scholarly journals Performance Evaluation of Elimination of Stagnation of Solar Thermal Systems

Processes ◽  
2020 ◽  
Vol 8 (5) ◽  
pp. 621 ◽  
Author(s):  
Miroslav Rimar ◽  
Marcel Fedak ◽  
Jakub Vahovsky ◽  
Andrii Kulikov ◽  
Peter Oravec ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Solar Thermal ◽  
Heat Transfer Fluid ◽  
Thermal Systems ◽  
Heat Transfer Medium ◽  
Limit Values ◽  
Fully Automatic ◽  
Thermal Saturation ◽  
Solar Thermal System ◽  
The Ideal

The study deals with the possibility of elimination of stagnation of thermal systems. The state of stagnation of thermal systems leads to overheating and evaporation of the heat transfer medium, which increases pressure and can lead to damage to the solar thermal system. Stagnation can occur due to a fault and stopping of the circulation pump, which causes the circulation of the heat transfer medium to stop. Another possibility is to achieve thermal saturation in the system, which can be affected by low heat consumption from the system. Elimination of stagnation is possible by various construction designs of collectors or by using other technical means. This study describes an experiment verifying the usability of a thermal collector’s tilting system to eliminate thermal stagnation of the system. The system is fully automatic, and when recording the limit values, ensures that the panel is rotated out of the ideal position, thus reducing the amount of received energy. In this way, the temperature of the medium in the system can be reduced by up to 10% in one hour. In the case of thermal saturation of the system, the solution is the automatic circulation of heat-transfer fluid through the system during the night and the release of thermal energy to the outside. These results suggest that the methods used actively eliminate stagnation of thermal systems.

scholarly journals Carbon-based Nanofluid Applications in Solar Thermal Energy

2019 ◽  
Vol 111 ◽  
pp. 01056
Author(s):  
Nur Çobanoğlu ◽  
Ziya Haktan Karadeniz ◽  
Alpaslan Turgut
Keyword(s):  
Heat Transfer ◽  
Renewable Energy ◽  
Solar Energy ◽  
Renewable Energy Sources ◽  
Energy Systems ◽  
Solar Thermal ◽  
Heat Transfer Fluid ◽  
Energy Sources ◽  
Solar Thermal Energy ◽  
Thermal Systems

Renewable energy sources such as solar, wind and geothermal are proposed as an alternative to fossil fuels whose excessive use causes global warming. The most popular one of the renewable energy sources is considered as solar energy due to the fact that required energy is provided by the sun entire year around the world. Solar energy systems convert the solar radiation to the useful heat or electricity. In order to achieve better performance in solar thermal systems many studies have been conducted. Some of these studies suggest that heat transfer fluid could be changed with the nanofluids which can be defined as new generation heat transfer fluid. Nanofluids are suspensions of nano-sized particles such as metals, metal-oxides, and Carbon-allotropes (C), in the conventional base-fluids (water, ethylene glycol and oil). Using nanofluid enhances the efficiency and thermal performance of solar systems due to their better thermophysical and optical properties. Recently, C-based nanofluids are getting attention due to their enhanced thermal conductivity and absorptivity at even low concentrations. The results show that C-based nanofluids have a potential to use in solar energy systems: solar collectors, solar stills, photovoltaic/thermal systems.

scholarly journals Modification of a Solar Thermal Collector to Promote Heat Transfer inside an Evacuated Tube Solar Thermal Absorber

2021 ◽  
Vol 11 (9) ◽  
pp. 4100
Author(s):  
Rasa Supankanok ◽  
Sukanpirom Sriwong ◽  
Phisan Ponpo ◽  
Wei Wu ◽  
Walairat Chandra-ambhorn ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Solar Thermal ◽  
Heat Transfer Fluid ◽  
Small Scale ◽  
Medium Temperature ◽  
Change Behavior ◽  
Set Up ◽  
Evacuated Tube ◽  
Heating Medium

Evacuated-tube solar collector (ETSC) is developed to achieve high heating medium temperature. Heat transfer fluid contained inside a copper heat pipe directly affects the heating medium temperature. A 10 mol% of ethylene-glycol in water is the heat transfer fluid in this system. The purpose of this study is to modify inner structure of the evacuated tube for promoting heat transfer through aluminum fin to the copper heat pipe by inserting stainless-steel scrubbers in the evacuated tube to increase heat conduction surface area. The experiment is set up to measure the temperature of heat transfer fluid at a heat pipe tip which is a heat exchange area between heat transfer fluid and heating medium. The vapor/ liquid equilibrium (VLE) theory is applied to investigate phase change behavior of the heat transfer fluid. Mathematical model validated with 6 experimental results is set up to investigate the performance of ETSC system and evaluate the feasibility of applying the modified ETSC in small-scale industries. The results indicate that the average temperature of heat transfer fluid in a modified tube increased to 160.32 °C which is higher than a standard tube by approximately 22 °C leading to the increase in its efficiency by 34.96%.

scholarly journals Comparison of Li2CO3-Na2CO3-K2CO3, KCl-MgCl2 and NaNO3-KNO3 as heat transfer fluid for different sCO2 and steam power cycles in CSP tower plant under different DNI conditions

2021 ◽  
Vol 13 (4) ◽  
pp. 168781402110119
Author(s):  
Kamran Mahboob ◽  
Awais A Khan ◽  
Muhammad Adeel Khan ◽  
Jawad Sarwar ◽  
Tauseef A Khan
Keyword(s):  
Heat Transfer ◽  
Power Plant ◽  
Rankine Cycle ◽  
Capacity Factor ◽  
Solar Thermal ◽  
Heat Transfer Fluid ◽  
Incident Power ◽  
Steam Power ◽  
Power Cycles ◽  
Plant Configuration

This work presents the characteristics of a solar thermal tower power plant in two different places (Seville and Dubai) using three different HTFs (NaNO3-KNO3, KCl-MgCl2 and Li2CO3-Na2CO3-K2CO3) and three different power cycles (Rankine, sCO2 Recompression and sCO2 Partial cooling cycles). An indirect configuration is considered for the Gemasolar power plant. Detailed modelling is carried out for the conversion of incident power on the heliostat to the output electricity. Optimization of the cycle is carried out to determine the most promising cycle configuration for efficiency. The results showed that for the Gemasolar power plant configuration, the performance of the KCl-MgCl2 based plant was poorest amongst all. NaNO3-KNO3 based plant has shown good performance with the Rankine cycle but plant having Li2CO3-Na2CO3-K2CO3 as HTF was best for all three cycles. Partial cooling was the best performing cycle at both locations with all three HTFs. Placing the Seville Plant in Dubai has improved the efficiency from 23.56% to 24.33%, a capacity factor improvement of 21 and 52 GW additional power is generated. The optimization of the plant in Dubai has shown further improvements. The efficiency is improved, the Capacity factor is increased by 31.2 and 77.8 GW of additional electricity is produced.

Central Receiver System Solar Power Plant Using Molten Salt as Heat Transfer Fluid

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
J. Ignacio Ortega ◽  
J. Ignacio Burgaleta ◽  
Félix M. Téllez
Keyword(s):  
Heat Transfer ◽  
Power Generation ◽  
Molten Salt ◽  
Thermal Power ◽  
Solar Thermal ◽  
Heat Transfer Fluid ◽  
Solar Thermal Power ◽  
Central Receiver ◽  
Spanish Legislation ◽  
Solar Thermal Power Generation

Of all the technologies being developed for solar thermal power generation, central receiver systems (CRSs) are able to work at the highest temperatures and to achieve higher efficiencies in electricity production. The combination of this concept and the choice of molten salts as the heat transfer fluid, in both the receiver and heat storage, enables solar collection to be decoupled from electricity generation better than water∕steam systems, yielding high capacity factors with solar-only or low hybridization ratios. These advantages, along with the benefits of Spanish legislation on solar energy, moved SENER to promote the 17MWe Solar TRES plant. It will be the first commercial CRS plant with molten-salt storage and will help consolidate this technology for future higher-capacity plants. This paper describes the basic concept developed in this demonstration project, reviewing the experience accumulated in the previous Solar TWO project, and present design innovations, as a consequence of the development work performed by SENER and CIEMAT and of the technical conditions imposed by Spanish legislation on solar thermal power generation.

Rheological Properties of Heat Transfer Liquids for Solar Thermal Systems

2016 ◽  
Vol 74 (1) ◽  
pp. 207-212
Author(s):  
M. Frk ◽  
J. Hylsky ◽  
D. Strachala
Keyword(s):  
Heat Transfer ◽  
Rheological Properties ◽  
Solar Thermal ◽  
Thermal Systems

scholarly journals Nanofluids in Solar Thermal Collectors: Review and Limitations

2020 ◽  
Vol 41 (11) ◽  
Author(s):  
Ifeoluwa Wole-osho ◽  
Eric C. Okonkwo ◽  
Serkan Abbasoglu ◽  
Doga Kavaz
Keyword(s):  
Heat Transfer ◽  
Material Science ◽  
Solar Thermal ◽  
Heat Transfer Fluid ◽  
Full Potential ◽  
Solar Collectors ◽  
Solar Thermal Collectors ◽  
Overall Efficiency ◽  
The Impact

Abstract Solar thermal collectors are systems that allow for the use of solar energy in thermal applications. These collectors utilize a heat transfer fluid to transport absorbed solar radiation to applications where they are needed. Scientists in a bid to improve the conversion efficiency of solar collectors have suggested different collector designs and improved collector materials. Over the last 25 years, the study of nanofluids and their applications have revolutionized material science, and nanotechnology has found applications in improving solar collector materials. This article reviews the impact of different nanomaterials on the efficiency of solar collectors. The study also outlines the limitations of applying nanofluids and discusses the long-term challenges of their application to solar collectors. Nanofluids have the potential to improve the overall efficiency of most solar collectors, however, the full potential of nanofluids in heat transfer applications cannot be completely achieved until some of the questions regarding hysteresis, stability, and the overall predictability of nanofluids are answered.

Fluid-Solid Coupled Simulation of a Novel Platelet Heat Exchanger Used in Solar Thermal Thruster

2014 ◽  
Vol 598 ◽  
pp. 281-287 ◽  
Author(s):  
Bao Yu Xing ◽  
Min Chao Huang ◽  
Mou Sen Cheng ◽  
Kun Liu
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Transfer Characteristic ◽  
Solar Thermal ◽  
Coupled Heat Transfer ◽  
Aerospace Applications ◽  
Heat Transfer Efficiency ◽  
Transfer Method ◽  
Solar Thermal Propulsion ◽  
Solar Thermal System

Solar thermal propulsion is a potential technology in aerospace applications, and it is a significant issue to improve the heat transfer efficiency of the solar thermal thruster. This paper proposes a novel platelet configuration to be used in the heat exchanger core, which is the most important component of solar thermal system. The platelet passage can enhance the heat transfer between the propellant and the hot core heated by the concentrated sunlight. Based on fluid-solid coupled heat transfer method, the paper utilized the platelet heat transfer characteristic to simulate the heat transfer and flow field of the platelet passage.The simulation result shows that the propellant can be heated to the design temperature of 2300K in the platelet passage of the solar thermal propulsion system, and the fluid-solid coupled method can solve the heat transfer in the platelet structure more precisely.

Heat Transfer Fluids for Optimal Year-Round Operation of Solar Thermal Systems in Central Europe

2014 ◽  
Vol 63 (1) ◽  
pp. 183-190
Author(s):  
J. Hylsky ◽  
L. imonova ◽  
M. Frk ◽  
J. ubarda ◽  
M. Kadlec
Keyword(s):  
Heat Transfer ◽  
Central Europe ◽  
Solar Thermal ◽  
Thermal Systems ◽  
Heat Transfer Fluids
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