Thermo-economic optimization of the direct-condensation radiant heating panel: A numerical-based approach

•An improved mathematical model closer to the actual device is established.•The analytical solutions of heat conduction of the composite fins are proposed.•Validation of analytical solution and improved model with experimental data.•Influence analysis of geometric parameters on thermo-economic performances.•Thermo-economic optimization of DRHP conducted with the PSO algorithm. The direct-condensation radiant heating panel (DRHP) is considered as an efficient heating terminal in space heating. In this study, a numerical-based optimization approach is proposed for the thermo-economic performance improvement of the DRHP. An improved numerical model of the DRHP considering the heat conduction of the composite straight-and-circular fins and that of the connecting segments is established. The analytical solutions of the heat conduction of the composite straight-and-circular fins are derived to improve the prediction accuracy and computation speed. The model is validated by the experimental data. Based on the proposed model, the particle swarm optimization (PSO) algorithm is adopted to maximize the heating capacity under per unit cost of the DRHP. The optimization constraints are determined with the parametric analysis and the iterations are examined to be 30. Based on the optimization approach, the optimized DRHPs are obtained for heat pump units with different output powers, and the heating capacity under per unit cost of the optimized DRHP is increased by 44.2%. The proposed optimization approach is appropriate for the optimization of DRHP.