Outlining the impact of discrete filling of metal foams on thermodynamic performance

Abstract

The desire of this paper is to present the numerical analysis of thermodynamic performance of high porosity metal foams with discrete filling inside the horizontal pipe. The heater is embedded on the pipe’s circumference and is assigned with known heat input. To enhance heat transfer, aluminum metal foam of 10 PPI (pores per inch) with porosity 0.95 is filled into the pipe. In filling, two kinds of arrangements are made. In the first arrangement, the metal foam is filled adjacent to the inner wall of the pipe (Model (1–3)), and in the second arrangement, the metal foam is located at the center of the pipe (Model (4–6)). So, six different models are inspected for different fluid velocities (0.7–7 m/s) under turbulent flow conditions. Darcy Extended Forchheimer (DEF) is combined with local thermal non-equilibrium (LTNE) models for estimating the flow features and heat transfer via metal foams and initially validated with experimental outcomes. The application of the second law of thermodynamics via metal foams is the novelty of current investigation. In the study, the thermal performance is assessed in terms of heat transfer enhancement ratio and heat transfer performance ratio, and the thermodynamic performance is evaluated based on exergy and irreversibility analysis. In the analysis, the parameters like mean exergy based Nusselt number (Nue), heat transfer and flow frictional irreversibility are considered for the evaluation. The overall thermal performance and exergy transfer found higher in Model (1–3) than the Model (4–6) respectively. The flow and heat transfer irreversibility found less in Model (1–3) than the Model (4–6) respectively. The superior thermodynamic performance is obtained from the metal foam filled cases than from the clear pipe. In that, Model-2 suits the best configuration for designing the thermal system.