Heat Transfer Characteristics of Evaporator Section for Separate-Type Heat Pipe
Wang Jianwei, Cao Zidong, Zheng Puyan, Zhu Changxin
(Xi'an Jiaotong University, Xi'an 710049, China)

Abstract: Using a large-scale model, an experiment is conducted to obtain the heat transfer characteristics of the horizontal evaporator section. The same is carried out for evaporator section with small in  clination angles of a separate type heat pipe. The wall temperature distribution  and heat transfer characteristics are obtained. Studied are the effects of heat flux, working temperature, inclination angle, and quantity of actuating medium on  heat transfer. The worse heat transfer is obtained in comparison with the vertical evaporator where the top and bottom wall temperature difference increased when the value of heat flux exceeds 20 kilowatts per square meter. The top wall temperature has a large fluctuation along the axes of the evaporator tubes, resulting in a reduction of heat transfer coefficient at the top wall and making the dry-out heat flux occur earlier, such that the work area of heat pipe is limited. In addition, an empirical dimentionless correlation is developed for the heat transfer coefficient of horizontal evaporator section.
Keywords: heat transfer;separate-type heat pipe;experimental investigation