Improved Thermal Boundary Layer Parameter for Semi-Theoretical Refrigerant/Lubricant Pool Boiling Model

Published

August 1, 2003

Author(s)

Mark A. Kedzierski

Abstract

This paper outlines the framework for an improvement in the thermalboundary layer parameter for a semi-theoretical model for predicting thepool boiling heat transfer of refrigerant/lubricant mixtures on aroughened, horizontal, flat pool-boiling surface. Refrigerant/lubricantpool boiling is significantly influenced by the excess lubricant thatresides in a thin layer on the boiling surface. The model is based onlubricant excess surface density measurements and a mass balance onlubricant deposition and removal from the wall. The original thermalboundary layer parameter that was derived for R123/lubricant mixturespredicts the R134a/lubricant data presented here for superheats below 6 K.The improvement in the thermal boundary layer enables the model to predictthe full range of superheats for the R134a/lubricant mixture measurements.Further work on the new thermal boundary layer parameter is necessary toinclude the effects of the lubricant composition, viscosity, and criticalsolution temperature with the refrigerant. These effects were included inthe original thermal boundary layer parameter. The new thermal boundarylayer parameter increases the range of superheats for which the model isvalid for the R134a/lubricant pool boiling heat transfer measurementspresented here.

Proceedings Title

International Congress of Refrigeration | 21st |Refrigerant/Lubricant Mixtures: Heat Transfer System Issues | |

Conference Dates

August 17-22, 2003

Conference Title

International Congress of Refrigeration

Pub Type

Conferences

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Keywords

excess surface density, heat transfer, lubricants, mixtures, pool boiling, predictions, Refrigerants

Citation

Kedzierski, M. (2003), Improved Thermal Boundary Layer Parameter for Semi-Theoretical Refrigerant/Lubricant Pool Boiling Model, International Congress of Refrigeration | 21st |Refrigerant/Lubricant Mixtures: Heat Transfer System Issues | |, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=860902 (Accessed April 23, 2024)