摘要:

AbstractAn experimental and numerical study of the transient non‐periodic wall heat transfer problem is presented. A computer‐controlled indoor/outdoor environment simulation system produces any desired variation of the air temperature, thus allowing measurement of the dynamic thermal behaviour of any test wall under the desired boundary conditions. Measurements of the temperature field within the wall, of the heat flow and of the convection coefficients at the wall surfaces are performed during step, ramp and cosine perturbations of the outdoor air temperature. The measurements are in very good agreement with the numerical predictions obtained by a developed finite difference solution procedure. The results showed that in building heat transfer applications, for example in air conditioning, the usual assumption of periodic outdoor conditions may lead to considerable errors in case of a significant temporary deviation of the temperature from periodic

ISSN:0363-907X    

DOI:10.1002/er.4440180602

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

年代:1994

数据来源: WILEY

摘要:

AbstractThe behaviour of a downdraft rice husk gasifier of diameter 200 mm and a height 940 mm has been studied. The gasification rate was varied in the range 1.8–4.3 × 10−2kg/m2s. The air velocity was varied in the range 0.032–0.099 m/s. The producer gas obtained from the gasifier has a calorific value in the range 3240–4382 kJ/m3. A set of theoretical kinetic equations on the assumption of nonequilibrium conditions has been developed and solved numerically. The simulated temperature profile and outlet gas composition have been compared with those obtained from experimental runs. The model developed from a mechanistic approach is found to explain the behaviour of the present system appreciably within the range of variables

ISSN:0363-907X    

DOI:10.1002/er.4440180603

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

年代:1994

数据来源: WILEY

摘要:

AbstractIn this paper the viscosity and thermal conductivity of both the liquid and vapour for the refrigerants R152a and R142b have been estimated and presented. Available properties of liquid thermal conductivity of R142b and R152a and the liquid viscosity of R152a are compared with the estimated values. It is found that the agreement is good. Transport properties of R142b, which is a potential replacement for R114 in medium temperature heat pump applications, is compared with that of R114. Also, the properties of R152a, which is considered as a possible replacement of R12 in refrigeration and low‐temperature heat pump applications, is compared with the properties of the other possible replacement of R134

ISSN:0363-907X    

DOI:10.1002/er.4440180604

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

年代:1994

数据来源: WILEY

摘要:

AbstractWe present a simple mathematical model of a heat‐pump‐assisted dryer developed from psychrometric processes. A term ‘contact factor’ is used in the theoretical model to characterize the drying chamber. The experimental data of the drying rates of different types of products are used to predict the values of the contact factor of the dryers. We examine the effect of various parameters such as the contact factor, air inlet conditions, and the moisture removal rate on the performance of the heat‐pump‐assisted dryer. It has been shown that the non dimensional contact factor of a dryer is insensitive to dryer air inlet temperature. Finally, a performance chart to guide the selection of the heat‐pump dryer component

ISSN:0363-907X    

DOI:10.1002/er.4440180605

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

年代:1994

数据来源: WILEY

摘要:

AbstractPresented in the paper is a brief description of the solar thermal water pump and its operation. The performance of such a solar water pump working on a flat‐plate collector of exposed area of 1 m2is studied for three different discharge heads, namely 6, 8 and 10 metres. The thermodynamic analysis reveals that, while the number of cycles and the quantity of water pumped per day decrease with an increase in the discharge head the overall efficiency increase

ISSN:0363-907X    

DOI:10.1002/er.4440180606

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.4440180607

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.4440180601

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

年代:1994

数据来源: WILEY