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Corresponding Author

Mostafa, Hesham

Subject Area

Mechanical Power Engineering

Article Type

Original Study

Abstract

Foerrced convection heat transfer for pulsating flow inside a horizontal hot cylinder partially filled with porous medium is expimentally investigated. The outer surface of the tested cylinder is exposed to saturated steam to maintain its surface at constant wall temperature. The experimental work is performed for laminar flow of water inside the cylinder. As steady and pulsating flow with different frequencies. Carbon steel balls with 6.35 mm diameter are used as particles, which filling the tested cylinder. An experimental set-up is designed and constructed to perform this aim for investigating the effect of pulsation frequencies on the amount of heat transferred, compared with steady flow for different water flow rates at different values of filling ratio with porous medium for the tested cylinder. The required experimental measurements of temperature, pressure, mass flow rate, frequency and pressure drop are collected for further data analysis. The operating parameters range are considered as; for Reynolds number from 400 to 2000, heat flux from 10 kW/m2 to 60 KW/m2 and pulsation frequencies from zero up to 5 Hz for different filling ratios from zero 10 unity. The obtained experimental results show that, for the considered range of the operating parameters Nusselt number and in turn heat transfer coefficient increase with increasing Reynolds number for steady flow and pulsating flow. Pressure drop also increases with increasing filling ratio with porous medium. Also, Nusselt number increase with increasing filling ratio with porous medium, for steady flow but for pulsating flow the variation of Nusselt number versus filling ratio with porous medium is monotonically. Also, it is found that, for filling ratio with porous medium equal to 0.35, Nusselt number for pulsating flow is bigger than steady flow and the value of pressure drop takes appropriate value as compared with other filling ratios. For higher values of filling ratios than 0.35, the value of Nusselt number for pulsating flow is lower than steady flow and the pressure drop takes higher values. Therefore, Rp < /sub> =0.35 was considered the optimum value of filling ratios for pulsating flow in the studied operating range. It is found that, the optimum value for strouhal number was equal to 4 (which corresponding to f = 2 Hz) to gave higher values of Nusselt number at optimum value of filling ratio (Rp < /sub> =0.35). Good agreement was obtained when comparing the present experimental results with the previous results. Also, an empirical formula was derived for Nusselt number as a function of Reynolds number, and pulsation frequencies in the studied operating ranges.

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