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Heat Transfer Enhancement in a Paraffin Wax Thermal Storage System
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1984
Year
EngineeringEnergy EfficiencyFluid MechanicsMechanical EngineeringThermal Energy StorageConvective Heat TransferRefrigerationThermal Storage SystemHeat Transfer ProcessFluid PropertiesMixed ConvectionTransport PhenomenaThermodynamicsMaterials ScienceLiquid PhaseHeat TransferThermal Fluids SystemsHeat ExchangerHeat Transfer EnhancementThermal ManagementThermal EngineeringThermo-fluid SystemsBoiling
The high thermal expansion coefficient and low viscosity of paraffin wax above 50 °C enable natural convection in the liquid phase even at small thicknesses. Experimental data on liquid production rate versus time and hot‑surface temperature were collected, and the interface heat‑transfer coefficient was calculated from the instantaneous moving‑boundary locations. Vertically arranged fins between heated and cooled horizontal finned‑tube arrangements enhance heat transfer by inducing buoyant flow that rapidly melts solid wax and creates a downdraft along the cooler surface.
Heat transfer enhancement in a thermal storage system consisting of vertically arranged fins between a heated and cooled horizontal finned-tube arrangement is reported. The high thermal expansion coefficient and low viscosity of paraffin wax, at temperatures above 50°C, are utilized to induce natural convection in the liquid phase even at small thicknesses. The experimental data on the rate of production of liquid as a function of time and temperature of the hot surface is presented. The photographs of the melted zone indicate a naturally buoyant flow induced in the neighborhood of the vertical fins causes a rapid melting of the solid wax and a downdraft along the cooler solid phase surface. The heat transfer coefficient at the interface is calculated from experimentally determined instantaneous locations of the moving boundary.