The Theory of Spring-Loaded Valves for Reciprocating Compressors

1950 ◽  
Vol 17 (4) ◽  
pp. 415-420
Author(s):  
Michael Costagliola
Keyword(s):  
Natural Frequency ◽  
Reciprocating Compressor ◽  
Important Criterion ◽  
Flow Area ◽  
Main Design ◽  
Design Variables ◽  
Flow Test ◽  
Piston Speed ◽  
Valve Dynamics ◽  
Static Flow

Abstract The inlet and discharge processes of a reciprocating compressor equipped with spring-loaded valves of the automatic type have been analyzed to determine the effects of the main design variables on performance. The most important criterion is found to be a parameter involving effective flow area through the valves and piston speed. Valve dynamics is a secondary consideration. For optimum valve dynamics, the valve would have no weight and a very small spring constant, giving an infinite natural frequency of the valve system. If certain valve characteristics are known (or measured by static-flow test), the performance of a compressor using these valves can be predicted with fair accuracy.

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.

scholarly journals Influence of compressible medium on the operation of a reciprocating compressor

2018 ◽  
Vol 245 ◽  
pp. 04009
Author(s):  
Andrey Kotlov ◽  
Leonid Kuznetsov ◽  
Boris Hrustalev
Keyword(s):  
Piston Compressor ◽  
Compressible Medium ◽  
Reciprocating Compressor ◽  
Flow Area ◽  
Suction System ◽  
Piston Velocity ◽  
Number Of Factors ◽  
Valve Dynamics ◽  
Pressure Changes ◽  
Oscillatory Processes

A reciprocating compressor is a volumetric machine. Consequently, the motion of gas in communications always is of non-stationary or pulsating character. The diagram of oscillatory processes in communications is complex because a number of factors affect the nature of the flow: cyclical gas supply, valve dynamics, change in the flow area of pipelines, variable cylinder volume, variable piston velocity, temperature gradients, etc. The analysis of non-stationary processes in the suction stage of a household refrigeration compressor is considered. A mathematical model of the flow of real gas in the suction system of a household refrigeration piston compressor has been developed. We performed a calculation study of the motion diagram of the suction valve, gas velocities in the suction pipe and pressure changes in the suction chamber. The results of a reciprocating compressor study while compressing various gases are given. The influence of the properties of refrigerants on the operation of the compressor and the suction system is considered.

Reliability Based Optimization of Steel Monopod Offshore-Towers

2008 ◽  
Author(s):  
H. Karadeniz ◽  
V. Togan ◽  
T. Vrouwenvelder
Keyword(s):  
Natural Frequency ◽  
Cross Section ◽  
Sequential Quadratic Programming ◽  
Limit State ◽  
State Function ◽  
Wave Loading ◽  
Extreme Wave ◽  
Design Variables ◽  
Reliability Based Optimization ◽  
Numerical Strategy

In this work, the implementation of reliability-based optimization (RBO) of a circular steel monopod-offshore-tower with constant and variable diameters (represented by segmentations) and thicknesses is presented. The tower is subjected to the extreme wave loading. For this purpose, the deterministic optimization of the tower is performed with constraints including stress, buckling, and the lowest natural frequency firstly. Then, a reliability-based optimization of the tower is performed. The reliability index is calculated from FORM using a limit state function based on the lowest natural frequency. The mass of the tower is considered as being the objective function; the thickness and diameter of the cross-section of the tower are taken as being design variables of the optimization. The numerical strategy employed for performing the optimization uses the IMSL-Libraries routine that is based on the Sequential Quadratic Programming (SQP). In addition, to check the results obtained from aforementioned procedure, the RBO of the tower is also performed using the genetic algorithms (GA) tool of the MATLAB. Finally, a demonstration of an example monopod tower is presented.

On Features of Thermal Design of Passive Evaporation-and-Condensation Systems of Reactor Thermal Shielding

2014 ◽  
Author(s):  
A. N. Gershuni ◽  
A. P. Nishchik ◽  
E. N. Pis'mennyi ◽  
V. G. Razumovskiy ◽  
I. L. Pioro
Keyword(s):  
Heat Removal ◽  
Fission Products ◽  
Thermal Design ◽  
Nuclear Engineering ◽  
Main Design ◽  
Evaporation And Condensation ◽  
The Third ◽  
Design Variables ◽  
Containment Shell ◽  
Further Development

Further development of nuclear engineering is inseparably linked with the requirement of vast application of the passive systems of heat removal running without human intervention. Creation of such systems is impossible, if only conventional engineering solutions are used. As known, to prevent propagation of the fission products into the environment there are three safety barriers. To provide operation of the third safety barrier (containment shell), in particular, of the reactor cavities both in operational and emergency modes a passive evaporation-and-condensation (EC) system of heat removal is proposed. The features of thermal design of the EC systems for thermal shielding of the reactor cavities are considered. They make it possible to determine the optimal main design variables of the EC systems and prove reasonability and efficiency of their application. The performed study validates engineering feasibility of an efficient EC system for thermal shielding of the reactor equipment.

scholarly journals Reliability Analysis and Optimization for the Brake Drum

2022 ◽  
Vol 2160 (1) ◽  
pp. 012010
Author(s):  
Jingdong Zhang ◽  
Bin Zheng ◽  
Zhigang Li ◽  
Zhuo Yang
Keyword(s):  
Modal Analysis ◽  
Reliability Analysis ◽  
Natural Frequency ◽  
Static Analysis ◽  
Six Sigma ◽  
Cumulative Distribution ◽  
Maximum Deformation ◽  
Drum Brake ◽  
Design Variables ◽  
Brake Drum

Abstract In order to research the static and dynamic characteristics of drum brake in the braking process and avoid resonance, it is necessary to carry out static analysis and modal analysis of drum brake. By establishing the three-dimensional model of the brake drum and imported to ANSYS for static analysis, the maximum equivalent stress and maximum deformation of the brake drum are obtained. The first, second and third natural frequencies and modal vibration shapes of the brake drum are obtained by modal analysis. Four dimensional parameters are selected as design variables, and the sensitivity is carried out by using experimental design. Taking the maximum deformation, first natural frequency, second natural frequency and mass of the brake drum as the objective function, the multi-objective optimization algorithm is used to optimize the design variables. Based on the optimization design, the six sigma reliability analysis of the brake drum is carried out, and the six sigma reliability analysis method is given in detail. The cumulative distribution graph of the maximum deformation, first natural frequency, second natural frequency and mass of the brake drum are obtained. The analysis results show that the reliability of the brake drum is close to 100%, and then it is judged that the brake drum has high reliability. The research results provide a reference basis for structural reliability analysis.

Optimum Structural Design of Naval Vessels

2003 ◽  
Vol 40 (03) ◽  
pp. 149-157
Author(s):  
Seo Seung II ◽  
Son Keon Ho ◽  
Park Myung Kyu
Keyword(s):  
Structural Analysis ◽  
Structural Design ◽  
Design Method ◽  
Design Standards ◽  
Naval Vessel ◽  
Main Design ◽  
Optimum Structural Design ◽  
Design Variables ◽  
Analysis Theory ◽  
The U.S

Naval vessels are not regulated by class rules, but by special regulations. This study introduces the concept and characteristics of the regulations of the U.S. Navy, which has been the most reliable in setting design standards of naval vessels and helps designers comprehend the effect of each regulation on design results. Also, an optimum structural design method combined with structural analysis theory is proposed for an actual naval vessel to be designed according to U.S. Navy regulations. The validity of the proposed method is shown by the optimum design results for the midship section. The optimum spacings of longitudinal and transverse web frames are found, and the effect of the main design variables is investigated.

scholarly journals Exergo-economic assessment of OTEC power generation

2021 ◽  
Vol 238 ◽  
pp. 01015
Author(s):  
Lorenzo Talluri ◽  
Giampaolo Manfrida ◽  
Lorenzo Ciappi
Keyword(s):  
Output Power ◽  
Large Fraction ◽  
Deep Ocean ◽  
Economic Assessment ◽  
Hot Water ◽  
Tropical Region ◽  
Main Design ◽  
Design Variables ◽  
Ocean Thermal Energy ◽  
The Cost

Ocean Thermal Energy Conversion is an important renewable energy technology aimed at harvesting the large energy resources connected to the temperature gradient between shallow and deep ocean waters, mainly in the tropical region. After the first small-size demonstrators, the current technology is focused on the use of Organic Rankine Cycles, which are suitable for operating with very low temperatures of the resource. With respect to other applications of binary cycles, a large fraction of the output power is consumed for harvesting the resource – that is, in the case of OTEC, for pumping the cold and hot water resource. An exergy analysis of the process (including thermodynamic model of the power cycle as well as heat transfer and friction modelling of the primary resource circuit) was developed and applied to determine optimal conditions (for output power and for exergy efficiency). A parametric analysis examining the main design constraints (temperature range of the condenser and mass flow ratio of hot and cold resource flows) is performed. The cost of power equipment is evaluated applying equipment cost correlations, and an exergo-economic analysis is performed. The results allow to calculate the production cost of electricity and its progressive build-up across the conversion process. A sensitivity analysis with respect to the main design variables is performed.

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