EXPERIMENTAL STUDY OF A COMPACT SOLAR COLLECTOR

The performance of a compact solar collector based on latent heat storage is investigated experimentally. In this collector the absorber plate-container unit performs the function of absorbing the solar energy and storing phase change material (PCM). The solar energy is stored in paraffin wax that is used as a PCM and is discharged to cold water flowing in pipes located inside the wax. The collector's effective area is assumed 1m² and its total volume is divided into 5 sectors. The experimental apparatus is designed to simulate one of the collector's sectors, with apparatus-absorber effective area of 0.2m². Outdoor experiments are carried out to demonstrate the applicability of using a compact solar collector for water heating. A total of 20 thermocouples are used to record the temperature variation of PCM. The time wise temperatures of the PCM are recorded during the processes of charging and discharging together with the solar intensity. Experiments are conducted for different water flow rates of 0.0083 to 0.0217kg/h m² and the useful heat gain (Qu) is calculated. The effect of the water flow rate on (Qu) is studied. The heat transfer coefficients are calculated for the charging process. The propagation of the melting and freezing front are studied during the charging and the discharging processes.

Experimental results show that in the charging process average heat transfer coefficient increases sharply after increasing the melt layer thickness as the natural convection grows strong. The local heat transfer coefficient is a strong function of distance from the top of the wax container as well as the time. In the discharge process the useful heat gained increases as the water mass flow rate increases.