Evaluation of performance an air conditioning systems using t-junction flash gas refrigerant
The purpose of this study was to determine the performance of air-cooled chiller system using T-junction flash gas bypass refrigerant. The experiment was conducted by installing T-junction after expansion device to separate the phase of refrigerant liquid and gas which flows to the evaporator. The working fluid is used as a cooling medium is R-290. To get performance data, measurements performed at the time of steady state when the water chilling temperature T = 15 C up to T = 10 C and flow rates kept constant at 1 GPM (6.3 x 10-5 m3/s). Finally, the use of T-junction mode in AC system generates an increase in the refrigerating effect and coefficient of performance systems (CoP) by 6% and 17.8 %, respectively. Also, it can decrease the heat of compression by 8.5%. This has implications for the lighter compressor work and saving the power consumption of the AC system.
Investigation on the improvement of car air conditioning system performance using an ejector
The purpose of this research is to know the improvement of car air conditioner system performance using an ejector. The study was conducted on a car engine with power 100 PS (74 kW) @ 5000 rpm. The test procedure is carried out under two conditions: the normal refrigeration cycle mode and the refrigeration cycle mode with the ejector. The working fluid used in the refrigeration cycle is R-134a. Performance data was measured on engine revolutions ranging from 1500 3000 rpm. Finally, the results showed that ejector usage on AC system generates an increase in the refrigeration effect and coefficient of performance (COP) of 25% and 22%, respectively. This has implications to better cooling capacity and compressor work that is lighter.
Prediction of the circumferential distribution of film thickness in horizontal and near-horizontal gas-liquid annular flows
Abstract A theoretical model for predicting the circumferential film thickness distribution in horizontal and near-horizontal annular two-phase flows is presented. It is based upon a disturbance wave flow model which consists of disturbance waves and a base film. It differs from Laurinat's and Lin's models in tbat liquid is transferred in the circumferential direction by the pumping action of disturbance waves, which counteracts the drainage due to gravity, and that the effects of the induced secondary flow in the gas flow and the surface tension force bave minor effects on the formation of the liquid film near the top of the tube cross section. The film thickness distribution predicted by the present model agrees with the experimental data much better than those predicted by Laurinat's model.