Horizontal Flow Boiling of Single Component and Binary Refrigerant Mixtures.
Horizontal Flow Boiling of Single Component and Binary
Kedzierski, M. A.; Didion, D. A.
ER-8006-2; Research Project 2792-09; 106 p. 1993.
Sponsor:Electrical Power Research Inst., Palo Alto, CA
Available from: Electrical Power Research Inst. (EPRI),
Palo Alto, CA
refrigerants; heat transfer; degradation; nucleation;
ozone; evaporation; flow boiling; visualization
This report contains three studies on refrigerant
mixture heat transfer funded by NIST and EPRI (RP
80006-21). The first study, Visualization of Nucleate
Flow for an R22/R114 Mixture and Its Components, is
presented in section 1. It investigates the phenomena
of the suppression of nucleation due to increased mass
flow while all other conditions are fixed. This study
also compares the nucleate activity of the binary
mixture to the nucleate activity of the pure components.
The fluids investigated are a 37.7% mole R114 binary
mixture and the individual components R22 and R114. The
second study, Causes of the Apparent Heat Transfer
Degradation for Refrigerant Mixtures, is presented in
section 2. It investigates the causes of the apparent
heat transfer degradation associated with horizontal -
annular flow evaporation of refrigerant mixtures. For
horizontal-annular flow evaporation, most of the heat
transfer degradation is a consequence of the use of the
locally uniform equilibrium temperature in the
measurements and calculation of the heat transfer
coefficient. The remainder of the heat transfer
degradation is due to nonlinear mixture property
effects. The focus of the study was to determine the
magnitude and the cause of the individual components of
the heat transfer degradation of the studied mixtures.
The third study, A Comparison of Experimental
Measurements of Local flow Boiling Heat Transfer
Coefficients for R11 and R123, is presented in section 3
and presents a comprison of the measured horizontal,
smooth-tube, flow boiling heat transfer coefficient of
R11 to that of its proposed near ozone safe replacement,
R123. The fluid properties of R11 and R123 are similar.
The flow boiling data for the two fluids are similar for
the convective region. However, the heat transfer
coefficient for R11 in the nucleate flow boiling region
was consistently observed to be, on average, 8.5% to 33%
larger than that for R123. For the convenience of the
reader, both the R123 and R11 property data used in this
study are presented.