1 Proceedings of the ASME International Mechanical Engineering Congress and Exhibition IMECE 2012 November 9 – 11, 2012, Houston, Texas IMECE 2012- 85491 Simplified Correlation Equations of Heat Transfer Coefficient During Phase Change Flow Inside Tubes Filled with Porous Media M. Hammad Prof. of Mechanical Engineering, University of Jordan, Jordan, Tel/fax: +962/6-5238783, hammad@ju.edu.jo A. Al-Shqirate Al-Shoubak University College, Al-Balqa Applied University, Al- Salt, Jordan, Abedalrzaq_alshqirate@yahoo.com M. Tarawneh The Hashemite University, Zarka, Jordan , mohammad.tarawneh@hu.edu.jo Abstract In this work an easy to use, simple and direct equations were formulated and tested. Heat transfer coefficients of phase change fluid flow were examined in this work. The considered fluid flow encountered convection heat flux inside rigid tubes filled with porous media. During the flow, phase change was assumed. Experimental work was conducted using Carbon dioxide as fluid. An analytical method using exponential non dimensional analysis was used. The Buckingham π theorem and method of indices was used to obtain simplified formula for the convection heat transfer coefficient and for the Nusselt number. Two different correlations can be extracted from this formula; one for the evaporation process and the other for the condensation process. As a case study, carbon dioxide was used. Resulted values were compared to the experimental values for validation purposes. Results also were compared to published values and found in the same range of uncertainty and exactness. The formulae obtained can be used to calculate the mean heat transfer coefficients, (h - corr ) and heat flux. Heat flux is the catalyst for phase change. Enhancement in heat transfer by increasing heat flux was due to the existence of the porous media inside the tube. Better heat exchanger design as well as better condensers and evaporators will result. Better energy use and higher effectiveness factors may result by using more simple and accurate equations. Keywords: Porous Media, Heat Transfer, Two Phase Flow, Change of Phase, Refrigeration, Carbon Dioxide. Introduction Heat transfer and fluid flow inside tubes have many applications, such as: heat exchangers, condensers, evaporators and boilers. Using porous media inside tubes enhances radial heat flux and increases heat transfer coefficients. Convection heat transfer for a phase change flow inside tubes was studied in the literature. Mini and micro-tubes were used. Many correlations for mean Nusselt number ( Nu ) and mean heat transfer coefficient ( h ) were obtained. Both Nu and h were calculated using the analytical correlation or using the experimental results for the purpose of validation. Bejan (1993) and Thome (2005) are good examples for literature work in this field. Both of them included a comprehensive review of boiling flow inside tubes heat transfer analysis.