Refrigerant side heat transfer and pressure drop estimates for direct expansion coils. A review of works in North American use
Abstract A review is made of data and methods currently used in North America for the estimation of heat transfer coefficients and pressure drops for refrigerant evaporation (two phase flow) in the tubes and tube-bends of direct expansion coils (DX-coils). Contemporary estimation techniques are summarized for the case of smooth tubes in the absence and presence of oil. Their range of application and limitations are presented together with the effects of oil-refrigerant mixtures on the heat transfer characteristics of evaporators. Generalized correlations for the estimation of the refrigerant side heat transfer and pressure drop factors for complete DX-coils, developed from experimental studies, are also presented.