Abstract
The scope of this research is concerned with the calculation of flow and heat transfer characteristics in evaporating for the adjustment and control of the expansion valve. The pressure drop during evaporation was considered and discussion of the effects of using external equalizer expansion valve on the flow and heat transfer characteristics of evaporation was used to form the basic of design theories. This thesis discussed the effect of having different capacity and different volume pre-compression expansion valve on the entire refrigeration system. A trend formed from the experimental results and the calculation of numerical simulations is included. This allows the establishment of a complete research method to discuss the influence of efficiency with regulate of expansion valve for refrigeration system. The result included the data from the experimental measurements and observations made on the trend change of parameters with the rate of expansion valve opening in the system. In numerical simulation, there are separate deductions of mathematical equations for the evaporator、the expansion valve and the compressor as well as a complete refrigeration system consisting of these components. We also obtained calculations for the flow and heat transfer characteristics and the converged mass flow rate.The results revealed good agreement between numerical simulation and experimental measurements. The best absorption point is about in 4.5 ~ 5.5 degrees of closed (about in 0.72 ~ 0.88 of all opening rate).