Theoretical and Experimental Investigation on Characteristics of CO_2 Mechanically Pumped Two Phase Cooling System

The two-phase mechanical pumped cooling loop(MPCL)by using CO_2 as the working fluid is a promising thermal control system which is just like a heat pipe to realize heat extraction from ener-electrical equipment by phase change efficiently.A brief review of system design and work principle was presented and a proposed experimental system was described.In order to apply CO_2 as a high quality work fluid,tests are performed to clearly comprehend its capability and to characterize the operation in different conditions.Special attention is paid to the system dynamic working characteristics under different conditions such as variation heat load and mass flow process.According to the experimental findings,the transient liquid transfer between the main loop and accumulator is analyzed to explain the temperature or pressure fluctuation in the accumulator and evaporator.It is concluded that the work fluid flowing into or out of the accumulator causes the absolute pressure and the temperature fluctuate in the accumulator,and the evaporator temperature would change as the following.At last,some characters were analyzed,it is demonstrated that a CO_2 MPCL presents a good performance and has more stable and robust characteristics for the special operation than the system by using other work fluid.