The Influence Of Aperture On The Distribution Of Gas-liquid Two Phase Flow In Parallel Flow Evaporator

Parallel flow evaporator attracts wide attention for its good thermal prosperities．Butthe application in low temperature is little, and the temperature distribution in flow field isnonuniform．Numerical simulation is applied in this thesis to research effect of the aperturediameter on the temperature distribution when the evaporator has8and10parallelevaporation tubes with a diameter of0.4cm，respectively，and the R134a refrigerant chargemass is the same；it also researches the variation of the temperature field when therefrigerant flow in the inlet changes and the tube pitch of the evaporation tubes changesrespectively；and makes a contractions of the temperature fields between the parallel flowevaporator and the serpentine tube evaporator．In the experimental aspect，the parallel flowevaporator is processed to validate the aperture diameter attained from simulation．It isfound from the research：1．When the velocity in the parallel flow evaporator inlet is0.01m/s，the closer to the inletthe evaporator tube is，the more refrigerant flow is；when the velocity in the parallel flowevaporator inlet is0.1m/s，the closer to the inlet the evaporator tube is，the less refrigerantflow is．2．When the parallel flow evaporator has8evaporation tubes and the velocity in theparallel flow evaporator inlet is0.04m/s，the temperature curve is dispersed when the tubepitch is5cm during the cooling stage；the temperature variation is smaller when the tubepitch is3cm，the cooling curve of the8evaporation tubes is concentration．3．When the mass flow in the parallel flow evaporator inlet is0.002kg/s，the cooling rate ofthe parallel flow evaporator and the serpentine tube evaporator is nearly the same，whenthe system is stable，the temperature difference between the evaporation tubes of theserpentine tube evaporator is bigger as a result of the pressure drop，and the temperatureof the serpentine tube evaporator decreases along the refrigerant flow direction．4．After adjusting the aperture diameter according to the simulation and experimental date，no uniform temperature field is found in the three experiments of the parallel evaporatorwith10evaporation tubes，according to the experiment date of the10evaporation tubes，analysis and adjust the aperture diameter of the8evaporation tubes，the experiment resultshows that the temperature field of the8evaporation tubes is more uniform．5．The refrigerant in aperture throttles as a result of the small parallel flow evaporatorheader and aperture diameter，the temperature difference of the refrigerant liquid in theevaporator tubes between the temperature drop because of throttle and temperature risebecause of absorption of heat is small，which makes the evaporation temperature of theevaporator stable, and the temperature field is better． 6．When the parallel flow evaporator works in the same condition，the cooling rate of thesimulation is higher than that of the experimental values，at the beginning stage, both thecooling curves coincide with each other；when the temperature drops to6℃，the coolingrate of the experimental temperature curve slackens，while the cooling rate of thesimulation keeps the same，and the system reaches stable after100s．The whole decreasetendency of the experimental temperature is slowly as a result of the refrigeration systemand the external environment；the system reaches stable800s later and the temperaturecoincides with the simulation value．...