A test facility is described that has been constructed to investigate local heat transfer and pressure drop for evaporating or condensing refrigerants. The empirical method of B. Pierre [1] for correlating the average heat-transfer coefficients of refrigerants evaporating in horizontal tubes is presented in conjunction with the data of several authors [3–6]. Data on local heat-transfer coefficients and pressure drop are presented for Refrigerant-22 evaporating in two 4-ft-long, 0.343-in-ID straight horizontal tubes, and are correlated by a refinement of the curve proposed in [1]. The procedure of Martinelli-Nelson [9] correlated the data for local pressure drop within 15 per cent.

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ABSTRACT-- ' .This paper describes a method for the determination of thermal diffusivities which has been developed specifically for substances which are poor conductors, and which have high melting points, Materials which are useful for thermal energy storage fall into this category.The method has several unique features, The basic principle involved consists of raising the surface temperature of a solid specimen at a uniform rate, After the initial transients have died out, the diffuefvity can be determined from temperature measurements alone.The advantages of the method are: 1, Heat flw measurements are not needed.2. Materials can be tested right up to the melting point since the specimens can be encapsulated and softening can be tolerated.. . 3,Large temperature ranges can be tested quickly. Data on other substances are still being produced, and results will be published at a later date.

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A quasisteady method for measuring the thermal diffusivity of molten salts at temperatures above their melting point is described. Essentially, the difference between the temperature at the surface and at the center of a cylindrical container is measured for a constant rate of surface temperature rise. The liquid, whose thermal diffusivity is to be measured, is contained in a narrow annular groove concentric with the surface. The advantages of this method are: (a) no heat flux measurements are needed; (b) no liquid temperature need be measured; (c) theoretically assumed boundary conditions can be experimentally realized; (d) absence of convection can be experimentally verified. Results of measurements are reported for liquid lithium fluoride and sodium nitrate. The results for sodium nitrate agree with previously published results. The thermal conductivity of lithium fluoride can be empirically expressed in terms of the melting point, the molecular weight and the density, as k=0.9Tm1/2ρm2/3M−7/6