Normalisation of Test Results in Air Screw Compressor Measurements as a Basis for Performance Estimation of Refrigeration and Process Gas Compressors

2011 ◽  
Author(s):  
Nikola Stosic
Keyword(s):  
Air Conditioning ◽  
Ideal Gas ◽  
Performance Estimation ◽  
Screw Compressor ◽  
Test Results ◽  
Process Gas ◽  
Scale Factors ◽  
Gas Compression ◽  
Air Compressors ◽  
Real Fluids

Common use of screw compressors is in compression of air. However, application of screw compressors in refrigeration and air conditioning, as well as in process gas compression is increasing rapidly in recent years. The existing experimental data basis for air compressors may conveniently serve as a source for performance estimation of these compressors. A procedure was derived in this work to find scale factors which connect compressors operating with different fluids and it was applied for performance estimation of refrigeration and process gas screw compressors on the basis of measurements obtained for air compressors. Refprop 8 by NIST was used for calculation of thermodynamic properties of real fluids and ideal gas relation was used for air.

Performance Estimation of Axial Flow Turbines

1970 ◽  
Vol 185 (1) ◽  
pp. 407-424 ◽  
Author(s):  
H. R. M. Craig ◽  
H. J. A. Cox
Keyword(s):  
Reynolds Number ◽  
Aspect Ratio ◽  
Gas Turbines ◽  
Three Dimensional ◽  
Axial Flow ◽  
Performance Estimation ◽  
Speed Ratio ◽  
Test Results ◽  
Wide Range ◽  
Relevant Variables

A comprehensive method of estimating the performance of axial flow steam and gas turbines is presented, based on analysis of linear cascade tests on blading, on a number of turbine test results, and on air tests of model casings. The validity of the use of such data is briefly considered. Data are presented to allow performance estimation of actual machines over a wide range of Reynolds number, Mach number, aspect ratio and other relevant variables. The use of the method in connection with three-dimensional methods of flow estimation is considered, and data presented showing encouraging agreement between estimates and available test results. Finally ‘carpets’ are presented showing the trends in efficiencies that are attainable in turbines designed over a wide range of loading, axial velocity/blade speed ratio, Reynolds number and aspect ratio.

Comparison on Simulation and Experiment of Supply Air through Metro Vehicle Air Conditioning Duct

2010 ◽  
Vol 44-47 ◽  
pp. 1724-1728
Author(s):  
Hong Ge Tao ◽  
Huan Xin Chen ◽  
Jun Long Xie ◽  
Jun Zhi Jiang
Keyword(s):  
Air Conditioning ◽  
Optimization Design ◽  
Simulation Method ◽  
Test Results ◽  
Air Velocity ◽  
Relative Deviation ◽  
Air Volume ◽  
Experiment Validation ◽  
Simulation And Experiment ◽  
Actual Test

CFD technique is often employed to simulate and optimize air duct design, but the corresponding experiment validation in metro vehicle is rare. By taking an independent metro vehicle duct as research object in this paper, supply air through air duct is simulated and compared with the actual test results from the angle of supply air velocity at each outlet and supply air volume through several outlets of air duct. The results show that the relative deviation of simulation and test value of air velocity at most of the outlets are within or near ±20%, which is acceptable for the engineering applications. Moreover, the ratio of supply air volume through several outlets to the corresponding total supply air volume through main air duct or flat duct in the case of simulation is consistent with that in the case of experiment. It can be concluded that numerical simulation method is effective and reliable in air duct optimization design of metro vehicle.

Mechanical Efficiency of Hydraulic Air Compressors

2016 ◽  
Vol 138 (6) ◽  
Author(s):  
Valeria Pavese ◽  
Dean Millar ◽  
Vittorio Verda
Keyword(s):  
Bubbly Flow ◽  
Mechanical Efficiency ◽  
Open Loop ◽  
Economic Implication ◽  
Intimate Contact ◽  
Air Compressor ◽  
Design Variables ◽  
Gas Compression ◽  
Large Heat ◽  
Air Compressors

After air and water mixing, the process of gas compression in the downcomer shaft or pipe of a hydraulic air compressor is considered nearly isothermal due to (i) the mass flow rate of water being typically of three orders higher than that of the gas it compresses, (ii) water having a heat capacity approximately four times that of air, and (iii) the intimate contact and large heat transfer area between the gas phase and the liquid phase of the bubbly flow. A formulation for estimation of the efficiency of a closed- or open-loop hydraulic air compressor, expressed in terms of the principal hydraulic air compressor design variables, is presented. The influence of a hitherto underappreciated factor affecting the performance of these installations, such as the solubility of the gas being compressed in the water, is explored. A procedure for estimating the yield of compressed gas, accounting for these solubility losses, is explained and used to determine the mechanical efficiency of historical hydraulic air compressor installations from reported performance data. The result is a significant downward revision of hydraulic air compressor efficiency by approximately 20% points in comparison to most reported efficiencies. However, through manipulation of cosolute concentrations in the water, and the temperature of the water (through regulation of the ejection of compression heat), the mechanical efficiency can be increased to the formerly reported levels. The thermo-economic implication of these efficiency determinations is that in a modern context, hydraulic air compressors may be able to outperform conventional mechanical gas compression equipment.

Contamination of Centrifugal Process Gas Compressor Lube Oil and Seal Oil Systems by Hydrocarbon Condensate

1981 ◽  
Author(s):  
L. Cootes
Keyword(s):  
Weight Space ◽  
Offshore Platforms ◽  
Supply Situation ◽  
Process Gas ◽  
Gas Compression ◽  
Seal Oil ◽  
Centrifugal Process ◽  
Uncertain Supply

In the wake of gas compression offshore the problem of contamination of Seal Oil and Lube Oil systems by the process gas has posed particular problems. These difficulties stem chiefly from the uniqueness of the offshore situation, viz.: The inability to “waste” contaminated seals return because of an uncertain supply situation (oil inventory bunkered by boat) and the twin constraints of weight space restrictions imposed by offshore design. “In situ” treatment of relatively large volumes of contaminated Lube Oil and Seal Oil on offshore platforms is possible using the method described in this paper.

Experimental Study on Performance Enhancement of Heat Pump With Screw Compressor

2004 ◽  
Author(s):  
Wu Huagen ◽  
Shu Pengcheng ◽  
Zhao Yuanyang ◽  
Xing Ziwen
Keyword(s):  
Heat Pump ◽  
Air Conditioning ◽  
Performance Enhancement ◽  
Coefficient Of Performance ◽  
Screw Compressor ◽  
Alternative Refrigerants ◽  
Air Source Heat Pump ◽  
Central Air Conditioning ◽  
Compressor Performance ◽  
Industrial Refrigeration

The air-source heat pump has been widely used in industrial refrigeration and central air-conditioning applications because of its unique superiority. An important consideration in the design of heat pump is improving its COP (coefficient of performance). In this paper, the results of experimental investigation on the effects of alternative refrigerants (R22, R134a, R404A and R407C) and economizer on the performance of heat pump are presented. The COP of the heat pump used R134a is up to 4.5% higher than R22, but its capacity got a 37.08% decrease. The refrigerant R407C applied in heat pump can improve the capacity up to 7.86% than R22, but its COP shows a decrease up to 5.92%. The refrigerant R404A used in heat pump will result in poor capacity and COP compared to R22. The economizer system used in heat pump will improve the COP, but as the superfeed pressure of the economizer increases, the system COP increases first, and then drops. So there exists an optimal superfeed pressure of the economizer for the best COP. Also, the effect of the economizer on the screw compressor performance is analyzed by recording the P-v indicator diagram.

The Design, Selection, and Application of Oil-Free Screw Compressors for Fuel Gas Service

1995 ◽  
Vol 117 (1) ◽  
pp. 74-80 ◽  
Author(s):  
K. D. Lelgemann
Keyword(s):  
Gas Flow ◽  
Coal Gasification ◽  
Landfill Gas ◽  
Coke Oven ◽  
Lubricating Oil ◽  
Screw Compressor ◽  
Fuel Gas ◽  
Process Gas ◽  
Design Selection ◽  
Shaft Seals

Fuel gas compressors installed in cogeneration systems must be highly reliable and efficient machines. The screw compressor can usually be designed to meet most of the gas flow rates and pressure conditions generally required for such installations. To an ever-increasing degree, alternative sources are being found for the fuel gas supply, such as coke-oven gas, blast-furnace gas, flare gas, landfill gas, and synthesis gas from coal gasification or from pyrolysis. A feature of the oil-free screw compressor when such gases are being considered is the isolation of the gas compression space from the bearing and gear lubrication system by using positive shaft seals. This ensures that the process gas cannot be contaminated by the lubricating oil, and that there is no risk of loss of lubricant viscosity by gas solution in the oil. This feature enables the compressed gas to contain relatively high levels of particulate contamination without danger of “sludge” formation, and also permits the injection of water or liquid solvents into the compression space, to reduce the temperature rise due to the heat of compression, or to “wash” any particulate matter through the compressor.

Paper 10: Lubrication of Air Compressors

1969 ◽  
Vol 184 (18) ◽  
pp. 93-105
Author(s):  
E. M. Evans ◽  
A. Hughes
Keyword(s):  
High Pressure ◽  
Test Method ◽  
Test Results ◽  
Process Industries ◽  
Air Compressors ◽  
Operating Instructions ◽  
Very High ◽  
Lubricant Performance ◽  
Pneumatic Equipment ◽  
Typical Test

There is an increasing use of pneumatic equipment in production and process industries and reliability of equipment in these industries is of paramount importance. The failure of an air compressor due to deficiencies in the lubricant can be very costly. In this paper important aspects of lubricant performance are discussed. The differences between the requirements of lubricants for rotary oil-cooled air compressors and for reciprocating air compressors are highlighted. Some of the requirements are conflicting and can cause problems if an oil is used in a type of compressor for which it is not designed. Mechanisms by which oil can cause failures are analysed. Some of the failures are common to certain types of compressor. Guidance is given which can reduce the risks of failures. This includes both design and operating instructions. Finally, full-scale methods of test for rotary oil-cooled and reciprocating air compressors are given, including a test method for very high-pressure reciprocating compressors; typical test results are supplied.

Polytropic Change of State Calculations

2014 ◽  
Author(s):  
Hans E. Wettstein
Keyword(s):  
Gas Turbines ◽  
Dissipation Rate ◽  
Pressure Ratio ◽  
Thermodynamic Cycle ◽  
Ideal Gas ◽  
Test Results ◽  
Stage Of Development ◽  
Change Of State ◽  
Calculation Algorithms ◽  
Polytropic Exponent

Polytropic change of state calculations are used within many thermodynamic cycle analysis tasks for turbomachinery like gas turbines or compressors. The typical approach is using formulas, which are theoretically valid for ideal gas conditions only. But often gases are used, which do certainly not behave like ideal gases. This is motivation to check how and which polytropic change of state algorithms can be used for real gases or corresponding mixtures. There is a vast experience on polytropic efficiencies achievable with existing turbomachinery. Manufacturers calibrate their performance analysis with real test results for compensating potential deviations from their analysis approach. But they normally do not disclose their approaches for the thermodynamic calculation and the corrections made based on their test results. But for investigations of new thermodynamic cycles before the stage of development with an available demonstrator a best possible prediction of the performance is desired. In this paper the assumptions and formulas for calculating polytropic changes of state and polytropic efficiencies are gathered from literature. The most fundamental assumption is based on a constant dissipation rate during the polytropic change of state. It could be tracked back to Zeuner, Stodola and Dzung. A numerically convenient approximation is the “polytropic exponent approach”. It fulfills the first assumption for an ideal gas but it is only an approximation for real gases. The temperature after a polytropic change of state is defined by its initial condition, the pressure ratio and the polytropic efficiency. Three different calculation algorithms are compared here: The recursive “constant dissipation rate algorithm” suggested by the author, the most used “ideal gas formula” and the “polytropic exponent formula” as the most used approximation for real gases. Numeric results for compression from 1bar to up to 100bar are shown for dry air, Argon, Neon, Nitrogen, Oxygen and CO2. The deviations of the different calculation approaches are considerable.

A Method and Apparatus for Direct Enthalpy Rise Measurement for Gas Compression

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
Klaus Brun ◽  
Sarah Simons ◽  
Kelsi Katcher ◽  
Ryan Cater ◽  
Brandon Ridens ◽  
...  
Keyword(s):  
Equation Of State ◽  
Performance Test ◽  
Elevated Temperatures ◽  
Equations Of State ◽  
Test Results ◽  
Test Apparatus ◽  
Compression Process ◽  
Test Gas ◽  
Gas Compression ◽  
Calibration Measurement

Gas property prediction is necessary for proper design of compressors. Equations of state are utilized to predict the thermo-physical gas properties needed for such calculations. These are semi-empirical models that allow the calculation of thermodynamic properties such as density, enthalpy, and speed of sound of gas mixtures for known pressures and temperature. Currently, there is limited or no data publically available to verify the results of these equation of state calculations for the range of pressures, temperatures, and gas compositions relevant to many oil and gas applications. Especially for isentropic enthalpy head (i.e., the enthalpy rise along constant entropy lines), which is a critical parameter required to accurately design and performance test compressors, limited public domain data are available for equation of state validation. In this paper, a method and test apparatus is described to measure compression enthalpy rise directly. In this apparatus, a test gas is compressed using a fast acting piston inside an adiabatic autoclave. Test results are then corrected using calibration efficiencies from a known reference gas compression process at a similar Reynolds number. The paper describes the test apparatus, calibration, measurement methodology, and test results for one complex hydrocarbon gas composition at elevated temperatures and pressures. An uncertainty analysis of the new measurement method is also presented and results are compared to several equations of state. The results show that commonly used equations of state significantly underpredicted the compression enthalpy rise for the test gas case by more than 6%.

Miniature Air Compressor Design Based on Cross-Slider Mechanism

2011 ◽  
Vol 486 ◽  
pp. 17-20 ◽  
Author(s):  
Gil Jun Lee ◽  
Suk Hwan Chi ◽  
Jay Kim ◽  
Tae Soo Lee
Keyword(s):  
Time History ◽  
Ideal Gas ◽  
Connecting Rod ◽  
Air Compressor ◽  
Flow Capacity ◽  
Pressure Time ◽  
Compressor Design ◽  
Scotch Yoke Mechanism ◽  
Air Compressors ◽  
Crank Mechanism

Most of the current air compressors are driven by a slider-crank mechanism consisted of the crank, connecting rod, and piston. Complexity of this mechanism, however, restricts miniaturization of air compressors. In this study, a design based on a new mechanism, a hybrid of cross-slider and scotch-yoke mechanism, is adopted to develop an oil-free, light-weighted air compressor for portable medical devices. By eliminating the connecting rod, the mechanism has several advantages in addition to the obvious weight reduction due to the simpler mechanism such as the longer seal life of the seal between the piston and cylinder (so called Teflon cup) and reduced shaking forces. Cylinder pressure time history is obtained based on the ideal gas behavior and the isentropic process. Shaking forces and motor torque are calculated from the dynamics equation of the air compressor. The flow capacity curve of the air compressor is obtained by considering the effect of the clearance volume. An actual prototype was fabricated and tested to demonstrate the feasibility of proposed concepts.

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