Analysis on heat transfer and heat loss characteristics of rock cavern thermal energy storage

Abstract The present study is aimed at demonstrating the feasibility of the rock cavern, compared with the above-ground tank, for the storage of large-scale high-temperature thermal energy by quantitatively evaluating the heat transfer inside the storage tank and the heat loss characteristics of the surrounding environment. As a conceptual model, we consider a thermal energy storage (TES) system coupled with an adiabatic compressed air energy storage plant (A-CAES), which utilizes loosely packed bed of rocks as heat storage medium and stores heat of up to 685 °C. The specifications of the TES model, such as the mass flow rate of the heat transfer material and the storage volume, were determined through the analysis of the heat transfer in the packed bed, using a quasi-one-dimensional two-phase numerical model developed in this study. In this procedure, the inlet and outlet fluid temperatures and the thermal energy rates to be stored or extracted were examined over 200 consecutive daily cycles to ensure the TES met the requirements for the power generation of the A-CAES plant. Then, with the determined specifications of the TES, a comparative study on the heat loss characteristics of the rock cavern-type TES and above-ground-type TES systems was performed by simulating the operations on a daily basis for a period of 10 years using a three-dimensional numerical model. The comparison results indicated that the amount of cumulative heat loss in the rock cavern-type TES system over the operation period was far smaller than that in the above-ground-type TES system because of the surrounding rock heating and the consequent reduction in the thermal gradient between the surrounding rock and the storage medium. In terms of long-term operation, the rate of heat loss from the rock cavern-type TES system exhibited less-sensitive and less-dependent behaviors with respect to the insulator performance than that of the above-ground-type TES system.

[1]  Jon T. Van Lew,et al.  Similarity and generalized analysis of efficiencies of thermal energy storage systems , 2012 .

[2]  Erich A. Farber,et al.  Two applications of a numerical approach of heat transfer process within rock beds , 1982 .

[3]  A. Mawire,et al.  Simulated performance of storage materials for pebble bed thermal energy storage (TES) systems , 2009 .

[4]  Aldo Steinfeld,et al.  High-temperature thermal storage using a packed bed of rocks - Heat transfer analysis and experimental validation , 2011 .

[5]  Evangelos Tsotsas,et al.  Heat transfer in packed beds with fluid flow: remarks on the meaning and the calculation of a heat transfer coefficient at the wall , 1990 .

[6]  S. Zunft,et al.  Adiabatic compressed air energy storage for the grid integration of wind power , 2006 .

[7]  Anton Meier,et al.  Experiment for modelling high temperature rock bed storage , 1991 .

[8]  Frank P. Incropera,et al.  Fundamentals of Heat and Mass Transfer , 1981 .

[9]  A. Steinfeld,et al.  Packed-bed thermal storage for concentrated solar power: Pilot-scale demonstration and industrial-scale design , 2012 .

[10]  Zhifeng Wang,et al.  Sensitivity analysis of the numerical study on the thermal performance of a packed-bed molten salt thermocline thermal storage system , 2012 .

[11]  Luisa F. Cabeza,et al.  Comparative study of different numerical models of packed bed thermal energy storage systems , 2013 .

[12]  R. Pitz-Paal,et al.  Cascaded latent heat storage for parabolic trough solar power plants , 2007 .

[13]  Refrigerating.  ASHRAE handbook of fundamentals , 1967 .

[14]  John Beek,et al.  Design of Packed Catalytic Reactors , 1962 .

[15]  T.E.W. Schumann,et al.  Heat transfer: A liquid flowing through a porous prism , 1929 .

[16]  Byung-hee Choi,et al.  The effect of aspect ratio on the thermal stratification and heat loss in rock caverns for underground thermal energy storage , 2013 .

[17]  Young-Min Kim,et al.  Potential and Evolution of Compressed Air Energy Storage: Energy and Exergy Analyses , 2012, Entropy.

[18]  R. Saini,et al.  A review on packed bed solar energy storage systems , 2010 .

[19]  K. Ismail,et al.  A parametric study on possible fixed bed models for pcm and sensible heat storage , 1999 .

[20]  K. Stephan,et al.  The Thermal Conductivity of Fluid Air , 1985 .

[21]  Peter Glarborg,et al.  Heat transfer in ash deposits: A modelling tool-box , 2005 .