SUMMARY

Condensation of hydrocarbons and zeotropic hydrocarbon mixtures in smooth horizontal tubes will be investigated in the proposed effort. Measurements of condensation heat transfer coefficients and frictional pressure drop will be taken over a range of mass fluxes (G = 150 – 450 kg m-2 s-1) and a range of reduced pressures (P_r = 0.25 - 0.95) for two tube diameters (D = 7.75 and 14.45 mm), several coolant-to-test fluid temperature differences (DT_LM = 3 – 14°C) and temperature glides (DT_Glide) between the dew and bubble points of 7 - 14°C. The systematic study of the influence of each of these parameters, as well as the range of conditions investigated in this study, will provide insights on the underlying phenomena that influence the condensation process. The trends in heat transfer coefficient and frictional pressure gradient will be discussed and compared with the predictions of correlations from the literature. The results of the experiments, combined with previous flow visualization studies on hydrocarbons, will be used to develop physically consistent heat transfer and frictional pressure gradient models that are applicable to pure fluids and zeotropic mixtures.

Accurate pure fluid models, which often serve as a baseline case for zeotropic mixture modeling, will facilitate more effective zeotropic mixture models, leading to increased efficiencies in chemical processing applications. In addition, the understanding of condensation heat transfer and pressure drop of such hydrocarbons and their mixtures could facilitate their use as environmentally harmless working fluids for refrigeration and air-conditioning cycles.