Modern lifestyle, industrialization and economy thrive on energy which is getting expensive overtime. Thermosyphon based systems are getting attraction for their promising heat transfer efficiency and zero energy utilization. Refrigerants having ozone depletion potential (ODP) and high Global Warming Potential (GWP) have been banned or under time bared permission under Montreal (1987) and Kyoto...

As part of an ongoing investigation into environmentally acceptable alternatives to the CFC refrigerants a series of tests have been completed comparing the thermodynamic performance of Rl34a with Rl2. The tests were carried out under controlled conditions in a well instrumented water/water heat pump test facility, using an open-drive reciprocating compressor and counter flow heat e%changers. B...

An important issue for optimal operation and plantwide control is to find the degrees of freedom available for optimal operation. A previously published systematic approach to determine the steady state degrees of freedom is expanded to take into account the active charge as a possible degree of freedom in cyclic processes. Additional degrees of freedom related to the composition of the circula...

We have developed a new CO2 heat pump water heater compressor with a single rotary mechanism in practical use for the first time in the world. CO2 refrigerant doesn't destroy the ozone layer, and the global warming potential (GWP) is less than 1/1000 in comparison to hydro-fluorocarbon refrigerants. However the operating pressure of CO2 refrigerant is approximately three times as high as that o...

The imminent phaseout of R-11, R-12, and R·llS because of their high ozone depletion potentials has prompted many independent investigations of alternative or subst:i t:uee refrigeranes, ei eher as pure compounds or as mixtures of t:wo or more environmentally acceptable fluids. There are several motivations for investigating mixtures. There are very few pure compounds which can be used for refr...

According to the results of the international testing program AREP, the most likely replacements for HCFC-22 refrigerant will be blends of HFCs. However, as concerns about their global warming potential increase, other options should also be considered. As a naturally occurring substance, propane would be an ideal refrigerant, except for its flammability. When dealing with a flammable refrigera...

Refrigerant mass migration and redistribution have been regarded as factors influencing the performance of air conditioning and refrigeration systems. This paper presents a dynamic model of an R134a automotive A/C system that is able to capture the shut-down and start-up cycling dynamics including the refrigerant mass migration transients. Building upon recent work (Li and Alleyne, 2010), the h...

Variable refrigerant flow (VRF) systems are easily subjected to performance degradation due to refrigerant leakage, mechanical failure or improper maintenance after years of operation. Ideal VRF systems should equip with fault detection and diagnosis (FDD) program to sustain its normal operation. This paper presents the fault diagnosis method for refrigerant charge faults of variable refrigeran...

Using identical mechanical hardware used in an automobile, a stationary test bench has been developed for an automotive air conditioning system (AACS). However, a number of additional sensors have been used in the system for an accurate assessment of its performance. The steady state performance of the system has been investigated for three independent variables, namely the refrigerant charge l...