Heat transfer characteristics of R410A-oil mixture flow boiling inside a 7 mm straight smooth tube

• Published in: Experimental thermal and fluid science Vol. 32; no. 3; pp. 857 - 869
• Main Authors: Hu, Haitao, Ding, Guoliang, Wei, Wenjian, Wang, Zhence, Wang, Kaijian
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01.01.2008; Elsevier Science
• Subjects: Applied sciences; BOILING; Correlation; CORRELATIONS; Deviation; Energy; Energy. Thermal use of fuels; ENGINEERING; Evaporation; Exact sciences and technology; Flow pattern; Fluid dynamics; Flux; HEAT FLUX; HEAT TRANSFER; Heat transfer coefficients; MASS TRANSFER; MIXTURES; Oil; OILS; PEAKS; R410A; REFRIGERANTS; TEMPERATURE RANGE 0273-0400 K; Theoretical studies. Data and constants. Metering; TUBES; TWO-PHASE FLOW; VAPORS; Correlation; Flow pattern; Oil; R410A; Heat transfer; Two phase flow; Coolant; Evaporation; Smooth tube; Heat transfer coefficient; Experimental study
• ISSN: 0894-1777; 1879-2286
• DOI: 10.1016/j.expthermflusci.2007.10.003

Two-phase flow patterns and heat transfer characteristics of R410A-oil mixture flow boiling inside a straight smooth tube with the outside diameter of 7.0 mm were investigated experimentally. The experimental conditions include the evaporation temperature of 5 °C, the mass flux from 200 to 400 kg m −2 s −1, the heat flux from 7.56 to 15.12 kW m −2, the inlet vapor quality from 0.2 to 0.7, nominal oil concentration from 0% to 5%. The test results show that the heat transfer coefficient of R410A-oil mixture increases with mass flux of refrigerant-oil mixture; the presence of oil enhances the heat transfer at the range of low and intermediate vapor qualities; there is a peak of local heat transfer coefficient at about 2–4% nominal oil concentration at higher vapor qualities, and the peak shifts to lower nominal oil concentration with the increasing of vapor qualities; higher nominal oil concentration gives more detrimental effect at high vapor qualities. The flow pattern map of R410A-oil mixture was developed based on refrigerant-oil mixture properties, and the observed flow patterns match well with the flow pattern map. New correlation to predict the local heat transfer of R410A-oil mixture flow boiling inside the straight smooth tube was developed based on flow patterns and local properties of refrigerant-oil mixture, and it agrees with 90% of the experiment data within the deviation of ±25%.