摘要:

AbstractAn analytical study is made of the free and forced convection boundary layer flow past a porous medium bounded by a semi‐infinite vertical porous plate. Locally similar solutions are then obtained by a perturbation method for large suction. Solutions for the velocity and temperature distributions are shown graphically for various suction velocities and values of the driving parameterGr/R e2, whereGris the Grashof number andReis the Reynolds number. The corresponding values of the skin friction coefficient and the Nusselt number are finally shown in tabular f

ISSN:0363-907X    

DOI:10.1002/er.4440170102

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe thermal analysis of forced‐air cooling processes being of primary concern, an experimental and analytical study program was undertaken to investigate the heat transfer during the cooling of figs as spherical food products. The process conditions were analysed according to a mathematical model to gain a better understanding of the product's behaviour. The heat transfer between the product and air was influenced by conduction inside the product, convection outside the product, radiation, respiratory heat rate (internal heat generation), and moisture evaporation at the surface of the product. These situations were considered as three cases, such ash=hc, h=hc+hc, andh=hc, +hr+he. The four various air velocities of 1.1, 1.5, 1.75, and 2.5 m/s were applied in the experimental study. The results obtained by the mathematical model in the estimation of the heat transfer rates from the products were compared with the experimental data, and the best agreement was found for the third case (h=hc+hr+he). The fastest cooling was accomplished with the highest airflow velocit

ISSN:0363-907X    

DOI:10.1002/er.4440170103

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe experimental and predicted performance of a prototype heat pump assisted continuous dryer is reported. The dryer was shown to be capable of specific moisture extraction rates (SMERs) of between 1.5 and 2.5 kg/kWh using wetted foam rubber as the test material being dried. The results highlight the importance of maintaining conditions of high relative humidity within the air stream entering the evaporator; an increase in the relative humidity from 30 to 80% was shown to give a two‐fold increase in the SMER. An optimum evaporator bypass air ratio of between 60 and 70% was observed for this dryer. The effects on performance of deviations from this optimum condition were found to be less significant than had been indicated by earlier models. The predicted performance of the dryer using a simulation model developed previously by the authors was in good agreement with the corresponding measured value

ISSN:0363-907X    

DOI:10.1002/er.4440170104

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe paper reports the results of a simple cointegration analysis applied to bivariate causality models and quarterly data on crude oil consumption, GDP and inflation in Thailand to investigate the long‐term relationships in the sense of Granger between oil and these two major macroeconomic aggregates. For the period from January 1966 to January 1991, the empirical evidence indicates that oil consumption, output growth and inflation rate, as formulated in our models, are not random walks. In addition, oil consumption is significantly cointegrated with economic growth and, unfortunately, inflation rat

ISSN:0363-907X    

DOI:10.1002/er.4440170105

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

年代:1993

数据来源: WILEY

摘要:

AbstractIn the paper, the development of final energy consumption in Lithuania, on the basis of realistic economic scenarios, is investigated. The main parameters influencing the energy consumption are the gross national product (GNP) and the wholesale price of energy. Owing to the uncertainties in former socialist economies, these parameters are described as ‘fuzzy sets.’ The theory of fuzzy sets is used to study the influences that the prices of preceding periods have on the actual final energy consumption, with a quasidynamic model. In so far as this mechanism cannot be ascertained for Lithuania, experiences with other former centrally planned economies, which have already turned into a kind of market economy, are applied to give realistic projections for the transitory period. The underlying scenarios for the GNP and price developments are taken from official Lithuanian projections. The results of the fuzzy quasidynamic model are compared with the official final energy demand projections, to provide policy advice for a proper restructuring of the energy sys

ISSN:0363-907X    

DOI:10.1002/er.4440170106

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe work described in the paper is concerned with the measurement of the flow of tracer gas and aerosol particles in rooms. Measurements were carried out in single‐ and two‐zone systems using SF6tracer gas and oil‐smoke particles. Initial tests were carried out in a single‐zone system using different arrangements of window opening. Results indicated that tracer‐gas exchange rates were generally higher than particle exchange rates. This was due to the fact that the ventilation air entering the zone contained a significant concentration of particles but a negligible quantity of tracer gas. The exchange rates of tracer gas and smoke particles through a doorway were also measured in a two‐zone system. The doorway coefficients of discharge were calculated using a theory based on the Bernoulli equation. The coefficients of discharge for the opening were in the range 0.4–0.96 for tracer gas measurements and 0.15–0.42 for smoke‐part

ISSN:0363-907X    

DOI:10.1002/er.4440170107

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe performance of a novel device has been tested. The device can be used as a collector cum storage type solar water heater during the winter, and, with minor adjustments, it can be used as a hot‐box solar cooker. The device can provide hot water at 50–60°C in the evening, which can be maintained at 40–45°C until the following morning. It can also be used for cooking food for about 40 people. The efficiencies of the device as a solar water heater and as a solar cooker have been found to be 67.7% and 29.8%, respectively. The payback period varies between 1.64 to 5.90 years depending on the fuel it replaces. The payback periods are of increasing length with respect to the fuels firewood, coal, electricity, LPG and k

ISSN:0363-907X    

DOI:10.1002/er.4440170108

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe unsteady magnetohydrodynamic flow of a dusty, viscous, incompressible liquid in a rotating channel, in the presence of a transverse magnetic field with Hall currents, is considered. Analytical expressions for the velocities of the liquid and the dust particles are obtained. The effects of Hall currentm, and the rotation parameterKon the velocity are shown graphically, and are discussed.

ISSN:0363-907X    

DOI:10.1002/er.4440170109

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

年代:1993

数据来源: WILEY

ISSN:0363-907X    

DOI:10.1002/er.4440170110

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

年代:1993

数据来源: WILEY

ISSN:0363-907X    

DOI:10.1002/er.4440170101

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

年代:1993

数据来源: WILEY