严寒地区单体建筑太阳能-相变墙系统蓄热特性研究

Study on thermal storage characteristics of solar energy-phase change wall system in single building in severe cold region

利用太阳能对水加热并通入相变墙进行蓄热,对减少严寒地区单体建筑供热能耗有重要意义。以大庆市某单体建筑为例,结合该地区太阳能分布特点及建筑热负荷大小,对适用于该地区的太阳能-相变墙系统进行集热与储热能力计算,并采用CFD方法研究单一工况下该系统的热工变化规律及不同热水参数、换热管规格对相变墙蓄热特性的影响。结果表明:该相变墙热稳定性良好,但受自然对流影响,底部相变材料熔化较慢;管径DN25、入口流速0.3 m/s、供水温度310.15 K、回水温度309.15 K、管间距107 mm时可使相变材料在4 h内完成蓄热,平均节能率为31.8%。研究结果可望为降低严寒地区建筑供热能耗提供新思路。

It has a great significance to reduce heating energy consumption of single building in severe cold region by using solar energy to heat water which flows into the phase change wall for heat storage. Taking a monomer building in Daqing as an example, combining with the distribution characteristic of solar energy and the heat load of the building in this region, the solar-phase change wall system was established and the capacities of collecting heat and storage heat had been calculated. The CFD method was used to simulate thermal variation of the system under single working conditions and the heat storage characteristics of the phase change wall under different water parameters and heat transfer tube specifications. The results show that the phase change wall has good thermal stability, but the bottom phase change material melts slowly due to natural convection. And the PCM can completely melt within 4 h when the diameter of pipe is DN25, the inlet flow rate is 0.3 m/s, the water supply temperature is 310.15 K, the backwater temperature is 309.15 K, and the space of pipe is 107 mm. The average energy saving rate is 31.8%. The research results are expected to provide new ideas for reducing the energy consumption of building heating in severe cold regions.