scholarly journals Experimental Study on Temperature Distribution and Heat Losses of a Molten Salt Heat Storage Tank

Energies ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1943 ◽  
Author(s):  
Xiaoming Zhang ◽  
Yuting Wu ◽  
Chongfang Ma ◽  
Qiang Meng ◽  
Xiao Hu ◽  
...  
Keyword(s):  
Temperature Distribution ◽  
Molten Salt ◽  
Storage Tank ◽  
Power Plants ◽  
Heat Storage ◽  
Thermal Power ◽  
Thermal Storage ◽  
Heat Losses ◽  
Temperature Stratification ◽  
Maximum Temperature

Two-tank molten salt heat storage systems are considered to be the most mature thermal storage technology in solar thermal power plants. As the key part of the system, the thermal performance of molten salt tanks is of great importance. An experimental thermal storage system with a new type of molten salt as a thermal energy storage medium has been built to investigate the temperature distribution of molten salt inside the tank during the cooling process from 550 °C to 180 °C. The temperature distribution of the salt was obtained, which reveals that temperature stratification appears at the bottom of the tank within the height of 200 mm. The position, with the maximum temperature difference of 16.1 °C, is at the lower edges of the molten salt storage tank. The temperature distribution was also measured to deepen our understanding of the insulation foundation, which shows that the maximum temperature appears at the middle upper part of the foundation and decreases radially. The heat losses of the molten salt tank were calculated by the classical equation, from which it was found that the heat loss decreases from 3.65 kWh to 1.82 kWh as the temperature of the molten salt drops from 550 °C to 310 °C. The effect of temperature stratification on the heat losses of the tank’s bottom was also analyzed.

scholarly journals CFD Analysis of the Cool Down Behaviour of Molten Salt Thermal Storage Systems

2008 ◽  
Author(s):  
Jan Schulte-Fischedick ◽  
Rainer Tamme ◽  
Ulf Herrmann
Keyword(s):  
Molten Salt ◽  
Power Plants ◽  
Thermal Power ◽  
Side Wall ◽  
Heat Losses ◽  
Maximum Temperature ◽  
Bottom Plate ◽  
Computational Fluid Mechanics ◽  
Cfd Analysis ◽  
Maximum Temperature Difference

CFD analysis has been conducted to obtain information on heat losses, velocity and temperature distribution of large molten salt Thermal Energy Storage (TES) systems. A two-tank 880 MWh storage system was modeled according to the molten salt TES containment design proposed for the 50 MWel commercial parabolic trough solar thermal power plants in Spain. Heat losses were established using the Finite Element Method (FEM), and used to determine the boundary conditions for the subsequent two- and three-dimensional Computational Fluid Mechanics (CFD) calculations. The investigations reveal that a high heat loss flux occurs at the lower edges of the salt storage tanks (between side wall and bottom plate). Thus the maximum temperature difference can be found at this location, resulting in the onset of local solidification within 3.25 days in the case of the empty cool tank. As a consequence, the detailed design of the lower edge has a large impact on both the overall heat losses and the period until the onset of local solidification.

Experimental Investigation of Thermal Storage Processes in a Thermocline Storage Tank

2011 ◽  
Author(s):  
Wafaa Karaki ◽  
Peiwen Li ◽  
Jon Van Lew ◽  
M. M. Valmiki ◽  
Cholik Chan ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Storage Tank ◽  
Power Plants ◽  
Thermal Power ◽  
Energy Charge ◽  
Thermal Storage ◽  
Packed Bed ◽  
Heat Transfer Fluid ◽  
Energy Storage Efficiency

This paper presents an experimental study and analysis of the heat transfer of energy charge and discharge in a packed-bed thermocline thermal storage tank for application in concentrated solar thermal power plants. Because the energy storage efficiency is a function of many parameters including fluid and solid properties, tank dimensions, packing dimensions, and time lengths of charge and discharge, this paper aims to provide experimental data and a proper approach of data reduction and presentation. To accomplish this goal, dimensionless governing equations of energy conservation in the heat transfer fluid and solid packed-bed material are derived. The obtained experimental data will provide a basis for validation of mathematical models in the future.

scholarly journals Thermophysical properties experimentally tested for NaCl-KCl-MgCl2 eutectic molten salt as a next generation high temperature HTF in CSP systems

2020 ◽  
pp. 1-13
Author(s):  
Xiaoxin Wang ◽  
Jusus Rincon ◽  
Peiwen Li ◽  
Youyang Zhao ◽  
Judith Vidal
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Power Systems ◽  
Molten Salt ◽  
Thermophysical Properties ◽  
Power Plants ◽  
Solar Power ◽  
Thermal Power ◽  
Thermal Storage ◽  
Heat Of Fusion

Abstract A new eutectic chloride molten salt, MgCl2-KCl-NaCl (wt.% 45.98-38.91-15.11), has been recognized as one of the most promising high-temperature heat-transfer fluids (HTF) for both heat transfer and thermal storage for the 3rd Generation concentrated solar thermal power (CSP) systems. For the first time, some essential thermophysical properties of this eutectic chloride molten salt needed for basic heat transfer and energy storage analysis in the application of concentrating solar power systems have been experimentally tested and provided as functions of temperature in the range from 450 °C to 700 °C. The studied properties include heat capacity, melting point, heat of fusion, viscosity, vapor pressure, density, and thermal conductivity. The property equations provide essential database for engineers to use to calculate convective heat transfer in concentrated solar receivers, heat exchangers, and thermal storage for concentrated solar power plants.

Optimal Design of a Molten Salt Thermal Storage Tank for Parabolic Trough Solar Power Plants

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
R. Gabbrielli ◽  
C. Zamparelli
Keyword(s):  
Optimal Design ◽  
Molten Salt ◽  
Storage Tank ◽  
Power Plants ◽  
Storage System ◽  
Thermal Storage ◽  
Parabolic Trough ◽  
Investment Cost ◽  
Total Investment ◽  
Solar Power Plants

This paper presents an optimal design procedure for internally insulated, carbon steel, molten salt thermal storage tanks for parabolic trough solar power plants. The exact size of the vessel and insulation layers and the shape of the roof are optimized by minimizing the total investment cost of the storage system under three technical constraints: remaining within the maximum allowable values of both temperature and stress in the steel structure, and avoiding excessive cooling and consequent solidification of the molten salt during long periods of no solar input. The thermal, mechanical and economic aspects have been integrated into an iterative step-by-step optimization procedure, which is shown to be effective through application to the case study of a 600MWh thermal storage system. The optimal design turns out to be an internally insulated, carbon steel storage tank characterized by a maximum allowable height of 11m and a diameter of 22.4m. The total investment cost is about 20% lower than that of a corresponding AISI 321H stainless steel storage tank without internal protection or insulation.

Methodology for optimized operation strategies of solar thermal power plants with integrated heat storage

Solar Energy ◽  
2011 ◽  
Vol 85 (4) ◽  
pp. 653-659 ◽  
Author(s):  
Michael Wittmann ◽  
Markus Eck ◽  
Robert Pitz-Paal ◽  
Hans Müller-Steinhagen
Keyword(s):  
Power Plants ◽  
Heat Storage ◽  
Thermal Power ◽  
Solar Thermal ◽  
Thermal Power Plants ◽  
Solar Thermal Power

Volume Sizing for Thermal Storage With Phase Change Material for Concentrated Solar Power Plant

2014 ◽  
Author(s):  
Ben Xu ◽  
Peiwen Li ◽  
Cholik Chan
Keyword(s):  
Power Plant ◽  
Phase Change ◽  
Phase Change Material ◽  
Storage Tank ◽  
Solar Power ◽  
Heat Storage ◽  
Storage System ◽  
Thermal Storage ◽  
Concentrated Solar Power ◽  
Change Material

With a large capacity thermal storage system using phase change material (PCM), Concentrated Solar Power (CSP) is a promising technology for high efficiency of solar energy utilization. In a thermal storage system, a dual-media thermal storage tank is typically adopted in industry for the purpose of reducing the use of the heat transfer fluid (HTF). While the dual-media sensible heat storage system has been well studied, a dual-media latent heat storage system (LHSS) still needs more attention and study; particularly, the sizing of volumes of storage tanks considering actual operation conditions is of significance. In this paper, a strategy for LHSS volume sizing is proposed, which is based on computations using an enthalpy-based 1D model. One example of 60MW solar thermal power plant with 35% thermal efficiency is presented. In the study, potassium hydroxide (KOH) is adopted as PCM and Therminol VP-1 is used as HTF. The operational temperatures of the storage system are 390°C and 310°C, respectively for the high and low temperatures. The system is assumed to operate for 100 days with 6 hours charge and 6 hours discharge every day. From the study, the needed height of the thermal storage tank is calculated from using the strategy of tank sizing. The method for tank volume sizing is of significance to engineering application.

Energy Storage Start-up Strategies for Concentrated Solar Power Plants With a Dual-Media Thermal Storage System

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
Ben Xu ◽  
Peiwen Li ◽  
Cho Lik Chan
Keyword(s):  
Energy Storage ◽  
Storage Tank ◽  
Heat Storage ◽  
Storage System ◽  
Electrical Energy ◽  
Thermal Storage ◽  
Energy Output ◽  
Concentrated Solar Power ◽  
Start Up ◽  
Hot Start

A concentrated solar power (CSP) plant typically has thermal energy storage (TES), which offers advantages of extended operation and power dispatch. Using dual-media, TES can be cost-effective because of the reduced use of heat transfer fluid (HTF), usually an expensive material. The focus of this paper is on the effect of a start-up period thermal storage strategy to the cumulative electrical energy output of a CSP plant. Two strategies—starting with a cold storage tank (referred to as “cold start”) and starting with a fully charged storage tank (referred to as “hot start”)—were investigated with regards to their effects on electrical energy production in the same period of operation. An enthalpy-based 1D transient model for energy storage and temperature variation in solid filler material and HTF was applied for both the sensible heat storage system (SHSS) and the latent heat storage system (LHSS). The analysis was conducted for a CSP plant with an electrical power output of 60 MWe. It was found that the cold start is beneficial for both the SHSS and LHSS systems due to the overall larger electrical energy output over the same number of days compared to that of the hot start. The results are expected to be helpful for planning the start-up operation of a CSP plant with a dual-media thermal storage system.

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