螺旋管式相变蓄热过程的数值模拟与系统优化

对地源热泵供热系统中，利用低谷电蓄能的相变蓄能装置进行研究，以提高供热系统的经济性．在研究中对相变材料蓄热装置结构进行改进，提高了相变材料蓄热能效．利用相变材料能量守恒原理，确定合理的边界条件，对蓄热工况的传热过程进行了三维数值模拟优化．模拟结果显示，当蓄热初始条件相同时，不同装置结构中相变材料发生相变的程度会不同，出现死区的面积也不同；结合相变材料传热特性和过程，通过改进装置结构，采用螺旋管中间连通直管段的圆柱体蓄热装置，改善了蓄热效果，解决了相变材料熔化过程存在死区的问题，相变材料熔化率由原来的72％提高到93％，蓄热总量有了明显提高．同时还对采用低谷电蓄热、高峰用能放热的经济性进行了分析．结果表明采用相变材料蓄热可充分利用谷电，节约运行成本，具有良好的经济性．

Numerical Simulation and Optimization of Phase Change Heat Storage Process with Spiral Pipe

To improve the economy of ground source heat pump heating system, the phase change material （PCM） energy storage equipment using off-peak power was researched in this paper. In course of research, the structure of PCM energy storage equipment was ameliorated, so the efficiency of PCM was increased. A three-dimensional heat transfer simulation was set up by using energy conservation methods and determining reasonable boundary condition. The simulation results show that in the same initial operating condition, when the structures of PCM energy storage equipment are different, the dead areas （no or less phase change area） and phase change processes are different too. The structure of spiral pipes with a straight pipe in the center was confirmed better. Its heat storage efficiency was higher and dead area was smaller. The melting rate of PCM increased from 72% to 93%. In addition, the economy of heating system using PCM energy storage equipment was analyzed, with heat storied in off-peak time and discharged in peak time. The results show that the system can make full use of the off-peak electricity and save electricity running cost. The economy is good by using PCM heat storage device.