Numerical modeling of an optimal heat accumulator with phase change

1991 ◽  
Vol 61 (5) ◽  
pp. 1345-1350 ◽  
Author(s):  
O. V. Dikhtievskii ◽  
G. V. Konyukhov ◽  
O. G. Martynenko ◽  
I. F. Yurevich
Keyword(s):  
Numerical Modeling ◽  
Phase Change ◽  
Heat Accumulator ◽  
Optimal Heat

Application of the Conservation Element and Solution Element Method in Numerical Modeling of Three-Dimensional Heat Conduction With Melting and/or Freezing

2004 ◽  
Vol 126 (6) ◽  
pp. 937-945 ◽  
Author(s):  
Anahita Ayasoufi ◽  
Theo G. Keith ◽  
Ramin K. Rahmani
Keyword(s):  
Numerical Modeling ◽  
Heat Conduction ◽  
Fluid Mechanics ◽  
Phase Change ◽  
Numerical Method ◽  
Analytical Solutions ◽  
Three Dimensional ◽  
Solution Element ◽  
Explicit Numerical Method ◽  
Element Method

The conservation element and solution element (CE/SE) method, an accurate and efficient explicit numerical method for resolving moving discontinuities in fluid mechanics problems, is used to solve three-dimensional phase-change problems. Several isothermal phase-change cases are studied and comparisons are made to existing analytical solutions. The CE/SE method is found to be accurate, robust, and efficient for the numerical modeling of phase-change problems.

Detailed Numerical Modeling of a Hybrid PCM-Air Heat Sink

2013 ◽  
Author(s):  
Y. Kozak ◽  
G. Ziskind
Keyword(s):  
Numerical Modeling ◽  
Phase Change ◽  
Heat Sink ◽  
Phase Change Materials ◽  
Void Formation ◽  
Solidification Process ◽  
Melting Process ◽  
Significant Rise ◽  
Air Interface ◽  
Vof Model

The ability of phase-change materials (PCMs) to absorb large amounts of heat without significant rise of their temperature during the melting process may be utilized in thermal energy storage and passive thermal management. This paper deals with numerical modeling of a hybrid PCM-air heat sink, in which heat may be either absorbed by the PCM stored in compartments with conducting walls, or dissipated to the air using fins, or both. Under the assumptions of perfect insulation (except for the air fins), identity and symmetry between all PCM channels, and negligible 3-D boundary effects, a 2-D model of the problem for half a PCM compartment of the heat sink is solved, saving calculation time and yet taking into account the essential physical phenomena. A commercial program, ANSYS Fluent, is used in order to solve the governing conservation equations. Phase-change is solved using the enthalpy-porosity method. PCM-air interface is modeled using the volume-of-fluid (VOF) approach. The model takes into account natural convection in the liquid PCM and air, volume change, phase- and temperature-dependence of thermal properties, and PCM-air interface interaction. Various scenarios for the hybrid heat sink operation are simulated and compared. The difference in the melting patterns is analyzed for the cases of heating with and without the fan operating. The solidification process with the fan operating is also simulated. It is shown that the VOF model enables simulating realistic void formation in the solidification process.

A Methodology of an Automotive Engine Cooling Using a Phase Change Material

2009 ◽  
Author(s):  
Kibum Kim ◽  
Kyung-wook Choi ◽  
Ki-hyung Lee ◽  
Kwan-soo Lee
Keyword(s):  
Phase Change ◽  
Phase Change Material ◽  
Heat Load ◽  
Cooling System ◽  
Heat Accumulator ◽  
Full Size ◽  
Automotive Engine ◽  
Excessive Heat ◽  
Engine Cooling ◽  
Change Material

The size of a cooling inventory is generally designed based on which size can endure the excessive heat load situations that occur sporadically. As a result, cooling systems are often too large for most normal driving modes. There have been numerous efforts to downsize the automotive engine cooling system using novel concepts and strategies (e.g. THEMIS cooling system, CoolMaster, UltimateCooling). However, in terms of the system design, preserving the passive cooling strategy may be simpler and more practical than implementing any major changes. Vetrovec (2008) proposed the use of a heat accumulator that has a phase change material (PCM) within the automotive cooling system. Excessive heat generated during severe operating conditions is stored in the heat accumulator, and it is dissipated during periods of low heat load. The heat dissipation capacity of the radiator and the amount of coolant in the cooling system are normally designed such that the system can sustain itself at peak heat load during acceleration and hill ascents in hot summer periods. Therefore, the unnecessarily large cooling inventory creates an overloaded vehicle which increases the fuel consumption rate. A heat accumulator which averages out the peak heat loads can reduce the entire cooling system remarkably in terms of both its volume and weight. Effective cooling in automobiles is beneficial in reducing harmful emissions as well as improving fuel economy. A simulation was conducted to validate the feasibility of using a novel cooling strategy that utilized the heat load averaging capabilities of a phase change material (PCM). Three prototypes were designed: full size, down sized, and a down sized prototype with a heat accumulator containing the PCM inside. When the full size of the cooling inventory was downsized by 30%, this smaller design failed to dissipate the peak heat load and consequently led to a significant increase in the coolant temperature, around 25 °C greater than that in the full size system. However, the peak heat load was successfully averaged out in the downsized system with a heat accumulator. Experimental study is also on-going to validate the simulation results and find more suitable PCM for the application.

Numerical modeling of phase change materials using simusol software

2020 ◽  
Vol 170 ◽  
pp. 114772 ◽  
Author(s):  
P. Dellicompagni ◽  
J. Franco ◽  
D. Heim ◽  
A. Wieprzkowicz
Keyword(s):  
Numerical Modeling ◽  
Phase Change ◽  
Phase Change Materials

New Mechanisms for Cryogenic Solid-Gas Sublimation Refrigeration

2015 ◽  
pp. 106-154
Author(s):  
Lin Chen
Keyword(s):  
Numerical Modeling ◽  
Low Temperature ◽  
Phase Change ◽  
Future Research ◽  
Two Phase ◽  
Food Engineering ◽  
Change Mechanism ◽  
Physical Problems ◽  
Industrial Sectors ◽  
Fast Cooling

Sublimation is one phase change mechanism which usually happens under low-to-moderate temperatures and at the same time large amounts of latent heat is absorbed or released. Low temperature sublimation has been proposed in a lot of applications as one useful fast cooling/refrigeration mechanisms, such as medical cooling, food engineering, chemical synthesis, domestic cooling and many industrial sectors. In this brief chapter, the basic mechanisms of static sublimation process and sublimation two-phase flows are clarified and analyzed first, which covers the theoretical and physical problems of sublimation phase-change. Then the previous studies are classified into numerical modeling and experimental verifications. Representative refrigeration systems are also introduced and compared in this chapter, which may give useful indications for future innovations in this field. Future research focuses are also summarized and proposed in this chapter.

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