Experimental study of gas–solid overall heat transfer coefficient in vertical tank for sinter waste heat recovery

• Heat transfer between the non-uniform sinter particles and cooling air is studied.
• The influences of gas superficial velocity and particle diameter on heat transfer are analyzed.
• A suitable correlation for gas–solid overall heat transfer coefficient is obtained.
• The applicability of experimental correlation is investigated.

This work experimentally investigates the gas–solid heat transfer behavior in vertical tank for sinter waste heat recovery. With the purpose of predicting the heat transfer Nusselt number, a homemade experimental setup is built to obtain the temperatures of cooling air and sinter particles over time. Sinter particles of average diameter d = 18, 27 and 36 mm with a range of sphericity of 0.68 ≤ Φ ≤ 0.89 are used in the experiments. The experiments are performed in the range of gas superficial velocity of 1.04~1.75 m/s and the sinter temperature in bed layer from 100 to 750 °C. The influences of gas superficial velocity and sinter particle diameter on the gas–solid overall heat transfer coefficient are analyzed in detail for the covered test cases. The heat transfer Nusselt number is obtained according to the regression analysis of experimental data, and the reliability of the heat transfer Nusselt number is also verified. It is found that the gas–solid overall heat transfer coefficient increases with the increase of gas superficial velocity, and decreases with increasing sinter particle diameter. A small increase in gas–solid overall heat transfer coefficient with the temperature of sinter particles is also observed in the experiments. Compared with the previous literature correlations, the experimental correlation for gas–solid heat transfer in the form of Nusselt number best fits the experimental data. The mean deviation between the experimental data of Nusselt number obtained from this work and the values calculated by the experimental heat transfer correlation is 4.37%, showing good prediction.

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