Assessment and optimization of exhaust gas heat exchanger with porous baffles and porous fins

Abstract

The shell and tube heat exchanger with segmental baffles is widely applied in industry owing to its low cost and easy maintenance. However, when adopted it as the exhaust heat exchanger in engine waste heat recovery system, the large pressure drops on shell side and low thermal efficiency greatly affect the efficiency of the whole system. To overcome the aforementioned shortcomings, a structure of shell and tube heat exchanger with porous baffles and porous fins is put forward and numerically analyzed in this study. Comparisons on the pressure drop, heat transfer and comprehensive performance are firstly conducted between the proposed heat exchanger and other five heat exchangers with different structures. The results show that adding porous baffles and porous fins can increase heat transfer by 92.14%, decrease pressure drop by 64.70%, and reduce weight by 11.35% under the mass flow rate is 0.1280 kg/s, hence the proposed heat exchanger owns the best overall performance among six heat exchangers. Subsequently, the effects of key design parameters (fins number per meter, inner tube pitch and porosity) on the performance of the proposed heat exchanger are analyzed and optimized by artificial neural network and genetic algorithm to achieve the best for comprehensive performance. The results are as follows: when the above three parameters are 94 m−1, 58.6 mm and 0.702 respectively, the performance achieved the best.