3238 -- A Theoretical Model for Prediction of the Heat Load in Flooded Refrigerant Evaporators ✓ Most Recent

A theoretical model has been developed to predict the performance of flooded refrigerant evaporators (FRE). The model is applicable to any refrigerant and water-side pass arrangement. The program predicts the heat duty for specified entering fluid conditions and tube bundle geometry. A key element of the model is the theoretical relations used to predict the refrigerant-side boiling coefficient and pressure drop. The Chen two-phase forced convection model is used to predict the boiling coefficient. The shell-side boiling coefficient is the sum of the singlephase forced convection and nucleate boiling cornponents. The model accounts for the effect of refrigerant pressure drop (across the tube bundle depth) on the refrigerant saturation. The pressure drop is calculated using the separated flow model A comparison of various correlations to estimate the frictional multiplier and void fraction are presented. A similar comparison of available correlations to predict the nucleate pool boiling heat transfer coefficient and the suppression factor S and F factor appearing in the Chen boiling model is provided. An incremental, iterative calculation procedure is outlined, which performs row-by-row calculations over specified incremental tube lengths for each water-side pass. The calculation methodology and recommended equations are outlined in detail.