Thermodynamics of Phase-Change Energy Storage: The Effects of Liquid Superheating During Melting, and Irreversibility During Solidification

1991 ◽  
Vol 113 (1) ◽  
pp. 2-10 ◽  
Author(s):  
M. De Lucia ◽  
A. Bejan
Keyword(s):  
Heat Source ◽  
Phase Change ◽  
Geometric Mean ◽  
Solidification Process ◽  
Melting Process ◽  
Optimum Temperature ◽  
Phase Change Temperature ◽  
The Third ◽  
Environment Temperature ◽  
Change Temperature

This paper considers the question of whether the optimum phase-change temperature for maximum exergy storage is universally equal to the geometric mean of the heat source and environment temperature, Tm=(T∞Te)1/2. The study consists of three parts. The first deals with the conduction-melting process, and shows that the optimum melting temperature is generally greater than the geometric mean of the source and environment temperatures. The second part covers the conduction-solidification process, and concludes that the irreversibility of solidification decreases monotonically as the phase-change temperature increases. The third part treats the complete cycle of melting (storage) followed by solidification (retrieval), and demonstrates that the optimum phase-change temperature is greater than the optimum temperature of the melting process alone.

A Study on the Cooling Characteristics of TMA Clathrate Compound with Additives

2006 ◽  
Vol 326-328 ◽  
pp. 1275-1278 ◽  
Author(s):  
Chang Oh Kim ◽  
Jin Heung Kim ◽  
Nak Kyu Chung
Keyword(s):  
Heat Source ◽  
Phase Change ◽  
Specific Heat ◽  
Freezing Point ◽  
Phase Change Temperature ◽  
Source Temperature ◽  
Heat Source Temperature ◽  
Clathrate Compound ◽  
Supercooling Degree ◽  
Change Temperature

This study aims to find out cooling characteristics of TMA 25wt%-water clathrate compound with ethanol such as supercooling, phase change temperature and specific heat. For this purpose, ethanol is added as per weight concentration and cooling experiment is performed at -6, -7 and -8, cooling heat source temperature, and it leads the following result. (1) Phase change temperature is decreased due to freezing point depression phenomenon. Especially, it is minimized as 5.1 and 5.0, 3.8 according to cooling source temperature in case that 0.5wt% of ethanol is added. (2) If 0.5wt% of ethanol is added, average supercooling degree is 0.9 and minimum supercooling is 0.8, 0.7 according to cooling heat source temperature. The restraint effect of supercooling is shown. (3) Specific heat shows tendency to decrease if ethanol is added. It is 3.013~3.048 kJ/kgK according to cooling heat source temperature if 0.5wt% of ethanol is added. Phase change temperature higher than that of water and inhibitory effect against supercooling can be confirmed through experimental study on cooling characteristics of TMA 25wt%-water clathrate compound by adding additive, ethanol.

scholarly journals Liquid Crystals as Phase Change Materials for Thermal Stabilization

2018 ◽  
Vol 2018 ◽  
pp. 1-8
Author(s):  
Eva Klemenčič ◽  
Mitja Slavinec
Keyword(s):  
Liquid Crystals ◽  
Heat Source ◽  
Electric Field ◽  
Phase Change ◽  
Phase Change Materials ◽  
Thermal Stabilization ◽  
Phase Change Temperature ◽  
Thermotropic Liquid Crystals ◽  
Key Factor ◽  
Change Temperature

Thermal stabilization exploiting phase change materials (PCMs) is studied theoretically and numerically. Using the heat source approach in numerical simulations, we focus on phase change temperature as a key factor in improving thermal stabilization. Our focus is to analyze possible mechanisms to tune the phase change temperature. We use thermotropic liquid crystals (LCs) as PCMs in a demonstrative system. Using the Landau-de Gennes mesoscopic approach, we show that an external electric field or appropriate nanoparticles (NPs) dispersed in LCs can be exploited to manipulate the phase change temperature.

scholarly journals Experimental Study on Flow Characters of Salt Hydrate Slurry in Phase Change Temperature Range

2017 ◽  
Vol 21 (5) ◽  
pp. 15-23
Author(s):  
Muhammad Irsyad ◽  
Yuli S. Indartono ◽  
Ari D. Pasek ◽  
Willy Adriansyah
Keyword(s):  
Experimental Study ◽  
Phase Change ◽  
Salt Hydrate ◽  
Phase Change Temperature ◽  
Temperature Range ◽  
Change Temperature

scholarly journals Effect of Ion Irradiation on Amorphous and Crystalline Ge–Se and Their Application as Phase Change Temperature Sensor

2020 ◽  
pp. 2000429
Author(s):  
Al-Amin Ahmed Simon ◽  
Lyle Jones ◽  
Yoshifumi Sakaguchi ◽  
Henri Kunold ◽  
Isabella van Rooyen ◽  
...  
Keyword(s):  
Phase Change ◽  
Temperature Sensor ◽  
Ion Irradiation ◽  
Phase Change Temperature ◽  
Change Temperature

Preparation and Thermal Propertites of Polyethylene Glycol/ Silica Hollow Nanospheres Composite as Shape-Stabilized Phase Change Materials

2013 ◽  
Vol 773 ◽  
pp. 534-537 ◽  
Author(s):  
Li Li Feng ◽  
Jing Jing Tong ◽  
Chong Yun Wang
Keyword(s):  
Thermal Properties ◽  
Polyethylene Glycol ◽  
Phase Change ◽  
Porous Structure ◽  
Phase Change Materials ◽  
Hollow Nanospheres ◽  
Lower Phase ◽  
Phase Change Temperature ◽  
Change Temperature ◽  
Change Material

Shape-stabilized phase change material (PCM) composed of polyethylene glycol and silica hollow nanospheres was prepared by a vacuum impregnating method. Thermal properties of the composite PCM were investigated by various techniques. Lower phase change temperature and enthalpy of the composite PCM were observed. It is concluded that the phase change properties of the composite PCM are influenced by the adsorption confinement of the PEG segments from the porous structure of the silica hollow nanospheres.

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