A RADIALLY ROTATING HEAT PIPE AS A TEMPERATURE REDUCER IN AUTOMOBILE DISK BRAKE

摘要

The paper describes utilization of the correlation to predict heat transfer rate of the radially rotating heat pipe at vertical position found from quantitative study of the authors to design the RRHP to reduce the automobile disk brake temperature. The 15 tubes of RRHP of inner diameter 9.5 mm. with length of 100 mm. were installed on the disk brake employing ethanol as the working fluid. From calculation using the correlation, at a braking torque was 75 N-m, braking period was 10 seconds per times and the experiment time of 6 minutes, the RRHP can transfer the heat of 392.93 Watts with a efficiency of 0.54 which is lower than that of the calculation. This might be because in practice, the condenser length of each tube is not equal, since it depends on the available area of disk brake, but in a correlation the condenser length of each tube is equal and as same as evaporator length. Moreover, all the experimental results support the correlation of Waoweaw et al. as seen in equation (1) for the practical application of a RRHP.