scholarly journals Water-Spray-Cooled Quasi-Isothermal Compression Method: Water-Spray Flow Improvement

Entropy ◽  
2021 ◽  
Vol 23 (6) ◽  
pp. 724
Author(s):  
Guanwei Jia ◽  
Xuanwei Nian ◽  
Weiqing Xu ◽  
Yan Shi ◽  
Maolin Cai
Keyword(s):  
Heat Transfer ◽  
Energy Storage ◽  
Flow Rate ◽  
Compressed Air ◽  
Water Spray ◽  
Compressed Air Energy Storage ◽  
Compression Process ◽  
Injection Water ◽  
The Difference ◽  
Spray Flow Rate

Water-spray-cooled quasi-isothermal compressed air energy storage aims to avoid heat energy losses from advanced adiabatic compressed-air energy storage (AA-CAES). The compression efficiency increases with injection water spray. However, the energy-generated water spray cannot be ignored. As the air pressure increases, the work done by the piston and the work converted into heat rise gradually in the compression process. Accordingly, the flow rate of the water needed for heat transfer is not a constant with respect to time. To match the rising compression heat, a time sequence of water-spray flow rate is constructed, and the algorithm is designed. Real-time water-spray flow rate is calculated according to the difference between the compression power and heat-transfer power. Compared with the uniform flow rate of water spray, energy consumption from the improved flow rate is reduced.

Storage Power and Efficiency Analysis Based on CFD for Air Compressors Used for Compressed Air Energy Storage

2012 ◽  
Author(s):  
Chao Zhang ◽  
Terrence W. Simon ◽  
Perry Y. Li
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Energy Storage ◽  
Temperature Rise ◽  
Compressed Air ◽  
Compressed Air Energy Storage ◽  
Compression Process ◽  
Aspect Ratios ◽  
And Storage ◽  
Polytropic Exponent

The compression process in a piston cylinder device in a Compressed Air Energy Storage (CAES) system is studied computationally. Twelve different cases featuring four different compression space length-to-radius aspect ratios and three different Reynolds numbers are studied computationally using the commercial CFD code ANSYS FLUENT. The solutions show that for compression with a constant velocity, the compression can be approximated by a polytropic pressure vs. volume relation. The polytropic exponent, n, characterizes the heat transfer and temperature rise of the air being compressed. For the cases computed, it varies from 1.124 to 1.305 and is found to be more affected by Reynolds number and less by the length-to-radius ratio. Since the efficiency and storage power of the compressor depend on pressure vs. volume trajectory during compression, they are written as functions of the pressure rise ratio and the polytropic exponent, n. The efficiency is high at the beginning of the compression process, and decreases as the compression proceeds. The effect of temperature rise or heat transfer on efficiency and storage power is shown by comparing the efficiency and storage power vs. volume curves having different n values. Smaller temperature rise always results in higher efficiency but lower dimensionless storage power for the same compression pressure ratio. The storage power is used in this study to distinguish the compression process effect (n effect) and the compressor’s size effect on the storage power. The likelihood of flow transitioning into turbulent flow is discussed. A k–ε Reynolds Averaged Navier Stokes (RANS) turbulence model is used to calculate one of the larger Reynolds number cases. The calculated polytropic exponent was only 0.02 different from that of the laminar flow solution. The CFD results show also that during compression, complex vorticity patterns develop, which help mix the cold fluid near the wall with the hot fluid in the inner region, beneficial to achieving a higher efficiency.

Analysis, Fabrication, and Testing of a Liquid Piston Compressor Prototype for an Ocean Compressed Air Energy Storage (OCAES) System

2014 ◽  
Vol 48 (6) ◽  
pp. 86-97 ◽  
Author(s):  
Joong-kyoo Park ◽  
Paul I. Ro ◽  
Xiao He ◽  
Andre P. Mazzoleni
Keyword(s):  
Heat Transfer ◽  
Energy Storage ◽  
Piston Compressor ◽  
Compressed Air ◽  
Compressed Air Energy Storage ◽  
Compression Process ◽  
Compression System ◽  
Numerical Studies ◽  
Piston System ◽  
Liquid Piston

AbstractPrevious work concerning ocean compressed air energy storage (OCAES) systems has revealed the need for an efficient means for compressing air that minimizes the energy lost to heat during the compression process. In this paper, we present analysis, simulation, and testing of a tabletop proof-of-concept experiment of a liquid piston compression system coupled with a simulated OCAES system, with special attention given to heat transfer issues. An experimental model of a liquid piston system was built and tested with two different materials, polycarbonate and aluminum alloy, used for the compression chamber. This tabletop liquid piston system was tested in conjunction with a simulated OCAES system, which consisted of a hydrostatic tank connected to a compressed-air source from the wall to mimic the constant hydrostatic pressure at ocean depth experienced by the air stored in an actual OCAES system. Good agreement was found between the experimental and numerical studies and demonstrated that the heat transfer characteristics of a liquid piston compression process are effective in reducing the increase in air temperature that occurs during the compression process. The results also suggest that it may be possible to achieve a near-isothermal process with a fully optimized liquid piston compression system.

Thermal Design and Analysis of a Solid-State Grid-Tied Thermal Energy Storage for Hybrid Compressed Air Energy Storage Systems

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Khashayar Hakamian ◽  
Kevin R. Anderson ◽  
Maryam Shafahi ◽  
Reza Baghaei Lakeh
Keyword(s):  
Energy Storage ◽  
Flow Rate ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Power Plants ◽  
Power Grid ◽  
Thermal Design ◽  
Compressed Air ◽  
Compressed Air Energy Storage ◽  
New Variant

Power overgeneration by renewable sources combined with less dispatchable conventional power plants introduces the power grid to a new challenge, i.e., instability. The stability of the power grid requires constant balance between generation and demand. A well-known solution to power overgeneration is grid-scale energy storage. Compressed air energy storage (CAES) has been utilized for grid-scale energy storage for a few decades. However, conventional diabatic CAES systems are difficult and expensive to construct and maintain due to their high-pressure operating condition. Hybrid compressed air energy storage (HCAES) systems are introduced as a new variant of old CAES technology to reduce the cost of energy storage using compressed air. The HCAES system split the received power from the grid into two subsystems. A portion of the power is used to compress air, as done in conventional CAES systems. The rest of the electric power is converted to heat in a high-temperature thermal energy storage (TES) component using Joule heating. A computational approach was adopted to investigate the performance of the proposed TES system during a full charge/storage/discharge cycle. It was shown that the proposed design can be used to receive 200 kW of power from the grid for 6 h without overheating the resistive heaters. The discharge computations show that the proposed geometry of the TES, along with a control strategy for the flow rate, can provide a 74-kW microturbine of the HCAES with the minimum required temperature, i.e., 1144 K at 0.6 kg/s of air flow rate for 6 h.

Design of an Interrupted-Plate Heat Exchanger Used in a Liquid-Piston Compression Chamber for Compressed Air Energy Storage

2013 ◽  
Author(s):  
Chao Zhang ◽  
Farzad A. Shirazi ◽  
Bo Yan ◽  
Terrence W. Simon ◽  
Perry Y. Li ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Energy Storage ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Plate Heat Exchanger ◽  
Compressed Air ◽  
Compressed Air Energy Storage ◽  
Plate Heat ◽  
Liquid Piston ◽  
Compression Chamber

In the Compressed Air Energy Storage (CAES) approach, air is compressed to high pressure, stored, and expanded to output work when needed. The temperature of air tends to rise during compression, and the rise in the air internal energy is wasted during the later storage period as the compressed air cools back to ambient temperature. The present study focuses on designing an interrupted-plate heat exchanger used in a liquid-piston compression chamber for CAES. The exchanger features layers of thin plates stacked in an interrupted pattern. Twenty-seven exchangers featuring different combinations of shape parameters are analyzed. The exchangers are modeled as porous media. As such, for each exchanger shape, a Representative Elementary Volume (REV), which represents a unit cell of the exchanger, is developed. The flow through the REV is simulated with periodic velocity and thermal boundary conditions, using the commercial CFD software ANSYS FLUENT. Simulations of the REVs for the various exchangers characterize the various shape parameter effects on values of pressure drop and heat transfer coefficient between solid surfaces and fluid. For an experimental validation of the numerical solution, two different exchanger models made by rapid prototyping, are tested for pressure drop and heat transfer. Good agreement is found between numerical and experimental results. Nusselt number vs. Reynolds number relations are developed on the basis of pore size and on hydraulic diameter. To analyze performance of exchangers with different shapes, a simplified zero-dimensional thermodynamic model for the compression chamber with the inserted heat exchange elements is developed. This model, valuable for system optimization and control simulations, is a set of ordinary differential equations. They are solved numerically for each exchanger insert shape to determine the geometries of best compression efficiency.

scholarly journals Energy and Exergy Analysis of Ocean Compressed Air Energy Storage Concepts

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Vikram C. Patil ◽  
Paul I. Ro
Keyword(s):  
Heat Transfer ◽  
Energy Storage ◽  
Heat Transfer Enhancement ◽  
Exergy Analysis ◽  
Compressed Air ◽  
Compressed Air Energy Storage ◽  
Transfer Enhancement ◽  
Energy And Exergy ◽  
Energy And Exergy Analysis ◽  
Liquid Piston

Optimal utilization of renewable energy resources needs energy storage capability in integration with the electric grid. Ocean compressed air energy storage (OCAES) can provide promising large-scale energy storage. In OCAES, energy is stored in the form of compressed air under the ocean. Underwater energy storage results in a constant-pressure storage system which has potential to show high efficiency compared to constant-volume energy storage. Various OCAES concepts, namely, diabatic, adiabatic, and isothermal OCAES, are possible based on the handling of heat in the system. These OCAES concepts are assessed using energy and exergy analysis in this paper. Roundtrip efficiency of liquid piston based OCAES is also investigated using an experimental liquid piston compressor. Further, the potential of improved efficiency of liquid piston based OCAES with use of various heat transfer enhancement techniques is investigated. Results show that adiabatic OCAES shows improved efficiency over diabatic OCAES by storing thermal exergy in thermal energy storage and isothermal OCAES shows significantly higher efficiency over adiabatic and diabatic OCAES. Liquid piston based OCAES is estimated to show roundtrip efficiency of about 45% and use of heat transfer enhancement in liquid piston has potential to improve roundtrip efficiency of liquid piston based OCAES up to 62%.

Thermal Design and Analysis of a Solid-State Grid-Tied Thermal Energy Storage for Hybrid Compressed Air Energy Storage Systems

2018 ◽  
Author(s):  
Khashayar Hakamian ◽  
Kevin R. Anderson ◽  
Maryam Shafahi ◽  
Reza Baghaei Lakeh
Keyword(s):  
High Temperature ◽  
Energy Storage ◽  
Solid State ◽  
Flow Rate ◽  
Thermal Energy ◽  
Concrete Block ◽  
Compressed Air ◽  
Compressed Air Energy Storage ◽  
Cost Of Energy ◽  
The Cost

Power overgeneration by renewable sources combined with less dispatchabe conventional power plants introduce the power grid to a new challenge, i.e., instability. The stability of the power grid requires constant balance between generation and demand. A well-known solution to power overgeneration is grid-scale energy storage. Although different energy storage technologies have been tested and demonstrated, reducing the cost of energy storage remains as a challenging goal for researchers, industries, and governments. Compressed Air Energy Storage (CAES) has been utilized for grid-scale energy storage for a few decades. However, conventional diabatic CAES systems are difficult and expensive to construct and maintain due to their high pressure operating condition. Hybrid Compressed Air Energy Storage (HCAES) systems are introduced as a new variant of old CAES technology to reduce the cost of energy storage using compressed air. The HCAES system split the received power from the grid into two subsystems. A portion of the power is used to compress air, as done in conventional CAES systems. The rest of the electric power is converted to heat in a high-temperature Thermal Energy Storage (TES) component using Joule heating. In this study, a solid-state grid-tied TES system is designed to operate with a HCAES system. The storage medium is considered to be high-temperature refractory concrete. The thermal energy is generated inside the concrete block using resistive heaters (wires) that are buried inside a concrete block. A computational approach was adopted to investigate the performance of the proposed TES system during a full charge/storage/discharge cycle. It was shown that the proposed design can be used to receive 200 kW of power from the grid for 6 hours without overheating the resistive heaters. The discharge computations show that the proposed geometry of the TES, along with a control strategy for the flow rate can provide a 74-kW micro-turbine of the HCAES with the minimum required temperature, i.e., 1144K at 0.6 kg/s of air flow rate for 6 hours. The computations were performed in ANSYS/FLUENT and the results were verified and validated using a grid independence study.

scholarly journals Design of a compression process to improve the operational flexibility of compressed air energy storage: FlexiCAES

2021 ◽  
Vol 46 ◽  
pp. 101251
Author(s):  
Francisco Vergara ◽  
Gabriel Barthelemy ◽  
Omar Aizpurúa ◽  
Marcelo F. Ortega ◽  
Bernardo Llamas
Keyword(s):  
Energy Storage ◽  
Compressed Air ◽  
Compressed Air Energy Storage ◽  
Operational Flexibility ◽  
Compression Process
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