Heat transfer and pressure drop characteristics of 3-D finned tube heat exchanger in ash-laden flue gas

Abstract

As an efficient heat transfer enhancement element, 3-D finned tube has good potential in the field of waste heat utilization of industrial flue gas. However, the industrial flue gas often contains a large amount of ash particles. Meanwhile, ash deposition on the surface of heat exchanger can worsen the heat transfer performance and even shorten the service life of the heat exchanger. Therefore, the research of coupling effect of heat transfer and ash deposition on 3-D finned tube heat exchanger is very necessary, and it is bound to affect the further promotion and application of 3-D finned tube heat exchanger. In this paper, the influence of ash deposition on heat transfer process of 3-D finned tube heat exchanger was further studied. The effects of ash deposition time on heat transfer rate and relative pressure drop were discussed firstly. It was found that both ofheat transfer and relative pressure drop basically tended to be stable with the running time up to 6 hours. Then, the influences of fin height of 3-D finned tube, gas velocity and particle concentration on fouling characteristics, heat transfer and flow performance were studied according to the orthogonal array design method. The optimized parameters corresponding to the smallest fouling coefficient and the least relative pressure drop after fouling were determined. Besides, the performance of 3-D finned tube heat exchanger with the optimized parameters was also compared with other tested heat exchangers. The results showed that the heat exchanger with optimized parameters had better heat transfer performance than the other cases under the same condition. At last, a correlation of fouling coefficient of 3-D finned tube heat exchanger under the optimized parameters with ash deposition time was obtained, and it can be useful in the design and evaluation of heat exchanger in dusty environment.