scholarly journals Performance of Graphite-Dispersed Li2CO3-K2CO3 Molten Salt Nanofluid for a Direct Absorption Solar Collector System

Molecules ◽  
2020 ◽  
Vol 25 (2) ◽  
pp. 375 ◽  
Author(s):  
M. A. Karim ◽  
Majedul Islam ◽  
Owen Arthur ◽  
Prasad KDV Yarlagadda
Keyword(s):  
Heat Transfer ◽  
Molten Salt ◽  
Solar Collector ◽  
Volume Fraction ◽  
Heat Transfer Fluid ◽  
Total Efficiency ◽  
Nanoparticle Volume Fraction ◽  
Direct Absorption ◽  
Solar Salt ◽  
Direct Absorption Solar Collector

Considered to be the next generation of heat transfer fluids (HTFs), nanofluids have been receiving a growing interest over the past decade. Molten salt nanofluids have been shown to have great potential as an HTF for use in high temperature applications such as direct absorption solar collector (DAC) system. Very few studies using molten salt nanofluids as the HTF in a DAC receiver can be found in the open literature. This study aimed to develop a 3D computational fluid dynamics model of the receiver of a DAC using graphite-nanoparticle-dispersed Li2CO3-K2CO3 molten salt nanofluid to investigate the effects of design and operation parameters on receiver performance. Receiver total efficiency using Li2CO3-K2CO3 salt was compared with that using solar salt nanofluid. Spectral properties of the base fluid and nanoparticles were modeled as wavelength-dependent and the absorption of the solar radiation was modeled as a volumetric heat release in the flowing heat transfer fluid. Initial results show that the receiver efficiency increases with increasing solar concentration, decreasing nanoparticle volume fraction, and decreasing receiver length. It was also found that the Carnot efficiency increases with increasing receiver length and nanoparticle volume fraction, and decreasing solar concentration and inlet velocity. Comparative study shows that solar salt HTF could provide higher total efficiency. However, a higher operating temperature of Li2CO3-K2CO3 will allow for a greater amount of thermal energy storage for a smaller volume of liquid.

scholarly journals Performance Investigation of High Temperature Application of Molten Solar Salt Nanofluid in a Direct Absorption Solar Collector

Molecules ◽  
2019 ◽  
Vol 24 (2) ◽  
pp. 285 ◽  
Author(s):  
M. Karim ◽  
Owen Arthur ◽  
Prasad Yarlagadda ◽  
Majedul Islam ◽  
Md Mahiuddin
Keyword(s):  
High Temperature ◽  
Molten Salt ◽  
Solar Collector ◽  
Volume Fraction ◽  
Heat Transfer Fluid ◽  
Total Efficiency ◽  
Total System ◽  
Direct Absorption ◽  
Wide Range ◽  
Direct Absorption Solar Collector

Nanofluids have great potential in a wide range of fields including solar thermal applications, where molten salt nanofluids have shown great potential as a heat transfer fluid (HTF) for use in high temperature solar applications. However, no study has investigated the use of molten salt nanofluids as the HTF in direct absorption solar collector systems (DAC). In this study, a two dimensional CFD model of a direct absorption high temperature molten salt nanofluid concentrating solar receiver has been developed to investigate the effects design and operating variables on receiver performance. It has been found that the Carnot efficiency increases with increasing receiver length, solar concentration, increasing height and decreasing inlet velocity. When coupled to a power generation cycle, it is predicted that total system efficiency can exceed 40% when solar concentrations are greater than 100×. To impart more emphasis on the temperature rise of the receiver, an adjusted Carnot efficiency has been used in conjunction with the upper temperature limit of the nanofluid. The adjusted total efficiency also resulted in a peak efficiency for solar concentration, which decreased with decreasing volume fraction, implying that each receiver configuration has an optimal solar concentration.

A Novel Design of Liquid Volumetric Plated Cavity Receiver for Central Tower Systems

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Om Singh ◽  
Kaustubh Bhatwadekar ◽  
N. G. Kartheek ◽  
Shireesh B. Kedare ◽  
Suneet Singh
Keyword(s):  
Heat Transfer ◽  
Molten Salt ◽  
High Heat ◽  
Heat Transfer Fluid ◽  
Solar Salt ◽  
Suitable Candidate ◽  
Storage Devices ◽  
Parallel Arrangement ◽  
High Heat Capacity ◽  
Novel Design

Abstract Previously reported studies have shown that the volumetric receivers have lower radiative and convective losses, leading to higher efficiency. However, the conventional volumetric receivers are difficult to use along with the thermal storage systems, owing to the use of air as the heat transfer fluid. Molten salt, having high heat capacity, emerges as a suitable candidate to be employed as the heat transfer fluid and for storing thermal energy in the storage devices. It is challenging to use the molten salt in the conventional volumetric receiver configuration; therefore, a novel design called Liquid Volumetric Plated Cavity Receiver is proposed, where the solar salt is used as heat transfer fluid. It consists of a parallel arrangement of hollow plates in an open cavity. Solar radiation concentrated by the heliostat field is absorbed on the outer surface of the hollow plates. The heat is then taken away by the molten salt flowing inside the hollow plates. The plates are arranged such that the molten salt gets heated up within the volume of the enclosure, effectively mimicking the heating performance of the volumetric receivers. Using an analytical model for heat losses, it is observed that the losses are very sensitive to the aspect ratio of the aperture and depth of the receiver. The effects of receiver inclination, plate orientations, radiation incident at the aperture, and surface emissivity have been investigated as well. The results show that a Liquid Volumetric Plated Cavity Receiver increases the efficiency (by ∼3%) as compared with that of the simple cubic receiver.

Evaluation of a Molten Salt Heat Transfer Fluid in a Parabolic Trough Solar Field

Solar Energy ◽  
2002 ◽  
Author(s):  
D. Kearney ◽  
U. Herrmann ◽  
P. Nava ◽  
B. Kelly ◽  
R. Mahoney ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Molten Salt ◽  
Eutectic Mixture ◽  
Heat Transfer Fluid ◽  
Diphenyl Oxide ◽  
Parabolic Trough ◽  
Solar Salt ◽  
Electricity Cost ◽  
Critical Issues ◽  
Solar Field

An evaluation was carried out to investigate the feasibility of utilizing a molten salt as the heat transfer fluid (HTF) and for thermal storage in a parabolic trough solar field to improve system performance and to reduce the levelized electricity cost. The operating SEGS plants currently use a high temperature synthetic oil consisting of a eutectic mixture of biphenyl/diphenyl oxide. The scope of this investigation included examination of known critical issues, postulating solutions or possible approaches where potential problems existed, and the quantification of performance and electricity cost using preliminary, but reasonable, cost inputs. The two leading candidates were the so-called solar salt (a binary salt consisting of 60% NaNO3 and 40% KNO3) and a salt sold commercially as HitecXL (a ternary salt consisting of 48% Ca(NO3)2, 7% NaNO3, and 45% KNO3).

scholarly journals Assisted convective heat transfer and entropy generation in a solar collector filled with nanofluid

2016 ◽  
Vol 13 (2) ◽  
pp. 135-150
Author(s):  
R. Nasrin ◽  
M.A. Alim ◽  
M. Hasanuzzzaman
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Rate ◽  
Entropy Generation ◽  
Solar Collector ◽  
Transfer Rate ◽  
Volume Fraction ◽  
Bulk Temperature ◽  
Outlet Temperature ◽  
Nanoparticle Volume Fraction ◽  
Collector Efficiency

Heat transfer phenomena of flat plate solar collector filled with different nanofluids has been investigated numerically. Galerkin’s Finite Element Method is used to solve the problem. Heat transfer rate, average bulk temperature, average sub-domain velocity, outlet temperature, thermal efficiency, mean entropy generation and Bejan number has been investigated by varying the solid nanoparticle volume fraction of water/Cu, water/Ag and water/Cu/Ag nanofluids from 0% to 3%. It is found that the solid nanoparticle volume fraction has great effect on heat transfer phenomena. It is observed that the increases of the solid volume fraction (up to 2%) enhances the heat transfer rate and collector efficiency where after 2% the rate of change almost constant. Higher heat transfer rate and collector efficiency has been obtained 19% and 13% for water/Ag nanofluid respectively.

scholarly journals Feasibility Study of Freeze Recovery Options in Parabolic Trough Collector Plants Working with Molten Salt as Heat Transfer Fluid

Energies ◽  
2019 ◽  
Vol 12 (12) ◽  
pp. 2340 ◽  
Author(s):  
Cristina Prieto ◽  
Alfonso Rodríguez-Sánchez ◽  
F. Ruiz-Cabañas ◽  
Luisa Cabeza
Keyword(s):  
Heat Transfer ◽  
Molten Salt ◽  
Molten Salts ◽  
Heat Transfer Fluid ◽  
Operational Experience ◽  
Parabolic Trough ◽  
Solar Salt ◽  
Parabolic Trough Collector ◽  
Overall Performance ◽  
Solar Field

Parabolic trough collector (PTC) technology is currently the most mature solar technology, which has led to the accumulation of relevant operational experience. The overall performance and efficiency of these plants depends on several components, and the heat transfer fluid (HTF) is one of the most important ones. Using molten salts as HTFs has the advantage of being able to work at higher temperatures, but it also has the disadvantage of the potential freezing of the HTF in pipes and components. This paper models and evaluates two methods of freeze recovery, which is needed for this HTF system design: Heat tracing in pipes and components, and impedance melting in the solar field. The model is used to compare the parasitic consumption in three molten salts mixtures, namely Solar Salt, HiTec, and HiTec XL, and the feasibility of this system in a freezing event. After the investigation of each of these subsystems, it was concluded that freeze recovery for a molten salt plant is possible.

scholarly journals JATROPHA OIL WITH IRON NANOPARTICLES APPLICATION IN DRILLING PROCESSES

2019 ◽  
Vol 59 (3) ◽  
pp. 299-304
Author(s):  
Veikko Shalimba ◽  
Vít Sopko
Keyword(s):  
Heat Transfer ◽  
High Performance ◽  
Iron Nanoparticles ◽  
Volume Fraction ◽  
Volume Ratio ◽  
Heat Transfer Fluid ◽  
Nanoparticle Volume Fraction ◽  
Jatropha Oil ◽  
Heat Transfer Fluids ◽  
Performance Of Heat Transfer

A performance of heat transfer fluids has a substantial influence on the size, weight and cost of heat transfer systems, therefore, a high-performance heat transfer fluid is very important in many industries. Over the last decades, nanofluids have been developed. According to many researchers and publications on nanofluids, it is evident that nanofluids have a high thermal conductivity. The aim of this experimental study was to investigate the change of the workpiece temperature during drilling using Jatropha oil with iron nanoparticles and water with iron nanoparticles as lubricating and cooling fluids. These experiments were carried out with samples of nanofluid with different nanoparticles volume ratio, such as samples JN1, JN5 and JN10 of iron nanoparticles in the base Jatropha oil with a nanoparticle volume fraction of 1 %, 5% and 10% respectively and samples WN1, WN5 and WN10 of iron nanoparticles in the base water with a nanoparticle volume fraction of 1 %, 5% and 10% respectively.

Numerical Simulation on the Performance of Nanofluid-Based Direct Absorption Solar Collector With Parabolic Trough Concentrator

2016 ◽  
Author(s):  
Wei Chen ◽  
Guoying Xu ◽  
Sainan Zhao ◽  
Xiaosong Zhang
Keyword(s):  
Heat Transfer ◽  
Solar Collector ◽  
Numerical Study ◽  
Radiation Absorption ◽  
Transfer Model ◽  
Direct Absorption ◽  
Operating Characteristics ◽  
Parabolic Trough ◽  
Weight Concentration ◽  
Direct Absorption Solar Collector

Nanofluids obtain high stability, improved heat transfer capability and excellent optical properties, the low-temperature nanofluid-based direct absorption solar collector (NDASC) has been previously investigated. However, the detailed radiation absorption and heat transfer mechanism for a NDASC with a solar concentrator operated on medium-temperature conditions were seldom researched. Therefore, this paper presents a numerical study on the solar collection characteristics of NDASC with a parabolic trough concentrator. CuO/oil nanofluids with various weight concentration from 0.05% to 0.1% were prepared, and used as working fluids of NDASCs, respectively. Using the developed heat transfer model, operating characteristics of NDASCs were simulated. Furthermore, the influences of weight concentration of nanofluids on the heat transfer characteristics in the NDASCs were analyzed and optimum weight concentration used for the designed NDASC obtained.

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