Online search tools such as Google scholar and IIT-Delhi library database are considered to explore the peer-reviewed articles using the range of keywords such as solar thermal technologies, industrial process heat applications, temperature requirements in industrial process heat, solar aided power generation, thermal energy storage, etc. Following, the …
The working fluid temperatures can range between 303 and 423 K depending on the collector system . For concentrating solar collectors, mirrors, reflectors, or solar trackers are used to focus solar radiation from the collector area to the absorbing area.
Discussion of solar thermal collectors The basic principle behind solar thermal collectors is to convert the absorbed sunlight to heat, and transfer this heat to a working fluid (liquid or gas). Solar thermal collectors can be classified into three categories according to the operating temperatures of the working fluid.
These working fluids have been improved by replacing the conventional HTF with a mixture of glycol, propylene, and water. These mixtures have been proven to slightly improve the thermal performance of the collectors , however, the potentials of nanofluids in improving the thermal efficiency of solar thermal collectors are enormous.
The thermal conductivity, viscosity and specific heat capacity of the base fluid affect its ability to absorb and transfer solar energy [4, 5, 6, 7]. By studying the properties of different base fluids, researchers can identify the optimal fluid composition that strikes a balance between optical absorption and thermal conduction.
Conventional surface absorption With the advent of direct absorption solar thermal collectors, absorbers can be segregated as ‘surface’ absorbers and ‘volumetric’ absorbers collectors.
In any solar thermal collector, the twin design goals are to maximize solar absorption and to minimize heat loss, and therefore maximize useful energy gain of the working fluid passing through the collector. This can be summarized in the definition of the solar thermal efficiency, a ratio of useful thermal energy gain to solar energy input [ 9 ].
Online search tools such as Google scholar and IIT-Delhi library database are considered to explore the peer-reviewed articles using the range of keywords such as solar thermal technologies, industrial process heat applications, temperature requirements in industrial process heat, solar aided power generation, thermal energy storage, etc. Following, the …
The work flow is sunlight → to a solar collector → absorber tube → pump and alloyed conduit to generate vapor to power the generator or thermal storage. To compare two …
Application of nano-fluid as working fluid in solar collector may offer enhanced thermo-physical (Zayed et al., 2019) and opto-electrical properties (Verma et al., 2018). Following basic empirical relations are very useful tools for interpretation of changed thermo-physical parameters of fluid compare to base fluid.
In this paper, the effect of a flat-plate solar collector components exergy destruction rates on the collector performance has been examined. A theoretical model based on energy and exergy balance for glass cover, absorber plate and working fluid resulted in nonlinear ordinary differentials non-autonomous system of equations that was solved numerically. Upon …
The work flow is sunlight → to a solar collector → absorber tube → pump and alloyed conduit to generate vapor to power the generator or thermal storage. To compare two different thermal transfer liquids, five assumptions are made. (i) the rate of heat transfer is the same, (ii) that liquids do not undergo a phase change, (iii) that the temperature rise is the …
In comparison to water, organic fluids are advantageous when the plant runs at low temperature or low power. The ORC is scalable to smaller unit sizes and higher efficiencies during cooler...
Presented review is an attempt to analyze progressive enhancement in performance of solar collectors in view of changes in design of collector components, changes …
Conventional solar thermal collectors required a solid surface to absorb and convert incoming solar energy to useful thermal energy. Developments in materials science …
Optimum air gap enhances highest convective heat transfer rate from absorber surface to air, which acts as working fluid in solar air heating system.
The thermodynamic cycles used for solar thermal power generation can be broadly classified as low, medium and high temperature cycles. Low temperature cycles work at maximum temperatures of about 100°C, medium temperature cycles work at maximum temperatures up to 400°C, while high temperature cycles work at tempera- tures above 400°C. Low temperature …
The solar thermal collector is a heat exchanger where a selective material absorbs radiation from the sun; this absorbed thermal energy is then transferred to a working fluid (air, water, nanofluid, or oil) for use in other applications. Even though the thermal efficiency of these collectors has generally improved with time, further ...
Direct solar thermal absorption collectors incorporating a nanofluid offers the opportunity to achieve significant improvements in both optical and thermal performance. Since nanofluids offer much greater heat absorbing and heat …
This review article focuses on the impact of working fluid characteristics, geometrical parameters and the operating coefficients in thermal efficiencies of direct …
Conventional solar thermal collectors required a solid surface to absorb and convert incoming solar energy to useful thermal energy. Developments in materials science have enabled a new type of absorber—a volumetric absorber—which utilizes nanoparticles suspended in a fluid to absorb sunlight.
Combining solar thermal energy to retrofit the system is considered an effective way to alleviate this problem. This study explores the off-design performance of organic Rankine cycle-based...
Presented review is an attempt to analyze progressive enhancement in performance of solar collectors in view of changes in design of collector components, changes and modifications in process...
Solar energy is a green, stable and universal source of renewable energy, with wide spectrum and broad area characteristics [1] is regarded as being one of the renewable energy sources with the greatest potential to achieve sustained, high intensity energy output [1], [2].The conflict between population growth and water shortage has become one of the most …
The solar thermal collector is a heat exchanger where a selective material absorbs radiation from the sun; this absorbed thermal energy is then transferred to a working fluid (air, water, nanofluid, or oil) for use in other …
High-temperature solar thermal power plants are thermal power plants that concentrate solar energy to a focal point to generate electricity.The operating temperature reached using this concentration technique is above …
The work flow is sunlight → to a solar collector → absorber tube → pump and alloyed conduit to generate vapor to power the generator or thermal storage. To compare two different thermal transfer liquids, five assumptions are made. (i) the rate of heat transfer is the same, (ii) that liquids do not undergo a phase change, (iii) that the ...
A low-temperature solar-thermal-electric power generation system, which uses HCFC123 as the working fluid of the organic Rankine cycle (ORC) and compound parabolic concentrator (CPC) as the solar ...
This review article focuses on the impact of working fluid characteristics, geometrical parameters and the operating coefficients in thermal efficiencies of direct absorption solar collectors (DASCs). Regarding working fluid parameters, the review emphasized the importance of type of base fluid, nanoparticle properties, such as material, size ...
In this work, heat transfer in solar thermal devices, viz., flat plate collector (FPC) (air and water), evacuated tube collector (ETC ), solar concentrating collectors, solar pond, solar distillation, solar dryer, and solar refrigeration are discussed in brief and critical observations made by various researchers are also presented. This work also incorporates those aspects of …
Direct solar thermal absorption collectors incorporating a nanofluid offers the opportunity to achieve significant improvements in both optical and thermal performance. Since nanofluids offer much greater heat absorbing and heat transfer properties compared to traditional working fluids.
An HTF (heat transfer fluid) like liquefied salt or artificial thermal oil or sometimes H2O, flows into the cylindrical tubular absorber to absorb solar radiations in the strenuous form [59]. To maximize short wave and minimize long wave emittance as spectrum selective covering micro structured Ni-Cd covering is generally used [60] .
Combining solar thermal energy to retrofit the system is considered an effective way to alleviate this problem. This study explores the off-design performance of organic Rankine cycle-based...
Solar thermal power plants today are the most viable alternative to replace conventional thermal power plants to successfully combat climate change and global warming. In this paper, the reasons behind this imminent and inevitable transition and the advantages of solar thermal energy over other renewable sources including solar PV have been discussed. The …
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