Serious erosion problem of the heat exchanger directly affects the safe and steady operation of waste heat utilization systems. Herein, a honeycomb H-type finned tube heat exchanger for waste heat utilization of dusty flue gas was proposed, and the collision and erosion behaviors of fly ash particles were numerically predicted via the discrete particle method (DPM). Firstly, the single factor analysis was used to investigate the effects of each structural parameter on the erosion rate. Then, the range analysis of different levels of different structural parameters was carried out via orthogonal test method. Finally, the prediction correlations of erosion rates were obtained based on multiple regression method. The results shows that the oblique tube pitch and fin pitch are negatively correlated with the erosion rate, while the slit width, fin height and fin thickness are positively correlated with the erosion rate. Among them, the fin pitch has the most significant impact on the erosion rate, while the effect of oblique tube pitch is the least. The optimized case (A4B2C3D1E4) was obtained by orthogonal experimental design. Compared with the baseline case, the maximum erosion rate of the five observation points in the optimized case decreases by the average of 33.74% with the maximum reduction of 36.32%, while the average erosion rate is reduced by the average of 37.57% and the maximum of 40.58%. The above results are contributed to the optimization of anti-erosion performance of high dust-containing flue gas waste heat utilization system and the development of efficient heat exchangers.

A CFD model is established to study the airside heat transfer and flow resistance performance of a novel H-type fin-and-tube tube heat exchangers (HFTHE). The simulation data are consistent with the experimental results. A novel heat exchanger with a varying tube diameter layout is proposed while attempting to maintain ease of processing and acceptable thermal-hydraulic performance. The influences of geometric parameters and Re number on thermal-hydraulic performance are examined, and it can be observed that the transverse tube pitch has the greatest impact on Nu and Eu numbers. The results show that the overall performance of the novel HFTHE is obviously superior to that of a typical double HFTHE within the studied Re number range (6833–20500). Nu number is increased by 4.3–13.6% and Eu number is decreased by 12.5–21.8%. The multiple regression method is adopted to fit the correlation formulas of Nu and Eu numbers, and the mean deviations are 3.43% and 2.39% respectively.

Ash deposition is the key factor restricting the heat utilization efficiency of a waste heat boiler in the cement kiln. The reasonable design of heat-transfer surfaces is a crucial issue for reducing ash deposition. In this paper, in order to overcome the manufacturing difficulty or unpractical problems of most heat-transfer surfaces, different designs based on the characteristics of the elliptical tube were proposed. To explore the overall performance of these designs, a detailed CFD model is established to study the ash deposition and thermal-hydraulic characteristics, and the dynamic mesh method is adopted to simulate the dynamic growth process of the ash deposited layer. Compared with the reference scheme (case 1), the performance evaluation criteria PEC of the novel design (case 3) in the clean state is improved by 13%, and the fouling thermal resistance and thermal attenuation coefficient are significantly reduced. Therefore, the novel designs that can effectively reduce particle deposition while maintaining easy manufacturing and acceptable thermal-hydraulic performance are applicable to waste heat utilization of dust-laden exhaust gas.