CG-14 Modifications to Resistance Proration Method in Xchanger Suite 9.3 and 9.4
The Resistance Proration Method (RPM) for the effective vapor-phase heat transfer coefficient in mixture condensation used a correction factor that requires knowledge of the inlet mole fraction of any noncondensing component. It was recommended that this inlet mole fraction should be replaced by a new parameter based on vapor-phase molecular weights, requiring no user input and restricting application of the correction factor to cases that are mass-transfer controlled. The new parameter should have a stronger physical basis and not require user input. In preliminary tests, predictions using the new parameter in the RPM agreed well with HTRI research data. As described in this report, the updated correction factor together with some additional adjustments to the RPM were recommended for Xchanger Suite 9.3 and 9.4. Users may note that the heat transfer coefficient usually increases in cases where the input mole fraction is greater than 0.72. For some cases that did not previously use the inlet vapor mole fraction, the heat transfer coefficient may decrease due to the improved physical basis of the updated method.