A Theoretical Study of the Phase Angle for the β Type Pulse-Steam Stirling Expander

2014 ◽  
Vol 597 ◽  
pp. 425-430
Author(s):  
Guang Jer Lai ◽  
C.K. Lin ◽  
Yoshiyuki Kobayashi ◽  
Masahiro Matsuo ◽  
Min Chie Chiu
Keyword(s):  
Mathematical Model ◽  
Output Power ◽  
Phase Angle ◽  
Small Scale ◽  
Steam Boiler ◽  
Isothermal Process ◽  
Characteristic Analysis ◽  
Flow Energy ◽  
Cogeneration System ◽  
The Mathematical Model

This paper introduces a small steam expander linked to a moderate/small industrial steam boiler to form a small scale cogeneration system for the purpose of energy conservation and carbon-emission reduction. Here, a traditional regulator will be replaced by the steam expander. In order to effectively extract the high pressure steam’s unused energy (flow energy) from the boiler, the steam will be induced into an expanding process. Here, a Pulse-Steam Stirling Expander (PSSE), which is different from a normal steam expander, is proposed in the study. In order to decrease the steam condensation and increase the overall output power, the PSSE expander adopts an isothermal process instead of the traditional isentropic process. The PSSE cycle, which is composed of an isothermal process and an isovolumetric process, is similar to the Stirling cycle. Therefore, considering the influence of the valve’s opening/closing within the PSSE cycle and adopting the Stirling engine’s Schmidt theory, the mathematical model of the PSSE cycle has been established. The characteristic analysis of the PSSE expander has been assessed based on the mathematical model. Moreover, a prototype of the PSSE expander has been constructed and tested. According to theoretical analysis and experimental data, the output power for the PSSE expander is closely related to the phase angle between the displacer and the piston. Consequently, the mathematical model of the PSSE expander proposed in this study can be applied to design the practical PSSE expander in industry.

Deep and Shallow Water Low-Speed Maneuvering Tests: Comparison Between Experimental and Simulation Results

2016 ◽  
Author(s):  
Felipe Ribolla Masetti ◽  
Pedro Cardozo de Mello ◽  
Guilherme F. Rosetti ◽  
Eduardo A. Tannuri
Keyword(s):  
Mathematical Model ◽  
Small Scale ◽  
Shallow Waters ◽  
Hydrodynamic Coefficients ◽  
Low Speed ◽  
Tunnel Model ◽  
Oceanographic Research ◽  
Simulation Results ◽  
The University ◽  
The Mathematical Model

This paper presents small-scale low-speed maneuvering tests with an oceanographic research vessel and the comparison with mathematical model using the real time maneuvering simulator developed by the University of São Paulo (USP). The tests are intended to verify the behavior of the vessel and the mathematical model under transient and low speed tests. The small-scale tests were conducted in deep and shallow waters, with a depth-draft ratio equal to 1.28, in order to verify the simulator ability to represent the vessel maneuverability on both depth conditions. The hydrodynamic coefficients used in the simulator model were obtained by CFD calculations and wind tunnel model tests carried out for this vessel. Standard turning circle and accelerating turn maneuvers were used to compare the experimental and numerical results. A fair agreement was achieved for shallow and deep water. Some differences were observed mainly in the initial phase of the accelerating turn test.

scholarly journals Study on the Mathematical Model of Vacuum Breaker Valve for Large Air Mass Conditions

Water ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1358
Author(s):  
Zhang ◽  
Fan ◽  
Yu ◽  
Zhang ◽  
Lv ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Theoretical Basis ◽  
Isothermal Process ◽  
Air Mass ◽  
Protection Scheme ◽  
Calculation Results ◽  
Air Valve ◽  
The Mathematical Model ◽  
Valve Model ◽  
Derivation Process

The mathematical model of vacuum breaker valve is significant to the protection scheme. The more accurate the vacuum breaker valve model, the more reliable the calculation results. In this study, the application conditions of the air valve model are analyzed according to the assumptions used in the derivation, and the contradictions between these assumptions are proposed. Then, according to the different working characteristics between the vacuum breaker valve on the siphon outlet pipe and the air valve, the vacuum breaker valve model is deduced based on the modified assumptions. In the derivation process, the thermodynamic change of the gas in the vacuum breaker valve is assumed to follow the isentropic process rather than an isothermal process, and the water level in the vacuum breaker valve is considered to be changeable. An engineering case is introduced, and the results calculated according to the vacuum breaker valve model are compared with those resulting from the air valve model. The results indicate that the vacuum breaker valve model is suitable for large air mass conditions and can provide a theoretical basis for the numerical simulation and settings of vacuum breaker valves.

scholarly journals The mathematical model of gas flowing in porous medium based on the homogenization method

2021 ◽  
Vol 252 ◽  
pp. 02046
Author(s):  
Wei Xiong
Keyword(s):  
Mathematical Model ◽  
Porous Medium ◽  
Flow Field ◽  
Homogenization Method ◽  
Darcy Law ◽  
Small Scale ◽  
Matrix System ◽  
Fluid Equation ◽  
Coal Matrix ◽  
The Mathematical Model

Considered the characteristics of porous medium in the coal seam and goaf, in order to reflect the accurately influence of various porous media against the gas flow, the mathematical model of discrete multi-scale network and macroscopic flow, CFCM (Coal-Fracture-Cavity-Model), was presented. The porous medium is classified into coal matrix, fracture and hole systems based on the size, and the coal matrix system includes micro fractures and micro-porous. The coal matrix system and fracture system can be regarded as diffusion and percolation areas; hole system can be regarded as a free-flowing area. The computation model of flow field in micro-scale, small-scale and large-scale are obtained according the Fick’s diffusion law, Darcy’s permeability law and Forchheimer generalized Darcy law respectively, the homogenization method is used to analyse the mathematical model by scale upgrading and the equivalent Darcy’s fluid equation of porous medium is got to describe the characteristics of the medium in the flow field accurately. An example calculated shows that the coal matrix and fracture systems are the most influential factors of the flow field in goaf and the two systems above would prevent the diffusion of airflow. The study validates the correctness of the classification method and the model of flow equation.

scholarly journals Milk runs model with overtime: application to cluster supply chain

2015 ◽  
Vol 14 (4) ◽  
pp. 139-147
Author(s):  
Michał Tomczak ◽  
Robert Bucoń
Keyword(s):  
Mathematical Model ◽  
Supply Chain ◽  
Outcome Analysis ◽  
Small Scale ◽  
Construction Sites ◽  
Construction Enterprises ◽  
Distribution Centre ◽  
The Mathematical Model ◽  
First Time ◽  
Organizational Principles

Paper identifies obstacles limiting functioning and development of small and medium construction enterprises. It also includes a description of cluster supply chain (CSC) idea as a suggested solution to some of the problems resulting from the small scale of company activities. One of more important issues of every distribution centre, i.e. portions of deliveries smaller than truck capacity for particular consumers, is also discussed. This problem was formulated for the first time in dairy industry, therefore, it was called milk runs. Moreover, the authors of this paper presented the outcome analysis of survey carried out among construction engineers and managers. This study aimed at determining organizational principles for logistic centre working with CSC framework. The mathematical model depicting milk runs deliveries with overtime consideration, done for many construction sites within a distribution centre is presented hereunder. This model may be potentially used to optimize distribution centres working within cluster supply chain framework.

Dynamic Analysis on the Starting Process of First Conveyor’s Scraper Chain

2016 ◽  
Vol 851 ◽  
pp. 279-285 ◽  
Author(s):  
Qiang Li ◽  
Ming Yu Zhang ◽  
Jun Mao
Keyword(s):  
Differential Equation ◽  
Mathematical Model ◽  
Characteristic Analysis ◽  
Technical Parameters ◽  
Adjustment Time ◽  
Start Up ◽  
Starting Process ◽  
Set Up ◽  
The Mathematical Model ◽  
Dynamics Characteristic

For the study of first conveyor chain dynamics behavior when it is started and seek the theory basis for the chain breakage on first conveyor, set up the mathematical model of the first conveyor and its scraper chain by using finite-element method. And then did the dynamics characteristic analysis between scraper chains with material, set up the differential equation. Took advantage of the mathematical model and the differential equation, and combined with the type of EBZ160 road header's technical parameters, did dynamic simulation. It draw a conclusion that during the start-up process the chain speed fluctuates a large range between, the maximum stress value on scraper chain is 1.15×104N appeared after 1s, chain tension adjustment time is about 10s, the biggest adjustment time is 12s.

Demagnetization Modeling and Characteristic Analysis of Belt Conveyor Permanent Magnet Electric Roller Based on Back Electromotive Force

2021 ◽  
Vol 16 (6) ◽  
pp. 957-966
Author(s):  
Lijie Yang ◽  
Caiming Deng ◽  
Guimei Wang
Keyword(s):  
Mathematical Model ◽  
Finite Element ◽  
Permanent Magnet ◽  
Electromotive Force ◽  
Element Model ◽  
Belt Conveyor ◽  
Characteristic Analysis ◽  
Calculation Results ◽  
Electric Roller ◽  
The Mathematical Model

The demagnetization of permanent magnet electric roller of coal mine belt conveyor will reduce the comprehensive performance of electric roller. In serious cases, the belt conveyor will stop suddenly or burn down, leading to the failure of normal production and safety accidents on the site. In this paper, starting from the A-phase current and output torque angles under different degrees of loss of magnetic fault, the B–H curve is fitted by linear ratio, and the reverse electromotive force is modeled by numerical analysis method. A diagnosis method for the degree of demagnetization of permanent magnet electric roller on account of the mathematical model of back electromotive force is presented. In this paper, a 200 KW permanent magnet electric roller used in a mine is taken as the research object. The finite element model is established by ANSYS Electronics Desktop and the demagnetization simulation of model is carried out. The model of mathematics on account of the back electromotive force is compared with a model of finite element simulation, and the back electromotive force waveform of the two methods is basically the same, and the error is less than 5%. The mathematical model based on the reverse electromotive force proposed in this paper can accurately reflect the degree of loss of magnetization of the motor, and the calculation results are accurate, which is conducive to determining the state of the permanent magnet electric roller more effectively, and provides a theoretical basis for predicting and diagnosing the failure of loss of magnetization of the permanent magnet electric roller.

scholarly journals Adaptation of a Mathematical Model of Generalized Heat Exchange in Furnaces

2020 ◽  
Vol 20 (4) ◽  
pp. 12-22
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Gas Flow ◽  
Calculated Data ◽  
Combustion Products ◽  
Steam Boiler ◽  
Gas Temperature ◽  
Condi Tions ◽  
Proposed Model ◽  
The Mathematical Model

Consideration of the scheme of flows of combustion products in furnaces and flow chambers of combus-tion within the framework of the heat transfer paradigm made it possible to determine the ratio of the genera-lized mechanisms of heat transfer – convection and radiation. The transition from uniform distribution of gas flow velocity to uneven distribution in furnaces with a geometrically peculiar fence has been implemented. This made it possible to take into account the use of recirculation gases, dual-light shades, changes in the shape and size of the cross-section of the furnace, and installation of shade surfaces in a furnace. The condi-tions for the correctness of the mathematical model are considered, and the eigenvalues of the boundary value problem under conditions of an asymmetric temperature field and the function of the gas temperature changing along the height of the furnace are obtained. A comparative analysis of the nature of the change in gas temperature with height according to the proposed model with the calculation for a steam boiler with a capacity of 950 t/h according to the standard method showed a satisfactory agreement of the calculated data with an accuracy of +4.87 %.

Coupling Simulation and Characteristic Analysis of Pure Water High-Speed On-Off Valve

2013 ◽  
Vol 328 ◽  
pp. 457-462
Author(s):  
Ling Yun Yan ◽  
Peng Fei Wu ◽  
Zeng Xian Bao
Keyword(s):  
Mathematical Model ◽  
Simulation Model ◽  
Dynamic Simulation ◽  
Hydraulic System ◽  
High Speed ◽  
Pure Water ◽  
Performance Parameters ◽  
Characteristic Analysis ◽  
Simulation Results ◽  
The Mathematical Model

The paper introduces the structure and operating principle of two-position three-way pure water high-speed solenoid on-off valve, establishes the mathematical model of on-off valve, obtains performance parameters of electromagnet through Ansoft simulation, imports the performance parameters of electromagnet into the solenoid on-off valve simulation model in AMESim, and realizes the coupling simulation among electromagnetic circuit, mechanical part and hydraulic system, so as to improve simulation precision and achieve relatively correct static-dynamic simulation results of high-speed solenoid on-off valve.

Validation of a Modular Mathematical Model for Low-Speed Maneuvering Using Small Scale Tests With an Oceanographic Research Vessel

2015 ◽  
Author(s):  
Felipe Ribolla Masetti ◽  
Eduardo A. Tannuri ◽  
Pedro Cardoso de Mello
Keyword(s):  
Mathematical Model ◽  
Real Time ◽  
Sao Paulo ◽  
Research Vessel ◽  
Small Scale ◽  
Low Speed ◽  
The Real ◽  
Oceanographic Research ◽  
The University ◽  
The Mathematical Model

This paper presents small scale low-speed maneuvering tests with an oceanographic research vessel model. The purpose of the tests is to validate the mathematical model of the real-time ship simulator for low-speed maneuvering developed by the University of São Paulo. The tests are intended to verify the behavior of the vessel and the model under transient and low-speed tests.

scholarly journals Steam boiler transfer function through fuel supply - steam pressure at boiler outlet

2021 ◽  
pp. 16-21
Author(s):  
M. A. Djamanbayev ◽  
E. K. Musabaev
Keyword(s):  
Mathematical Model ◽  
Steam Pressure ◽  
Analytical Relationship ◽  
Stable Operation ◽  
Steam Boiler ◽  
Tuning Parameters ◽  
Simulink Simulation ◽  
Vaporization Process ◽  
The Mathematical Model ◽  
The Given

The article provides an analytical relationship (mathematical model) between the steam pressure at the exit of the steam boiler and the fuel supplied to the boiler. The mathematical model was determined on the basis of the characteristics obtained experimentally through the channel "fuel - steam pressure in the boiler". The experimental data were processed by the method of M.P. Simo and E.P. Stephanie. The dynamics of the change in steam pressure in a steam boiler is simulated in the Matlab (Simulink) simulation environment. The resulting model will be used to develop an automatic control system for the vaporization process. In particular, when establishing the region of stable operation of the regulator, when choosing the optimal values of the tuning parameters of the regulator that satisfy the given quality indicators of technological processes.

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