scholarly journals Utilization of an Air-PCM Heat Exchanger in Passive Cooling of Buildings: A Simulation Study on the Energy Saving Potential in Different European Climates

Energies ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 1133 ◽  
Author(s):  
Pavel Charvát ◽  
Lubomír Klimeš ◽  
Martin Zálešák
Keyword(s):  
Heat Exchanger ◽  
Phase Change ◽  
Energy Saving ◽  
Operating Conditions ◽  
Heat Of Fusion ◽  
Passive Cooling ◽  
Phase Change Temperature ◽  
Set Point ◽  
Energy Saving Potential ◽  
Change Temperature

The energy saving potential (ESP) of passive cooling of buildings with the use of an air-PCMheat exchanger (cold storage unit) was investigated through numerical simulations. One of the goals of the study was to identify the phase change temperature of a PCM that would provide the highest energy saving potential under the specific climate and operating conditions. The considered air-PCM heat exchanger contained 100 aluminum panels filled with a PCM. The PCM had a thermal storage capacity of 200 kJ/kg in the phase change temperature range of 4 ∘ C. The air-PCM heat exchanger was used to cool down the outdoor air supplied to a building during the day, and the heat accumulated in the PCM was rejected to the outdoors at night. The simulations were conducted for 16 locations in Europe with the investigated time period from 1 May–30 September. The outdoor temperature set point of 20 ∘ C was used for the utilization of stored cold. In the case of the location with the highest ESP, the scenarios with the temperature set point and without the set point (which provides maximum theoretical ESP) were compared under various air flow rates. The average utilization rate of the heat of fusion did not exceed 50% in any of the investigated scenarios.

Regeneration of Waste Diatomite from Palm Oil Production Process as a Support Material for PCMs in Thermal Energy Storage in Buildings

2019 ◽  
Vol 1151 ◽  
pp. 29-33 ◽  
Author(s):  
Karen Acurio ◽  
Andrés Chico-Proano ◽  
Javier Martínez-Gómez ◽  
Marco Orozco
Keyword(s):  
Stearic Acid ◽  
Phase Change ◽  
Production Process ◽  
Latent Heat ◽  
Palm Oil ◽  
Heat Of Fusion ◽  
Support Material ◽  
Latent Heat Of Fusion ◽  
Phase Change Temperature ◽  
Change Temperature

In this study, the use of spent diatomite, an industrial waste in the palm oil production process, was evaluated as a support material for phase change materials (PCMs). Calcination tests of the diatomite were carried out at different temperatures (400, 550 and 700 °C) and times (1 and 2 h). For the PCMs preparation, the organic phase, mixtures of palm oil and commercial stearic acid esters, were impregnated on calcined diatomite under vacuum. Differential scanning calorimetry (DSC) analyses were performed in order to select the PCM with the highest latent heat of fusion and a range of phase change temperature corresponding to the thermal comfort range. DSC, TGA and FT-IR analyses were performed before and after the application of 360 thermal cycles to establish the thermal and chemical reliability of the PCM. It was found that 700 °C and 1 h are the best conditions of the calcination process, and the PCM consisting in 100 % methyl esters of commercial stearic acid presented the highest value of latent heat of fusion (34.67 J/g) and a phase change temperature range of 16.4 to 33.5 °C. After the thermal cycles, the results show that the prepared PCMs has thermal and chemical stability.

Mineral Sepiolite Energy-Saving Residential Materials

2010 ◽  
Vol 178 ◽  
pp. 185-190 ◽  
Author(s):  
Da Hua Jiang ◽  
An Gui Li ◽  
Fa En Shi ◽  
Ru Shan Ren
Keyword(s):  
Phase Change ◽  
Energy Saving ◽  
Low Cost ◽  
Eutectic Mixture ◽  
Good Prospect ◽  
Building Energy Efficiency ◽  
Thermal Reliability ◽  
Phase Change Temperature ◽  
Wide Range ◽  
Change Temperature

Mineral sepiolite as inorganic carrier, lauric acid(LA)-stearic acid(SA)as binary PCM(phase change material), CTAB as modifier, ethanol as solvent, mineral energy storage residential composite was prepared by intercalation, and the properties of composites were characterized using thermogravimetry(TG)/differential thermal analysis(DTA),scanning electron microscope(SEM),X-ray diffraction(XRD).Orthogo-nal experimental results show that the optimum proportion of composite materials is A3B2C1D3, the initial phase change temperature is 31.44 °C, phase transition peak temperature is 35.25°C, a wide range of endothermic peak is between 30.0~40.0°C, scope of phase change temperature is 3.81. LA-SA eutectic mixture could be retained by adding into 42.3 wt% porous sepiolite, treated at 80 °C. The weight loss of the composites is no more than 2% when melting/freezing cycling within 100°C, so it has good thermal reliability when applied to building material. Mainly due to relatively high content of mineral impurity, high temperature and CTAB can significantly help improve adsorption rate of mineral sepiolite. Sepiolite as a carrier material has features with low cost, broad sources, non-toxic and non-pollution. The composite material is a healthy residential energy-saving material, and it provides a good prospect for the realization of building energy efficiency, regulating room temperature in summer, and improving human comfort.

scholarly journals Modeling PCM Phase Change Temperature and Hysteresis in Ventilation Cooling and Heating Applications

Energies ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 6455
Author(s):  
Yue Hu ◽  
Rui Guo ◽  
Per Kvols Heiselberg ◽  
Hicham Johra
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Phase Change ◽  
Building Energy ◽  
Heat Transfer Process ◽  
Strong Impact ◽  
Phase Change Temperature ◽  
Change Temperature ◽  
Modelling Methods

Applying phase change material (PCM) for latent heat storage in sustainable building systems has gained increasing attention. However, the nonlinear thermal properties of the material and the hysteresis between the two-phase change processes make the modelling of PCM challenging. Moreover, the influences of the PCM phase transition and hysteresis on the building thermal and energy performance have not been fully understood. This paper reviews the most commonly used modelling methods for PCM from the literature and discusses their advantages and disadvantages. A case study is carried out to examine the accuracy of those models in building simulation tools, including four methods to model the melting and freezing process of a PCM heat exchanger. These results are compared to experimental data of the heat transfer process in a PCM heat exchanger. That showed that the four modelling methods are all accurate for representing the thermal behavior of the PCM heat exchanger. The model with the DSC Cp method with hysteresis performs the best at predicting the heat transfer process in PCM in this case. The impacts of PCM phase change temperature and hysteresis on the building energy-saving potential and thermal comfort are analyzed in another case study, based on one modelling method from the first case study. The building in question is a three-room apartment with PCM-enhanced ventilated windows in Denmark. The study showed that the PCM hysteresis has a larger influence on the building energy consumption than the phase change temperature for both summer night cooling applications and for winter energy storage. However, it does not have a strong impact on the yearly total energy usage. For both summer and winter transition seasons, the PCM hysteresis has a larger influence on the predicted percentage of dissatisfied (PPD) than the phase change temperature, but not a strong impact on the transition season average PPD. It is therefore advised to choose the PCM hysteresis according to whether it is for a summer night cooling or a winter solar energy storage application, as this has a significant impact on the system’s overall efficiency.

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 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

Performance Improvement of Gas Turbine Power Plant by Intake Air Passive Cooling Using Phase Change Material Based Heat Exchanger

2017 ◽  
Author(s):  
Devendra Dandotiya ◽  
Nitin D. Banker
Keyword(s):  
Heat Exchanger ◽  
Ambient Temperature ◽  
Phase Change ◽  
Gas Turbine ◽  
Air Temperature ◽  
Power Output ◽  
Ambient Air ◽  
Passive Cooling ◽  
Air Intake ◽  
Change Material

The power output of a gas turbine plant decreases with the increase in ambient temperature. Moreover, the ambient temperature fluctuates about 15–20°C in a day. Hence, cooling of intake air makes a noticeable improvement to the gas turbine performance. In this regard, various active cooling techniques such as vapor compression refrigeration, vapor absorption refrigeration, vapor adsorption refrigeration and evaporative cooling are applied for the cooling of intake air. This paper presents a new passive cooling technique where the intake air temperature is reduced by incorporating phase change material (PCM) based heat exchanger parallel to conventional air intake line. During the daytime, the air is passed through the PCM which has melting temperature lower than the peak ambient temperature. This will reduce the ambient air temperature before taking to the compressor. Once the PCM melts completely, the required ambient air would be drawn from the ambient through conventional air intake arrangement. During the night, when there is lower ambient temperature, PCM converts from liquid to solid. The selected PCM has a melting temperature less than the peak ambient temperature and higher than the minimum ambient temperature. It is observed from the numerical modeling of the PCM that about four hours are required for the melting of PCM and within this time, the intake air can also be cooled by 5°C. The thermodynamic analysis of the results showed about 5.2% and 5.2% improvement in net power output and thermal efficiency, respectively for four hours at an ambient temperature of 45°C.

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
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