scholarly journals Reviewing the Exergy Analysis of Solar Thermal Systems Integrated with Phase Change Materials

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 724
Author(s):  
Macmanus Chinenye Ndukwu ◽  
Lyes Bennamoun ◽  
Merlin Simo-Tagne

The application of thermal storage materials in solar systems involves materials that utilize sensible heat energy, thermo-chemical reactions or phase change materials, such as hydrated salts, fatty acids paraffin and non-paraffin like glycerol. This article reviews the various exergy approaches that were applied for several solar systems including hybrid solar water heating, solar still, solar space heating, solar dryers/heaters and solar cooking systems. In fact, exergy balance was applied for the different components of the studied system with a particular attention given to the determination of the exergy efficiency and the calculation of the exergy during charging and discharging periods. The influence of the system configuration and heat transfer fluid was also emphasized. This review shows that not always the second law of thermodynamics was applied appropriately during modeling, such as how to consider heat charging and discharging periods of the tested phase change material. Accordingly, the possibility of providing with inappropriate or not complete results, was pointed.

2021 ◽  
Vol 877 (1) ◽  
pp. 012038
Author(s):  
Abbas Sahi Shareef ◽  
Hayder Jabbar Kurji ◽  
Hassan Abdulameer Matrood

Abstract Various human activities have led to the consumption of large quantities of pure water, which has led researchers to find efficient and economical methods for desalinating seawater and water containing impurities. In this review paper, solar energy where it is permanent, abundant and environmentally friendly, to produce pure water was discussed using a new solar distillation device, representing the paper’s novelty. The distillation was designed and used in the way led to increase efficiency and improve productivity by adding a solar collector to the system and equipped with a tank containing phase change material (PCM). It has a low melting point and can change the phase by absorbing the system’s latent heat to maintain the system’s temperature. Which contributes to increasing the distillation period even after sunset, thus increasing the daily productivity of freshwater. Using phase change materials will increase distillation hours from (3-4) hours after sunset, increasing the amount of production between (75 - 90) %.


2020 ◽  
Vol 160 ◽  
pp. 02004
Author(s):  
Suhil Kiwan ◽  
Hisham Ahmad ◽  
Ammar Alkhalidi ◽  
Wahib O Wahib ◽  
Wael Al-Kouz

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.


2021 ◽  
Vol 4 (2) ◽  
pp. 105
Author(s):  
T Sasilatha ◽  
Elavarasi R ◽  
V. Karthikeyan

Solar still is the ancient low cost device to distillate the saline water. Paraffin is a kind of phase change material which has a thermal storage characteristic and it can absorb and release a large amount of latent heat during the phase transition process. Ethylene Glycol was used as a PCM to study the thermal characteristics of water and absorption rate. A Nano phase change material plays a vital role in solar energy conversion and is used to enhance the thermal conductivity behavior on thermal energy storage systems. Materials at the nanoscale have a larger surface area and it has higher thermal properties than the macro particles. Incorporating NPCM into basin material helps to improve the productivity and the evaporation rate. The performance of the single basin double slope solar still was higher than the single slope solar still. Despite significant efforts, there are some challenges, such as the thermo physical properties of basin material, flow rate, insulation material and thickness that must be overcome in order for this technique to be useful in practice. In this paper, a detailed comparison of the various solar stills, designs, fabrications and water production analyses are discussed. Hence it is confirmed that NPCM has a higher potential than PCM for saline water desalination processes. This study confirmed that the Paraffin composites are stable up to 160°C and it increases the efficiency due to increased thermal properties of NPCM.


2015 ◽  
Vol 766-767 ◽  
pp. 451-456 ◽  
Author(s):  
V. Saikrishnan ◽  
P.S. Jagadeesh ◽  
K.R. Jayasuriyaa

An Experimental study on phase change heat energy storage system (PCHES) using Erythritol as a phase change material (PCM) has been carried out. Simple and popularly used domestic solar thermal applications make use of direct radiation energy of the sun for cooking, liquid heating, drying and many others as it is the remarkable potential renewable energy source. Effective utilization of such energy can be made with the development of economically operating phase change heat energy storage (PCHES) which is elemental in spanning the gap between supply and demand of energy. PCHES that stores the latent heat of fusion of phase change materials is provocative because of its huge storage density. An integrated Solar wax melting unit with phase change thermal energy storage using ethylene glycol as heat transfer fluid(HTF) to transfer the heat from parabolic dish collector to the wax melting unit is investigated. In this experimental setup, the paraffin wax container is kept in an insulated heat retrieval unit. Heat stored during the daytime by the PCHES is utilized in the off sunshine hours.


2019 ◽  
Vol 112 ◽  
pp. 01010
Author(s):  
Dorin Stanciu ◽  
Camelia Stanciu ◽  
Valentin Apostol ◽  
Horatiu Pop

Storage processes are usually integrated in solar energy systems applications due to daily variation of this energy source availability. Among different thermal storage solutions, phase change materials (PCM) lately became more extensively used covering a wide range of operating temperatures. In this regard, a numerical simulation of a PCM melting process is performed under ANSYS CFD environment. A particular configuration is considered consisting in a 2m length annular tube having a 5.48 cm external diameter. The tube is filled with paraffin chosen as PCM. A concentric interior tube of 2.54 cm diameter is used for transporting the heat transfer fluid (HTF) from the solar collector. Heat is transferred through the 1 mm thick pipe wall to the PCM placed all around the HTF tube. The numerical results reveal the melting process of the PCM at different instances and tube sections. The time variation of the PCM liquid fraction is emphasized. The results describe the dynamic behavior of a PCM melting process and might be further integrated in any solar power plant storage charging process simulation.


2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Guansheng Chen ◽  
Nanshuo Li ◽  
Huanhuan Xiang ◽  
Fan Li

It is well known that attaching fins on the tubes surfaces can enhance the heat transfer into and out from the phase change materials (PCMs). This paper presents the results of an experimental study on the thermal characteristics of finned coil latent heat storage unit (LHSU) using paraffin as the phase change material (PCM). The paraffin LHSU is a rectangular cube consists of continuous horizontal multibended tubes attached vertical fins at the pitches of 2.5, 5.0, and 7.5 mm that creates the heat transfer surface. The shell side along with the space around the tubes and fins is filled with the material RT54 allocated to store energy of water, which flows inside the tubes as heat transfer fluid (HTF). The measurement is carried out under four different water flow rates: 1.01, 1.30, 1.50, and 1.70 L/min in the charging and discharging process, respectively. The temperature of paraffin and water, charging and discharging wattage, and heat transfer coefficient are plotted in relation to the working time and water flow rate.


Proceedings ◽  
2020 ◽  
Vol 63 (1) ◽  
pp. 41
Author(s):  
Hanae El Fakiri ◽  
Lahoucine Ouhsaine ◽  
Abdelmajid El Bouardi

The thermal dynamic behavior of buildings represents an important aspect of the energy efficiency and thermal comfort of the indoor environment. For this, phase change material (PCM) wallboards integrated into building envelopes play an important role in stabilizing the temperature of the human comfort condition. This article provides an assessment of the thermal behavior of a “bi-zone” building cell, which was built based on high-energy performance (HEP) standards and heated by a solar water heater system through a hydronic circuit. The current study is based on studying the dynamic thermal behavior, with and without implantation of PCMs on envelope structure, using a simplified modeling approach. The evolution of the average air temperature was first evaluated as a major indicator of thermal comfort. Then, an evaluation of the thermal behavior’s dynamic profile was carried out in this study, which allowed for the determination of the PCM rate anticipation in the thermal comfort of the building cell.


2021 ◽  
Vol 1059 (1) ◽  
pp. 012010 ◽  
Author(s):  
N Boopalan ◽  
B Kalidasan ◽  
D Raj Kumar ◽  
E Ragupathi ◽  
M Gurumoorthy ◽  
...  

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