Peng Ju

Experimental Study on Heat Transfer Characteristics of Separated Type Heat Pipe

Separated heat pipe is an efficient passive heat transfer device. It is widely used in chemical and aerospace industry. In this paper, the heat transfer characteristics of the separated heat pipes which applied to containment cooling system were studied. According to the experimental data, the influences of the system pressure, the initial vacuum degree of the system, and the system resistance coefficient on the heat transfer capability of the separated heat pipes were analyzed. Based on the theoretical analysis, the correlation for the natural circulation flow rate of the system was obtained. Relative errors of experimental test data were less than ±20 %. Comparing the experimental data with the calculated results, it shows that main parameters that affect the heat transfer capability of the heat pipe loop are system state parameters (including system pressure, the temperature difference between heat source and heat sink as well as the resistance coefficient) and system boundary conditions (including noncondensable gas percentage and system boundary pressure). Natural circulation flow rate increases with the increase of the system pressure and the initial vacuum degree of the system.

Annular Flow Interfacial Shear Stress in Pipes

Annular flow is of essential importance in studying critical heat flux during dry out. In annular flow, interfacial shear stress is an important parameter in pressure gradient calculation and modeling of two-fluid model. In this paper, first, the form of interfacial shear stress to the interfacial friction factor has been defined. Then based on the former researcher’s derivation, the interfacial shear stress’s calculation has been given with some reasonable assumptions. Finally, the weights of each term’s effect on the interfacial shear stress have been calculated and the pressure drop term is found to be the dominant forces.