experimentally study of thermal resistance coefficient in closed loop pulsating heat pipe and the effect of filling ratio and evaporator to condenser length ratio on it

In this paper, using experimental studies, the effect of volumetric filling ratio and evaporator and condenser length ratio on the performance of the pulsating heat pipe has been investigated using the response surface methodology. The surface methodology is a response to a set of statistical techniques and applied mathematics to construct experimental models with the aim of reducing experiments. In order to improve the performance of the pulsating heat pipe, the present study studies the minimum thermal resistance under the influence of two parameters. The pulsating heat pipe with general dimensions of 3 × 210 × 200 mm consists of four rounds of copper pipe with internal and external diameters of 2.4 and 3 mm, respectively. Experimental results show that the changes in thermal resistance in terms of the parameters of the volume filling ratio and the ratio of the length of the evaporator to the condenser, has a turning point before which the relationship between thermal resistance and each of the parameters will be inverted and then direct.