摘要:

AbstractThe paper illustrates a method to derive the long run marginal cost (LMRC) of extracting light crude oil in Australia. This LMRC function is then used in the evaluation of domestic crude oil production operations in the context of changing world oil prices. The criterion for evaluation is economic rent. This criterion is applied in terms of two social objectives, namely economic efficiency and import reduction.

ISSN:0363-907X    

DOI:10.1002/er.4440140402

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe free convection boundary layer flow with simultaneous heat and mass transfer in a porous medium is studied when the boundary wall moves in its own plane with suction. The study also incorporates chemical reaction for the very simple model of a binary reaction with Arrhenius activation energy. For large suction, asymptotic approximate solutions are obtained for the flow variables for various values of the activation energy.

ISSN:0363-907X    

DOI:10.1002/er.4440140403

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe paper describes a simulation model developed to predict the performance of drying systems assisted by vapour‐compression heat pumps. The heat is used to preheat the air stream before it enters the drying chamber. Energy consumption is thus reduced, as the heat pump is capable of delivering more energy as heat than it in fact consumes as input work. Ambient air provides the heat source. A computer program, based on simplified modelling of components (compressor, heat exchangers and drying chamber) has been developed. Results have been produced for a typical application, revealing that a considerable reduction in energy consumption can be obtained with the use of a heat pump. The effect of air flow rate on system performance is also studie

ISSN:0363-907X    

DOI:10.1002/er.4440140404

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe paper shows that, in certain circumstances, wind convectors have economic and technical advantages over conventional fan‐assisted heat‐pump evaporators. This assessment compares wind convectors with conventional fin‐tube evaporators from energy, maintenance, capital cost and other viewpoints. Compared to conventional fan‐assisted heat pump evaporators, wind convector technology is estimated to provide energy savings of between 10 and 20%, maintenance savings of approximately 50% and a reduction of heat pump capital costs of approximately 10

ISSN:0363-907X    

DOI:10.1002/er.4440140405

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

年代:1990

数据来源: WILEY

摘要:

AbstractA finite‐difference solution of the transient free convection flow of water near 4°C past an infinite vertical porous plate has been carried out. The most appropriate relation for the density in terms of the temperature, as derived by Gebhart and Mollendorf, is employed. It has been observed that, when the buoyancy force is in the upward direction, the velocity profiles are positive and opposite to those in the case where the buoyancy force is in the downward direction. Also, the skin friction is more when the buoyancy force is in the upward direction than when the buoyancy force is in the downward directi

ISSN:0363-907X    

DOI:10.1002/er.4440140406

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe performance of two R‐11‐charged integrated solar water heater collectors was investigated experimentally for forced and natural circulation water flows. The heat transfer from the refrigerant loop to the hot water storage tank took place through a condenser of novel design integrated within the collector frame.The effect of the condenser inclination on the system efficiency was remarkable for natural circulation water flow but had no significant effect for forced circulation flow. The difference in thermal response between the refrigerant and water loops caused buildup of stored energy in the condenser. This energy affected the buoyancy forces and generated flow pulsation that caused a harmonic‐like variation of the system efficiency. This effect vanished with forced water circulation flow. The system efficiency varied between 20 and 50% depending on the solar insol

ISSN:0363-907X    

DOI:10.1002/er.4440140407

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe paper sets out, with reasons, the chosen values of the various parameters (air enrichment, air preheat temperature, magnetic field, duct length, duct velocity etc.) involved in the determination of the plant performance of a open‐cycle steam‐bottomed coal‐fired MHD generator. The effect on the overall cycle performance of varying the important parameters in the system is considered. Optimum values of the chosen parameters have been obtained for maximum overall plant effic

ISSN:0363-907X    

DOI:10.1002/er.4440140408

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

年代:1990

数据来源: WILEY

摘要:

AbstractBritish Coal, in collaboration with Senior Green Ltd., has incorporated a novel twin‐bed coal‐fired combustor into a 2.8 MWtwater tube boiler. The firing system comprises two interconnected shallow fluidized beds operated as a pyrolyser and a char combustor, respectively. Gas temperatures well in excess of bed temperatures are achieved when the hot gas streams from the two beds are mixed in a common chamber. Particular attributes of the system are high combustion intensity (without in‐bed tubes), inherently low NOxemission levels and wide turndown range (up to 10: 1). As part of the ongoing R&D programme, mathematical modelling techniques are being applied to provide a sound theoretical understanding of the physical and chemical processes occurring within the system. In order to assess the factors affecting scale‐up of the twin‐bed unit, Gloucestershire College of Arts and Technology (GLOSCAT), in collaboration with the Coal Research Establishment of British Coal, is currently developing a comprehensive mathematical model of the system.The paper describes one aspect of the system model, namely solids mixing. The application of simple analytic methods has been found useful to describe the process. Assuming uniform conditions in the vertical plane, mixing of coal and sand within a bed has been regarded as a diffusion process, and a system of ordinary differential equations have been established to predict carbon concentration and temperature profiles for each bed. Although a number of simplifying assumptions have been made, the models provide useful sensitivity analyses, allowing an assessment of the factors influencing scale‐up, e.g. the effect of mixing rate and char particle size on temperature profiles. Analytic solutions are presented, and the sensitivity analyses are illustrated using standard comput

ISSN:0363-907X    

DOI:10.1002/er.4440140409

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

年代:1990

数据来源: WILEY

摘要:

AbstractThis paper is concerned with the steady magnetohydrodynamical free convective flow through a porous medium of a viscous heat‐generating rarefied gas past a vertical plate when a strong magnetic field is imposed in a plane which makes an angle α normal to the plate. Expressions for the velocity and temperature fields are obtained, and the effect of Hall currents on the flow is studied for various values of α (angle) and δ (heat sou

ISSN:0363-907X    

DOI:10.1002/er.4440140410

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe hemispherical total emittance of a selective coating on a tubular absorber is determined from the heat‐loss factor obtained by an indoor test set‐up. For this an analytical equation has been developed for the heat‐loss factor of a tubular absorber with a concentric glass cover in the case of natural convection over the

ISSN:0363-907X    

DOI:10.1002/er.4440140411

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

年代:1990

数据来源: WILEY