A Design Model of a New Positive Displacement Rotary Compressor Based on Trochoidal Geometry for High Pressure Applications

2005 ◽  
Author(s):  
Ahmed Abdelwahab
Keyword(s):  
Gas Flow ◽  
Thermodynamic Cycle ◽  
Experimental Results ◽  
Design Model ◽  
Rotary Compressor ◽  
Mechanical Reliability ◽  
High Discharge ◽  
Positive Displacement ◽  
Performance Trends ◽  
Compressor Performance

The desire to achieve high discharge pressures at low manufacturing and maintenance costs has resulted in the development of a number of new positive displacement rotary compressor designs. The proposed design involves a compressor with a trochoidal casing geometry and a rotor orbiting the casing interior. This arrangement generates a varying trapped volume between the rotor and the casing thus providing the necessary compression for the compressor. The major advantage of this design is its inherent simple two-dimensional configuration which makes it a very cheap device to manufacture. Furthermore, the oil-flooded lubrication system used with this design not only acts as a lubricant but also as a coolant to the main gas flow and consequently improves the mechanical reliability of the compressor. This paper presents a complete design model developed to investigate the performance of the compressor. The geometrical, kinematic, and dynamic equations of the casing and rotor are derived. A model of the compressor thermodynamic cycle and gasdynamic performance is presented. A comparison between the developed model and the experimental results of a prototype compressor testing is presented. The comparison shows that the developed model indeed captures the compressor performance trends with considerable accuracy at the design conditions. Deviation between the model and experimental results at the off design conditions is due to inaccuracies in the inlet and exit port loss models at the off design conditions.

scholarly journals Thermochemical Heat Storage in a Lab-Scale Indirectly Operated CaO/Ca(OH)2 Reactor—Numerical Modeling and Model Validation through Inverse Parameter Estimation

2021 ◽  
Vol 11 (2) ◽  
pp. 682
Author(s):  
Gabriele Seitz ◽  
Farid Mohammadi ◽  
Holger Class
Keyword(s):  
Numerical Model ◽  
Gas Flow ◽  
Reaction Rate ◽  
Heat Storage ◽  
Bulk Material ◽  
Fixed Bed ◽  
Experimental Results ◽  
Fixed Bed Reactor ◽  
Thermochemical Heat Storage ◽  
Speed Up

Calcium oxide/Calcium hydroxide can be utilized as a reaction system for thermochemical heat storage. It features a high storage capacity, is cheap, and does not involve major environmental concerns. Operationally, different fixed-bed reactor concepts can be distinguished; direct reactor are characterized by gas flow through the reactive bulk material, while in indirect reactors, the heat-carrying gas flow is separated from the bulk material. This study puts a focus on the indirectly operated fixed-bed reactor setup. The fluxes of the reaction fluid and the heat-carrying flow are decoupled in order to overcome limitations due to heat conduction in the reactive bulk material. The fixed bed represents a porous medium where Darcy-type flow conditions can be assumed. Here, a numerical model for such a reactor concept is presented, which has been implemented in the software DuMux. An attempt to calibrate and validate it with experimental results from the literature is discussed in detail. This allows for the identification of a deficient insulation of the experimental setup. Accordingly, heat-loss mechanisms are included in the model. However, it can be shown that heat losses alone are not sufficient to explain the experimental results. It is evident that another effect plays a role here. Using Bayesian inference, this effect is identified as the reaction rate decreasing with progressing conversion of reactive material. The calibrated model reveals that more heat is lost over the reactor surface than transported in the heat transfer channel, which causes a considerable speed-up of the discharge reaction. An observed deceleration of the reaction rate at progressed conversion is attributed to the presence of agglomerates of the bulk material in the fixed bed. This retardation is represented phenomenologically by mofifying the reaction kinetics. After the calibration, the model is validated with a second set of experimental results. To speed up the calculations for the calibration, the numerical model is replaced by a surrogate model based on Polynomial Chaos Expansion and Principal Component Analysis.

scholarly journals Simulation of Compressor Performance Deterioration due to Erosion

1989 ◽  
Author(s):  
W. Tabakoff ◽  
A. N. Lakshminarasimha ◽  
M. Pasin
Keyword(s):  
Fault Model ◽  
Experimental Results ◽  
Performance Tests ◽  
Individual Stage ◽  
One Stage ◽  
Before And After ◽  
Performance Deterioration ◽  
Compressor Performance ◽  
Multistage Compressor ◽  
The Individual

Experimental results obtained from cascades and one stage compressor performance tests before and after erosion were used to test a fault model to represent erosion. This model was implemented on a stage stacking program developed to demonstrate the effect of erosion in a multistage compressor. The effect of the individual stage erosion on the overall compressor performance is also demonstrated.

scholarly journals 1D–3D Coupling Algorithm of Gas Flow for the Valve System in a Compression Ignition Engine

2021 ◽  
Vol 9 (10) ◽  
pp. 1061
Author(s):  
Kyeong-Ju Kong
Keyword(s):  
Gas Flow ◽  
Flow Analysis ◽  
Emission Control ◽  
Experimental Results ◽  
Exhaust Gas ◽  
Compression Ignition ◽  
Valve System ◽  
Ci Engine ◽  
Control Devices ◽  
Coupling Algorithm

Emission control devices such as selective catalytic reduction (SCR), exhaust gas recirculation (EGR), and scrubbers were installed in the compression ignition (CI) engine, and flow analysis of intake air and exhaust gas was required to predict the performance of the CI engine and emission control devices. In order to analyze such gas flow, it was inefficient to comprehensively analyze the engine’s cylinder and intake/exhaust systems because it takes a lot of computation time. Therefore, there is a need for a method that can quickly calculate the gas flow of the CI engine in order to shorten the development process of emission control devices. It can be efficient and quickly calculated if only the parts that require detailed observation among the intake/exhaust gas flow of the CI engine are analyzed in a 3D approach and the rest are analyzed in a 1D approach. In this study, an algorithm for gas flow analysis was developed by coupling 1D and 3D in the valve systems and comparing with experimental results for validation. Analyzing the intake/exhaust gas flow of the CI engine in a 3D approach took about 7 days for computation, but using the developed 1D–3D coupling algorithm, it could be computed within 30 min. Compared with the experimental results, the exhaust pipe pressure occurred an error within 1.80%, confirming the accuracy and it was possible to observe the detailed flow by showing the contour results for the part analyzed in the 3D zone. As a result, it was possible to accurately and quickly calculate the gas flow of the CI engine using the 1D–3D coupling algorithm applied to the valve system, and it was expected that it can be used to shorten the process for analyzing emission control devices, including predicting the performance of the CI engine.

Meta-Analysis of Gas Flow Resistance Measurements Through Packed Beds

1995 ◽  
Vol 117 (1) ◽  
pp. 176-180
Author(s):  
Malcolm S. Taylor ◽  
Csaba K. Zoltani
Keyword(s):  
Reynolds Number ◽  
Statistical Methods ◽  
Flow Resistance ◽  
Gas Flow ◽  
Meta Analysis ◽  
Experimental Results ◽  
Packed Beds ◽  
Flow Through ◽  
Effective Representation ◽  
Number Of Authors

Measurements of the resistance to flow through packed beds of inert spheres have been reported by a number of authors through relations expressing the coefficient of drag as a function of Reynolds number. A meta-analysis of the data using improved statistical methods is undertaken to aggregate the available experimental results. For Reynolds number in excess of 103 the relation log Fv = 0.49 + 0.90 log Re′ is shown to be a highly effective representation of all available data.

Predictive Study of Combustion Temperature of Liquefied Petroleum Gas (LPG) on the Spherical Packed-Bed Porous Burner

2019 ◽  
Vol 805 ◽  
pp. 109-115
Author(s):  
Rapeepong Peamsuwan ◽  
Anucha Klamnoi ◽  
Narongsak Yotha ◽  
Bundit Krittacom
Keyword(s):  
Standard Error ◽  
Gas Flow ◽  
Combustion Temperature ◽  
Packed Bed ◽  
Experimental Results ◽  
Coefficient Of Determination ◽  
Maximum Temperature ◽  
Liquefied Petroleum Gas ◽  
Independent Variables ◽  
Porous Burner

The relation between the significant factors and the combustion temperature (T) of Liquid Petroleum Gas (LPG) on the spherical packed-bed porous burner is investigated. Alumina-Cordierite ceramic balls having the average diameter (d) of 3 mm. and the porosity (ε) of 0.322 are employed as porous media. The multiple-linear and multiple-quadratic regressions are used to analyze the data at the equivalence ratio (F) of 0.58 – 0.66 and volumetric premixed-gas flow rate (Vmix) in a range of 10 – 25 m3/h. The porous thickness (H) is in the range of 2.5 – 7.5 cm. Thus, independent variables are F, Vmix and H. The dependent variable is the maximum temperature (T) of combustion LPG on the porous burner. For statistical analysis, both main and interaction of independent variables effecting to the combustion temperature are investigated. The results showed that, for the case of multiple-linear regression, an equations recommended in prediction of the T on porous burner is T = 1375.603(F) +179.636(H) – 295.028(FH) – 9.628(HVmix) + 16.368(FVmixH) with a coefficient of determination (R2) of 0.998 and the standard error of the estimation of 42.7365. In the case of multiple- quadratic regression, a proper equation used in predicting T on porous burner is T = 2133.184(F)2 + 1.247(Vmix)2 + 17.248(H)2 – 2.916(FVmix )2 – 42.107(FH)2 – 0.049(VmixH)2 + 0.123(FVmixH)2 with R2 of 0.997 and standard error of the estimation of 44.2979. In addition, the comparison between the experimental results and the predicted estimation is reported that different percentage of both regressions and experimental results is satisfied.

Accelerated Cooling of Optical Fiber

1989 ◽  
Vol 172 ◽  
Author(s):  
S. Kyriacou ◽  
C. E. Polymeropoulos ◽  
V. Sernas
Keyword(s):  
Optical Fiber ◽  
Gas Flow ◽  
Small Diameter ◽  
Experimental Results ◽  
Accelerated Cooling ◽  
Fiber Motion

AbstractA novel apparatus for accelerated cooling of optical fiber has been used at different fiber speeds using Nitrogen and Helium as the cooling gases. The gas flow was counter to the direction of the fiber motion inside a small diameter tube. The experimental results show significant improvement over natural cooling, as well as over available transverse cooling.

Experiences With Simulation of Reciprocating Compressor Valve Dynamics

1996 ◽  
Author(s):  
Brian Howes ◽  
Leonard Lin ◽  
Val Zacharias
Keyword(s):  
Gas Flow ◽  
Economic Effect ◽  
Operating Conditions ◽  
Valve Lift ◽  
Reciprocating Compressor ◽  
Compression Process ◽  
Flow Area ◽  
Valve Dynamics ◽  
Compressor Performance ◽  
Cylinder Flow

Experience with compressor valve modelling has shown that reciprocating compressor performance can sometimes be improved by subtle changes in valve design. Modelling has led to a better understanding of the physical behaviour of valves and of the compression process. Three compressor valve studies presented here demonstrate the benefits of valve modelling. Case 1 challenges the commonly held assumption that reducing the lift of a compressor valve will reduce the efficiency of the compressor. The capacity of this compressor is increased by reducing the valve lift. A plot of BHP/MMSCFD versus valve lift shows an inflection point that assists the analyst in optimizing the design. Case 1 also presents a method of calculating the economic effect of improvements in valve performance. Case 2 demonstrates the effect of inadequate flow area through the valve. Pressure in the clearance volume cannot decrease fast enough if flow areas are inadequate; the result is late valve closure, and therefore decreased valve life. Case 3 shows the importance of considering the design of the cylinder casting in addition to that of the valves. Here, insufficient cylinder flow area constricted gas flow. Since these cases were simulated, the analyst had the opportunity to evaluate the proposed solution over the entire range of operating conditions. He was able to select a valve which solved the immediate problem and be confident that it would perform adequately throughout the specified range of conditions.

Identification of Mechanical Alterations From Their Effect on Performance of a Radial Compressor

1995 ◽  
Author(s):  
K. Mathioudakis ◽  
A. Tsalavoutas
Keyword(s):  
Experimental Study ◽  
Tip Clearance ◽  
Experimental Results ◽  
Reference Condition ◽  
Performance Parameters ◽  
Vaned Diffuser ◽  
Radial Compressor ◽  
Compressor Performance ◽  
Stage Performance

An experimental study of the influence of mechanical alterations in a stage of a radial compressor with a vaned diffuser is presented. The mechanical alterations considered correspond to changes which can be produced by the occurrence of faults or deterioration of the compressor. They include the insertion of an inlet obstruction, an obstruction in a diffuser passage, increase of impeller tip clearance, and impeller fouling. The change in the compressor performance parameters, from the reference condition, is established from the experimental results. These changes are referred to the overall stage performance but also to its components, impeller, and diffuser. In order to establish diagnostic abilities, appropriate indices are introduced. The behaviour of these indices is related to the altered stage conditions and the possibility of using them for identifying the stage condition is demonstrated.

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