Experimental Study on Heat Transfer Performance of Separated Heat Pipe Heat Exchanger in Communication Base Station

Communication base stations are facing the problems of uneven heat dissipation and high energy consumption of the heat dissipation systems. The separated heat pipe heat exchanger can replace air-conditioning in communication base stations and effectively reduce the energy consumption of base station heat dissipation systems. The heat transfer performance of separated heat pipe heat exchanger is affected by factors such as filling ratio, working fluid type and air volume. In order to study the influence of different factors on heat transfer performance, the difference between theoretical filling ratio and the actual filling ratio was analyzed through theoretical calculation. The experimental platform was built to study the heat transfer performance of heat exchanger under different filling ratios, the difference of heat exchanger performance under different high and medium temperature working fluids, and the influence of indoor and outdoor fan power change on heat exchanger performance. The study finds that when the working fluid R134a is used, the error between the theoretical value and the actual value of the minimum filling ratio is 4.74%, the optimal filling ratio range of the heat exchanger is 27.1%~47.9%, the optimal filling ratio is 31.6%, and the equivalent heat transfer coefficient of the heat exchanger under the optimal filling ratio is 909 W/℃. With the increase of filling ratio, the phase change area inside the heat exchanger increases first and then decreases, and the heat transfer form changes from sensible heat transfer of vapor working fluid to latent heat transfer of the phase change of the working fluid, and then to sensible heat transfer of the liquid working fluid. The high temperature working fluid is not suitable for the separated heat pipe heat exchanger. When using the high temperature working fluid, there is no obvious phase change area inside the heat exchanger. The lower the boiling point of the working fluid is used, the larger the phase change area, the better the performance of heat exchanger, and the larger the range of its optimal filling ratio. With the increase of power of indoor and outdoor fans, the performance of the heat exchanger increases rapidly and then slows down. However, due to the poor heat dissipation conditions on evaporator side, the improvement of the heat transfer performance of the system by increasing the power of internal fan is more significant than that of the external fan.