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Performance study of a partitioned thermally stratified storage tank in a solar

Performance study of a partitioned thermally stratified

storage tank in a solar powered absorption air

conditioning system

Z.F.Li,K.Sumathy *

Department of Mechanical Engineering,University of Hong Kong,Hong Kong

Received 20September 2001;accepted 21February 2002

Abstract

Accurate modeling of solar heating or cooling with storage generally requires an accounting of the stratification within such storage tank,since overall system performance is significantly affected by the storage temperature distribution.In this study,a simple one-dimensional multi-node approach,taking into account of the axial heat conduction between nodes,has been used to theoretically analyze temperature stratification in the thermal storage tank.The results indicate that,for less collector area,the heat removal factor plays a major role in increasing the system performance,than the thermal stratification.Also,an optimum ratio of tank volume over collector area exists for a solar powered absorption air conditioning system.This paper also reviews the state of the art on different kinds of variable inlet design,and a simple new inlet design (partitioning the tank)has been introduced to effect better thermal stratification in storage tank.Ó2002Elsevier Science Ltd.All rights reserved.

Keywords:Stratification;Partitioned storage tank;Solar energy;Absorption air conditioning

1.Introduction

The efficiency of thermal energy systems can usually be improved by providing storage for hot and cold water depending on the load [1].For conventionally operated large air-conditioning systems,utility costs may be considerably reduced by operating the equipment at night,when off-peak electricity rates are low,and make use of the chilled water that w
as stored during the night to meet the next day’s load demand.Likewise,the performance of the entire solar

The efficiency of thermal energy systems can usually be improved by providing storage for hot and cold water depending on the load [1].For conventionally operated large air-conditioning systems,utility costs may be considerably reduced by operating the equipment at night,when off-peak electricity rates are low,and make use of the chilled water that was stored during the night to meet the next day’s load demand.Likewise,the performance of the entire solar

Performance study of a partitioned thermally stratified storage tank in a solar

cooling/heating Applied Thermal Engineering 22(2002)

Performance study of a partitioned thermally stratified storage tank in a solar

1207–1216

*Corresponding author.Fax:+852-2858-5415.

E-mail address:ksumathy@hkucc.hku.hk (K.Sumathy).

1359-4311/02/$-see front matter Ó2002Elsevier Science Ltd.All rights reserved.

PII:S1359-4311(02)00048-0

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Sumathy, Performance study of a partitioned thermally strati?ed storage tank in a solar powered absorption air conditioning system, Applied Thermal Engineering...