EXPERIMENTAL INVESTIGATION AND LIFE-CYCLE COST ANALYSIS OF A MULTI-PIPE ARRAY HEAT STORAGE SYSTEM USING PHASE-CHANGE MATERIALS FOR SOLAR GREENHOUSE HEATING

Abstract

To simplify the structure of accumulator and enhance the utilization of phase-change materials (PCM), this paper presents the development, experimental investigation, and life-cycle cost of a novel phase-change heat storage system with multi-pipe array type for greenhouse heating. The platforms of single accumulator performance evaluation and multi-pipe array storage system performance evaluation were established in the paper, and the life-cycle cost analysis was also studied in contrast to the PCM wallboard storage system and coal-fired heating system. It was found from the experimental investigation that the blackened coating treatment of PVC pipe could improve the thermal storage capacity by 66.7% compared to the original surface after 6 h of sun exposure. The preferred package size in multi-pipe array system was 75 mm in diameter under an illumination time of 6 h and long-lasting heat release (> 10 h), which not only guaranteed higher thermal storage capacity and transformation ratio but also maintained long-term heat discharge. The PCM loading capacity of 1560 kg can raise the night temperature by 1.6°C in the multi-pipe array storage system performance evaluation experiments under ambient temperature range of -18°C-+5&#176C. Due to its cost-effectiveness in terms of both system operation and initial investment, the life-cycle costs of the multi-pipe array system were USD1606, which was only 63.2 and 31.3% that of the wallboard system and coal-fired heater, respectively.