Design and thermal performance evaluation of a new solar air collector with comprehensive consideration of five factors of phase‐change materials

Abstract

Solar air collectors are widely used for the heating of buildings in cold areas owing to their high light-heat conversion rate, non-freezing of air medium, and low manufacturing cost. However, the intermittency of solar energy conflicts with the user's comprehensive heating demands, thereby hindering the promotion of solar air collectors. To solve the above issue, in this study, a solar air collector model with a new heat storage device (Type 2) was designed by comprehensively considering five factors, such as phase-change temperature, heat storage capacity, heat transfer efficiency, heat storage time, and heat release time. Thereafter, the ordinary solar air collector model (Type 1) was compared with the Type 2 solar air collector. Comparative analysis of the thermal performance evaluation index revealed that the heat release time of the Type 2 solar air collector was approximately 15 h after sunset, and the heat storage time was only approximately 7.5 h. Compared with Type 1 solar air collectors and previousachievements, the average daily heat collection efficiency of Type 2 solar air collectors decreased by 20.08% and 16.58%. The findings of this study indicate that the Type 2 solar air collector has a good effect in terms of heat storage time, heat release time, and heat peak migration, and is thus conducive to solving the contradiction between the intermittence of solar energy and user's comprehensive heating demands.comparative experimental method, evaluation index comparative analysis method, phasechange materials (PCMs), solar air collector, thermal performance | INTRODUCTIONResidential houses are mainly single-family houses with three or less floors in rural areas. As some rural houses are far away from towns, their heating infrastructure is poor, and is associated with scattered distribution and Abbreviations: DAHCE, daily average heat collection efficiency; DSC, differential scanning calorimeter; IHCE, instantaneous heat collection efficiency; PCMs, phase-change materials; PCM-SAHPHS, solar air heat pump heating system with Phase change materials.