Influence of Concentration and Additives on R123/Paraffinic Material Oil Boiling Heat Transfer Performance.
Influence of Concentration and Additives on
R123/Paraffinic Material Oil Boiling Heat Transfer
Performance.
(430 K)
Kedzierski, M. A.; Han, D. H.
NISTIR 7336; 46 p. September 2006.
Keywords:
refrigerants; additives; boiling; heat transfer;
mixtures; paraffinic mineral oil; enhanced heat
transfer; lubricants
Abstract:
This report investigates the effect that oil
concentration had on the boiling performance of an
R123/paraffinic mineral oil mixture on a roughened,
horizontal flat surface. For all compositions (0.5 %,
1%, and 2%), the lubricant caused a heat transfer
degradation relative to the heat transfer of pure R123
of between 2% and 70% for the range of measured heat
fluxes. The heat transfer degradation was shown to
increase with lubricant mass fraction. The minimum heat
transfer degradation for each mixture ranged between 2%
and 12% and occurred at approximately 20 kW/m2. For a
given composition, the heat transfer degradation
increased as the heat flux increased from roughly 20
kW/m2 to 90 kW/m2. In addition, the effect of two trial
additives on the pool boiling heat transfer of an
R123/paraffinic mineral oil mixture was examined in
order to test the validity of a theory for choosing oil
additives to enhance boiling performance. The
verification tests were inconclusive. More research with
lubricants and additives with greater differences in
surface tensions is required to develop a more rigorous
and quantifiable theory for designing additives that
improve boiling heat transfer.
