Correlations of Two-phase Friction of Refrigerant in Horizontal Smooth Tube with 2.5 mm inside Diameter

IntroductionReduction of the refrigerant charge in refrigeratingsystems is a significant mechanismfor mini mizing refrigerantleakage , which results in a worldwide redirection oftransport phenomena research and development ,from macroscale (conventional) to micro scale equipments . The use of aphysically small heat exchanger for a given capacity isadvantageous for several reasons : smaller evaporatorssignify the reduction of the plant size ; small physical sizeoften i mplies relatively lower m…

Correlations of Two-phase Friction of Refrigerant in Horizontal Smooth Tube with 2.5 mm inside Diameter

Two-phase flow pressure drop measurements are made during phase change heat transfer process of R-22 in small horizontal smooth tubes with 2. 5 mm inside diameter.Conclusions are drawn that the quality corresponding to pressure gradient peak value of small tubes became higher than that of large tubes and that effects of quality on pressure drop become weak as the increase of mass flux.The experiment data are compared with predicted values of the state-of-the-art correlations from the open literature,which indicates that most of the state-of-the-art correlations fail to predict the present experimental data. Chisholm model shows a relatively better predictive ability than the other empirical correlations because it has the lowest mean deviation of 26.7%. But the predicted values of Chisholm model are 50% lower than experimental data when quality becomes higher. In this regard, an new empirical correlation based on Chisholm model is developed and this modified Chisholm correlation can describe 95% of the present data with ± 20% mean deviations.