The efficient collection and long term storage of solar energy in the UK, using air as the working fluid

Abstract

This thesis describes the results of four years work on the design, construction, testing and evaluation of a high performance air heating collector designed to supply heat to a communal interseasonal store, which could heat many houses all the year round in the U.K. Interseasonal storage utilizing a pebble bed was investigated but shown to be costly both in terms of money and energy. The performance of medium to high temperature storage is shown to improve with high performance collectors. The level of insulation specified in the 1978 Building Regulations is found to be inadequate for solar heating with long and short term storage, because it is more economic to add more insulation than to install solar heating. While investigating the interseasonal storage of solar energy in pebble beds, data on the design and operation of air heating solar collectors was found lacking. Therefore the development and testing of both a high and low performance solar air heater was undertaken. The standard methods of testing collectors and in particular high performance collectors are shown not to provide an adequate method of comparing the daily efficiency of various types of collectors. Methods of testing air collectors are presented under transient conditions more representative of collector operation in the U.K. The parameters affecting high performance collectors are examined, in particular the reduction of heat loss between cover and absorber, and the effect on performance of diffuse and transient radiation. Results are also presented for testing a low cost plastic collector