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...

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...

To probe differential control of substrate specificities for 4-nitrophenyl-α-L-arabinofuranoside (4NPA) and 4-nitrophenyl-β-D-xylopyranoside (4NPX), residues of the glycone binding pocket of GH43 β-D-xylosidase/α-L-arabinofuranosidase from Selenomonas ruminantium were individually mutated to alanine. Although their individual substrate specificities (kcat/Km) 4NPX and (kcat/Km) 4NPA are lowered...

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...

R502 is due to be banned in the near future, and ti)e need for an immediately available and easy-to-use alternative is becoming more and more urgent. Retrofitting refrigerating units can prove easier and less expensive if the mineral or alkylbenzene lubricants usually adopted with R502 have a certain miscibility in the drop-in mixtures. This paper examines the near-azeotropic mixture Rl43a/290/...