Experiments and Analysis on the Molten Salt Direct Absorption Receiver Concept

1988 ◽  
Vol 110 (1) ◽  
pp. 45-51 ◽  
Author(s):  
M. S. Bohn ◽  
K. Y. Wang
Keyword(s):  
Heat Transfer ◽  
Numerical Model ◽  
Molten Salt ◽  
Test Facility ◽  
Working Fluid ◽  
Direct Absorption ◽  
Film Stability ◽  
Maintenance Costs ◽  
Salt Film ◽  
Central Receiver

This paper presents results of experiments on the Direct Absorption Receiver (DAR) concept using molten salt as the working fluid. The DAR concept may result in a solar central receiver that costs 50 percent less than the current tube receiver and has significantly lower operational and maintenance costs. These experiments were aimed at determining whether the DAR concept is technically feasible and were carried out at the Advanced Components Test Facility, Atlanta, GA. Results are based on several days of operating with solar flux ranging up to 50 W/cm2 and also on a numerical model that is capable of predicting the thermal performance of the DAR salt film. Issues relating to thermal efficiency, absorber-to-salt heat transfer, and salt film stability are addressed.

Economic Chances and Technical Risks of the Internal Direct Absorption Receiver (IDAR)

2012 ◽  
Author(s):  
Cs. Singer ◽  
R. Buck ◽  
R. Pitz-Paal ◽  
H. Müller-Steinhagen
Keyword(s):  
Molten Salt ◽  
Power Plants ◽  
Power Level ◽  
Management Strategies ◽  
Direct Absorption ◽  
Film Stability ◽  
Salt Film ◽  
Receiver System ◽  
And Performance ◽  
The Cost

Increased receiver temperatures of solar tower power plants are proposed to decrease the plants levelized electricity costs (LEC) due to the utilization of supercritical steam power plants and thus higher overall plant efficiency. Related to elevated receiver temperatures preliminary concept studies show a distinct LEC reduction potential of the internal direct absorption receiver (IDAR), if it is compared to liquid in tube (LIT) or beam down (BD) receiver types. The IDAR is characterized by a downwards oriented aperture of a cylindrical cavity, whose internal lateral area is illuminated from the concentrator field and cooled by a liquid molten salt film. The objective is the further efficiency enhancement, as well as the identification and assessment of the technical critical aspects. For this a detailed fluid mechanic and thermodynamic receiver model of the novel receiver concept is developed to be able to analyze the IDAR’s operating performance at full size receiver geometries. The model is used to analyze the open parameters concerning the feasibility, functionality and performance of the concept. Hence, different system management strategies are examined and assessed, which lead to the proposal of a cost optimized lead-concept. This concept involves a rotating receiver system with inclined absorber walls. The spatial arrangements of the absorber walls minimize thermal losses of the receiver and enhance film stability. The centrifugal forces acting on the liquid salt film are essential to realize the required system criteria, which are related to the maximal molten salt temperature, film stability and droplet ejection. Compared to the state of the art at a 200 MWel power level the IDAR concept can lead to a LEC reduction of up to 8%. The cost assumptions made for the assessment are quantified with sensitivity analysis.

Economic Chances and Technical Risks of the Internal Direct Absorption Receiver

2013 ◽  
Vol 136 (2) ◽  
Author(s):  
Csaba Singer ◽  
Reiner Buck ◽  
Robert Pitz-Paal ◽  
Hans Müller-Steinhagen
Keyword(s):  
Molten Salt ◽  
Power Plants ◽  
Power Level ◽  
Management Strategies ◽  
Direct Absorption ◽  
Film Stability ◽  
Salt Film ◽  
Receiver System ◽  
And Performance ◽  
The Cost

Increased receiver temperatures of solar tower power plants are proposed to decrease the plants levelized electricity costs (LEC) due to the utilization of supercritical steam power plants and thus higher overall plant efficiency. Related to elevated receiver temperatures preliminary concept studies show a distinct LEC reduction potential of the internal direct absorption receiver (IDAR), if it is compared to liquid in tube (LIT) or beam-down (BD) receiver types. The IDAR is characterized by a downward oriented aperture of a cylindrical cavity, whose internal lateral area is illuminated from the concentrator field and cooled by a liquid molten salt film. The objective is the further efficiency enhancement, as well as the identification and assessment of the technical critical aspects. For this a detailed fluid mechanic and thermodynamic receiver model of the novel receiver concept is developed to be able to analyze the IDAR's operating performance at full size receiver geometries. The model is used to analyze the open parameters concerning the feasibility, functionality and performance of the concept. Hence, different system management strategies are examined and assessed, which lead to the proposal of a cost optimized lead-concept. This concept involves a rotating receiver system with inclined absorber walls. The spatial arrangements of the absorber walls minimize thermal losses of the receiver and enhance film stability. The centrifugal forces acting on the liquid salt film are essential to realize the required system criteria, which are related to the maximal molten salt temperature, film stability and droplet ejection. Compared to the state of the art at a 200 MWel power level the IDAR concept can lead to a LEC reduction of up to 8%. The cost assumptions made for the assessment are quantified with sensitivity analysis.

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.

A Numerical Model of a Reciprocating-Mechanism Driven Heat Loop for Two-Phase High Heat Flux Cooling

2016 ◽  
Vol 8 (4) ◽  
Author(s):  
Olubunmi Popoola ◽  
Ayobami Bamgbade ◽  
Yiding Cao
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Numerical Model ◽  
Performance Optimization ◽  
Numerical Study ◽  
High Heat ◽  
Working Fluid ◽  
High Heat Flux ◽  
Two Phase ◽  
Transfer Device

An effective design option for a cooling system is to use a two-phase pumped cooling loop to simultaneously satisfy the temperature uniformity and high heat flux requirements. A reciprocating-mechanism driven heat loop (RMDHL) is a novel heat transfer device that could attain a high heat transfer rate through a reciprocating flow of the two-phase working fluid inside the heat transfer device. Although the device has been tested and validated experimentally, analytical or numerical study has not been undertaken to understand its working mechanism and provide guidance for the device design. The objective of this paper is to develop a numerical model for the RMDHL to predict its operational performance under different working conditions. The developed numerical model has been successfully validated by the existing experimental data and will provide a powerful tool for the design and performance optimization of future RMDHLs. The study also reveals that the maximum velocity in the flow occurs near the wall rather than at the center of the pipe, as in the case of unidirectional steady flow. This higher velocity near the wall may help to explain the enhanced heat transfer of an RMDHL.

The Design and Testing of a Molten Salt Steam Generator for Solar Application

1988 ◽  
Vol 110 (1) ◽  
pp. 38-44 ◽  
Author(s):  
W. A. Allman ◽  
D. C. Smith ◽  
C. R. Kakarala
Keyword(s):  
Molten Salt ◽  
Steam Generator ◽  
Test Facility ◽  
Process Conditions ◽  
Test Results ◽  
Overall Design ◽  
Central Receiver ◽  
And Performance ◽  
Design And Testing ◽  
Solar Application

This paper describes the design and testing of the Steam Generator Subsystem (SGS) for the Molten Salt Electric Experiment at Sandia Laboratories in Albuquerque, New Mexico. The Molten Salt Electric Experiment (MSEE) has been established at the Department of Energy’s five megawatt thermal Solar Central Receiver Test Facility, to demonstrate the feasibility of the molten salt central receiver concept. The experiment is capable of generating 0.75 megawatts of electric power from solar energy, with the capability of storing seven megawatt-hours of thermal energy. The steam generator subsystem transfers sensible heat from the solar-heated molten nitrate salt to produce steam to drive a conventional turbine. This paper discusses the design requirements dictated by the steam generator application and also reviews the process conditions. Details of each of the SGS components are given, featuring the aspects of the design and performance unique to the solar application. The paper concludes with a summary of the test results confirming the overall design of the subsystem.

Operation of Large-Scale Pumps and Valves in Molten Salt

1994 ◽  
Vol 116 (3) ◽  
pp. 137-141 ◽  
Author(s):  
D. C. Smith ◽  
E. E. Rush ◽  
C. W. Matthews ◽  
J. M. Chavez ◽  
P. A. Bator
Keyword(s):  
Molten Salt ◽  
Power Plants ◽  
Large Scale ◽  
Solar Power ◽  
Test Facility ◽  
Plant Design ◽  
Thermal Test ◽  
Central Receiver ◽  
Solar Power Plants ◽  
Careful Design

The molten salt pump and valve (P&V) test loops at Sandia National Laboratories (SNL) National Solar Thermal Test Facility (NSTTF) operated between Jan. 1988 and Oct. 1990. The purpose of the P&V test was to demonstrate the performance, reliability, and service life of full-scale hot and cold salt pumps and valves for use in commercial central receiver solar power plants. The P&V test hardware consists of two pumped loops; the “Hot Loop” to simulate the hot (565°C) side of the receiver and the “Cold Loop” to simulate the receiver’s cold (285°C) side. Each loop contains a pump and five valves sized to be representative of a conceptual 60-MWe commercial solar power plant design. The hot loop accumulated over 6700 hours of operation and the cold loop over 2500 hours of operation. This project has demonstrated that standard commercial scale pump and valve designs will work in molten salt. The test also exposed some pitfalls that must be avoided in specifying such equipment. Although certainly not all of the pitfalls were discovered, careful design and specification should result in reliable or at least workable equipment.

A Numerical Model for Off-Design Performance Calculation of Parabolic Trough Based Solar Power Plants

2010 ◽  
Author(s):  
Andrea Giostri ◽  
Claudio Saccilotto ◽  
Paolo Silva ◽  
Ennio Macchi ◽  
Giampaolo Manzolini
Keyword(s):  
Heat Transfer ◽  
Numerical Model ◽  
Heat Transfer Fluid ◽  
Working Fluid ◽  
Design Calculation ◽  
Fluid Temperature ◽  
Parabolic Trough ◽  
Design Algorithm ◽  
Energy Balances ◽  
Steam Cycle

The paper deals with the development and testing of an innovative code for the performance prediction of solar trough based CSP plants in off-design conditions. The code is developed in MS Visual Basic 6.0 with Excel as user interface. The proposed code originates from a previously presented algorithm for on-design sizing and cost estimation of the solar field lay-out, as well as of the main components of the plant, including connecting piping and the steam cycle. Off-design calculation starts from data obtained through the on-design algorithm and considers steady-state situations. Both models are implemented in the same software, named PATTO (PArabolic Trough Thermodynamic Optimization), which is very flexible: the optical-thermal model of collectors can simulate different kinds of parabolic trough systems in commerce, including a combination of various mirrors, receivers and supports. The code is also flexible in terms of working fluid, temperature and pressure range, and can also simulate direct steam generation plants (DSG). Regarding the power block, a conventional steam cycle with super-heater, eventually a re-heater section, and up to seven regenerative bleedings is adopted. The off-design model calculates thermal performance of collectors taking into account proper correlations for convective heat transfer coefficients, considering also boiling regime in DSG configurations. Solar plant heat and mass balances and performances at off-design conditions are estimated by accounting for the constraints imposed by the available heat transfer areas in heat exchangers and condenser, as well as the characteristic curve of the steam turbine. The numerical model can be used for a single calculation in a specific off-design condition, as well as for a whole year estimation of energy balances with an hourly resolution. The model is tested towards real applications and reference values found in literature; in particular, focusing on SEGS VI plant in the USA and SAM® code. Annual energy balances with ambient condition taken from TMY3 database are obtained, showing good accuracy of predicted performances. The code potentiality in the design process reveals twofold: it can be used for plant optimization in feasibility studies; moreover it is useful to find the best control strategy of a plant, especially the mass flow of heat transfer fluid in each operating condition.

scholarly journals Optimization of a New Design of Molten Salt-to-CO2 Heat Exchanger Using Exergy Destruction Minimization

Entropy ◽  
2020 ◽  
Vol 22 (8) ◽  
pp. 883
Author(s):  
María José Montes ◽  
José Ignacio Linares ◽  
Rubén Barbero ◽  
Beatriz Yolanda Moratilla
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Molten Salt ◽  
High Heat ◽  
Exergy Destruction ◽  
Solar Thermal Energy ◽  
Heat Exchanger Design ◽  
Central Receiver ◽  
High Heat Transfer ◽  
Supercritical Phase

One of the ways to make cost-competitive electricity, from concentrated solar thermal energy, is increasing the thermoelectric conversion efficiency. To achieve this objective, the most promising scheme is a molten salt central receiver, coupled to a supercritical carbon dioxide cycle. A key element to be developed in this scheme is the molten salt-to-CO2 heat exchanger. This paper presents a heat exchanger design that avoids the molten salt plugging and the mechanical stress due to the high pressure of the CO2, while improving the heat transfer of the supercritical phase, due to its compactness with a high heat transfer area. This design is based on a honeycomb-like configuration, in which a thermal unit consists of a circular channel for the molten salt surrounded by six smaller trapezoidal ducts for the CO2. Further, an optimization based on the exergy destruction minimization has been accomplished, obtained the best working conditions of this heat exchanger: a temperature approach of 50 °C between both streams and a CO2 pressure drop of 2.7 bar.

Heat Transfer Augmentation in Solar Collectors Using Nanofluids: A Review

2020 ◽  
Vol 6 (2) ◽  
pp. 72-81 ◽  
Author(s):  
Morteza Anbarsooz ◽  
Maryam Amiri ◽  
Iman Rashidi ◽  
Mohammad Javadi
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Heat Transfer Process ◽  
Heat Transfer Fluid ◽  
Working Fluid ◽  
Optical Parameters ◽  
Solar Collectors ◽  
Direct Absorption ◽  
Heat Transfer Augmentation

Background: Enhancing the heat transfer rate in solar collectors is an essential factor for reducing the size of the system. Yet, various methods have been presented in the literature to increase the heat transfer rate from an absorber to the heat transfer fluid. The most important methods are: the use of evacuated receivers, addition of swirl generators/turbulators and use of various nanofluids as the heat transfer fluid. Objective: The current study reviews the achievements in the enhancement of solar collectors’ heat transfer process using various types of nanofluids. The review revealed that the most widely employed nanoparticles are Al2O3 and Carbon nanotubes (CNTs) and the most popular base fluid is water. Most of the investigations are performed on indirect solar collectors, while recently, the researchers focused on direct absorption methods. In the indirect absorption collectors, the thermal conductivity of the working fluid is essential, while in a direct absorption collector, the optical properties are also crucial. Optimization of the optical parameters along with the thermophysical properties of the nanofluid is suggested for the applications of solar collector.

Ocean Thermal Energy Conversion Heat Exchangers: A Review of Research and Development

1985 ◽  
Vol 22 (01) ◽  
pp. 64-73
Author(s):  
Eugene H. Kinelski
Keyword(s):  
Heat Transfer ◽  
Heat Exchangers ◽  
Low Cost ◽  
Cost Effective ◽  
Department Of Energy ◽  
Test Facility ◽  
Working Fluid ◽  
Ocean Energy ◽  
The U.S ◽  
Mechanical Cleaning

The goal of the OTEC heat exchanger program within the Division of Ocean Energy Systems in the U.S. Department of Energy was to develop designs, evaluate enhanced surfaces, and control biofouling using corrosion-resistant materials that were cost-effective. This report summarizes the available data on a closed-cycle OTEC power system and shows how such data could be applicable to heat exchangers used by the power industry, the U.S. Navy, and merchant ships. Ammonia was selected as the best choice for an OTEC working fluid because of its superior thermodynamics properties at the temperatures involved and its low cost. It was chosen for the advanced tests of the prototypical shell-and-tube and compact heat exchangers. The most effective biocontrol procedure for maintaining clean heat transfer surfaces in the evaporators was intermittent chlorination with possibly periodic mechanical cleaning. Preliminary, short-term test data indicated that cold seawater (at the Seacoast Test Facility at Ke-ahole Point, Hawaii) does not appear to cause fouling in condensers; however, long-term data are still needed to determine the level of biocontrol needed. Titanium and the high-alloy stainless alloys, such as AL-6X and AL-29-4C, are expected to provide the 30-year life in OTEC systems. The use of aluminum alloys is predicated upon the reduction of frequency of mechanical cleaning (to remove biofouling) that will reduce the erosion-corrosion of the heat-transfer surfaces.

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