windows as functions of environmental variables, such as temperature and wind speed. Window designs are becoming more complex in response to the need for energy conservation. In this paper, we develop a general procedure for calculating the net energy flux through the glazed area of a window composed of an arbitrary number of solid layers. These layers, which may have thin‐film coatings, can have any specified solar and thermal radiation properties and enclosed spaces between solid layers can contain either air or other gases. We verified our results by comparing them with experimental measurements of heat flow using a calibrated hot

ISSN:0363-907X    

DOI:10.1002/er.4440060405

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractIn the present investigation the performance behaviour of thermosyphonic circulation solar water heaters using packed bed collectors has been analysed. Iron chips, gravels and stones have been used as packing materials. Average tank water temperature, collector as well as system efficiency and mony pay‐back for these packed bed solar water heaters are compared with those for solar water heater using a plane collector. Experimental results reveal that the performance of solar water heater improves appreciably by packing its collector with packing material. Among the packed‐bed solar water heaters tested the iron chips packed‐bed solar water heater gives the overall best perfor

ISSN:0363-907X    

DOI:10.1002/er.4440060406

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractThermochemical energy conversion at moderate or low temperature (>about 400°C) employing liquid phase components throughout a cycle is suggested as a promising concept for high‐efficiency conversion of various energy sources (e.g. solar or industrial waste heat) to a convenient chemical form. In particular, we propose liquid phase Diels‐Alder cycloaddition chemistry as an important class of reversible reactions for such low or moderate temperature thermochemical energy conversion systems. One of the important attributes of thermally driven Diels‐Alder reactions is their concerted mechanism, with consequent high yields and efficiencies relative to liquid photochemical systems. Since the systems we propose involve organic species, with thermal stability concerns above about 400°C, it is important to demonstrate equilibrium shift capability for the highly energetic reactions sought. We have therefore carried out experimental studies with model liquid Diels‐Alder systems that clearly demonstrate the degree of control over equilibrium available through substituent entropy effects. For example,Keqis unity at about 420°C (T*) for the anthracene/maleic anhydride system (in solvent) while a phenyl substituent on the anthracene or isopropyl substituent on the anhydride reduceT* to about 200°C at constant ΔH0. These results are of importance as regards subsequent systematic identification of Diels‐Alder reactions having ideal thermochemical and physical properties. We also have developed a rapid NMR technique for qualitative screening of candidate reactions, and have applied this technique to the study of various bicyclic diene/fumaric acid ester systems. Our paper further points to the need for better understanding of the catalysis likely required for these liquid phase Diels

ISSN:0363-907X    

DOI:10.1002/er.4440060407

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractThere has been considerable interest in the use of solar electrical converters for supplying electric drive motors in pumping schemes for rural areas. The optimum control of solar electric drive motors is desirable because it leads firstly, to higher apparent efficiency of solar energy conversion, and, secondly, to reduced cost per useful watt. Although the ‘fuel’ for solar drives is free, the cost of solar cells is high. Optimization means that smaller areas of solar panels are required, thus reducing the overall cost of the solar drive system. The present investigation has been directed towards the development of a reliable electronic controller, which would ensure stable and optimal performance characteristics of solar electric‐powered pumping scheme over a broad range of operating conditions. The design goals are low cost, reasonable accuracy, control capability and efficient utilization of the electrically converted solar power. The developed electronic optimizer provides constant voltage operation of the solar generator so that maximum power can be delivered to the drive motor for any light intensity. The main part of the optimizer is a servo chopper. The chopper operation is automatically adjusted so that the overall system efficiency is always maintained at a maximum value. Details of the electronic optimizer circuits are given and the overall system performance is investigated. Valuable information for the design and operation of the solar electric drive system with the electronic optimizer is gained from this ana

ISSN:0363-907X    

DOI:10.1002/er.4440060408

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractThis paper is the result of a survey of cities engaged in the Comprehensive Community Energy Program. It states the underlying themes of local energy analysis and summarizes methodology and conclusions reached in the various studies with special emphasis on economic methodologies.

ISSN:0363-907X    

DOI:10.1002/er.4440060409

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractStudies on simultaneous utilization of solar stills as a thermo‐concentration cell and as a distillation system have been reported. Cell characteristics have been studied. The electrical energy has been found to increase both with the increase in concentration of sodium chloride (salinity) and the temperature of the saline water. This two way utilization of solar stills has an added advantage that overall utilization efficiency of solar energy is increased against a nominal additional input. For application in rural areas where water needs treatment, (distillation) this extra electrical energy may make it more attractive. The possibility of application of such systems in the industrial sector has also been mentione

ISSN:0363-907X    

DOI:10.1002/er.4440060410

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractThe photovoltages and photocurrent in a photogalvanic cell containing flavin mononucleotide (FMN) and a reducing agent, ethylenediaminetetraacetic acid (EDTA) have been determined and found to be appreciable. The efficiency of the cell has been estimated to be ∼ 0‐048 percent. The electrochemical behaviour of FMN in the presence of EDTA has been examined by cyclic voltame

ISSN:0363-907X    

DOI:10.1002/er.4440060411

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY