Research On The Controllable Separate Heat Pipe And Its Application In The Cool-storage Refrigerator

The cool-storage technology has been widely applied in the novel energy-saving refrigerators,including cool-storage and solar refrigerators.The accurate heat transport between the cool-storage component and the fresh food compartment and the precise temperature control are the key technologies.Separate heat pipe is a two-phase heat transfer component and is considered simple and low-cost.This thesis put forward the controllable separate heat pipe(CSHP,or controllable loop thermosyphon),which can actively control the heat transfer rate of separate heat pipe by regulating its inner flow and heat transfer cycle.Therefore,the separate heat pipe is upgraded to an active temperature control component with high accuracy.The CSHP is not only promising in improving the precision of temperature control and the efficiency of cool-storage refrigerators but also potential for realizing efficient and accurate temperature control technologies.This thesis aims at the application research on controllable separate heat pipes under the background of refrigerator,the main achievements are outlined as follows:1.The CSHP is proposed,and the test system for CSHP is built;the operating condition in steady state is optimized based on the simulated and experimental research.On this basis,the impact of the non-condensable gas(NCG)is tested.When the filling ratio of R134a reaches 38.9%,the heat transfer capability of CSHP is optimal;the experimentally fitted value reachs 384.6 W.2.The heat transfer start-stop behaviours are preliminarily verified and the impact of the control mode is studied.Resultes show that the CSHP can sart up in 10?25 s,shut down in 70 s,and re-start up quickly when the filling ratio is suitable.Even the NCG amount increases to 0.31%,a start-stop cycle of CSHP is still within 2 min.3.A test platform for CSHP with a reservoir is designed and fabricated.The impacts of reservoir on the heat transfer performance in steady state and on the heat transfer control are tested.Then,the location of the control valve is optimized.The reservoir stabilizes the heat transfer condition of CSHP;however,it decreases the stability of start-stop control when the filling ratio is low.When the filling ratio is 62%,the control mode C,which use control valves at low position,shows the best start-stop behaviour;the start-up and stopping time reaches 25 s and 80 s,respectively.4.A fresh food compartment cooling system with the CSHP is designed and built.The filling amount of R 134a is optimized and the heat transfer and start-stop behaviours of CSHP are verified.The temperature adjustment and precise control of the fresh food compartment are systematically tested.When the ambient temperature is 16?,the optimal filling ratio is 35%;the average temperature of fresh food compartment is discretionarily regulated within 2-8? and the maximum temperature fluctuation can be reduced to 0.4 ?.The precise temperature control performance of the system is obviously higher than the traditional direct-cooling refrigerator.5.Based on the research on the start-stop control of CSHP,the method to adjust its heat transfer is proposed,the test platform is constructed.The behaviors under static and dynamic adjustment modes are examined and analyzed within the opening angle range of 30?180°.The maximum ratio of heat transfer adjustment is approximately 85%.The heat transfer adjustment capability of CSHP is reliable.