Paper 3: An Analytical and Experimental Study of Self-Acting Valves in a Reciprocating Air Compressor

1969 ◽  
Vol 184 (18) ◽  
pp. 24-33 ◽  
Author(s):  
J. F. T. MacLaren ◽  
S. V. Kerr
Keyword(s):  
Mathematical Model ◽  
Experimental Study ◽  
Differential Equations ◽  
Digital Computer ◽  
Pressure Difference ◽  
Operating Conditions ◽  
Air Compressor ◽  
Ring Plate ◽  
Discharge Valve ◽  
Compressor Performance

A digital computer is used to solve the differential equations which form a mathematical model of a self-acting valve. The model describes the movement of a suction or a discharge valve, and the pressure difference across the valve. The computer results are compared with experimental records obtained over a range of operating conditions from a single-stage air compressor fitted with spring-loaded ring-plate valves. Subsequently the analysis provides conventional criteria of compressor performance.

scholarly journals A mathematical model for the virtual simulator of the power unit electrical part

2022 ◽  
Vol 1216 (1) ◽  
pp. 012009
Author(s):  
P Baran ◽  
Y Varetsky ◽  
V Kidyba ◽  
Y Pryshliak
Keyword(s):  
Mathematical Model ◽  
Power Plant ◽  
Differential Equations ◽  
Power System ◽  
Real Time ◽  
Power Unit ◽  
Operating Conditions ◽  
Auxiliary System ◽  
Algebraic Differential Equations ◽  
Electrical Part

Abstract The mathematical model is developed for a virtual training system (simulator) of the power unit electrical part operators of a thermal (nuclear) power plant. The model is used to simulating the main operating conditions of the power unit electrical part: generator idling, generator synchronization with the power system, excitation shifting from the main unit to the backup one and vice versa, switching in the power unit auxiliary system, and others. Furthermore, it has been implemented modelling some probable emergency conditions within a power plant: incomplete phase switching, damage to standard power unit equipment, synchronous oscillations, asynchronous mode, etc. The model of the power unit electrical part consists of two interacting software units: models of power equipment (turbine, generator with excitation systems, auxiliary system) and models of its control systems, automation, relay protection and signalling. The models are represented by the corresponding algebraic-differential equations that provide real-time mapping power unit processes at the operator’s request. The developed model uses optimal solving algebraic-differential equations to ensure the virtual process behaviour in real-time. In particular, the implicit Euler method is used to solve differential equations, which is stable when simulating processes in significant disturbances, such as accidental disconnection of the unit from the power system, tripping and energizing loads, generator excitation loss, etc.

Experimental Investigation of a Single Stage Helium Axial Compressor of HTGR-10 Power Conversion Unit

2008 ◽  
Author(s):  
Rongkai Zhu ◽  
Qun Zheng ◽  
Jiguo Zou ◽  
Rakesh Bhargava
Keyword(s):  
Experimental Investigation ◽  
Power Conversion ◽  
Axial Compressor ◽  
Operating Conditions ◽  
Working Fluid ◽  
Brayton Cycle ◽  
Flow Conditions ◽  
Air Compressor ◽  
Conversion Unit ◽  
Compressor Performance

This paper focuses on an experimental investigation of a helium compressor, a major component of the Power Conversion Unit (PCU), used in a High Temperature Gas Cooled Reactor (HTGR). The PCU system uses a direct Helium Brayton cycle for the power conversion. In this configuration, there is a strong coupling between the helium compressor and the other components of the PCU system. The estimations of compressor performance in stable and transient operational states are of high importance for the designer. Because of the difficulties in testing a compressor with helium as a working fluid, simulations methods using air to replace helium as a compressor working fluid in the experiments are researched. An experimental compressor system is built to investigate the performance of a helium compressor. Under different operating conditions, the compressor performance characteristics are obtained and compared with that of an air compressor. The possibility and the effective approach of designing a helium compressor based on the experimental data of an air compressor are studied. The experimental results showed that air under the correct flow conditions, identified using similitude analysis, can be used to test a helium compressor instead of far more expensive helium.

A Scheme to Assist in the Evaluation of Tenter Frame Dryer Performance

1979 ◽  
Vol 101 (1) ◽  
pp. 80-84 ◽  
Author(s):  
W. F. Beckwith ◽  
J. N. Beard
Keyword(s):  
Mathematical Model ◽  
Differential Equations ◽  
Operating Conditions ◽  
Temperature Profiles ◽  
Simulation Studies ◽  
Drying Process ◽  
Optimal Operating

One of the textile industry’s largest consumers of energy is the tenter frame dryer. To assist the industry in operating these dryers efficiently, a mathematical model which simulates the drying process and a scheme to solve for the parameters in the differential equations of the model have been developed and are presented in this paper. Temperature profiles predicted from the model are compared with profiles measured on commercial dryers. Also dryer simulation studies to elucidate optimal operating conditions are discussed.

Experimental study on a two-stage rolling piston CO2 compressor based on p–V indicator diagrams

2011 ◽  
Vol 226 (4) ◽  
pp. 995-1003 ◽  
Author(s):  
J Yang ◽  
Z Qi ◽  
J Chen ◽  
Z Chen
Keyword(s):  
Experimental Study ◽  
Operating Conditions ◽  
Test Rig ◽  
Two Stage ◽  
Second Stage ◽  
Compressor Inlet ◽  
Compressor Performance ◽  
Overall Efficiency ◽  
Rolling Piston ◽  
Discharge Pressure

In this article, a new two-stage rolling piston CO2 compressor was developed. A test rig was designed to measure the performance of this compressor. Based on the measured p–V indicator diagram, the distributions of indicated power and compressor performance under various operating conditions have been analysed in detail. It is shown that the discharge passage loss of the first stage and the suction passage loss of the second stage are much higher than other losses for the tested compressor. The overall efficiency of the tested compressor decreases by 1.2 per cent with the decrease of the discharge pressure at the same suction conditions. It is also found that the superheating at the compressor inlet has very small (0.3 per cent) effect on the compressor performance.

Pendelluft Flow in Symmetric Airway Bifurcations

1998 ◽  
Vol 120 (4) ◽  
pp. 463-467 ◽  
Author(s):  
Z. C. Feng ◽  
C.-S. Poon
Keyword(s):  
Mathematical Model ◽  
Experimental Study ◽  
Fluid Flow ◽  
Differential Equations ◽  
Physiological Parameters ◽  
Airway Bifurcation

We propose a mathematical model for pendelluft flow in a single airway bifurcation. The model is motivated by an apparatus used in an experimental study of the pendelluft by Ultman et al. (1988). We derive differential equations governing the fluid flow, which directly connect physiological parameters to the variables determining the pendelluft; this approach allows us to include nonlinearity in the model. If nonlinearity is neglected, our model is identical to the R-I-C circuits used by previous investigators. If nonlinearity is retained, we show that pendelluft can occur even in perfectly symmetric airway bifurcations. For the specific apparatus used in the experiments of High et al. (1991), we demonstrate that two qualitatively different pendelluft flows can occur in the system.

Experimental study and first thermodynamic law analysis of a solar water heater system

2015 ◽  
Vol 40 (3) ◽  
Author(s):  
Vahid Madadi ◽  
Hamid Beheshti ◽  
Touraj Tavakoli ◽  
Amir Rahimi
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Experimental Study ◽  
Pilot Scale ◽  
Operating Conditions ◽  
Solar Water Heater ◽  
System Efficiency ◽  
System Behavior ◽  
Water Heater ◽  
Solar Water

AbstractThe performance of a pilot scale flat plate solar water heater system is investigated theoretically and experimentally. The effect of the operating conditions and characteristic factors of the collector on the system efficiency is studied. A conceptual mathematical model is developed in order to analyze the system behavior in different operating conditions by considering the physical and constructive aspects of the system. The accuracy of the model result is estimated by comparing the model results with the existing experimental data. The highest obtained system thermal efficiency is 45%, and the optimum local values for surface azimuth and tilt angles are obtained at 180 degrees from north and 33 degrees, respectively, for the constructed solar water heater in Isfahan, Iran, with the local latitude of

scholarly journals Study of the dynamics of the working cell of the automatic mill of the pipe-rolling unit

2018 ◽  
pp. 74-80
Author(s):  
S.R. Rakhmanov ◽  
V.T Vyshinskyi
Keyword(s):  
Mathematical Model ◽  
Differential Equations ◽  
Mechanical System ◽  
Equations Of Motion ◽  
Retention Mechanism ◽  
Operating Conditions ◽  
Dynamic Processes ◽  
Real Spectrum ◽  
Pipe Rolling ◽  
Automatic Mill

Purpose. Determining the real spectrum and the level of dynamic loads would make it possible to develop recommendations for improving the TPA-350 automatic mill, with the aim of expanding its technological capabilities, improving the reliability of operation and durability. Metodology. This work was carried out on the basis of the development of a mathematical model of dynamic processes in the mechanical system of an automatic TPA mill, where an attempt was made to identify the features of the functioning of a working stand with a rolled sleeve in the formulation of dynamic problems. Obviously, the proposed approach is more correct and convenient when studying complex dynamic phenomena in the elements of an automatic TPA mill. Findings. The results of the study of the dynamics of the working stand of the automatic mill of the pipe-rolling unit (TPA) are given The basic parameters of the functioning of the working stand, such as the automatic mill TPA 350, are established, and a mathematical model of the basic problem of the dynamics of a mechanical system is developed. The differential equations of motion for the selected model of the working stand and the elastic elements of the bed retention mechanism on the support nodes of the automatic TPA mill have been compiled. The corresponding patterns of oscillations of the working stand were obtained. Some features of the functioning of the working stand are identified by the example of an automatic mill TPA 350. The dynamic parameters of the working stand of the mill, affecting the difference in the thickness of the rolled sleeves, are established. Originality. The interrelation of the working stand dynamics with the operating conditions of an automatic TPA mill on the basis of a simplified mathematical model of dynamic processes is established. A mathematical model of the mechanical system of a working working stand of an automatic TPA mill has been compiled. In the most general form, the mechanical system of a working stand of a mill is described using differential equations describing the behavior of the selected design scheme of a system with two degrees of freedom. Practical value. A scheme has been proposed for modernizing the working stand and the mechanism for holding the working stand of the TPA-350 automatic mill. IL. 4. Biblography: 8 titles.

Glycemia monitoring

1998 ◽  
Vol 2 ◽  
pp. 23-30
Author(s):  
Igor Basov ◽  
Donatas Švitra
Keyword(s):  
Diabetes Mellitus ◽  
Mathematical Model ◽  
Numerical Methods ◽  
Differential Equations ◽  
Blood Sugar ◽  
Self Regulation ◽  
Physiological System ◽  
Non Linear ◽  
The Mathematical Model

Here a system of two non-linear difference-differential equations, which is mathematical model of self-regulation of the sugar level in blood, is investigated. The analysis carried out by qualitative and numerical methods allows us to conclude that the mathematical model explains the functioning of the physiological system "insulin-blood sugar" in both normal and pathological cases, i.e. diabetes mellitus and hyperinsulinism.

Validation of mathematical model of electrothermal calculation of DC catenary on the basis of scale model

2018 ◽  
Vol 77 (4) ◽  
pp. 222-229 ◽  
Author(s):  
A. V. Paranin ◽  
A. B. Batrashov
Keyword(s):  
Mathematical Model ◽  
Operating Conditions ◽  
Scale Model ◽  
Contact Network ◽  
Scaled Model ◽  
Cross Sectional ◽  
Current Collection ◽  
Topological Features ◽  
Study Results ◽  
Real Physical Process

The article compares the results of calculation of the finite element simulation of current and temperature distribution in the scale model of the DC catenary with the data of laboratory tests. Researches were carried on various versions of the structural design of catenary model, reflecting the topological features of the wire connection, characteristic of the DC contact network. The proportions of the cross-sectional area of the scaled model wires are comparable to each other with the corresponding values for real DC catenary. The article deals with the operating conditions of the catenary model in the modes of transit and current collection. When studying the operation of the scale catenary model in the transit mode, the effect of the structural elements on the current distribution and heating of the wires was obtained. Within the framework of the scale model, theoretical assumptions about the current overload of the supporting cable near the middle anchoring have been confirmed. In the current collection mode, the experimental dependences of the current in the transverse wires of the scale model are obtained from the coordinate of the current collection point. Using the model it was experimentally confirmed that in the section of the contact wire with local wear, not only the temperature rise occurs but also the current redistribution due to the smaller cross section. Thus, the current share in other longitudinal wires of the scale model increases and their temperature rises. Scale and mathematical models are constructed with allowance for laboratory clamps and supporting elements that participate in the removal of heat from the investigated wires. Obtained study results of the scale model allow to draw a conclusion about the adequacy of the mathematical model and its correspondence to the real physical process. These conclusions indicate the possibility of applying mathematical model for calculating real catenary, taking into account the uneven contact wear wire and the armature of the contact network.

scholarly journals Comprehensive Parameters Identification and Dynamic Model Validation of Interior-Mount Line-Start Permanent Magnet Synchronous Motors

Machines ◽  
2019 ◽  
Vol 7 (1) ◽  
pp. 4 ◽  
Author(s):  
Luqman S. Maraaba ◽  
Zakariya M. Al-Hamouz ◽  
Abdulaziz S. Milhem ◽  
Ssennoga Twaha
Keyword(s):  
Mathematical Model ◽  
Permanent Magnet ◽  
High Efficiency ◽  
Experimental Tests ◽  
Induction Machines ◽  
Test Methods ◽  
Operating Conditions ◽  
Test Method ◽  
Permanent Magnet Synchronous Motors ◽  
Synchronous Motors

The application of line-start permanent magnet synchronous motors (LSPMSMs) is rapidly spreading due to their advantages of high efficiency, high operational power factor, being self-starting, rendering them as highly needed in many applications in recent years. Although there have been standard methods for the identification of parameters of synchronous and induction machines, most of them do not apply to LSPMSMs. This paper presents a study and analysis of different parameter identification methods for interior mount LSPMSM. Experimental tests have been performed in the laboratory on a 1-hp interior mount LSPMSM. The measurements have been validated by investigating the performance of the machine under different operating conditions using a developed qd0 mathematical model and an experimental setup. The dynamic and steady-state performance analyses have been performed using the determined parameters. It is found that the experimental results are close to the mathematical model results, confirming the accuracy of the studied test methods. Therefore, the output of this study will help in selecting the proper test method for LSPMSM.

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