Design of an Experimental Test Facility for Supercritical CO2 Brayton Cycle

2014 ◽  
Author(s):  
Pardeep Garg ◽  
Pramod Kumar ◽  
Pradip Dutta ◽  
Thomas Conboy ◽  
Clifford Ho
Keyword(s):  
Heat Exchanger ◽  
Pressure Drop ◽  
Supercritical Co2 ◽  
Exchange Process ◽  
Test Facility ◽  
Brayton Cycle ◽  
Pressure Drops ◽  
Loop Design ◽  
Indian Institute Of Science ◽  
Cycle Temperature

A supercritical CO2 test facility is currently being developed at Indian Institute of Science, Bangalore, India to analyze the performance of a closed loop Brayton cycle for concentrated solar power (CSP) generation. The loop has been designed for an external heat input of 20 kW, a pressure range of 75–135 bar, flow rate of 11 kg/min, and a maximum cycle temperature of 525 °C. The operation of the loop and the various parametric tests planned to be performed are discussed in this paper. The paper addresses various aspects of the loop design with emphasis on design of various components such as regenerator and expansion device. The regenerator design is critical due to sharp property variations in CO2 occurring during the heat exchange process between the hot and cold streams. Two types of heat exchanger configurations 1) tube-in-tube (TITHE) and 2) printed circuit heat exchanger (PCHE) are analyzed and compared. A PCHE is found to be ∼5 times compact compared to a TITHE for identical heat transfer and pressure drops. The expansion device is being custom designed to achieve the desired pressure drop for a range of operating temperatures. It is found that capillary of 5.5 mm inner diameter and ∼2 meter length is sufficient to achieve a pressure drop from 130 to 75 bar at a maximum cycle temperature of 525 °C.

Effect of Pressure Drop on Thermal and Exergetic Performance of Supercritical CO2 Recompression Brayton Cycle Integrated With a Central Receiver

2016 ◽  
Author(s):  
Ricardo Vasquez Padilla ◽  
Yen Soo Too ◽  
Andrew Beath ◽  
Robbie McNaughton ◽  
Wes Stein
Keyword(s):  
Pressure Drop ◽  
Surface Temperature ◽  
Supercritical Co2 ◽  
Brayton Cycle ◽  
Concentrated Solar Power ◽  
Pressure Drops ◽  
Effect Of Pressure ◽  
Central Receiver ◽  
Solar Receiver ◽  
Exergy Performance

Concentrated Solar Power using supercritical CO2 (S-CO2) Brayton cycles offers advantages of similar and even higher overall thermal efficiencies compared to conventional Rankine cycles using superheated or supercritical steam. In this paper, a S-CO2 Recompression Brayton cycle is integrated with a central receiver. The effect of pressure drops in heat exchangers and solar receiver surface temperature on the thermal and ex-ergetic performance of the recompression Brayton cycle with and without reheat condition is studied. Energy, exergy and mass balance are carried out for each component and first law and exergy destruction are calculated. In order to obtain optimal operating condition, optimum cycle pressure ratios are obtained by maximising the thermal efficiency. The results showed that under low solar receiver pressure drops and solar receiver temperature approach, the S-CO2 Recompression Brayton cycle has more thermal and exergy efficiencies than the no reheat case. Pressure drop reduces the gap between reheat and no reheat case, and for pressure drops in the solar receiver of 2.5% or higher, reheat has significant impact on thermal and exergy performance of the cycle studied. The overall exergy efficiency showed a bell shaped, reaching a maximum value between 19.5–22.5% at turbine inlet temperatures in the range of 660–755 °C for solar receiver surface temperature approach among 100–200 °C.

Shellside Waterflow Pressure Drop Distribution Measurements in an Industrial-Sized Test Heat Exchanger

1988 ◽  
Vol 110 (1) ◽  
pp. 60-67 ◽  
Author(s):  
H. Halle ◽  
J. M. Chenoweth ◽  
M. W. Wambsganss
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Operating Cost ◽  
Power Requirement ◽  
Pressure Drops ◽  
Pressure Losses ◽  
Finned Tubes ◽  
Heat Exchanger Design ◽  
Isothermal Water

Throughout the life of a heat exchanger, a significant part of the operating cost arises from pumping the heat transfer fluids through and past the tubes. The pumping power requirement is continuous and depends directly upon the magnitude of the pressure losses. Thus, in order to select an optimum heat exchanger design, it is is as important to be able to predict pressure drop accurately as it is to predict heat transfer. This paper presents experimental measurements of the shellside pressure drop for 24 different segmentally baffled bundle configurations in a 0.6-m (24-in.) diameter by 3.7-m (12-ft) long shell with single inlet and outlet nozzles. Both plain and finned tubes, nominally 19-mm (0.75-in.) outside diameter, were arranged on equilateral triangular, square, rotated triangular, and rotated square tube layouts with a tube pitch-to-diameter ratio of 1.25. Isothermal water tests for a range of Reynolds numbers from 7000 to 100,000 were run to measure overall as well as incremental pressure drops across sections of the exchanger. The experimental results are given and correlated with a pressure drop versus flowrate relationship.

Experimental Analysis of an Air-to-Air Heat Exchanger for Use in a Refrigeration Brayton Cycle

Volume 3 ◽  
2004 ◽  
Author(s):  
Alireza Kargar ◽  
Mohammad H. Hosni ◽  
Steve Eckels ◽  
Tomas Gielda
Keyword(s):  
Heat Exchanger ◽  
Pressure Drop ◽  
Removal Rate ◽  
Experimental Results ◽  
Airflow Rate ◽  
Brayton Cycle ◽  
Moisture Removal ◽  
Research Project ◽  
Cycle System ◽  
Automotive Air Conditioning

The refrigeration Brayton cycle, which has been used extensively in various industries, has an excellent potential for use in automotive air conditioning applications. However, the air-cycle system has a couple of drawbacks including fog generation and low cycle efficiency. In this research project, an air-to-air heat exchanger called a ‘mixer’ is designed and used at the outlet of a refrigeration Brayton cycle. The primary function of the mixer is to remove moisture from the secondary warm airflow into the system. Successful moisture removal from the secondary airflow results in achieving the second function of fog dissipation from the primary cold airflow. In order for the system to perform appropriately, the moisture removal rate must be kept at the highest possible rate. The experimental results from this research project reveal that to enhance moisture removal rate, one may either increase the primary cold airflow rate, decrease the secondary warm airflow rate, or the combination of the above airflow adjustments. Furthermore, based on experimental results, one may speculate that there is an optimum point in decreasing the secondary airflow rate. However, in increasing the primary airflow rate, one must be aware of the pressure drop through the cold side of the mixer as the higher pressure drop results in higher power consumption for the Brayton cycle. It is important to point out that appropriate levels of the primary and secondary airflows impacts the mixer effectiveness, and that for a constant cold airflow rate, decreasing the warm airflow rate below the cold airflow rate results in higher effectiveness.

Dimensionless Analysis of Pressure Drop and Heat Transfer on HTGR Coupled With Closed Brayton Cycle

2010 ◽  
Author(s):  
Zhenjia Yu ◽  
Xiaoyong Yang ◽  
Xiaoli Yu ◽  
Jie Wang
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Compression Ratio ◽  
High Efficiency ◽  
Great Influence ◽  
Brayton Cycle ◽  
Local Pressure ◽  
Reynolds Analogy ◽  
Pressure Drops ◽  
Frictional Pressure Drop

High temperature gas-cooled reactor with direct helium turbine cycle is based on the closed Brayton cycle. Its outstanding feature is the high efficiency of power generation. Pervious researches showed that recuperator was the key component to promote the cycle’s efficiency. And pressure drops in components were unavoidable in actual projects and had significant influence on cycle efficiency. A dimensionless model was proposed to analyze cycle’s features of HTGR coupled with gas turbine. The parameters’ effect on cycle’s efficiency was analyzed, with full consideration of the frictional and local pressure drops respectively. Under the restriction of materials and state-of-art of technologies, it showed that the cycle’s efficiency depended on compression ratio, recuperator’s effectiveness and pressure drops of components. However the pressure drop ratios of different components were inherently connected due to the closed cycle. Furthermore pressure drops inside the recuperator were also the function of effectiveness of the heat transfer based on the Reynolds analogy. Therefore cycle’s efficiency just depended on recuperator’s effectiveness with fixed compression ratio. So there existed optimal recuperator’s effectiveness and maximum cycle’s efficiency, which varied with the pressure ratio and other parameters as temperature ratio. The calculation also indicated that the pressure drop in pipes was close to that in heat exchangers. That was, the local pressure drop and frictional pressure drop should be considered respectively, and the local pressure drop made quite large reduction of cycle’s efficiency. The result also showed that local pressure drop had great influence on parameters such as optimal compression ratio and recuperator’s effectiveness.

Heat Exchanger Shellside Pressure Drop: Comparison of Predictions With Experimental Data

1988 ◽  
Vol 110 (1) ◽  
pp. 68-76 ◽  
Author(s):  
R. S. Kistler ◽  
J. M. Chenoweth
Keyword(s):  
Experimental Data ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
National Laboratory ◽  
Argonne National Laboratory ◽  
Flow Induced Vibration ◽  
Ongoing Research ◽  
Pressure Drops ◽  
Complementary Method ◽  
Nozzle Pressure

A unique set of heat exchanger shellside pressure drop experimental data has become available from experiments at Argonne National Laboratory as a part of an ongoing research program in flow-induced vibration. These data provide overall pressure drop for a number of typical industrial heat exchanger configurations in addition to incremental pressure drop measurements along the shellside path. The test program systematically varied the baffle spacing, the tubefield pattern, and nozzle size for a series of isothermal water tests for segmentally baffled bundles. Also recently a comprehensive method has been published in the Heat Exchanger Design Handbook (HEDH) for the prediction of bundle shellside pressure drops. A search of the literature failed to reveal a complementary method for predicting the shellside nozzle pressure losses. This paper compares the predicted with the measured data and validates the adequacy and limitations of the HEDH method for full bundles of plain tubes. It further applies an extension to the method for no-tubes-in-the-window bundles. Adjustments were indicated to improve the predictions for finned tubes and methods were developed to predict shellside nozzle pressure drops. Overall pressure drop predictions were within plus or minus 20 percent.

Pressure Drop During Refrigerant Condensation Inside Horizontal Smooth, Helical Microfin, and Herringbone Microfin Tubes

2004 ◽  
Vol 126 (5) ◽  
pp. 687-696 ◽  
Author(s):  
Jonathan A. Olivier ◽  
Leon Liebenberg ◽  
Mark A. Kedzierski ◽  
Josua P. Meyer
Keyword(s):  
Heat Exchanger ◽  
Pressure Drop ◽  
Saturation Temperature ◽  
Mean Deviation ◽  
Pressure Gradients ◽  
Test Results ◽  
Pressure Drops ◽  
Mass Fluxes ◽  
R 134A ◽  
Microfin Tubes

This paper presents a study of pressure drops during condensation inside a smooth, an 18-deg helical microfin, and a herringbone microfin tube. Measurements were conducted with refrigerant flowing through the tube of a concentric heat exchanger, with water flowing in a counterflow direction in the annulus. Each tube was part of a condenser consisting of eight subcondensers with instrumentation preceding each subcondenser. Three refrigerants were used, namely, R-22, R-407C, and R-134a, all operating at a saturation temperature of 40 °C with mass fluxes ranging from 400 to 800kg/m2 s. Inlet qualities ranged from 0.85 to 0.95 and outlet qualities ranged from 0.05 to 0.15. The test results showed that on average for the three refrigerants the pressure gradients of the herringbone microfin tube were about 79% higher than that of the smooth tube and about 27% higher than that of the helical microfin tube. Further, a correlation from the literature for predicting pressure drops inside a helical microfin tube was modified for the herringbone microfin tube. The modified correlation predicted the data to within an error of 1% and had an absolute mean deviation of 6.8%. This modified correlation compared well with a correlation from the literature that predicted the data to within an error of 7%.

Effect of Pressure Drop and Reheating on Thermal and Exergetic Performance of Supercritical Carbon Dioxide Brayton Cycles Integrated With a Solar Central Receiver

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
Ricardo Vasquez Padilla ◽  
Yen Chean Soo Too ◽  
Andrew Beath ◽  
Robbie McNaughton ◽  
Wes Stein
Keyword(s):  
Carbon Dioxide ◽  
Pressure Drop ◽  
Supercritical Carbon Dioxide ◽  
Surface Temperature ◽  
Brayton Cycle ◽  
Pressure Drops ◽  
Central Receiver ◽  
Maximum Value ◽  
Solar Receiver ◽  
Exergy Performance

Concentrated solar power using supercritical carbon dioxide (S-CO2) Brayton cycles offers advantages of similar or higher overall thermal efficiencies than conventional Rankine cycles using superheated or supercritical steam. The high efficiency and compactness of S-CO2, as compared with steam Rankine cycles operating at the same temperature, make this cycle attractive for solar central receiver applications. In this paper, S-CO2 Brayton cycle is integrated with a solar central receiver that provides heat input to the power cycle. Three configurations were analyzed: simple, recompression (RC), and recompression with main intercooling (MC). The effect of pressure drop in heat exchangers and solar receiver and solar receiver surface temperature on the thermal and exergetic performance of the CO2 Brayton cycle with and without reheat condition was studied. Energy, exergy, and mass balance were carried out for each component and the cycle first law and exergy efficiencies were calculated. In order to obtain optimal operating conditions, optimum pressure ratios were obtained by maximizing the cycle thermal efficiency under different pressure drops and solar receiver temperature conditions. Optimization of the cycle first law efficiency was carried out in python 2.7 by using sequential least squares programing (SLSQP). The results showed that under low pressure drops, adding reheat to the S-CO2 Brayton cycle has a favorable effect on the thermal and exergy efficiencies. Increasing pressure drop reduces the gap between efficiencies for reheat and no reheat configuration, and for pressure drop factors in the solar receiver above 2.5%, reheat has a negligible or detrimental effect on thermal and exergy performance of S-CO2 Brayton cycles. Additionally, the results showed that the overall exergy efficiency has a bell shape, reaching a maximum value between 18.3% and 25.1% at turbine inlet temperatures in the range of 666–827 °C for different configurations. This maximum value is highly dependent on the solar receiver surface temperature, the thermal performance of the solar receiver, and the solar field efficiency. As the solar receiver surface temperature increases, more exergy destruction associated with heat transfer losses to the environment takes place in the solar receiver and therefore the overall exergy efficiency decreases. Recompression with main intercooling (MC) showed the best thermal (ηI,cycle > 47% at Tin,turbine > 700 °C) and exergy performance followed by RC configuration.

Setup of the Supercritical CO2 Test Facility “SCARLETT” for Basic Experimental Investigations of a Compact Heat Exchanger for an Innovative Decay Heat Removal System

2018 ◽  
Vol 4 (3) ◽  
Author(s):  
Wolfgang Flaig ◽  
Rainer Mertz ◽  
Joerg Starflinger
Keyword(s):  
Heat Exchanger ◽  
Supercritical Co2 ◽  
Nuclear Power ◽  
Power Plants ◽  
Heat Removal ◽  
Test Facility ◽  
Experimental Investigations ◽  
Decay Heat ◽  
Heat Removal System ◽  
Removal System

Supercritical fluids show great potential as future coolants for nuclear reactors, thermal power, and solar power plants. Compared to the subcritical condition, supercritical fluids show advantages in heat transfer due to thermodynamic properties near the critical point. A specific field of interest is an innovative decay heat removal system for nuclear power plants, which is based on a turbine-compressor system with supercritical CO2 as the working fluid. In case of a severe accident, this system converts the decay heat into excess electricity and low-temperature waste heat, which can be emitted to the ambient air. To guarantee the retrofitting of this decay heat removal system into existing nuclear power plants, the heat exchanger (HE) needs to be as compact and efficient as possible. Therefore, a diffusion-bonded plate heat exchanger (DBHE) with mini channels was developed and manufactured. This DBHE was tested to gain data of the transferable heat power and the pressure loss. A multipurpose facility has been built at Institut für Kernenergetik und Energiesysteme (IKE) for various experimental investigations on supercritical CO2, which is in operation now. It consists of a closed loop where the CO2 is compressed to supercritical state and delivered to a test section in which the experiments are run. The test facility is designed to carry out experimental investigations with CO2 mass flows up to 0.111 kg/s, pressures up to 12 MPa, and temperatures up to 150 °C. This paper describes the development and setup of the facility as well as the first experimental investigation.

Performance Characteristics of an Operating Supercritical CO2 Brayton Cycle

2012 ◽  
Author(s):  
Thomas Conboy ◽  
Steven Wright ◽  
James Pasch ◽  
Darryn Fleming ◽  
Gary Rochau ◽  
...  
Keyword(s):  
Supercritical Co2 ◽  
Waste Heat ◽  
Electrical Power ◽  
Heat Removal ◽  
Test Facility ◽  
Working Fluid ◽  
Inlet Temperature ◽  
Brayton Cycle ◽  
Compact Size ◽  
Test Loop

Supercritical CO2 (S-CO2) power cycles offer the potential for better overall plant economics due to their high power conversion efficiency over a moderate range of heat source temperatures, compact size, and potential use of standard materials in construction [1,2,3,4]. Sandia National Labs (Albuquerque, NM, US) and the US Department of Energy (DOE-NE) are in the process of constructing and operating a megawatt-scale supercritical CO2 split-flow recompression Brayton cycle with contractor Barber-Nichols Inc. [5] (Arvada, CO, US). This facility can be counted among the first and only S-CO2 power producing Brayton cycles anywhere in the world. The Sandia-DOE test-loop has recently concluded a phase of construction that has substantially upgraded the facility by installing additional heaters, a second recuperating printed circuit heat exchanger (PCHE), more waste heat removal capability, higher capacity load banks, higher temperature piping, and more capable scavenging pumps to reduce windage within the turbomachinery. With these additions, the loop has greatly increased its potential for electrical power generation — according to models, as much as 80 kWe per generator depending on loop configuration — and its ability to reach higher temperatures. To date, the loop has been primarily operated as a simple recuperated Brayton cycle, meaning a single turbine, single compressor, and undivided flow paths. In this configuration, the test facility has begun to realize its upgraded capacity by achieving new records in turbine inlet temperature (650°F/615K), shaft speed (52,000 rpm), pressure ratio (1.65), flow rate (2.7 kg/s), and electrical power generated (20kWe). Operation at higher speeds, flow rates, pressures and temperatures has allowed a more revealing look at the performance of essential power cycle components in a supercritical CO2 working fluid, including recuperation and waste heat rejection heat exchangers (PCHEs), turbines and compressors, bearings and seals, as well as auxiliary equipment. In this report, performance of these components to date will be detailed, including a discussion of expected operational limits as higher speeds and temperatures are approached.

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