scholarly journals Modeling of Pressure Exchanger for Energy Recovery on Trans Critical CO2 Refrigeration Cycle

2019 ◽  
Author(s):  
Ahmed Elatar ◽  
Kashif Nawaz ◽  
Brian Fricke ◽  
Vishaldeep Sharma
Keyword(s):  
High Pressure ◽  
Fluid Pressure ◽  
Low Pressure ◽  
Pressure Variation ◽  
Water Desalination ◽  
Working Fluid ◽  
Refrigeration System ◽  
Fluid Behavior ◽  
High Pressure Co2 ◽  
Contour Plots

Abstract Pressure exchanger is a device used to recover energy from high pressure working fluid in systems like Reverse Osmosis water desalination. The pressure exchanger enables the high-pressure fluid to transfer portion of its energy to the low-pressure fluid by transferring the fluid pressure. This working concept can be applied to systems where there is a significant pressure variation of the working fluid along the system. Trans critical CO2 refrigeration system is a good example for significant pressure variation during the flow path. The high-pressure CO2 exiting the condenser can be recovered by the low-pressure CO2 upstream of the compressor using a pressure exchanger to increase the system overall efficiency. The proposed research is to numerically simulate a prototype pressure exchanger for trans critical CO2 refrigeration system. The focus of this study is to understand the thermo-fluid behavior of the system when CO2 is used as the working fluid. Contour plots of velocity and pressure are presented for qualitative analysis.

Pressure Variation in Low Pressure Side of Shell and Tube Heat Exchanger After Tube Rupture

2014 ◽  
Author(s):  
Ganesh S. Katke ◽  
M. Venkatesh ◽  
N. P. Gulhane
Keyword(s):  
High Pressure ◽  
Heat Exchanger ◽  
Low Pressure ◽  
Pressure Variation ◽  
Operating Pressure ◽  
Pressure Side ◽  
Tube Heat Exchanger ◽  
Analytical Algorithm ◽  
Shell And Tube ◽  
Design Pressure

This paper presents an analytical algorithm to determine the pressure variation on the Low Pressure side of a Shell and Tube Heat Exchanger (STHE) after a tube rupture and its validation using CFD simulation. STHEs are often used for exchanging heat between high-pressure (HP) and low-pressure (LP) fluids in the chemical process industry. In case tube rupture occurs in a STHE having a large pressure difference between HP and LP side, there is a risk of release of significant quantity of fluid from the HP side to the LP side. The consequent pressure build-up can lead to the failure of LP side pressure envelope. Generally, design pressure of the LP side is about 10–20% higher than the operating pressure of the LP side fluid, but well below the operating pressure on the HP side. There is no well-established methodology to design the LP side to withstand sudden release of high pressure fluid following a tube rupture. Three dimensional analyses were carried out using Computational Fluid Dynamics to study the pressure variation in LP side (shell side) of a Gas Cooler and to validate the results obtained from the analytical algorithm. It has been observed that the pressure on the LP side exceeds the design pressure instantaneously due to generation of a pressure pulse after tube rupture. This may lead to damage of LP envelope (shell) and internal structure of STHE.

Reynolds Averaged Navier-Stokes Simulation of Highly Turbulent, Under-Expanded Jets and Effects of Impingement at Elevated Injection Pressure

2019 ◽  
Author(s):  
Jacob Riglin ◽  
Adam Wachtor ◽  
Robert Morgan ◽  
Ryan Holguin ◽  
John Bernardin
Keyword(s):  
High Pressure ◽  
Initial Pressure ◽  
Low Pressure ◽  
Mach Disk ◽  
Navier Stokes ◽  
Working Fluid ◽  
Jet Formation ◽  
Wide Range ◽  
Pressure Cylinder ◽  
Reynolds Averaged Navier Stokes

Abstract Under-expanded jets have wide range of application from fuel injection to rocket propulsion. In the present work, a numerical model was generated to investigate the fluid mechanics behavior of under-expanded jet formation and wall interaction of a jet produced by exhausting a high pressure cylinder through a narrow tube into a low pressure cylinder. Axisymmectic, Reynolds Averaged Navier Stokes simulations were conducted employing the ANSYS FLUENT explicit, Coupled Pressure-Velocity solver to determine the stagnation pressure at the wall downstream of the orifice. Transient cases were conducted using timestep sizes of 1.0 × 10−8 s and 5.0 × 10−9 s. Various gases were investigated with Hydrogen being the primary working fluid with pressure ratios ranging from 10 to 100. This paper will focus primarily on the Hydrogen jets for pressure ratios of 10, 20, and 70. Numerical results were validated from both experimental results and higher fidelity Large Eddy Simulation results specifically analyzing the jet formation. Error between Mach disk height, Mach disk width, and Prandtl-Meyer expansion fan angles of the jet for pressure ratios of 10 and 70 were kept below 5%. The peak stagnation pressures at the center of the far wall for pressure ratios of 10, 20, and 70 were observed to be 86,843 Pa, 127,786 Pa, and 315,843 Pa, respectively. The predicted peak pressures show a linear relationship with respect to the initial pressure ratio existing between the high pressure and low pressure regions when the ratios are bounded between 10 and 70.

Optimization of Fuel Two-Stage Screw Centrifugal Pump of Rocket Powerful Turbopump Unit

2018 ◽  
Author(s):  
Vasilii Zubanov ◽  
Andrei Volkov ◽  
Valeriy Matveev ◽  
Grigorii Popov ◽  
Oleg Baturin
Keyword(s):  
High Pressure ◽  
Rocket Engine ◽  
Mathematical Optimization ◽  
Low Pressure ◽  
Working Fluid ◽  
Geometrical Parameters ◽  
Rotor Speed ◽  
Optimization Software ◽  
Centrifugal Stage ◽  
Ansys Cfx

The article describes a refining method for a fuel pump of rocket powerful turbo-pump unit by the joint usage of mathematical optimization software IOSO, meshing complex NUMECA and CFD complex ANSYS CFX. The optimization software was used for automatic change of the geometry of low-pressure impeller, transition duct and high-pressure impeller to find the optimal design. It was mandatory to keep the original variant of the remaining parts of the pump. For this reason, only geometrical parameters of the blades were varied without changing the contours of the pump meridional flow part. The investigated pump consists of five parts: inlet duct, low-pressure screw centrifugal stage, transition duct, high-pressure screw centrifugal stage and volute outlet duct. The pump main parameters with water as the working fluid (based on experiment data) were the following: high-pressure stage rotor speed was 13300 rpm; low-pressure rotor speed was 3617 rpm by gearbox; inlet total pressure was 0.4 MPa; outlet mass flow was 132.6 kg/s at the nominal mode. Creation of vane unit mesh (rotors and stator transition duct) was performed using NUMECA AutoGrid5. Sector models were used for the calculation simplification. The flow around only one blade or screw was considered. Setting up and solution of the task were carried out in the ANSYS CFX solver. Comparison of calculated characteristics of the basic pump with the experimental data was performed before the optimization. The analysis of characteristics for the obtained optimized pump geometry was carried out. It was found that pump with optimized geometry has greater efficiency in comparison with the original pump variant. The obtained reserve can be used to boost the rocket engine, and/or to reduce the loading of the main turbine, which operates in aggressive oxidizing environment.

Low-pressure CO2 sorption in poly(vinyl benzoate) conditioned to high-pressure CO2

1988 ◽  
Vol 35 (7) ◽  
pp. 1715-1724 ◽  
Author(s):  
Takuji Hirose ◽  
Keishin Mizoguchi ◽  
Yasutoshi Naito ◽  
Yoshinori Kamiya
Keyword(s):  
High Pressure ◽  
Low Pressure ◽  
Co2 Sorption ◽  
High Pressure Co2

scholarly journals Optimisation of power generation cycles using saturated liquid expansion to maximise heat recovery

2016 ◽  
Vol 231 (1) ◽  
pp. 57-69 ◽  
Author(s):  
MG Read ◽  
IK Smith ◽  
N Stosic
Keyword(s):  
Power Generation ◽  
High Pressure ◽  
Heat Recovery ◽  
Volume Ratio ◽  
Low Pressure ◽  
Working Fluid ◽  
Two Stage ◽  
Low Pressure Turbine ◽  
Screw Machine ◽  
Temperature Heat

The use of two-phase screw expanders in power generation cycles can achieve an increase in the utilisation of available energy from a low-temperature heat source when compared with more conventional single-phase turbines. The efficiency of screw expander machines is sensitive to expansion volume ratio, which, for given inlet and discharge pressures, increases as the expander inlet vapour dryness fraction decreases. For single-stage screw machines with low inlet dryness, this can lead to underexpansion of the working fluid and low isentropic efficiency. The cycle efficiency can potentially be improved by using a two-stage expander, consisting of a machine for low-pressure expansion and a smaller high-pressure machine connected in series. By expanding the working fluid over two stages, the built-in volume ratios of the two machines can be selected to provide a better match with the overall expansion process, thereby increasing the efficiency. The mass flow rate though both stages must be matched, and the compromise between increasing efficiency and maximising power output must also be considered. This study is based on the use of a rigorous thermodynamic screw machine model to compare the performance of single- and two-stage expanders. The model allows optimisation of the required intermediate pressure in the two-stage expander, along with the built-in volume ratio of both screw machine stages. The results allow specification of a two-stage machine, using either two screw machines or a combination of high-pressure screw and low-pressure turbine, in order to achieve maximum efficiency for a particular power output. For the low-temperature heat recovery application considered in this paper, the trilateral flash cycle using a two-stage expander and the Smith cycle using a high-pressure screw and low-pressure turbine are both predicted to achieve a similar overall conversion efficiency to that of a conventional saturated vapour organic Rankine cycle.

Fouling Is the Beginning: Upcycling Biopolymer-Fouled Substrates for Fabricating High-Permeance Thin-Film Composite Polyamide Membranes

2020 ◽  
Author(s):  
Ruobin Dai ◽  
Hongyi Han ◽  
Tianlin Wang ◽  
Jiayi Li ◽  
Chuyang Y. Tang ◽  
...  
Keyword(s):  
Thin Film ◽  
High Pressure ◽  
End Of Life ◽  
Water Purification ◽  
Low Pressure ◽  
Polymeric Membranes ◽  
Membrane Recycling ◽  
Film Composite ◽  
Thin Film Composite ◽  
First Time

Commercial polymeric membranes are generally recognized to have low sustainability as membranes need to be replaced and abandoned after reaching the end of their life. At present, only techniques for downcycling end-of-life high-pressure membranes are available. For the first time, this study paves the way for upcycling fouled/end-of-life low-pressure membranes to fabricate new high-pressure membranes for water purification, forming a closed eco-loop of membrane recycling with significantly improved sustainability.

INFLUENCE OF WORKING FLUID ON THERMAL PERFORMANCE OF THERMOSYPHONS FOR APPLICATION IN HIGH PRESSURE VACUUM TUBE SOLAR COLLECTORS

2020 ◽  
Author(s):  
Guilherme Antonio Bartmeyer ◽  
Victor Vaurek Dimbarre ◽  
Pedro Leineker Ochoski Machado ◽  
PAULO HENRIQUE DIAS DOS SANTOS ◽  
Thiago Antonini Alves
Keyword(s):  
High Pressure ◽  
Thermal Performance ◽  
Working Fluid ◽  
Solar Collectors ◽  
Vacuum Tube
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