Study On The Performance Of Liquid-vapor Separation Plate Condenser

During the condensation process in the plate condenser,the refrigerant vapor gradually condenses into liquid.Due to gravity,a large amount of condensate will accumulate in the lower part of the plate condenser.The liquid film becomes thicker and the thermal resistance increases,which leads to the decreasing of heat transfer coefficient and increasing of the pressure drop.This research applies the liquid-vapor separation condensation into the plate condenser.The multi-paths liquid-separation plate condenser is proposed.The condensate is discharged between the plates,reducing the accumulation of condensate and the thickness of the liquid film.Therefore,the vapor quality of the next path is improved,resulting in the heat transfer enhancement.Moreover,due to the discharged condensate,the mass flow rate is reduced,leading to the decreaing of pressure drop.As a result,the performance of the plate condenser is effectively improved.This research contents is addressed as following:Firstly,the structures of a liquid-separation plate condenser with multi-path(two paths,three paths,and four paths)are proposed.The mathematical model of the multi-path liquid-separation plate condenser is established,which is suitable for both ordinary plate condenser and liquid-vapor separation plate condenser.The differences between the calculation results and the experiments are within ±25%.Secondly,the influences of the path length ratio and corrugation height on the performance evaluation parameter(PEC)of multi-path liquid-separation plate condenser are discussed.The results show that the performance of the multi-path liquid-separation plate condenser is better than the ordinary plate condenser.The best path ratios of the two-path,three-path and four-path liquid-separation plate condenser are 6:4 and 4:3:3 and 3:3:2:2,the corresponding PEC is 1.073,1.107 and 1.118,respectively.As the number of paths increases,that is,the times of liquid-vapor separation increases,the average heat transfer coefficient,heat load and PEC of the liquid-separation plate condenser are all increased.Thirdly,under variable working conditions,comparisons between the multi-path liquid-separation plate condenser and ordinary plate condenser are carried out by using the above-mentioned optimal path ratio structure.The results indicate that the performance of the multi-path liquid-separation plate condenser is always better than that of the ordinary plate condenser.The four-path liquid-separation plate condenser is best in terms of PEC.Compared to the ordinary plate condenser,the average heat transfer coefficient is increased by 14%-25.8%,the heat load is increased by 2.3%-10.6%,and the PEC is increased by9.8%-12.1% in the studied working conditions.Finally,the experimental research on both the liquid-separation plate condenser and the ordinary plate condenser are conducted.It is found that the pressure drop of the liquid-separation plate condenser is 46.7%-63.2% lower than that of the ordinary plate condenser.However,because part of the vapor-phase refrigerant is carried by the separated liquid in the liquid-vapor separator,the heat load of the liquid-vapor separation plate condenser is also reduced by 8.0%-12.7%,and supercooling also occurs.