CALCULATION OF THE THERMAL PERFORMANCE OF SMALL HOT WATER SOLAR HEATING SYSTEMS USING LOW FLOW OPERATION

Abstract

ABSTRACT Experiments have shown that small solar heating systems using low flow operation and a hot water tank with an enclosing mantle perform extremely well. A detailed mathematical model simulating the thermal behaviour of such solar heating systems has been developed and validated by means of indoor experiments with a mantle heat storage. The yearly thermal performance of different designs of and operation strategies for small low flow solar heating systems have been calculated. By use of the model it is possible to optimize the design of the system, the operation and control strategy of the system. The calculated thermal performance of the low flow system is compared to the calculated thermal performance of a traditional solar heating system using a normal flow rate. The calculated increase of thermal performance of the low flow system is somewhat smaller than the measured increase of the thermal performance. Therefore, work is still necessary in order to validate the developed model by means of experiments with a complete solar heating system.