农业基站室外自然冷能微热管阵列式空冷器性能

针对农业生产服务基站内通讯及储备电源等设施发热量高的问题,该文设计了一种基于微热管阵列的室外空冷器,在北方冬季及过渡季节利用自然冷能对通讯基站散热降温,节能降耗。利用多功能气候实验室模拟不同的室外环境温度,对空冷器在不同流程(顺流和逆流)和不同温度及流量下的换热性能、温度分布、?效率及阻力特性等进行分析。结果表明:逆流式空冷器的换热性能相较于顺流式提升了16.9%。微热管阵列传热单元具有优良的导热性能和均温性能。试验过程中空冷器最大换热量为7.5 kW,空气流动的平均压降为164.9 Pa,水循环管路平均压降为7.96 kPa,?效率最高为38.8%,相较于常规冷却塔,微热管阵列式空冷器适用环境温度范围广且阻力较小。与平直翅片的板翅换热器的流动特性与阻力特性对比结果表明,本文锯齿形翅片的空冷器综合性能提升了36.1%。研究结果可为微热管阵列式空冷器在农业基站的应用提供参考。

Performance of outdoor natural cooling microheat pipe array air cooler for agricultural base station

The requirement of integration and heat dissipation of communication equipment and reserve battery in agricultural base station is getting higher and higher. High temperature affects the stability of server equipment operation which reduces the comprehensive performance and service life of the equipment. In order to solve this problem, air conditioners with enough redundancy need to operate continuously to ensure the normal operation of equipment. In order to maximize the use of natural cold energy to reduce the huge energy consumption of air conditioners in winter and transition season, this research proposed a new type outdoor natural cooling air cooler(NCAC),which is composed of micro heat pipe array(MHPA) with serrated fins.The serrated fins are used to increase the air convective heat transfer area, and to enhance air disturbance and heat transfer.The parallel flow tube with tiny porous channel(PFT) is used to increase the water heat transfer area and contact area to reduce the thermal resistance. Under different outdoor environment temperature,the performance of NCAC under different flow processes(downstream and countercurrent), inlet temperature, water ? ow rate and air flow rate were separately investigated, the heat transfer performance, temperature distribution, exergy efficiency and resistance characteristics were also analyzed. Results showed that there was little heat loss between air and water side of NCAC, the heat loss rate was under 11%.The heat transfer performance of NCAC of countercurrent process was better than that of downstream process, the maximum heat exchange rate was 7.5 kW of countercurrent process, which is increased by 16.9% than that of the downstream process.For the NCAC of countercurrent process, the temperature distribution uniformity of the micro heat pipe array was better, and the maximum vertical temperature difference in the condensation section of the heat pipe was 1.03 ℃. The temperature difference between the evaporation section and the condensation section was 6.96 ℃, the equivalent thermal conductivity reached to 1.72×104 W/(m · K). The pressure drop of the air side and water was at a low level, the maximum resistance of the air was 345.5 Pa, and the maximum resistance of the water was 8.92 kPa. The highest exergy efficiency researched 38.8%, the heat transfer capacity of NCAC still has large space for improvement. The average energy efficiency factor was over 17.2, the air cooler was in a better operation state. The experimental values of heat transfer factor and friction factor were obtained according to the test of NCAC with serrated fins, the average value of comprehensive evaluation index was about 0.049,which increased by 36.1% compared to the plate fin heat exchanger with plain fins. The experimental results show that with the increase of air flow, the increase of pressure drop is greater than the increase of heat transfer rate, and various factors must be considered comprehensively in the process of heat transfer enhancement. The research results can provide reference for design calculation, model simulation and practical application of air cooler used in base station.