Multi-objective optimization of the foam filled counterflow double-pipe heat exchanger under high temperature condition

•Multi-objective optimization of foam filled double-pipe heat exchanger is performed.•The mechanisms of radiative heat transfer within the system is vividly revealed.•Optimization method integrated SVR model with NSGA-II algorithm is established.•The optimal combination of structural parameters for the filling foam is obtained. Double-pipe heat exchanger (DPHE) filled with porous foam is a promising heat transfer enhancement device that could be applicable for high temperature applications. At present, complex coupled heat transfer process hinders the optimization design. In this study, a multi-objective optimization model that integrates the support vector regression (SVR) and non-dominated sorting genetic algorithm (NSGA-II) is employed for considering the trade-off relationship between heat transfer and pressure drop. A complete conjugated heat transfer model is established to obtain performance indicators: the Nusselt number (Nu) and the friction factor (fr). The Local Thermal Non-equilibrium (LTNE) effect and interfacial wall coupling effect are considered. And Monte Carlo method (MCM) is adopted to solve radiative heat transfer. Porosity and pore density of the porous foam are considered as design variables. The surrogated model is established by utilizing Latin hypercube sampling and sequential design scheme based on the converging Pareto-frontier. The results show that Nu tends to be enhanced when a low pore density and high porosity foam block is filled in the inner pipe, which matches that filling for the annular pipe with reverse structural parameters. A compromised solution provides the optimal combination of design variables by weighting the two performance indicators. An increase of 7.5% in Nu and decrease of 60.5% in fr are respectively achieved, when it is compared with the results based on single-objective indicator reported by other authors. These results reveal that this multi-objective optimization strategy is effective for optimizing the thermohydraulic performance of foam filled DPHE with thermal radiation effect considered.