Parametric study on heat transfer enhancement of pipe bundles with porous layer

Heat transfer devices play a vital role in the modernization of the energy industry, contributing significantly to the improvement of energy efficiency and the development of sustainable systems. Among the various technologies available, the utilization of pipes with porous coating layers has emerged as a promising method for enhancing heat transfer performance. This technique improves the thermal efficiency of heat exchangers by increasing the surface area available for heat exchange. However, there remains a gap in the comprehensive optimization of porous layer parameters, particularly in specific heat exchanger designs, which limits the full potential of this technology. In this study, we numerically investigate the thermal-hydraulic performance of the pipe bundles with porous coating layers. A non-isothermal numerical model was developed to simulate singlephase flow in porous media, incorporating the relevant physical properties and heat transfer mechanisms. This simulation approach was verified using multi-scale models, and further validated through experimental data. The experiment procedure is: 1) fabricate porous pipes under different conditions; 2) conduct porous pipe parameter calibration, composition analysis, and surface morphology analysis; 3) insert the specific tubular heat exchanger in parallel with hightemperature steam and cooling water, perform temperature measurements, and conduct data processing. The numerical study focuses on optimizing porous layer parameters as the primary variables. Factors are also considered such as flow rate variations, counter-flow direction, pipe bundle arrangement, temperature distribution, pressure drop, heat transfer efficiency, and overall performance in the heat exchanger design and operation. To optimize the geometric features of the pipe bundles, the Non-dominated Sorting Genetic Algorithm (NSGA) is employed. It is a robust optimization method, to analyze both parallel-flow and cross-flow configurations. This approach allows for the identification of optimal design solutions based on multiple objectives. Additionally, the effects of porosity, porous layer thickness, and permeability on the heat transfer performance of the coated pipe bundles are explored. The results indicate that the optimal porosity for achieving maximum heat transfer efficiency is 0.25 for the parallel-flow configuration and 0.7 for the cross-flow configuration. Furthermore, enhancing the porous layer thickness and permeability positively impacts the figure of merit by increasing the surface area and flow velocity within the porous media, leading to improved heat transfer. This study offers valuable theoretical insights and practical guidelines for the commercial and industrial application of porous-coated pipe heat exchangers, with the potential to improve the design and performance of heat transfer systems in various energy devices.