Effects of non-condensable gas on the performance of oscillating heat pipe, part I: Theoretical study

In this paper, we investigate the effects of non-condensable gas (NCG) on the phase change phenomena, flow characteristics of liquid slugs-vapor plugs, pressure difference of heating-cooling section and heat transfer performance of oscillating heat pipe (OHP), theoretically through simulation. In the simulation, the NCG is assumed to be un-dissolved in the liquid slugs. The NCG is also assumed to be perfectly mixed with vapor, as form of plugs. The simulation results show that NCG decreases the pressure difference between heating and cooling section, which means the decreasing of driving force. The decreasing of driving force due to the decreasing the total amount of condensation, which means that NCG disturbed the condensation phenomena. Finally, the heat transfer performance of OHP also decreases due to the decreasing of driving force. Compared with the other types of heat pipe from previous studies, the effects of NCG in the OHP is smaller than that in the loop heat pipe and conventional heat pipe.