2010
DOI: 10.1115/1.4001931
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Nucleate Pool Boiling Heat Transfer of R134a and R134a-PVE Lubricant Mixtures on Smooth and Five Enhanced Tubes

Abstract: Pool boiling heat transfer coefficients of R134a with different lubricant mass fractions for one smooth tube and five enhanced tubes were tested at a saturation temperature of 6°C. The lubricant used was polyvinyl ether. The lubrication mass fractions were 0.25%, 0.5%, 1.0%, 2.0%, 3.0%, 5.0%, 7.0%, and 10.0%, respectively. Within the tested heat flux range, from 9000 W/m2 to 90,000 W/m2, the lubricant generally has a different influence on pool boiling heat transfer of these six tubes.

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Cited by 42 publications
(8 citation statements)
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“…The majodty of these studies have been geared towards heating, ventilating, and air-conditioning applications and thus are limited to lower heat fluxes (i.e., that do not reach the CHF) and use cylindrical/tube heater geometries [8][9][10]. However, there are a few studies that document HFC-134a boiling curves up to the CHF.…”
Section: Introductionmentioning
confidence: 97%
See 1 more Smart Citation
“…The majodty of these studies have been geared towards heating, ventilating, and air-conditioning applications and thus are limited to lower heat fluxes (i.e., that do not reach the CHF) and use cylindrical/tube heater geometries [8][9][10]. However, there are a few studies that document HFC-134a boiling curves up to the CHF.…”
Section: Introductionmentioning
confidence: 97%
“…Within the refrigeration industry, millimeter-sized fin structures may be employed as a means of enhancing phase change within flooded evaporators[8][9][10]. Ji et al[8] investigated the effect of five enhanced tube geometries on HFC-134a pool boiling heat transfer. The fin geometries studied ranged from 0.567 mm to 1.4 mm in height with maximum fin densities of 1761 fins per meter.…”
mentioning
confidence: 99%
“…For the two tubes under practically cooperating conditions, the boiling HTC of R-1233zd(E) was observed to be reduced by more than 40% when compared to R-134a. Ji et al [47] assessed the pool boiling HTCs for R-134a combined with a lubricant (PVE). Figure 10 comprises the performance of R-134a at a T sat = 6 • C. The oil mass fraction ranged from 0.25 to 10%, and the surface heat fluxes from 9 to 90 kW/m 2 .…”
Section: Characteristics Of Lgwp Refrigerants For Nucleate Pool Boili...mentioning
confidence: 99%
“…For nearly the same range, the additive caused no change in the pool boiling heat flux of R123/mineral oil mixture. The key parameters of lubricant excess surface density and interfacial surface tensions were used to form the basis of a hypothesis for predicting, whether the additives will enhance or degrade refrigerant/lubricant pool boiling.Ji et al [36]studiedpool boiling heat transfer coefficients of R134a with polyvinyl ether lubricant of mass fractions 0.25%, 0.5%, 1.0%, 2.0%, 3.0%, 5.0%, 7.0%, and 10.0%, respectively on one smooth tube, one integral and four enhanced tubes at a saturation temperature of 6°C. The heat flux range was from 9000 W/m 2 to 90,000 W/m 2 .…”
Section: Refrigerant With Oil Mixturesmentioning
confidence: 99%