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Journals and Conferences
Heat transfer coefficients are an important consideration when selecting a refrigerant, however, heat transfer is affected by the type and amount of lubricant circulation. HFC-blend R-404A is a leading candidate to replace R-502. The focus of this study was a comparison of the effects that different lubricants, such as a naphthenic mineral oil, a… (More)
Evaporation of HFC134a inside smooth, horizontal tubes is studied. Te,;ts are made with pure refngerant and with oil-refrigerant mixtures. Heat flux has varied from 2 kW/n? to 10 kW/m . The inner diameter of the tubes are 12 mm. T1.1o evaporators are used, 4 and 10 m long. Oil content is varied from 0 to 2.5 mass percentage (synthetic oil, EXP-0275). Oil… (More)
Michael B. Pate, Tom M. Doerr, and Dan T. Ray Iowa State University Ames Iowa 50011 Chlorine-free HFC refrigerants, such as R-407C and R-410A, are being considered as viable alternatives for R-22 refrigerant. Heat transfer coefficients are important considerations to meet the performance needs of the heat exchanger. Heat transfer is affected by the type and… (More)
Heat transfer coefficient data was taken during in-tube evaporation of five differenct refrigerant mixtures. These measurements were performed in a 318" O.D. (9.7 mm) smooth copper tube at refrigerant temperatures of -zoe and 4°C. Four different mass fluxes ranging from 125 to 375 kg/s-m2 were tested. On a mass basis, the five different mixtures tested… (More)
Miscibility data is being obtained for a variety of non-CFC' refrigerants and their potential lubricants under a program initiated and supported by the Air-Conditioning and Refrigeration Technology Institute. At least ten (10) different refrigerants and seven (7) different lubricants are being investigated. Experiments are being performed in two phases:… (More)
Stargell, Gregory, "Devising a more robust automated detection method using audio frequency spectra" (2008). Retrospective Theses and Dissertations. Paper 14925.
Thermal conductivity is an important transport propeny in understanding heat transfer characteristics. It can be evaluated either from experimental measurements or theoretical predictions. In the present srudy, a theoretical model is proposed for predicting the thermal conductivity of a refrigerant mixture. This method requires speed of sound information… (More)
An energy and cost analysis of residential ground-source heat pumps in Iowa" (2008). Retrospective Theses and Dissertations. Paper 15437.
Tests were run with both R-12 and R-l34a in a water calorimeter. Refrigerant 12 was run with mineral oil as the lubricant. Evaporating and condensing heat transfer coefficients were calculated over a range of temperatures. To evaluate the impact of the lubricant on the heat transfer coefficients, a oil separator was added. Tests were then run with the oil… (More)