Thermal performance of phase change material integrated heat pipe evacuated tube solar collector system: An experimental assessment

This manuscript presents an experimental investigation of heat pipe evacuated tube solar collector with and without phase change material for water heating application under the same weather conditions. In this study, a comparative analysis of two systems has been done in the same weather condition. Where evacuated tubes of the first system (evacuated tube collector-A) were left without phase change material and second system (evacuated tube collector-B) was integrated with SA-67 as phase change material. In order to ensure the thermal and chemical stability of the selected phase change material, thermal cycling treatment was carried out. The results showed that SA-67 has excellent chemical and thermal stability even after 1500 thermal cycling treatment. In order to analyze the thermal performance of the designed systems, the experiment was conducted with five different water flow rates (8, 12, 16, 20 and 24 L per hour). The daily thermal efficiency of evacuated tube solar collector with and without phase change material was varied in the range of 42-55% and 79-87% respectively. Although, the daily energy efficiency of evacuated tube collector integrated with phase change material was 37.56%, 35.31%, 36.69%, 32.34%, and 32.73% higher than evacuated tube collector without phase change material for water flow rates of 8, 12, 16, 20 and 24 L per hour respectively. The daily thermal efficiency for both systems was maximum at the flow rate of 20 L per hour. The heat transfer parameters for the designed systems have also been evaluated and compared.