Freezing of single materials is an important thermal process in several equipment and in thermal energy storage systems.Freezing studies pertaining to cylinders under various thermal conditions are numerous in literature.The importance of study of freezing in non-circular crosssectional cylinders was noted.We wish to present a comparative study based on experiments in cylinders of elliptical and circular crosssections. Two PHASE CHANGE MATERIALS(PCM) namely n-octadecane(MP 28C) and

paraffin wax (MP 58-60C)are being used.The range of variables to be covered are: volume of PCM:50cc to 1000cc,L/d:1 to 5,temperature drop across the PCM:2 to 20C,initial superheat of PCM:0 to 25C.Elliptical cylinders of eccentricity variation 0.4 to 0.95 are fabricated in copper.Experimental data would include frozen mass variation with time and temperature distribution(in two dimensions)in the PCM during freezing.Earlier work of the author indicated accurate correlations of data of frozen mass/area with the product of (melting point-wall temperature)xtime by power law type expressions for n-Octadecane.However the proportionality constant appears to be a complex function of the physical properties of the pcm.The data of paraffin wax show significant deviatios from the correlation and the theoretical equations.Both frozen mass variation with time and temperature distribution with time for circular and elliptical cylinders would be discussed.