Application of Porous-Embedded shell and tube heat exchangers for the Waste heat Recovery Systems

Abstract

• Investigation of heat transfer mechanisms inside porous-filled STHX designs. • Detailed comparison over the velocity, temperature, and pressure fields between the porous-filled and traditional STHX designs. • Investigation of the influence of porous-foam on the thermofluidic properties of traditional STHX designs. • A comprehensive sensitivity analysis of the operational condition for the porous-filled and the traditional designs. Among the techniques offered to improve the efficiency of Waste Heat Recovery Shell and Tube Heat Exchangers (WHR-STHX), the porous-filling is reported as an effective technique to improve the heat transfer rate. In this regard, the current study performs a numerical investigation to evaluate the heat transfer performance and pressure loss of several porous-filled STHXs. However, the novelty of this study stems from identifing the mechanisms that manipulated the flow structures and heat transfer to achieve a homogeneous thermal distribution, not from achieving an optimized porous-filling. Furthermore, the industrial feasibility of the porous-filled designs was evaluated by comparing their performance with the conventional type in a wide range of thermofluidic conditions. Based on the results, both porous-filled designs have substantially attenuated the interfacial thermal jumps observed in the conventional STHX; thus, a uniform thermal distribution was achieved. Furthermore, the heat transfer efficiency of the porous-filled cases was improved up to 60% compared with the conventional type; however, they imposed higher pressure drop values. Fortunately, since partially porous-filling provided a lower amount of pressure drop (almost half of full-foam), the noted design was found to be appropriate for low-scale applications in which pressure drop could not be tolerated.