| There are many technology of heat transfer enhancement in tube condensation. Enhanced tubes were usually used to enhance the condensation heat transfer coefficient in industry. However, enhanced tube improving the heat transfer coefficient also causes the flow resistance increases, which results in the not ideal integrated effect of heat transfer enhancement. Air cooled liquid-vapor separation condenser (LSC) is a new type of condenser. Though the condensing zone structure of LSC resembles the parallel flow condenser (PFC), some special design liquid-vapor separation baffles were set in it, which can drain away the condensate in time during condensation process and increase quality of the working-fluid into next tube pass. So as to achieve enhanced heat transfer, lowed flow resistance and even flow distribution.An air cooled liquid-vapor separation condenser (LSC) was produced. Taking HFC134a as working fluid, experimental investigation of this new condenser was carried out. At the inlet quality of0.97and saturation temperature of45℃, the mass velocity of364kg·m-2·1-1to644kg·m·s-1and heat flux of4.7～8.1kW·m-2were tested. The results showed that, with the constant inlet quality, the condensation heat transfer coefficient and friction pressure drop of LSC were increase with increasing mass velocity, and with the increase of heat flux decreases. By regression analysis of experimental data, heat transfer and pressure drop correlations were also built.Based on the same heat transfer area, the condensation heat transfer coefficient and pressure drop of serpentine condenser (SC) and parallel condenser (PFC) were theoretical calculated by the classical heat transfer and pressure drop of empirical correlation. Compared with the results of LSC, the heat transfer coefficient of LSC was lower than those of them at low mass velocity, but higher at high mass velocity. The pressure drop of LSC was lower than those of the other condenser for all calculated conditions. The Penalty factor (PF) was used to evaluate the integrated performance, the results showed that, compared with SC, the PF value of LSC was decreased by3.3%～31.2%at heat flux of4.7～6.4kW·m-2with mass velocity of364～644kg·m-2·s-1. And compared with PFC, the PF value of LSC was decreased by3%～43.6%at heat flux of4.7～6.4kW·m-2with mass velocity of420～644kg·m-2·s-1.The three condensers with the same heat exchange area of the condenser were redesigned and placed in the same HCFC22refrigeration system. In the standard enthalpy difference lab, experimental investigation were carried out under different controlled the condenser side dry bulb temperature29～41℃and the evaporator side dry and wet bulb temperature were fixed at27℃and19℃, respectively. The results showed the performance of LSC system was better than that of SC and PFC system. At the experimental conditions, compared with the system with SC and PFC, the coefficient of performance of the LSC system was improved5.47%～7.33%and5.87%～6.88%, respectively. And the exergy efficiency also improved by6.89%to9.13%and6.89%to8.71%, respectively.The refrigerant adaptability study for LSC were carried out, it is find that a good performance of HCFC22LSC is not suitable for HFC410A. The liquid-vapor separation and uniform flow distribution are failure, resulting in the heat transfer coefficient decreases and the pressure drop increases. Therefore, it is necessary for the working fluid to redesign the liquid-vapor separation baffle, tube pass and length of tube. |
