The primary goal of the work described in this paper was to evaluate and extend a virtual refrigerant charge sensor (VRC) for determining refrigerant charge for equipment having variable-speed compressors and fans. To evaluate the accuracy of the VRC, data were first collected from previous laboratory tests for different systems and over a wide range of operating conditions. In addition, new la...

A variety of hydrofluorocarbon (HFC) compounds, both as pure substances and mixtures, are being developed as alternative refrigerants to replace the exsting chlorofluorocarbons and hydrofluorocarbons which have been linked to stratospheric ozone depletion. The use ofHFC's in refrigeration systems will require new lubricants, and polyolesters are being widely promoted as the lubricant of choice ...

Data is presented for the vapor liquid equilibrium viscosity reduction of lubricants with two refrigerant blends at two temperatures. The lubricants tested were a 32 ISO VG mixed acid polyolester and a 32 ISO VG branched acid polyolester. The refrigerant blends used were HFC-125/143a/134a (44/52/4% w/w), and HFC-125/143a (50/50% w/w). INTRODUCTION This experiment detennined the vapor liquid equ...

Multi-evaporator vapor compression systems (ME-VCS) provide cooling to multiple zones. The thermodynamic conditions in these zones are independent: the heat loads often differ, and the occupants of these spaces often have different desired room temperatures. Therefore, in order to regulate each zone to its desired setpoint temperature, the amount of thermal energy removed by each evaporator mus...

A series of tests has been completed comparing the system performance of four long term replacements HP62 (44% R~125/ 54% R-143a/ 4% R-134a), AZ-50 (50% R-125/ 50% R-143a), Klea 60 (20% R-32/ 40% R-125/ 40% R-134a), and Klea 61 (1 0% R-32/ 70% R-125/ 20% R-134a) as potential alternatives for the CFC-containing low temperature refrigerant R-502. The tests were carried out under controlled condit...

Besides compressor rotary speed and parameters of water flowing through gas cooler and evaporator, refrigerant charge amount and electronic expansion valve (EEV) opening are two important parameters that have significant effects on the performance of a transcritical CO2 heat pump system. In this study, the effects of refrigerant charge amount on the performance of a transcritical CO2 heat pump ...

The transition from CFC-12 (GWP=10,900) to HFC-134a (GWP=1,430) in the 1990’s in new vehicle air conditioners eliminated the contribution to ozone depletion potential (ODP) from new vehicles and reduced the direct Global Warming Potential (GWP) by over 80%. One proposed alternative is HFC-1234yf (GWP=4). Despite the phase-in success of HFC-134a as a zero ODP automotive refrigerant it is still a...

Refrigerant mixtures seem the most promising candidates as replacement fluids in refrigeration devices and heat pumps. In this paper two prediction methods are proposed for th~ evaluation of the thermal conductivity of refrigerant mixtures in their saturated liquid state and in the subcooled region. The first method is based on the use of mixing rules applied to pure refrigerant data evaluated ...

This paper describes the development of a computer simulation model of an integrated supermarket refrigeration and heating system using natural refrigerants (namely ammonia and hydrocarbons). Initial resultS of the model's performance are presented, showing the influence of some of the operating parameters on system thermal efficiency. This will be validated using data collected from monitoring...