Oil return from the evaporator to the compressor suction port is an important requirement. It is affected by the refrigerant/lubricant properties, gas velocities and piping geometry. The refrigerant R -134a has successfully replaced R-12 in household refrigerators and freezers. This paper describes a test method to estimate the mean oil film thickness and to observe the flow pattern in vertical...

This paper presents how the refrigerant dissolved in oil affects on Journal bearings reliability. The bearing model test is performed using the hermetic test apparatus. The oil film pressure is measured under several types of bearing grooves, L/D ratios and mixing ratios of refrigerant to oil. As a result, the means by which the refrigerant dissolved in oil causes damage to journal bearings is ...

f liquid g gas ABSTRACT The experimental apparatus was build according to the national standards of India.. The performance of the refrigeration system depends upon the heat transfer capacity of the refrigerant. Normally R12, R22, R600, R600a and 134a are used as a refrigerant. This refrigerant heat transfer capacity is not so good and increase power consumption. Due to these limitation nanoflu...

Refrigerant mass migration and redistribution are regarded as key factors affecting the cycling perfor­ mance of air conditioning and refrigeration systems. A dynamic model of an R134a automotive air conditioning system is presented as an example in this paper to capture the refrigerant migration during compressor shut-down and start-up operations. Model validation against experimental data dem...

Air conditioning refrigerant R134a has value of global warming potential (GWP) 1300, which is much higher than MAC Directive (GWP below 150) passed in July 2006. This prompted a search for alternative refrigerant with GWP value less than 150. R1234yf is a new refrigerant which has lower GWP value of 4. Effect of blower speed has been compared and flammability issue of R1234yf has been addre...

Improvement of compressor efficiency using the alternative refrigerant is demanded strongly to reduce CO2 emission, which causes the global warming. Especially the compressor using in frozen temperature level has long lifetime, and the correspondence to above-mentioned is one of the most important subjects. The scroll compressor is the promising structure to solve this problem. A technical poin...

New lubricant which can dissolve with ammonia refrigerant was developed. PAG based oil was found to be dissolved with ammonia and to have fine stability. It contributes to realize maintenancefree refrigerating system because oil returning are possible. It also helps to reduce refrigerant amount because of improvement of thermal conductivity. Ammonia refrigerant will be focused more as an altern...

Title of Document: INVESTIGATION OF REFRIGERANT DISTRIBUTION IN A HOUSEHOLD REFRIGERATOR WITH A FOCUS ON THE ROLE OF THE ACCUMULATOR Cara Sanderson Martin, M.S. Mechanical Engineering, 2007 Directed By: Professor Reinhard Radermacher, Ph.D. Department of Mechanical Engineering In order to maximize household refrigerator performance, it is important to understand the basic relationship between e...

For the environmentally aware, natural refrigerant such as CO2 is recommended and pursued by researchers for refrigerators. In this paper, a transcritical CO2 heat pump system was set up to investigate the influence of refrigerant charge on the performance of a small-sized heat pump water heater. The transcritical CO2 heat pump system was composed of a rotary compressor, a tube-in-tube evaporat...

During the process of refrigerant alternative, R290 (propane), as a nature refrigerant used in Room Air Condition (RAC) system, is thought as a long-team substance and has attracted great attention. This paper simply introduced the characteristics and standard demands of R290 application, then, based on a 1HP R290 DC INV. RAC system at first, then finished the comparison test when a one-cylinde...