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Cesar J. Deschamps - One of the best experts on this subject based on the ideXlab platform.
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A Simplified Computational Fluid Dynamics Model for the Suction Process of Reciprocating Compressors
2020Co-Authors: Claudio J. Santos, Cesar J. Deschamps, Rodrigo Kremer, Rua Rui BarbosaAbstract:The Suction process in reciprocating compressors is strongly affected by the Valve dynamics and the pulsating flow throughout the Suction muffler. This paper describes a simplified computational fluid dynamics (CFD) model to simulate the flow through the muffler, Suction Valve and a small region inside the cylinder. The proposed method is applied to predict the Suction process of a small reciprocating compressor and its adequacy is compared with a more time elaborate model in terms of accuracy, computation cost and usability.
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Influence of break-in on the leakage through reed-type Valves of low-capacity refrigeration compressors
International Journal of Refrigeration-revue Internationale Du Froid, 2019Co-Authors: Fernanda Dos Santos, Ernane Silva, Cesar J. DeschampsAbstract:Abstract Valve leakage can significantly decrease the efficiency of reciprocating compressors adopted in household refrigeration systems, especially in low-capacity and oil-free compressors. These leakages occur through the Valves due to geometric irregularities resulting from the manufacturing and assembly processes, which form leakage paths between the reeds and seats. Valve leakage is generally measured using completely new Valve systems, which may not represent the actual leakage in Valves after break-in. The aim of this study was to assess the influence of break-in on the leakage through reed-type Valves of low-capacity refrigeration compressors. The leakage was measured for the Suction and discharge Valves of a R600a compressor before and after the Valves were subjected to a break-in period. The Valve leakage was characterized by the geometric parameter edge gap, defined as the gap between the reed and seat at the internal border of the Valve orifice. The results indicate that the edge gap, and consequently leakage, is reduced with break-in. The leakage was reduced by up to 76% for the Suction Valve and by up to 95% for the discharge Valve after break-in, while the edge gap was reduced by up to 50% for the Suction Valve and by up to 73% for the discharge Valve. It should be mentioned that the reed and seat surfaces of the Suction Valve had their maximum roughness reduced by 40% and 29%, respectively, after break-in, suggesting that the edge gap is related to the surface finishing.
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Modeling of gas leakage through compressor Valves
International Journal of Refrigeration, 2015Co-Authors: Leandro R. Silva, Cesar J. DeschampsAbstract:This paper describes a model developed to predict gas leakage in cases of incomplete sealing of the reed-type Valves of small reciprocating compressors adopted for household refrigeration. The model assumes a one-dimensional formulation for the flow, considering the effects of viscous friction, slip-flow regime and compressibility. Reed bending into the port due to the pressure load is also taken into account to characterize the Valve clearance. Computations are carried out during the compression cycle and the effect of leakage on both the isentropic and volumetric efficiencies is quantified for two operating conditions. It was found that leakage significantly reduces the compressor efficiency even for very small Valve clearances and that leakage in the discharge Valve is of greater importance than that in the Suction Valve.
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A Simplified CFD Model for Simulation of the Suction Process Of Reciprocating Compressors
2013Co-Authors: Evandro L. L. Pereira, Cesar J. Deschamps, Claudio J. Santos, Rodrigo KremerAbstract:The Suction process in reciprocating compressors is strongly affected by the Valve dynamics and the pulsating flow throughout the Suction muffler. This paper describes a simplified computational fluid dynamics (CFD) model to simulate the flow through the muffler, Suction Valve and a small region inside the cylinder. The proposed method is applied to predict the Suction process of a small reciprocating compressor and its adequacy is compared with a more time elaborate model in terms of accuracy, computation cost and usability.
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A Procedure to Optimize Reed Type Valves Considering Efficiency and Bending Fatigue
2012Co-Authors: Ernane Silva, Cesar J. Deschamps, Eduardo A. FancelloAbstract:Reed Valves are the most common type of Valves used in small compressors due to their simplicity and low cost. Such Valves greatly affect the compressor volumetric and isentropic efficiencies and their suitable design is also crucial for reliability, since they may be subjected to severe bending and impact stresses. This paper reports an optimization procedure for reed type Valves considering efficiency and bending fatigue, which is attained by coupling a thermodynamic model for the compression cycle and a finite element model for the Valve dynamics. Then, a genetic algorithm is adopted to find different Valve geometries that give the best compromise between efficiency and reliability. As an example, the method is applied to optimize the Suction Valve of a small reciprocating compressor.
Xueyuan Peng - One of the best experts on this subject based on the ideXlab platform.
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Investigation on the Suction Reed Valve Motion with Sticky Force in a Refrigerator Compressor
Energies, 2018Co-Authors: Wei Zhang, Lantian Ji, Ziwen Xing, Xueyuan PengAbstract:The Valve motion strongly couples with the differential pressure between the cylinder and the Suction and discharge plenum, which has a significant influence on the performance of the refrigerator compressor. To examine the interaction between the pressure and the reed Valve motion, this paper presents an experimental investigation into the inner workings of the refrigerator compressor, particularly the p-V diagram and the motion of the Suction Valve. The refrigerator compressor was modified to conveniently mount the sensors. Three pressure sensors were installed to measure the p-V diagram and pressure pulsation, while a strain gauge was employed to measure the motion of the Suction Valve. The interaction between the differential pressure and the Valve motion were clearly observed from the experimental results. It was found that there was a considerable power loss up to 14.5% in the Suction process under experimental conditions. The sticky force of the oil had a significant effect on both the motion of the Suction Valve and the Suction phase of the compressor. The delayed opening of the reed Valve increased the amplitude of the pressure pulsation in the Suction plenum. The experimental method which integrates the pressure variety and the Valve movement proposed in this paper could contribute to the efficient testing and the optimization of the refrigerator compressor.
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investigation on the delayed closure of the Suction Valve in the refrigerator compressor by fsi modeling
International Journal of Refrigeration-revue Internationale Du Froid, 2018Co-Authors: Zhilong He, Xueyuan PengAbstract:Abstract The backflow through Valve due to the delayed closure, is quite difficult to predict as the effective flow area of Valve is highly dependent upon the interaction between the fluid flow and the Valve's motion. To solve this issue, this paper presents the simulation of the complete compression cycle of a refrigerator compressor by a three-dimensional fluid structure interaction (FSI) model. This proposed FSI model was validated by experiments, which showed that the FSI method was able to detailedly analyze the thermodynamic process during the compression cycle. Based on the FSI model, the effects of compressor rotation speed and Valve parameters on the oscillation and delayed closure of the Valve were investigated. The characteristic rotation speed for a reed Valve was found and defined, at which the maximal delayed closure and backflow occurred. According to the simulation results, an empirical correlation to predict the characteristic rotation speed was obtained.
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investigation of the thermodynamic process of the refrigerator compressor based on the m θ diagram
Energies, 2017Co-Authors: Tao Wang, Zhilong He, Xueyuan PengAbstract:The variation of refrigerant mass in the cylinder of refrigerator compressor has a great influence on the compressor’s thermodynamic process. In this paper, the m-θ diagram, which represents the variation of refrigerant mass in compressor cylinder (m) and the crank angle (θ), is proposed to investigate the thermodynamic process of the refrigerator compressor. Comparing with the traditional pressure-Volume (p-V) indicator diagram, the refrigerant’s backflow trigged by the delayed closure of Valve can be clearly expressed in the m-θ diagram together with the mass flow rate. A typical m-θ diagram was obtained by experimental and theoretical investigations. To improve the thermodynamic model of the compressor, a 3D fluid-structure interaction (FSI) FEA model has been introduced to find out the effective flow area of the Valves. Based on the m-θ diagram, the effect of rotating speed on the backflow through the Valve, which depends on the movement of the Valve, has been investigated. Specific to the compressor used in this study, the maximum backflow through the Suction Valve and discharge Valve occur at 3500 r·min−1 and 5500 r·min−1, respectively.
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Experimental study on performance of BOG compressor
IOP Conference Series: Materials Science and Engineering, 2015Co-Authors: Bin Zhao, Xueyuan Peng, Tao Wang, Jianmei FengAbstract:The boil-off gas (BOG) compressor is widely used for recycling the excessive boil-off gas of liquefied natural gas (LNG), and the extra-low Suction temperature brings about great challenges to design of the BOG compressor. In this paper, a test system was built to examine the effects of low Suction temperature on the compressor performance, in which the lowest temperature reached -178°C by means of a plate-fin heat exchanger with liquefied nitrogen. The test results showed that, as the Suction temperature decreased from 20°C to -150°C, the volumetric efficiency of the compressor dropped by 37.0%, and the power consumption decreased by 10.0%. The preheat of the gas by the pipe through the Suction flange to Suction Valve was larger than 20°C as the Suction temperature was -150°C, and this value increased with the decreased Suction temperature. The pressure loss through the Suction Valve at lower Suction temperature was larger than that at ambient temperature while the volume flow rate was kept the same.
William E. Cohn - One of the best experts on this subject based on the ideXlab platform.
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EMBC - A mock circulatory loop for designing and evaluating total artificial hearts.
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and, 2020Co-Authors: Holley C. Love, Daniel L. Timms, Frank Nestler, O. H. Frazier, William E. CohnAbstract:A mock circulatory loop was constructed to facilitate total artificial heart development. The loop includes many novel features such as a pressure-regulated tank to simulate exercise conditions, controllable systemic and pulmonary vascular resistance to create left-right flow imbalances as seen in postural change and breathing, and a left atrial Suction Valve. Dual HeartMate II pumps and the BiVACOR® rotary total artificial heart were used to generate pressure and flow data characterizing the flow loop.
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A mock circulatory loop for designing and evaluating total artificial hearts
2014 36th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2014Co-Authors: Holley C. Love, Daniel L. Timms, Frank Nestler, O. H. Frazier, William E. CohnAbstract:A mock circulatory loop was constructed to facilitate total artificial heart development. The loop includes many novel features such as a pressure-regulated tank to simulate exercise conditions, controllable systemic and pulmonary vascular resistance to create left-right flow imbalances as seen in postural change and breathing, and a left atrial Suction Valve. Dual HeartMate II pumps and the BiVACOR® rotary total artificial heart were used to generate pressure and flow data characterizing the flow loop.
Liansheng Li - One of the best experts on this subject based on the ideXlab platform.
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dynamic performance of Suction Valve in stepless capacity regulation system for large scale reciprocating compressor
Applied Thermal Engineering, 2016Co-Authors: Yuanyang Zhao, Bin Tang, Liansheng LiAbstract:Abstract Regulating capacity by controlling Suction Valve has a good application value for the large-scale reciprocating compressor used in the petrochemical industries. A mathematical model coupled with compressor, actuator and hydraulic system is built in this paper, and some performances of the system are tested by the experiment. The results show that the maximum displacement of actuator increases with the oil pressure until it is limited by the lift limiter. The low hydraulic oil pressure leads to the partially opened condition of Suction Valve, and the Valve plate impacts on the actuator at the same time, which influences the accuracy of indicated powers and mass flow rate. The reset response time of Valve plate cannot be improved by increasing oil pressure after the actuator is completely opened. The mass flow rate decreases with the hold time after the closing process of Suction Valve is delayed until nothing is discharged. The reset response time can be improved by increasing the reset spring stiffness and the path diameter of solenoid Valve, or decreasing diameter of hydraulic cylinder. All the power consumption and mass flow rate decrease apparently caused by the delayed compression process. The power consumption decreases 21% when the capacity is 70% of the full load based on the experiment.
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Dynamic Performance of Valve in Reciprocating Compressor Used Stepless Capacity Regulation System
2014Co-Authors: Yuanyang Zhao, Bin Tang, Le Wang, Qichao Yang, Liansheng LiAbstract:Capacity regulation system by controlling Suction Valve is useful for large scale reciprocating compressor in petrochemical engineering field. The dynamic performance of adjustment device influences the stability and accurancy of this system. In this paper, a mathematical model of adjustment device coupled with the motion of Suction Valve is built, and the dynamic performances of Valve plate are simulated. The results show that the displacement of actuator increases with the hydraulic oil pressure until the Valve plate is keeped to be opened. The closing process of Valve plate is delayed when the hold time of actuator is larger enough. Although the gas flow rate and power consumption of comressor decrease with the relax angle of actuator, the power is also consumed when the gas is not discharged through the discharge Valve. The closing time decreases with the reset spring stiffness but increases with the diameter of hydraulic.
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Simulation on actuator response time of capacity adjustment system in reciprocating compressor
2014 ISFMFE - 6th International Symposium on Fluid Machinery and Fluid Engineering, 2014Co-Authors: Yuanyang Zhao, Bin Tang, Le Wang, Qichao Yang, Liansheng LiAbstract:Large scale reciprocating compressor in petrochemical process is usually operated under partial load based on the system condition, and adjusted its capacity by controlling Suction Valve is an efficient method for energy saving. In this paper, a mathematical model coupled Suction Valve and actuator is built to describe the dynamic response process of Suction Valve and actuator and the response time influenced by some parameters are analyzed. The simulation results show that the power consumption has a variation of approximately direct proportion with the mass flow rate. The response time of actuator increases with the diameter of hydraulic cylinder either in opening or closing process. The high pressure oil supply and low pressure oil discharge lead to the faster motion of actuator. The larger opening time and smaller closing time can be obtained by increasing the thickness of reset spring. Optimizing the parameters of actuator is helpful to improve the system performance.
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Dynamic characteristics of Suction Valves for reciprocating compressor with stepless capacity control system
Proceedings of the Institution of Mechanical Engineers Part E: Journal of Process Mechanical Engineering, 2013Co-Authors: Bin Tang, Yuanyang Zhao, Liansheng Li, Le Wang, Qichao Yang, Haiping Xu, Wenhui MengAbstract:The dynamic characteristics of Suction Valves for reciprocating compressor with a stepless capacity control system are studied in this article. The self-acting Valve model that is applicable for stepless capacity control condition is derived. For the Suction Valve movement controlled by actuator, a simulation of the hydraulic and mechanical system is conducted. An experimental platform is setup, which is used to test the Valve dynamic when it is controlled by actuator. The results from the mathematical model show that the Valve impact speeds are influenced by the Valve lift, Mach number of the flow in the Valve clearance and the initial crank rotation angle of the Valve closing process. The simulation results agree well with experimental results. The simulated maximum speed is about 0.53 m/s, and the maximum speed tested by experiment is about 0.58 m/s, both of which are much lower than the speed of the automatic Valve (3 m/s). In addition, simulation results show that the maximum speed is at constant whe...
Yuanyang Zhao - One of the best experts on this subject based on the ideXlab platform.
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dynamic performance of Suction Valve in stepless capacity regulation system for large scale reciprocating compressor
Applied Thermal Engineering, 2016Co-Authors: Yuanyang Zhao, Bin Tang, Liansheng LiAbstract:Abstract Regulating capacity by controlling Suction Valve has a good application value for the large-scale reciprocating compressor used in the petrochemical industries. A mathematical model coupled with compressor, actuator and hydraulic system is built in this paper, and some performances of the system are tested by the experiment. The results show that the maximum displacement of actuator increases with the oil pressure until it is limited by the lift limiter. The low hydraulic oil pressure leads to the partially opened condition of Suction Valve, and the Valve plate impacts on the actuator at the same time, which influences the accuracy of indicated powers and mass flow rate. The reset response time of Valve plate cannot be improved by increasing oil pressure after the actuator is completely opened. The mass flow rate decreases with the hold time after the closing process of Suction Valve is delayed until nothing is discharged. The reset response time can be improved by increasing the reset spring stiffness and the path diameter of solenoid Valve, or decreasing diameter of hydraulic cylinder. All the power consumption and mass flow rate decrease apparently caused by the delayed compression process. The power consumption decreases 21% when the capacity is 70% of the full load based on the experiment.
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Dynamic Performance of Valve in Reciprocating Compressor Used Stepless Capacity Regulation System
2014Co-Authors: Yuanyang Zhao, Bin Tang, Le Wang, Qichao Yang, Liansheng LiAbstract:Capacity regulation system by controlling Suction Valve is useful for large scale reciprocating compressor in petrochemical engineering field. The dynamic performance of adjustment device influences the stability and accurancy of this system. In this paper, a mathematical model of adjustment device coupled with the motion of Suction Valve is built, and the dynamic performances of Valve plate are simulated. The results show that the displacement of actuator increases with the hydraulic oil pressure until the Valve plate is keeped to be opened. The closing process of Valve plate is delayed when the hold time of actuator is larger enough. Although the gas flow rate and power consumption of comressor decrease with the relax angle of actuator, the power is also consumed when the gas is not discharged through the discharge Valve. The closing time decreases with the reset spring stiffness but increases with the diameter of hydraulic.
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Simulation on actuator response time of capacity adjustment system in reciprocating compressor
2014 ISFMFE - 6th International Symposium on Fluid Machinery and Fluid Engineering, 2014Co-Authors: Yuanyang Zhao, Bin Tang, Le Wang, Qichao Yang, Liansheng LiAbstract:Large scale reciprocating compressor in petrochemical process is usually operated under partial load based on the system condition, and adjusted its capacity by controlling Suction Valve is an efficient method for energy saving. In this paper, a mathematical model coupled Suction Valve and actuator is built to describe the dynamic response process of Suction Valve and actuator and the response time influenced by some parameters are analyzed. The simulation results show that the power consumption has a variation of approximately direct proportion with the mass flow rate. The response time of actuator increases with the diameter of hydraulic cylinder either in opening or closing process. The high pressure oil supply and low pressure oil discharge lead to the faster motion of actuator. The larger opening time and smaller closing time can be obtained by increasing the thickness of reset spring. Optimizing the parameters of actuator is helpful to improve the system performance.
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Dynamic characteristics of Suction Valves for reciprocating compressor with stepless capacity control system
Proceedings of the Institution of Mechanical Engineers Part E: Journal of Process Mechanical Engineering, 2013Co-Authors: Bin Tang, Yuanyang Zhao, Liansheng Li, Le Wang, Qichao Yang, Haiping Xu, Wenhui MengAbstract:The dynamic characteristics of Suction Valves for reciprocating compressor with a stepless capacity control system are studied in this article. The self-acting Valve model that is applicable for stepless capacity control condition is derived. For the Suction Valve movement controlled by actuator, a simulation of the hydraulic and mechanical system is conducted. An experimental platform is setup, which is used to test the Valve dynamic when it is controlled by actuator. The results from the mathematical model show that the Valve impact speeds are influenced by the Valve lift, Mach number of the flow in the Valve clearance and the initial crank rotation angle of the Valve closing process. The simulation results agree well with experimental results. The simulated maximum speed is about 0.53 m/s, and the maximum speed tested by experiment is about 0.58 m/s, both of which are much lower than the speed of the automatic Valve (3 m/s). In addition, simulation results show that the maximum speed is at constant whe...
