Storage periods and heating terminals types influence on the solar heating thermal storage volume in the Tibetan Plateau regions

Abstract

The scale of the thermal storage system is critical to balancing system fluctuations caused by the mismatch between solar heat collection and heating load in time and space for solar heating systems. This study investigates the relationship between solar collector area and heat storage volume under the different storage periods and heating terminals types. This research simulates the heat storage volumes using a typical day, continuous overcast days, and heating period as thermal storage periods, based on solar radiation intensity, building heating load, and cloudy days in seven typical Tibetan regions. According to the results, the storage volume per unit collector area Vs/Ac increases with increasing temperature difference and storage period in the Tibetan Plateau. It is proposed that Lhoka, Chamdo, Nagqu, Lhasa, Shigatse, and Nyingchi take continuous overcast and cloudy days as thermal storage periods, and Ngari uses the heating period as thermal storage periods, corresponding to the Vs/Ac ranges of 0.27 m3/m2–0.9 m3/m2 and 1.6 m3/m2–1.8 m3/m2. Specifically, preheating the heat storage tank can improve the solar fraction fsim by 2.5 %, with the recommended preheating temperature of 50 °C. In addition, the variation equation for design solar fraction fn and Vs/Ac was obtained. These results can be utilized to develop solar heating systems on the Tibetan plateau.