Experiment study on heat transfer characteristics of dusty gas flowing through a granular bed with buried tubes

This paper reports an experimental study of the heat transfer characteristics of dusty gas flowing through a granular bed with buried tubes. The effects of the dust concentration and the flow velocity on the temperature distribution of the bed layer are investigated. Then, the heat transfer model between flue gas and cooling medium is established using the logarithmic mean temperature difference to deal with the temperature data of the bed layer, and the influences of filter particle filling, dust concentration, and airflow velocity on the comprehensive heat transfer coefficient are analyzed. Results show that filter filling and increasing the dust concentration and air velocity can enhance the comprehensive heat transfer between flue gas and cooling medium. Under the same conditions, the heat transfer coefficient increases by 12% after filter particle filling. When the dust concentration increases from 2000 mg/m³ to 4000 mg/m³, the heat transfer coefficient increases by 16%. When air velocity increases from 0.3 m/s to 0.6 m/s, heat transfer coefficient increases by 51%. Under the experimental conditions, the temperature changes of the bed layer after three-layer heat exchange tube fluctuate little. Experienced formula of heat transfer coefficient versus dust concentration and gas velocity has been also proposed.