scholarly journals Effects of Neglecting PCM Hysteresis While Making Simulation Calculations of a Building Located in Polish Climatic Conditions

2021 ◽  
Vol 11 (19) ◽  
pp. 9166
Author(s):  
Anna Zastawna-Rumin ◽  
Katarzyna Nowak
Keyword(s):  
Surface Temperature ◽  
Phase Change ◽  
Phase Change Materials ◽  
Model Building ◽  
Experimental Tests ◽  
Climatic Conditions ◽  
Heat Accumulation ◽  
Noticeable Effect ◽  
Change Temperature ◽  
The Impact

The use of phase change materials (PCM) in different building applications is a hot topic in today’s research and development activities. Numerous experimental tests confirmed that the hysteresis of the phase change process has a noticeable effect on heat accumulation in PCM. The authors are trying to answer the question of whether the neglecting of hysteresis or the impact of the speed of phase transformation processes reduce the accuracy of the simulation. The analysis was performed for a model building, created to validate the energy calculations. It was also important to conduct simulations for the polish climatic conditions. The calculations were conducted for three variants of materials. In addition, in the case of models containing layers with PCM, calculations were made both taking into account, as well as excluding material hysteresis in the calculations. In the analyzed examples, after taking into account hysteresis in the calculations, the period of time when surface temperature is below the phase change temperature of the materials decreased by 10.6% and 29.4% between 01 June to 30 September, for the options with PCM boards and Dupont boards, respectively. Significant differences in surface temperature were also observed. The effects of neglecting, even relatively small hysteresis, in the calculations are noticeable and can lead to significant errors in the calculation.

Suitability Assessment and Experimental Characterization of Phase Change Materials for Energy Conservation in Indian Buildings

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Rajat Saxena ◽  
Naman Agarwal ◽  
Dibakar Rakshit ◽  
S. C. Kaushik
Keyword(s):  
Phase Change ◽  
Phase Change Materials ◽  
Thermal Capacity ◽  
Climatic Conditions ◽  
Melting Temperatures ◽  
Suitability Assessment ◽  
Efficiency Measures ◽  
Prime Concern ◽  
Change Temperature ◽  
And Performance

Abstract With increasing energy consumption in buildings, energy efficiency measures are matter of prime concern. A huge portion of energy consumed in buildings is used for regulating the thermal comfort. A solution to this is to incorporate phase change material (PCM) within the building elements which increases their overall thermal capacity. In the present study, the temperature of inner room surface, with and without PCM incorporation, is calculated for composite climate of Delhi. The analysis of PCM sandwiched walls has been performed. The performance analysis of five PCMs, having different melting temperatures, is carried out with nodal temperatures as the output. The results show that a phase change temperature range of 34–38 °C is suitable for peak summer conditions of Delhi. It is also observed that due to the low thermal conductivity of PCMs, they act as both storage medium and insulation, thus reducing temperature fluctuation during summer/winter. Based on the simulation, three PCMs were found suitable and hence were experimentally tested for their characteristic charging and discharging properties and performance, using differential scanning calorimeter (DSC). Based on the characterization results, it is concluded that two commercially available PCMs (Eicosane and OM35) are suitable for Delhi. All the other PCMs have also been simulated for different climatic conditions in India and their impact on heat gain has been assessed.

Experimental Investigation and Numerical Modeling of Room Temperature Control in Buildings by the Implementation of Phase Change Material in the Roof

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
N. Beemkumar ◽  
D. Yuvarajan ◽  
M. Arulprakasajothi ◽  
S. Ganesan ◽  
K. Elangovan ◽  
...  
Keyword(s):  
Thermal Comfort ◽  
Phase Change ◽  
Layer Thickness ◽  
Phase Change Material ◽  
Energy Demand ◽  
Model Building ◽  
Climatic Conditions ◽  
Air Conditioners ◽  
The Impact ◽  
Change Material

Abstract Due to the increasing demand for air conditioners to maintain thermal comfort in buildings, it is necessary to search for alternatives that can reduce the soaring temperature and meet total air conditioning demands. There are several proven technologies for maintaining thermal comfort in buildings of which the use of phase change material (PCM) in buildings provides improved thermal comfort with fewer energy requirements. The present study analyzes the impact of the incorporation of PCM in roofs on the thermal behavior of buildings. The experiments were conducted in two identical model building roofs with and without the implementation of PCM. A numerical model was developed to find the effect of variation in the PCM layer thickness and month wise temperature variations. To get minimum variation in the results, the simulation was run continuously for 5 days assuming average climatic conditions. The results showed that temperature fluctuations in the room were reduced with the use of PCM, and also the average peak temperature rise was reduced by 2–4°C. The increased PCM layer thickness resulted in decreased energy demand for maintaining the required thermal comfort in buildings at an almost constant temperature.

scholarly journals Thermo-physical characteristics of building integrated phase change materials (PCM) and their applicability to energy efficient homes

2021 ◽  
Author(s):  
Omar Siddiqui
Keyword(s):  
Compressive Strength ◽  
Phase Change ◽  
Phase Change Materials ◽  
Energy Savings ◽  
Physical Characteristics ◽  
Comfort Level ◽  
Thermal Mass ◽  
Lower Phase ◽  
Physical Test ◽  
The Impact

The applicability of utilizing a variety of thermal mass including phase change materials with commonly used building materials is investigated through the use of simulations and physical testing. The thermal performance and occupant comfort potential of a novel solid-solid phase change material, known as Dal HSM, is compared and contrasted to commonly available forms of thermal mass. Detailed experimentation is conducted to successfully integrate Dal HSM with gypsum and concrete. The measurement of physical characteristics such as compressive strength and modulus of rupture is conducted to ensure that the PCM-composite compound retains the structural integrity to be utilized in a typical building. The use of thermal mass in the Toronto Net Zero house was found to contribute to energy savings of 10-15% when different types of thermal mass were used. The comfort level of the indoor occupants was also found to increase. The performance of Dal HSM was found to be comparable to a commercially available PCM known as Micronal in the heating mode. The cooling mode revealed that Dal HSM provided slightly lower energy savings when compared to Micronal due to a lower phase transition temperature and latent heat. The performance of physical test revealed a decrease in the compressive strength as the concentration of Dal HSM was increased in the PCM-gypsum specimens. Tests were also performed to analyze the impact of increasing the PCM concentration on the flexural strength of PCM-gypsum composite.

scholarly journals The effect of metal wool on the charging and discharging rate of the phase transition thermal storage material

2021 ◽  
Vol 4 (5(112)) ◽  
pp. 12-20
Author(s):  
Olga Khliyeva ◽  
Vitaly Zhelezny ◽  
Aleksey Paskal ◽  
Yana Hlek ◽  
Dmytro Ivchenko
Keyword(s):  
Power Systems ◽  
Phase Change ◽  
Phase Change Materials ◽  
Thermal Storage ◽  
Heating Time ◽  
Phase Changes ◽  
Storage Material ◽  
Heat Accumulation ◽  
Heating And Cooling ◽  
Efficiency And Reliability

Thermal energy storage (TES) plays an important role in solar heat power systems. The use of phase change materials (PCM) and selecting additives to increase the rate of heat accumulation is a promising way to increase the efficiency and reliability of such systems. The objects of the study were pure paraffin wax (PW) and composite PCMs based on it (containing aluminum and copper wool of 30 and 45 μm in diameter, respectively). An experimental setup with a cylindrical measuring cell was created, which was also considered as a model of a capsule with a thermal storage material. The rate of temperature change in the pure PW sample and samples of composite PCMs was experimentally measured. Two modes of heating and cooling were investigated: from 48 to 59 °C (mode with a phase change) and from 30 to 40 °C (mode without phase changes). Heating time from 48 to 59 °C for the PW sample was 13 min., for the PW samples with the content of aluminum wool of 0.00588 and 0.01780 m3·m-3 − 11 and 10.5 min., for the PW samples with the content of copper wool of 0.00524 and 0.01380 m3·m-3 − 11 and 8 min., correspondingly. The minimum heating time from 30 to 40 °C was 6 min. for the sample of PW with 0.01380 m3·m-3 of copper wool in comparison with 9 min. for the sample of pure PW. The expediency of using copper wool as an additive to thermal storage materials of PW to increase the charging and discharging rate of TES devices without significantly raising their price was confirmed. The presence of metal wool in molten PW suppresses bottom-up convective currents, so the main mechanism of heat transfer is thermal conductivity. This fact will contribute to a faster equalization of the temperature field by the height of heat storage capsules

Phase Change Process Inside a Small-radii Cylinder Subjected to Cyclic Convective Boundary Conditions: a Numerical Study

2021 ◽  
Author(s):  
Yousef Kanani ◽  
Avijit Karmakar ◽  
Sumanta Acharya
Keyword(s):  
Heat Transfer ◽  
Surface Temperature ◽  
Phase Change ◽  
Phase Change Materials ◽  
Numerical Study ◽  
Convective Boundary Condition ◽  
Freezing Process ◽  
Fourier Number ◽  
Two Phase ◽  
Convective Boundary

Abstract We numerically investigate the melting and solidi?cation behavior of phase change materials encapsulated in a small-radii cylinder subjected to a cyclic convective boundary condition (square wave). Initially, we explore the effect of the Stefan and Biot numbers on the non-dimensionalized time required (i.e. reference Fourier number Tref ) for a PCM initially held at Tcold to melt and reach the cross?ow temperature Thot. The increase in either Stefan or Biot number decreases Tref and can be predicted accurately using a correlation developed in this work. The variations of the PCM melt fraction, surface temperature, and heat transfer rate as a function of Fourier number are reported and analyzed for the above process. We further study the effect of the cyclic Fourier number on the periodic melting and freezing process. The melting or freezing front initiates at the outer periphery of the PCM and propagates towards the center. At higher frequencies, multiple two-phase interfaces are generated (propagating inward), and higher overall heat transfer is achieved as the surface temperature oscillates in the vicinity of the melting temperature, which increases the effective temperature difference driving the convective heat transfer.

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.

scholarly journals Photovoltaic Cooling Utilizing Phase Change Materials

2020 ◽  
Vol 160 ◽  
pp. 02004
Author(s):  
Suhil Kiwan ◽  
Hisham Ahmad ◽  
Ammar Alkhalidi ◽  
Wahib O Wahib ◽  
Wael Al-Kouz
Keyword(s):  
Phase Change ◽  
Experimental Test ◽  
Phase Change Materials ◽  
Experimental Tests ◽  
Photovoltaic System ◽  
Cell Temperature ◽  
Average Cell ◽  
Solar Systems ◽  
Pv Panel ◽  
Change Material

A theoretical analysis based on mathematical formulations and experimental test to a photovoltaic system cooled by Phase Change Material (PCM) is carried out and documented. The PCM is attached to the back of the PV panel to control the temperature of cells in the PV panel. The experimental tests were done to solar systems with and without using PCM for comparison purposes. A PCM of paraffin graphite panels of thickness15 mm has covered the back of the panel. This layer was covered with an aluminum sheet fixed tightly to the panel frame. In the experimental test, it was found that when the average cell temperature exceeds the melting point temperature of the PCM, the efficiency of the system increases. However, when the cell temperature did not exceed the melting temperature of the PCM, the use of the PCM will affect negatively the system efficiency.

Selection Principles and Investigation of Substances for Synthesis of Composite Medium-Temperature Phase Change Materials for Space Heating and Domestic Hot Water

2020 ◽  
Vol 989 ◽  
pp. 165-171
Author(s):  
A.M. Morzhukhin ◽  
D.S. Testov ◽  
S.V. Morzhukhina
Keyword(s):  
Phase Change ◽  
Phase Change Materials ◽  
Hot Water ◽  
Temperature Phase ◽  
Heat Accumulation ◽  
Medium Temperature ◽  
Domestic Hot Water ◽  
Selection Principles ◽  
Salt Hydrates ◽  
Selection Of

The types of heat accumulation and the types of heat-accumulating materials are considered. It is shown that the most promising as heat-accumulating materials for heating and hot water are the salts hydrates. Based on the conducted factor analysis, a number of criteria are excluded from further consideration, which significantly reduces the list of criteria considered for selecting phase change materials (PCM) and simplifies further work on the selection of the most promising materials. There were selected from over 160 salt hydrates as PCM for the future of composite synthesis for the heating and hot water the Na (CH3COO) •3H2O, Ba (OH)2•8H2O, Mg (NO3)2 •6H2O and Zn (NO3)2•6H2O.

Composite phase change materials improve the photo-thermal effects of cotton fabrics

2020 ◽  
pp. 004051752097561
Author(s):  
Wei Zhang ◽  
Shang Hao ◽  
Jiali Weng ◽  
Yibo Zhang ◽  
Jiming Yao ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Surface Temperature ◽  
Ambient Temperature ◽  
Phase Change ◽  
Latent Heat ◽  
Thermal Effects ◽  
Phase Change Materials ◽  
Thermal Storage ◽  
Cotton Fabrics ◽  
Composite Phase Change Materials

We report on the impregnation-based preparation of composite phase change materials (CPCMs) with thermal storage properties, using paraffin wax and multi-walled carbon nanotubes (MWCNTs). We coated the CPCMs on the fabric by scraper coating, then evaluated their shape stability, latent heat, thermal conductivity, thermal storage stability and photo-thermal effects. Results show that CPCMs with 10% acid-oxidized MWCNTs introduce only a small phase leakage when heated at 50℃ for 900 s; their latent heat energy reduces by 16.5%, while their thermal conductivity increases by 131.9% compared to pure paraffin. When exposed to sunlight at an ambient temperature of 12.5℃, the cotton fabrics coated with CPCMs record a 12.8℃ higher surface temperature than the pristine fabric, while their heat dissipation is delayed by 120–180 s. The fabric surface temperature increases to twice the ambient temperature during daytime. Overall, these findings indicate that the coated fabric has excellent thermal stability, affirming its potential as photo-thermal functional material.

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