Computational study of a latent heat thermal energy storage system enhanced by highly conductive metal foams and heat pi
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Computational study of a latent heat thermal energy storage system enhanced by highly conductive metal foams and heat pipes Saeed Tiari1 · Mahboobe Mahdavi2 Received: 20 November 2019 / Accepted: 15 January 2020 © Akadémiai Kiadó, Budapest, Hungary 2020
Abstract Numerical simulations are performed to analyze the thermal characteristics of a latent heat thermal energy storage system with phase change material embedded in highly conductive porous media. A network of finned heat pipes is also employed to enhance the heat transfer within the system. ANSYS-FLUENT 19.0 is used to create a transient multiphase computational model to simulate the thermal behavior of the storage unit. Copper foam is the porous medium used to enhance the heat transfer and is impregnated with the phase change material, potassium nitrate (KNO3). The effects of the porosity of the metal foam and the quantity of heat pipes on the thermal characteristics of storage unit have been investigated. The results indicated that increasing the quantity of the embedded heat pipes leads to drastic acceleration of both charging and discharging process. Impregnating the copper foam with potassium nitrate phase change material significantly affects the total charging and discharging times of the storage unit. It was shown that the porosity of the metal foam plays a key role in the thermal behavior of the system during the charging and discharging processes. Keywords Computational study · Thermal energy storage · Melting · Solidification · Porous media · Heat pipe List of symbols Latin cp Specific heat (J kg−1 K−1) Cf Inertial coefficient Cmushy Mushy zone constant df Fiber diameter (m) dp Pore diameter (m) fl Liquid fraction g Gravitational acceleration (m s−2) h Sensible enthalpy (kJ kg−1) hsl Latent heat of fusion (kJ kg−1) H Enthalpy (kJ kg−1) K Permeability (m2) L Length (m) p Pressure (Pa) * Saeed Tiari [email protected] Mahboobe Mahdavi [email protected] 1
Biomedical, Industrial and Systems Engineering Department, Gannon University, Erie, PA, USA
Mechanical Engineering Department, Gannon University, Erie, PA, USA
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n Normal vector S Spacing (m) Sx x-Momentum source term Sy y-Momentum source term T Temperature (K) Tl Liquidus temperature (K) Ts Solidus temperature (K) t Thickness (m) u, v Velocity components (m s−1) x, y Cartesian coordinate components Greek β Thermal expansion coefficient (K−1) 𝜀 Porosity ΔH Latent heat (kJ kg−1) λ Thermal conductivity (W m−1 K−1) µ Dynamic viscosity (kg m−1 s−1) ρ Density (kg m−3) τ Time (s) Subscripts eff Effective f Fin hp Heat pipe m Melting pcm Phase change material
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r Evaporator ref Reference value s Solid
Introduction Latent heat thermal energy storage (LHTES) is one of the most effective and promising options to resolve the intermittency problem of concentrated solar power generation systems. They are also widely used in electronics cooling [1], food drying equipment [2], cold storage [3] and heating and hot water systems [4
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