摘要:

AbstractKinetic parameters, the pre‐exponential factor and the activation energy, of two Thai lignite char of different ash contents and electrode carbon have been experimentally determined based on the Semenov's thermal ignition theory adapted to single particle ignition. Combustion rate constants obtained have been comparatively plotted with those from Field's correlation (1969). Results indicated that the reaction rate coefficient for lignite char approaches value estimated from Field's equation at temperature about 850

ISSN:0363-907X    

DOI:10.1002/er.4440180402

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

年代:1994

数据来源: WILEY

摘要:

AbstractAn analysis for steady‐state heat transfer between an underground vertical infinite cylindrical structure and ground is presented, and is used as a direct method to evaluate conduction shape factor for the structure. Numerical values of the shape factor have been determined after solving the transcendental equation involved here, subject to some valid approximation, and found to converge to a finite value. The convergence has also been verified by studying the numerical values of the shape factor for different length:radius ratio of the cylindrical structure and the result is convincin

ISSN:0363-907X    

DOI:10.1002/er.4440180403

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

年代:1994

数据来源: WILEY

摘要:

AbstractIn the present analysis the thermal performance of a parallel earth air‐pipe system has been evaluated in terms of annual heating and cooling potential. The influence of the pipes on each other's thermal performance has been considered. The effect of seasonal variation of environmental parameters (ambient temperature, solar radiation, relative humidity, earth temperature etc.) has been considered. The results are obtained for the hot‐dry climate of Jodhpur and the composite climate of Delhi. From the various possible earth surface treatments to increase the effectiveness of earth storage systems for air conditioning purposes, the results are presented for wet‐shaded earth surface conditions, the most effective earth surface treatment for the climate considered. Thermal performance of the parallel air‐pipe system is evaluated for the two cases. In the first case, inlet air temperature to the pipes is taken to be the hourly mean of the ambient air temperature of the average day of each month, and, in the second case, the inlet air temperature is taken to be equal to that of a conditioned room whose set‐point temperature varies from month

ISSN:0363-907X    

DOI:10.1002/er.4440180404

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

年代:1994

数据来源: WILEY

摘要:

AbstractFreeze‐drying has received renewed interest in connection with biotechnology, food preservation and chemical industries. Freeze‐drying under reduced pressure causes sublimation to occur. Simultaneous freezing of the moisture phase couples the two processes of freezing and sublimation and creates a self‐driven process without need for any additional application of external energy other than that required to lower the surface temperature and pressure initially. A mathematical model consisting of coupled diffusion equations describing thermal and mass equilibrium in the solid‐liquid and solid‐vapour regions is solved analytically. The liquid‐solid region is included with unknown freezing interfacial conditions. The effects of various parameters, such as conductivity ratio, latent heats, initial concentration, surface pressure and surface temperature, are examined with respect to the freezing and sublimation rates. The freezing rate is faster than the sublimation rate, though slower than the corresponding rate for constant freezing temperature. The freezing temperature is higher than the sublimation temperature for a constant compositi

ISSN:0363-907X    

DOI:10.1002/er.4440180405

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

年代:1994

数据来源: WILEY

摘要:

AbstractThis paper describes an integrated energy system planning approach for Wardha District in Maharashtra State, India, for the year AD 2000 and gives an optimal mix of new/conventional energy technologies using a computer‐based mixed integer linear programming model. The district level planning is accomplished by successively applying in two stages a new statistical extrapolation technique for moving first from the village level energy scenarios based on surveys to the corresponding energy scenarios at the block level and then for moving next from the block level scenarios to the desired district level planning profile. The model is suitably scaled for obtaining the optimal results at the district level owing to limitations on the available memory on the PC‐AT system in use. Energy options for seasonal crops have been considered explicitly in the model. Post‐optimal analysis based on a linear programming model to study the effect of the variations in parameters on the optimal solution has been perf

ISSN:0363-907X    

DOI:10.1002/er.4440180406

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

年代:1994

数据来源: WILEY

摘要:

AbstractDrying of agricultural products is an energy‐intensive operation. High prices and shortages in fossil fuels increase the emphasis on using solar energy as an alternative energy source, especially in developing countries. In this respect, a new solar dryer, which consisted of a solar air heater and a drying chamber, was developed and used for drying various fruits and vegetables, i.e., sultana grapes, green beans, sweet peppers and chilli peppers and was successfully tested. In order to make a comparison, the traditional sun‐drying experiments were employed. Results showed that the solar dryer reduced the drying time significantly and prevented mass losses, and essentially provided better product qual

ISSN:0363-907X    

DOI:10.1002/er.4440180407

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

年代:1994

数据来源: WILEY

ISSN:0363-907X    

DOI:10.1002/er.4440180408

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

年代:1994

数据来源: WILEY