Improving the performance of finned latent heat thermal storage devices using a Cartesian grid solver and machine-learning optimization techniques
01 Jan 2018-
About: The article was published on 2018-01-01 and is currently open access. It has received 2 citations till now. The article focuses on the topics: Thermal energy storage & Solver.
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01 Jan 1998
TL;DR: A finite-difference based formulation for a scalar transport equation is presented, designed to alleviate some of the concerns associated with interface tracking on a fixed underlying grid and to demonstrate the second-order accuracy of the solutions.
Abstract:
In tracking moving boundaries that arise in several flow problems, a mixed Eulerian-Lagrangian algorithm can prove quite useful. In such a method, the grid on which the flow computations are performed remains stationary, while the interface is immersed in and moves through the grid. In this report we present a finite-difference based formulation for a scalar transport equation, which will be designed to alleviate some of the concerns associated with interface tracking on a fixed underlying grid. By performing truncation error analysis, the presentation of the method also sheds light on the expected accuracy of the solutions. The finite-difference operations are performed to maintain nominal global second-order accuracy. To demonstrate the second-order accuracy of the solutions, we present grid refinement studies preformed for some test problems.
1 citations
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Journal Article•
TL;DR: The proposed experimental plans are composed of individually randomized one-factor-at-a-time designs, and data analysis is based on the resulting random sample of observed elementary effects, those changes in an output due solely to changes in a particular input.
Abstract: A computational model is a representation of some physical or other system of interest, first expressed mathematically and then implemented in the form of a computer program; it may be viewed as a function of inputs that, when evaluated, produces outputs. Motivation for this article comes from computational models that are deterministic, complicated enough to make classical mathematical analysis impractical and that have a moderate-to-large number of inputs. The problem of designing computational experiments to determine which inputs have important effects on an output is considered. The proposed experimental plans are composed of individually randomized one-factor-at-a-time designs, and data analysis is based on the resulting random sample of observed elementary effects, those changes in an output due solely to changes in a particular input. Advantages of this approach include a lack of reliance on assumptions of relative sparsity of important inputs, monotonicity of outputs with respect to inputs, or ad...
3,396 citations
"Improving the performance of finned..." refers methods in this paper
...The second measure that increases the efficiency of the optimization process is the use of an elementary effect-based variable screening procedures [136]....
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...The screening process used here, based on the work of Morris [136], calculates the sensitivity of the objective function to variation in the design parameters at random locations in the parameters space....
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...The elementary effect for n independent variables is calculated by performing n+1 simulations [136]....
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TL;DR: In this article, an enthalpy formulation based fixed grid methodology is developed for the numerical solution of convection-diffusion controlled mushy region phase-change problems, where the basic feature of the proposed method lies in the representation of the latent heat of evolution, and of the flow in the solid-liquid mushy zone, by suitably chosen sources.
1,892 citations
"Improving the performance of finned..." refers methods in this paper
...The phase-change boundary is determined using the enthalpy-porosity method [51, 52, 62, 63]....
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TL;DR: In this paper, the phase change problem has been formulated using pure conduction approach but the problem has moved to a different level of complexity with added convection in the melt being accounted for, which makes it difficult for comparison to be made to assess the suitability of PCMs to particular applications.
Abstract: This paper reviews the development of latent heat thermal energy storage systems studied detailing various phase change materials (PCMs) investigated over the last three decades, the heat transfer and enhancement techniques employed in PCMs to effectively charge and discharge latent heat energy and the formulation of the phase change problem. It also examines the geometry and configurations of PCM containers and a series of numerical and experimental tests undertaken to assess the effects of parameters such as the inlet temperature and the mass flow rate of the heat transfer fluid (HTF). It is concluded that most of the phase change problems have been carried out at temperature ranges between 0 °C and 60 °C suitable for domestic heating applications. In terms of problem formulation, the common approach has been the use of enthalpy formulation. Heat transfer in the phase change problem was previously formulated using pure conduction approach but the problem has moved to a different level of complexity with added convection in the melt being accounted for. There is no standard method (such as British Standards or EU standards) developed to test for PCMs, making it difficult for comparison to be made to assess the suitability of PCMs to particular applications. A unified platform such as British Standards, EU standards needs to be developed to ensure same or similar procedure and analysis (performance curves) to allow comparison and knowledge gained from one test to be applied to another.
1,630 citations
"Improving the performance of finned..." refers background or result in this paper
...Perhaps the most promising approach to inexpensive small-scale heat storage involves the use of phase change materials (PCM) as a medium for thermal storage systems [17-19]....
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...This work agrees with earlier work [17, 32, 93-101] in concluding that fins are an...
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...change materials (PCM) as a medium in thermal storage systems [17-19]....
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TL;DR: A review of experimental/computational studies to enhance the thermal conductivity of phase change materials (PCM) that were conducted over many decades is presented in this paper, where the authors focus on studies that concern with positioning of fixed, stationary high conductivity inserts/structures.
Abstract: A review of experimental/computational studies to enhance the thermal conductivity of phase change materials (PCM) that were conducted over many decades is presented. Thermal management of electronics for aeronautics and space exploration appears to be the original intended application, with later extension to storage of thermal energy for solar thermal applications. The present review will focus on studies that concern with positioning of fixed, stationary high conductivity inserts/structures. Copper, aluminum, nickel, stainless steel and carbon fiber in various forms (fins, honeycomb, wool, brush, etc.) were generally utilized as the materials of the thermal conductivity promoters. The reviewed research studies covered a variety of PCM, operating conditions, heat exchange and thermal energy storage arrangements. The energy storage vessels included isolated thermal storage units (rectangular boxes, cylindrical and annular tubes and spheres) and containers that transferred heat to a moving fluid medium passing through it. A few studies have focused on the marked role of flow regimes that are formed due to the presence of thermally unstable fluid layers that in turn give rise to greater convective mixing and thus expedited melting of PCM. In general, it can be stated that due to utilization of fixed high conductivity inserts/structures, the conducting pathways linking the hot and cold ends must be minimized.
1,028 citations
"Improving the performance of finned..." refers background or result in this paper
...This work agrees with earlier work [17, 32, 93-101] in concluding that fins are an...
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...Investigators have suggested numerous ways to do this, including the use of microencapsulation, interspersed high conductivity particles, and metal matrices, among others [27-32]....
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...include enhancement of the thermal conductivity of the PCM itself as well as the inclusion of additional high-conductivity pathways within the PCM [27, 32, 80-82]....
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TL;DR: In this paper, a new method for obtaining approximate equations for natural convection flows is presented, which allows the specification of the conditions under which the traditional Boussinesq approximation applies to a given Newtonian liquid or gas.
940 citations
"Improving the performance of finned..." refers background in this paper
...for the validity of the Boussinesq approximation [116]....
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...1 limit often cited as the upper limit for the validity of the Boussinesq approximation [116]....
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