scholarly journals Analysis of Thermal Energy Storage Material With Change-of-Phase Volumetric Effects

1993 ◽  
Vol 115 (1) ◽  
pp. 22-31 ◽  
Author(s):  
Thomas W. Kerslake ◽  
Mounir B. Ibrahim

NASA’s Space Station Freedom proposed hybrid power system includes photovoltaic arrays with nickel hydrogen batteries for energy storage and solar dynamic collectors driving Brayton heat engines with change-of-phase thermal energy storage (TES) devices. A TES device is comprised of multiple metallic, annular canisters which contain a eutectic composition LiF-CaF2 phase change material (PCM) that melts at 1040 K. A moderately sophisticated LiF-CaF2 PCM computer model is being developed in two stages considering first one-dimensional and then two-dimensional canister geometries. One-dimensional model results indicate that the void has a marked effect on the phase change process due to PCM displacement and dynamic void heat transfer resistance. Equally influential are the effects of different boundary conditions and liquid PCM free convection. For the second stage, successful numerical techniques used in the one-dimensional phase change model are extended to a two-dimensional (r,z) PCM containment canister model. A prototypical PCM containment canister is analyzed and the results are discussed.

1994 ◽  
Vol 116 (2) ◽  
pp. 114-121 ◽  
Author(s):  
T. W. Kerslake ◽  
M. B. Ibrahim

The Solar Dynamic Power Module being developed for Space Station Freedom uses a eutectic mixture of LiF-CaF2 phase-change salt contained in toroidal canisters for thermal energy storage. This paper presents results from heat transfer analyses of the phase-change salt containment canister. A two-dimensional, axisymmetric finite difference computer program which models the canister walls, salt, void, and heat engine working fluid coolant was developed. Analyses included effects of conduction in canister walls and solid salt, conduction and free convection in liquid salt, conduction and radiation across salt vapor-filled void regions, and forced convection in the heat engine working fluid. Void shape and location were prescribed based on engineering judgment. The salt phase-change process was modeled using the enthalpy method. Discussion of results focuses on the role of free convection in the liquid salt on canister heat transfer performance. This role is shown to be important for interpreting the relationship between ground-based canister performance (in 1-g) and expected on-orbit performance (in micro-g). Attention is also focused on the influence of void heat transfer on canister wall temperature distributions. The large thermal resistance of void regions is shown to accentuate canister hot spots and temperature gradients.


2000 ◽  
Author(s):  
Bing-Chwen Yang ◽  
Shr-Hau Huang ◽  
Hsiang-Hui Lin

Abstract In this paper, the feasibility of phase change material that used for thermal energy storage in the range of 400 ∼ 600°C in the form of latent heat is examined for nine different salts and eutectic salts. The Differential Scanning Calorimeter (DSC) was used to perform the quantitative measurement of the phase change temperature (Tm) and latent heat (ΔH). The thermal properties of NaCl-CaCl2 at repeated heating and cooling cycles were studied with a heating chamber. The quality observation for this phase change material was also performed with this heating chamber to understand its physical phenomena during heating and cooling process. It is found that NaCl-CaCl2 is a good candidate of thermal energy storage material for its stable properties, low cost, and no toxic. Finally, the thermal storage unit with NaCl-CaCl2 as thermal energy storage material was tested to study and evaluate its performance as the application in the waste heat recovery system.


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