Simulation Study on Characteristics of Separated Gravity Heat Pipe Based on Nocturnal Radiative Cooling PCM Wall
The nocturnal radiative cooling PCM(Phase Change Material)wall can effectively use natural cooling sources to reduce the energy consumption of buildings for cooling as well as carbon emission,serving as one of the effective means for building energy efficiency.Separated gravity heat pipe is an important part of the heat transport of the wall system,and its heat transfer characteristics directly affect the thermal performance of nocturnal radiative cooling PCM walls.In this paper,a two-dimensional numerical model of the separated gravity heat pipe was built using the VOF method.The thermal and flow characteristics of the heat pipe under the thermal boundary of the wall system were simulated and analyzed.Results show that when the boundary of 28 ℃ at the evaporation end and 22 ℃ at the condensation end,the overall temperature of the working fluid inside the heat pipe in the equilibrium state is about 26.4 ℃.The heat exchange can reach 524 W/m2 and the flow speed of the working fluid is about 0.2 m/s.The influence of different evaporation/condensation temperature differences on the heat transfer effect was further studied.The larger the temperature difference,the better the heat transfer effect of the heat pipe.
nocturnal radiative cooling phase change material wallseparated gravity heat pipebuilding energy efficiencythermal characteristicVOF model