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).

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

2003 ◽  
Vol 125 (2) ◽  
pp. 170-176 ◽  
Author(s):  
D. Kearney ◽  
U. Herrmann ◽  
P. Nava ◽  
B. Kelly ◽  
R. Mahoney ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Molten Salt ◽  
Mojave Desert ◽  
Storage System ◽  
Eutectic Mixture ◽  
Heat Transfer Fluid ◽  
Diphenyl Oxide ◽  
Parabolic Trough ◽  
Electricity Cost ◽  
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 (Solar Electric Generating Systems located in Mojave Desert, California) 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 exist, and the quantification of performance and electricity cost using preliminary 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% CaNO32, 7% NaNO3, and 45% KNO3). Assuming a two-tank storage system and a maximum operation temperature of 450°C, the evaluation showed that the levelized electricity cost can be reduced by 14.2% compared to a state-of-the-art parabolic trough plant such as the SEGS plants. If higher temperatures are possible, the improvement may be as high as 17.6%. Thermocline salt storage systems offer even greater benefits.

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.

Natural Convection of Heat Transfer Fluid (Therminol VP-1) in Square Cavity Heated From Below

2013 ◽  
Author(s):  
Titan C. Paul ◽  
A. K. M. M. Morshed ◽  
Elise B. Fox ◽  
Ann E. Visser ◽  
Nicholas J. Bridges ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Convective Heat Transfer Coefficient ◽  
Eutectic Mixture ◽  
Heat Transfer Fluid ◽  
Diphenyl Oxide ◽  
Measured Temperature ◽  
Parabolic Trough ◽  
Square Enclosure ◽  
Solar Thermal Collector

Heat transfer fluid (HTF) plays an important role in the efficiency and cost effectiveness of solar thermal collector. From several choices, Therminol VP-1 (eutectic mixture of diphenyl oxide and biphenyl) are successfully used as heat transfer fluid in the collector field of parabolic trough plants. This paper experimentally analyzes the buoyancy driven heat transfer performance of Therminol VP-1 in a square enclosure with uniformed heating from below and for a Rayleigh number up to 1.11×108. Thermophysical properties such as density, viscosity, and thermal conductivity of Therminol VP-1 were also measured experimentally. The results show that the density, viscosity, and thermal conductivity decrease with temperature within the measured temperature range 10–60°C. The obtained convective heat transfer coefficient was lower than the De-Ionized (DI) water, whereas the dimensionless Nusselt number was observed higher than DI water, which is because of the low thermal conductivity (approximately 25% of DI water) of Therminol VP-1.

Comparison of Two-Tank Indirect Thermal Storage Designs for Solar Parabolic Trough Power Plants

2009 ◽  
Author(s):  
Joseph Kopp ◽  
R. F. Boehm
Keyword(s):  
Power Generation ◽  
Molten Salt ◽  
Heat Exchangers ◽  
Power Plants ◽  
Thermal Storage ◽  
Heat Transfer Fluid ◽  
Base Case ◽  
Parabolic Trough ◽  
Trade Offs ◽  
Solar Field

The performance of a solar thermal parabolic trough plant with thermal storage is dependent upon the arrangement of the heat exchangers that ultimately transfer energy from the sun into steam. An indirect two-tank molten salt storage system that only transfers heat with the solar field heat transfer fluid is the most commercially acceptable thermal storage design. Annual electricity generation from two differing indirect two-tank molten salt storage designs and a base case with no thermal storage were modeled. Four components were characterized in a quasi-steady state analysis dependent upon key ambient and operational parameters: solar field, storage, heat exchangers, and power block. The parameters for the collector field remained constant for all models and were based on the SEGS VI plant. The results of net power generation favor storage though the design that maximizes annual output depends on whether maximum power generation or power generation during the evening peak demand hours is desired. Additionally, the economic trade offs are discussed for the three arrangements.

Enhanced heat transfer in a parabolic trough solar receiver by inserting rods and using molten salt as heat transfer fluid

2018 ◽  
Vol 220 ◽  
pp. 337-350 ◽  
Author(s):  
Chun Chang ◽  
Adriano Sciacovelli ◽  
Zhiyong Wu ◽  
Xin Li ◽  
Yongliang Li ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Molten Salt ◽  
Heat Transfer Fluid ◽  
Parabolic Trough ◽  
Enhanced Heat Transfer ◽  
Solar Receiver

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.

Engineering aspects of a molten salt heat transfer fluid in a trough solar field

Energy ◽  
2004 ◽  
Vol 29 (5-6) ◽  
pp. 861-870 ◽  
Author(s):  
D. Kearney ◽  
B. Kelly ◽  
U. Herrmann ◽  
R. Cable ◽  
J. Pacheco ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Molten Salt ◽  
Heat Transfer Fluid ◽  
Solar Field
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