Session: K6-04: HEAT TRANSFER IN ENERGY SYSTEMS - ENERGY STORAGE II

Paper Number: 131196

131196 - Convergent and Divergent Shell and Tube TES Partially Filled With PCM and Metal Foam 

Abstract: 

Nowadays, in response to the European energy crisis and the needed to reduce carbon emissions, the study of energy storage systems plays a crucial rule. The topic of this research is the latent heat thermal energy storage system (LTEs).

Among various types of thermal energy storage systems (TESs), latent heat thermal energy storage systems (LTESs) stand out. In comparison to sensible TESs, latent one exhibit higher thermal energy storage capacities per unit mass and operate within a smaller temperature range due to heat interactions based on phase change at quasi-constant temperatures. One promising approach utilizes phase change materials (PCMs), with their low thermal conductivities and limited heat transfer capabilities being enhanced by combining them with metal foams.

By using metal foams as porous media, the thermal conductivity of the PCM significantly increases, enabling the creation of a thermal energy storage system with a fast-absorbing energy zone defined by low thermal resistance. Despite a slight reduction in the heat storage capacity of the system due to metal foam presence, this method proves effective.

In the proposed study, an investigation is conducted on a vertical shell and tube geometry with a no constant section of the internal tube. The shell configuration is filled by a combination of two regions: one consisting of PCM embedded in a metal foam and the other composed only of PCM, the combination follows a filling ratio parameter. Aluminum foam serves as porous media filled with pure paraffin wax as the PCM. The top, bottom, and external surfaces of the hollow cylinder are adiabatic, indeed the inner surface is consistently maintained above the PCM melting point. The Darcy-Forchheimer model is applied to analyze the aluminum foam saturated with paraffin, assuming the Local Thermal Equilibrium (LTE). Additionally, the enthalpy-porosity theory represents the phase change process in paraffin wax. The Ansys-Fluent commercial code is employed for numerical solutions to the governing equations.

Furthermore, the study explores how natural convection influences heat transfer within the TESs by analyzing the influence of the inclination angle and the type of the inclination inside of the shell and tube cylinder. Numerical simulation results are presented over time, reporting melting time, average temperature, and specific energy storage rate. The outcomes demonstrate that the combination of metal foam with PCM enhances heat transfer in the LTES system, leading to a significantly faster phase change process compared to pure PCM and a reduction in melting time particularly in the converging tube cases. This numerical model can be expanded to simulate other combinations of metal foam and PCMs.

Presenting Author: Renato Elpidio Plomitallo Università degli studi della Campania "Luigi Vanvitelli"

Presenting Author Biography: Researcher at Università degli studi della Campania "Luigi Vanvitelli". My research focus on Thermal Energy Storage Systems, with a specific emphasis on numerical simulations in the field of thermofluid dynamics. I am particularly focused on optimizing Latent Heat Thermal Energy Storage systems by utilizing materials like aluminum foam and phase change materials such as paraffin wax.

Authors:

Bernardo Buonomo Università degli studi della Campania "Luigi Vanvitelli"
Maria Rita Golia Università degli studi della Campania "Luigi VanvitellI"
Oronzio Manca Università degli studi della Campania "Luigi Vanvitelli"
Sergio Nardini Università degli studi della Campania "Luigi Vanvitelli"
Renato Elpidio Plomitallo Università degli studi della Campania "Luigi Vanvitelli"