scholarly journals High-Temperature Receiver Designs for Supercritical CO2 Closed-Loop Brayton Cycles

2014 ◽  
Author(s):  
C. K. Ho ◽  
T. Conboy ◽  
J. Ortega ◽  
S. Afrin ◽  
A. Gray ◽  
...  
Keyword(s):  
High Temperature ◽  
Supercritical Co2 ◽  
Closed Loop ◽  
High Efficiency ◽  
Power Cycles ◽  
Advantages And Disadvantages ◽  
Solar Powered ◽  
Solar Receiver ◽  
Alternative Designs ◽  
Indirect Heating

High-temperature receiver designs for solar powered supercritical CO2 Brayton cycles that can produce ∼1 MW of electricity are being investigated. Advantages of a supercritical CO2 closed-loop Brayton cycle with recuperation include high efficiency (∼50%) and a small footprint relative to equivalent systems employing steam Rankine power cycles. Heating for the supercritical CO2 system occurs in a high-temperature solar receiver that can produce temperatures of at least 700 °C. Depending on whether the CO2 is heated directly or indirectly, the receiver may need to withstand pressures up to 20 MPa (200 bar). This paper reviews several high-temperature receiver designs that have been investigated as part of the SERIIUS program. Designs for direct heating of CO2 include volumetric receivers and tubular receivers, while designs for indirect heating include volumetric air receivers, molten-salt and liquid-metal tubular receivers, and falling particle receivers. Indirect receiver designs also allow storage of thermal energy for dispatchable electricity generation. Advantages and disadvantages of alternative designs are presented. Current results show that the most viable options include tubular receiver designs for direct and indirect heating of CO2 and falling particle receiver designs for indirect heating and storage.

High Efficiency SOFC Power Cycles With Indirect Natural Gas Reforming and CO2 Capture

2015 ◽  
Vol 12 (2) ◽  
Author(s):  
Stefano Campanari ◽  
Matteo Gazzani
Keyword(s):  
High Temperature ◽  
Natural Gas ◽  
Gas Turbine ◽  
Co2 Capture ◽  
Heat Exchangers ◽  
High Efficiency ◽  
Power Production ◽  
Operating Conditions ◽  
Power Cycles ◽  
Power Cycle

Driven by the search for the highest theoretical efficiency, several studies have investigated in the last years the adoption of fuel cells (FCs) in the field of power production from natural gas with CO2 capture. Most of the proposed power cycles rely on high temperature FCs, namely, solid oxide FCs (SOFCs) and molten carbonate FCs (MCFCs), based on the concept of hybrid FC plus gas turbine cycles. Accordingly, high temperature FCs are integrated with a simple or modified Brayton cycle. As far as SOFCs are concerned, CO2 can be separated downstream the FC via a range of available technologies, e.g., chemical or physical separation processes, oxy-combustion, and cryogenic methods. Following a literature review on promising plant configurations, this work investigates the potential of adopting an external natural gas conversion section with respect to the plant efficiency. As a reference plant, we considered a power cycle proposed by Adams and Barton (2010, “High-Efficiency Power Production From Natural Gas With Carbon Capture,” J. Power Sources, 195(7), pp. 1971–1983), whose performance is the highest found in literature for SOFC-based power cycles, with 82% LHV electrical efficiency. It is based on a prereforming concept where fuel is reformed ahead the SOFC, which thus works with a high hydrogen content fuel. After reproducing the power cycle with the ideal assumptions proposed by the original authors, as second step, the simulations were focused on revising the power cycle, implementing a complete set of assumptions about component losses and more conservative operating conditions about FC voltage, heat exchangers minimum temperature differences (which were previously neglected), maximum steam temperature (set according to heat recovery steam generator (HRSG) practice), turbomachinery efficiency, component pressure losses, and other adjustments. The simulation also required to design an appropriate heat exchangers network, which turned out to be very complex, instead of relying on the free allocation of heat transfer among all components. Considering the consequent modifications with respect to the original layout, the net electric efficiency changes to around 63% LHV with nearly complete (95%+) CO2 capture, a still remarkable but less attractive value. On the other hand, the power cycle requires a complicated and demanding heat exchangers network and heavily relies on the SOFC performances, not generating a positive power output from the gas turbine loop. Detailed results are presented in terms of energy and material balances of the proposed cycles. All simulations have been carried out with the proprietary code GS, developed by the GECOS group at Politecnico di Milano.

Application of Sol-Gel Method as a Protective Layer on a Specular Reflective Surface for Secondary Reflector in a Solar Receiver

2016 ◽  
Author(s):  
Samia Afrin ◽  
John Dagdelen ◽  
Zhiwen Ma ◽  
Vinod Kumar
Keyword(s):  
Optical Properties ◽  
High Temperature ◽  
High Efficiency ◽  
Elevated Temperatures ◽  
Sol Gel ◽  
Film Structure ◽  
Gel Method ◽  
Sol Gel Method ◽  
Reflective Surface ◽  
Solar Receiver

Highly-specular reflective surfaces that can withstand elevated-temperatures are desirable for many applications including reflective heat shielding in solar receivers and secondary reflectors, which can be used between primary concentrators and heat collectors. A high-efficiency, high-temperature solar receiver design based on arrays of cavities needs a highly-specular reflective surface on its front section to help sunlight penetrate into the absorber tubes for effective flux spreading. Since this application is for high-temperature solar receivers, this surface needs to be durable and to maintain its optical properties through the usable life. Degradation mechanisms associated with elevated temperatures and thermal cycling, which include cracking, delamination, corrosion/oxidation, and environmental effects, could cause the optical properties of surfaces to degrade rapidly in these conditions. Protected mirror surfaces for these applications have been tested by depositing a thin layer of SiO2 on top of electrodeposited silver by means of the sol-gel method. To obtain an effective thin film structure, this sol-gel procedure has been investigated extensively by varying process parameters that affect film porosity and thickness. Endurance tests have been performed in a furnace at 150°C for thousands of hours. This paper presents the sol-gel process for intermediate-temperature specular reflective coatings and provides the long-term reliability test results of sol-gel protected silver-coated surfaces.

scholarly journals Supercritical Carbon Dioxide(s-CO2) Power Cycle for Waste Heat Recovery: A Review from Thermodynamic Perspective

Processes ◽  
2020 ◽  
Vol 8 (11) ◽  
pp. 1461
Author(s):  
Liuchen Liu ◽  
Qiguo Yang ◽  
Guomin Cui
Keyword(s):  
High Temperature ◽  
Supercritical Co2 ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Combustion Engine ◽  
Power Cycles ◽  
Power Cycle ◽  
Thermodynamic Cycles ◽  
Cogeneration System

Supercritical CO2 power cycles have been deeply investigated in recent years. However, their potential in waste heat recovery is still largely unexplored. This paper presents a critical review of engineering background, technical challenges, and current advances of the s-CO2 cycle for waste heat recovery. Firstly, common barriers for the further promotion of waste heat recovery technology are discussed. Afterwards, the technical advantages of the s-CO2 cycle in solving the abovementioned problems are outlined by comparing several state-of-the-art thermodynamic cycles. On this basis, current research results in this field are reviewed for three main applications, namely the fuel cell, internal combustion engine, and gas turbine. For low temperature applications, the transcritical CO2 cycles can compete with other existing technologies, while supercritical CO2 cycles are more attractive for medium- and high temperature sources to replace steam Rankine cycles. Moreover, simple and regenerative configurations are more suitable for transcritical cycles, whereas various complex configurations have advantages for medium- and high temperature heat sources to form cogeneration system. Finally, from the viewpoints of in-depth research and engineering applications, several future development directions are put forward. This review hopes to promote the development of s-CO2 cycles for waste heat recovery.

Design and Optimization of Non-Supercritical CO2 Thermal Power Cycle for “P2H2P” Energy Storage System

2020 ◽  
Author(s):  
Ondrej Burian ◽  
Radek Skoda
Keyword(s):  
Energy Storage ◽  
Supercritical Co2 ◽  
Liquid Metals ◽  
Storage System ◽  
Thermal Power ◽  
Energy Storage System ◽  
Power Cycles ◽  
Design And Optimization ◽  
Power Cycle ◽  
Advantages And Disadvantages

Abstract Most of the current research and development of CO2 cycles for power to heat - heat to power (P2H2P) energy storage systems are focused on applications of supercritical CO2 cycles. However, this work is focused on alternative application of CO2 power cycle with standard (i.e., non-supercritical) cycle and modified industrial turboexpanders as main working machines. Thermal Cycle for power storage system with thermal energy accumulator for energy storage and non-supercritical CO2 power cycle for backward production of electricity is described in this paper. The CO2 cycle is compared with Nitrogen cycle with same parameters as well. Initially, the thermal accumulator design, option of accumulation media (molten salts or liquid metals), and its parameters are described. The main part of the paper is focused on non-supercritical CO2 power cycles. Possible configurations of cycle, design aspects of main parts of cycle, possibilities of efficiency improvement are discussed; such as regeneration or intercooling. Finally, advantages and disadvantages of this CO2 and N2 cycle are discussed and compared. The concluding result of this paper is a very similar efficiency of the two working fluids at the selected parameters.

scholarly journals Design, Fabrication, and Partial Characterization of a Solar Receiver and Air-Cooled Heat Exchanger for a Concentrated Solar Power Supercritical CO2 Testbed

2020 ◽  
Vol 142 (6) ◽  
Author(s):  
Danielle Nobles-Lookingbill ◽  
Aaron Sahm ◽  
Rick Hurt ◽  
Robert Boehm
Keyword(s):  
Heat Exchanger ◽  
Supercritical Co2 ◽  
Experimental System ◽  
Open Loop ◽  
Cycle System ◽  
Low Mass ◽  
Solar Powered ◽  
System Configurations ◽  
Air Cooled Heat Exchanger ◽  
Solar Receiver

Abstract This research details the design, fabrication, and partial testing of a concentrated solar receiver and an air-cooled heat exchanger. The solar receiver and heat exchanger have been fabricated for use in an experimental system that uses the supercritical carbon dioxide Brayton cycle. They are coupled with a Science Applications International Corporation (SAIC) solar dish 250× concentrator located on the University of Nevada, Las Vegas campus. The purpose of this solar-powered supercritical CO2 system is to function as a testbed for testing the cycle, system components, and alternate system configurations. Photographic flux mapping of the dish showed peak solar flux just above 200× and is used to appropriately size the receiver. Sun tests of the tubing, receiver, and air-cooled heat exchanger were performed achieving fluid temperatures in the range of 973 K (700 °C) using nitrogen in an open loop at low mass flowrates, and above 1173-K (900 °C) receiver wall temperatures in a no-flow case.

scholarly journals Fluidized-bed Technology Enabling the Integration of High Temperature Solar Receiver CSP Systems with Steam and Advanced Power Cycles

2015 ◽  
Vol 69 ◽  
pp. 1404-1411 ◽  
Author(s):  
B. Sakadjian ◽  
S. Hu ◽  
M. Maryamchik ◽  
T. Flynn ◽  
K. Santelmann ◽  
...  
Keyword(s):  
High Temperature ◽  
Fluidized Bed ◽  
Power Cycles ◽  
Solar Receiver

Comparison of Dc-Dc SEPIC, CUK and Flyback Converters Based LED Drivers

2020 ◽  
pp. 99-107
Author(s):  
Erdal Sehirli
Keyword(s):  
Integrated Circuit ◽  
Closed Loop ◽  
Input Voltage ◽  
Open Loop ◽  
Current Sensor ◽  
Switching Frequency ◽  
Led Driver ◽  
Advantages And Disadvantages ◽  
Led Drivers ◽  
Conduction Mode

This paper presents the comparison of LED driver topologies that include SEPIC, CUK and FLYBACK DC-DC converters. Both topologies are designed for 8W power and operated in discontinuous conduction mode (DCM) with 88 kHz switching frequency. Furthermore, inductors of SEPIC and CUK converters are wounded as coupled. Applications are realized by using SG3524 integrated circuit for open loop and PIC16F877 microcontroller for closed loop. Besides, ACS712 current sensor used to limit maximum LED current for closed loop applications. Finally, SEPIC, CUK and FLYBACK DC-DC LED drivers are compared with respect to LED current, LED voltage, input voltage and current. Also, advantages and disadvantages of all topologies are concluded.

The Potential of Photoelectrochemical Carbon Sinks

2018 ◽  
Author(s):  
Matthias May ◽  
Kira Rehfeld
Keyword(s):  
Global Warming ◽  
High Temperature ◽  
Greenhouse Gas ◽  
Large Scale ◽  
High Efficiency ◽  
Carbon Sink ◽  
Solar Fuels ◽  
Negative Emissions ◽  
Viable Approach ◽  
Low Sensitivity

Greenhouse gas emissions must be cut to limit global warming to 1.5-2C above preindustrial levels. Yet the rate of decarbonisation is currently too low to achieve this. Policy-relevant scenarios therefore rely on the permanent removal of CO<sub>2</sub> from the atmosphere. However, none of the envisaged technologies has demonstrated scalability to the decarbonization targets for the year 2050. In this analysis, we show that artificial photosynthesis for CO<sub>2</sub> reduction may deliver an efficient large-scale carbon sink. This technology is mainly developed towards solar fuels and its potential for negative emissions has been largely overlooked. With high efficiency and low sensitivity to high temperature and illumination conditions, it could, if developed towards a mature technology, present a viable approach to fill the gap in the negative emissions budget.<br>

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