Air conditioning contributes significantly to building energy consumption in hot climate regions. In addition to greater cooling requirements in hot climates, cooling equipment efficiency decreases with increasing outdoor temperature. Therefore, it is advantageous to develop improved technologies that can achieve higher efficiency at high ambient conditions. In this paper, two novel compression...

The objective of this study is to design and briefly investigate the cooling performances of an air conditioning system for a special purpose vehicle under various experimental conditions. An air conditioning system with two parallel refrigeration cycles consisting of two compressors and two condensers for satisfying the required cooling performance of the special purpose vehicle was tested und...

The Refrigerant RS02, an azeotrope of CFCllS and HCFC22, is an important refrigerant in commercial refrigeration, especially for low temperature applications using single stage compressors. current users of R502 are faced with an earlier than ~nticipated phase-out and are under great pressure to find suitable alternates for retrofit and o.E.M. (new) applications. Single components like HCFC12S,...

A fully equipped automotive air-conditioning test system consists of 5 main components: a compressor, a condenser, an orifice tube, an evaporator and an accumulator. R-134a is used as refrigerant. The coefficient of performance, evaporator cooling capacity, compressor power consumption, total mass flow rate, vapor mass flow rate, liquid mass flow rate and oil in circulation, pressures and tempe...

In this work, the inversion scheme was used to determine the potential energy surfaces of five polar refrigerant mixtures. The systems studied here are R123-R134a, R123-R142b, R123-R152a, R142b-R134a, and R142b-R152a. The low-density transport coefficients of the refrigerant mixtures were calculated from the new invert potentials by the classical kinetic theory. The viscosity coefficient, binar...

The phaseout ofhydrochlorofluorocarbon (HCFC)-22 will require manufacturers of air-conditioning and refrigeration equipment to find suitable alternatives for this widely-used refrigerant. The R-22 Alternative Refrigerants Evaluation Program (AREP) was established by the Air-Conditioning and Refrigeration Institute (ARI) to assist manufacturers in obtaining performance data on a multitude of R-2...

A comparison of the start-up cooling capacities for an automotive R744 and an automotive R134a air conditioning system is presented. It is shown that development of the cooling capacities during start-up can be described with one correlation for both systems. The comparison of the cooling capacities and the redistribution of refrigerant mass during start-up suggest a strong relationship between...

Flow maldistribution in evaporators can lead to significant degradation of capacity and efficiency of vapor compression equipment. A significant amount of work has previously been done to mend these issues. For variable air flow maldistribution, refrigerant compensation was proposed to reduce the performance degradation. For fixed air side maldistribution, refrigerant circuitry modifications we...

Estimation of starting torque is very important for motor design and for improvement in compressor efficiency. Especially, when compressors are restarted after a period of inoperation, motors sometimes meet large starting torque. The assumed reasons are as follow . The compressors temperature is sometimes lower than any other parts of the refrigerant cycle. In this case, the refrigerant tends t...

The migration characteristics of carbon nanotubes from liquid phase to vapor phase in the refrigerant-based nanofluid pool boiling were investigated experimentally. Four types of carbon nanotubes with the outside diameters from 15 to 80 nm and the lengths from 1.5 to 10 μm were used in the experiments. The refrigerants include R113, R141b and n-pentane. The oil concentration is from 0 to 10 wt....