Experimental investigation of new single- and dual-purpose solar heating system

In this study، a single-purpose water heating system is experimentally compared to a dual-purpose air and water heating system at the same conditions. The system consists of a dual-purpose flat plate solar collector and a vertical water storage tank which operates at no removal condition. Air and water flow naturally and forcefully inside the collector، respectively. The aim of using dual-purpose systems is to reach greater efficiency and reduce heat loss. These systems can be used for simultaneous heating of air and water. The hot water can be used as domestic hot water and in heating systems. Besides، the hot air can be used in dryers and air conditioning systems. Therefore، application of such systems will result in high energy saving. In this study، variation of collector temperature، average storage tank temperature، and system efficiency at two different air flow rates at different times are presented. Moreover، hourly efficiency is compared for single-purpose and dual-purpose systems. The results indicate that the average efficiency was 67. 8% for the single-purpose system. Furthermore، the average efficiency was 71. 6 and 72. 3% at air velocities of 2. 8 and 3. 2m/s، respectively.