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Parametric distributions of a horizontal-tube falling film evaporator for desalination

DESALINATION AND WATER TREATMENT 2016年第25期57卷 11699-11711页

作者： Gong, Luyuan Shen, Shengqiang Liu, Hua Mu, Xingsen Dalian Univ Technol Key Lab Liaoning Prov Desalinat Dalian 116024 Liaoning Peoples R China

Three independent experiments which correspond to the characteristic study on the performance of the horizontal-tube falling film evaporators were carried out, and each came out with a validated model for its performance prediction. A comprehensive distributed parameter model was developed based on the above three models to simulate a large tube bundle consisting of 160 rows and 80 columns aluminum-brass tubes in a horizontal-tube falling film evaporator. The simulation was conducted with the superficial evaporation temperature on the shell side of 60 degrees C, the superficial overall temperature difference of 3.0 degrees C, the inlet brine salinity of 30g/kg, the inlet brine spray density of 0.06kg/ms, and the maximum steam inlet velocity of 40m/s. The non-uniform distributions of several thermal parameters are presented and discussed.

关键词： Falling film evaporator Horizontal-tube bundle distributed parameter model Distributions of parameters

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Impact of the geometric parameters on the thermal performance of a large-scale falling film evaporator for desalination

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DESALINATION AND WATER TREATMENT 2019年 157卷 281-289页

作者： Gong, Luyuan Guo, Yali Mu, Xingsen Shen, Shengqiang Dalian Univ Technol Natl United Engn Res Ctr Thermal Energy Integrat Key Lab Liaoning Prov Desalinat Dalian 116024 Liaoning Peoples R China

Based on a validated distributed parameter model, the thermal performance of a large-scale falling film evaporator was simulated under different geometric parameters including the tube length and the row-column ratio of the tube bundle. On considering that the falling film evaporators applied in the multi-effect evaporation are operated under small temperature difference thus sensitive to the temperature variation inside the evaporator, the variation of the local temperature difference is presented in detail. The distributions of the local heat transfer coefficient and heat flux were also exhibited under different geometric parameters. Results show that both the tube length and tube bundle row-column ratio have significant impact on the distribution of thermodynamic parameters in the falling film evaporator. The maximum value of the average heat flux of the evaporator is obtained when the length of the tube is 7 m. The maximum heat flux of the evaporator is obtained when the tube bundle row-column ratio is 2.5.

关键词： Falling film evaporator Horizontal tube bundle distributed parameter model Geometric parameters Thermal performance

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Dynamic modeling and infinite-dimensional observer-based control for manipulation of flexible beam by a multi-link robot

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COMPLEX & INTELLIGENT SYSTEMS 2023年第3期9卷 3249-3260页

作者： Liu, Shuyang Li, Yuanchun Changchun Univ Technol Dept Control Sci & Engn Yanan St Changchun 10012 Jilin Peoples R China

This paper concerns an infinite-dimensional observer for manipulation of flexible beam by a rigid arm robot. The complex dynamic of the system is described by distributed parameter model in terms of ordinary differential equations and partial differential equation. A novel infinite-dimensional observer is proposed to estimate the vibration information of the flexible object. In addition, an observer-based independent joint controller is designed to achieve the position control and vibration suppression, which do not need end-point boundary control. The semigroup theory and LaSalle's invariance principle are adopted to prove the asymptotic stability of the robot system. The efficiency of the observers and the proposed control strategy are demonstrated by numerical simulations.

关键词： Infinite-dimensional observer Flexible beam Independent joint control distributed parameter model

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Pressure pulsations in reciprocating pump piping systems .1. modelling

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PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART I-JOURNAL OF SYSTEMS AND CONTROL ENGINEERING 1997年第3期211卷 229-237页

作者： Shu, JJ Burrows, CR Edge, KA University of Bath Fluid Power Centre School of Mechanical Engineering

A distributed parameter model of pipeline transmission line behaviour is presented, based on a Galerkin method incorporating frequency-dependent friction. This is readily interfaced to an existing model of the pumping dynamics of a plunger pump to allow time-domain simulations of pipeline pressure pulsations in both suction and delivery lines. A new model for the pump inlet manifold is also proposed.

关键词： reciprocating plunger pump pipeline dynamics pressure pulsations distributed parameter model

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Evolution of contaminant distribution at steady airflow field with an arbitrary initial condition in ventilated space

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ATMOSPHERIC ENVIRONMENT 2008年第28期42卷 6775-6784页

作者： Li, Xianting Chen, Jiujiu Tsinghua Univ Sch Architecture Dept Bldg Sci Beijing 100084 Peoples R China

Transient contaminant dispersion is of high importance to human comfort, health and safety. Lumped parameter model is usually applied to predict the evolution of contaminant dispersion, which, however, will not be effective when the contaminant distribution is not uniform. When airflow field is steady, the contaminant concentration distribution versus time will be determined by the concentration of supply air, contaminant source and initial concentration distribution in the ventilated space. An analytic expression of distributed contaminant concentration was developed using the accessibility of supply air (ASA), accessibility of contaminant source (ACS) and accessibility of initial condition (AIC). The ASA, ACS and AIC describe the contribution of supply air, contaminant source and initial condition to any point in ventilated space, and are determined by the airflow field if the contaminant sources and initial distribution are given. The analytic expression was validated by the tracer gas measurement in a test chamber. Based on the application of the expression in typical cases, the differences as well as connections between the analytic expression and lumped model were discussed. It is shown that the analytic expression is helpful for the understanding of the contaminant evolution process and may be used to obtain effective ventilation strategy for comfort and emergency. (C) 2008 Elsevier Ltd. All rights reserved.

关键词： Gas contaminant Transient dispersion Ventilation Accessibility of initial condition (AIC) Analytic expression distributed parameter model

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Thermal performance analysis of submerged combustion vaporizer at supercritical pressure

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CRYOGENICS 2019年 100卷 41-52页

作者： Pan, Jie Bai, Junhua Tang, Linghong Li, Ran Wu, Gang Xian Shiyou Univ Coll Petr Engn Xian 710065 Shaanxi Peoples R China Xian Shiyou Univ Coll Mech Engn Xian 710065 Shaanxi Peoples R China

In this paper, an energy balance-based model considering icing effects was established for estimating the heat transfer of submerged combustion vaporizer (SCV) under supercritical LNG pressure, where introduces some empirical correlations to evaluate the convection heat transfer of water bath-side and LNG-side. Based on this model, the thermal performance of a typical SCV was predicted numerically, and good agreement between the predicted and actual water bath temperatures indicates that the model is reliable. The results indicated that the operation parameters, such as LNG pressure, operating load, inlet LNG temperature, have significantly different influences on the thermal performance of SCV, including required minimum water bath temperature and flue gas flow rate, and the length and average thickness of ice layer outside the LNG tube bundle. The heat transfer enhancement techniques can improve the heat transfer efficiency markedly, although they also cause an increase in flow resistance. The wire coil insert with a helix angle of 75 degrees is a better choice than the twisted tape insert with a helix angle of 45 degrees and the wire coil insert with a helix angle of 45 degrees considering its effects on both heat transfer and flow resistance.

关键词： Thermal performance SCV distributed parameter model Heat transfer tube Supercritical pressure Heat transfer enhancement

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Developing models of Turbine Thermal Processes in Low-Steam and Motor Modes

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THERMAL ENGINEERING 2021年第8期68卷 612-618页

作者： Pikina, G. A. Arakelyan, E. K. Pashchenko, F. F. Filippov, G. A. Natl Res Univ Moscow Power Engn Inst Moscow 111250 Russia Russian Acad Sci Trapeznikov Inst Management Problems Moscow 117997 Russia

The main purpose of the motor mode is to keep the turbine in hot standby (with the boiler off) without generating electricity to the grid. To do this, the generator is switched to the engine mode, which rotates the turbine rotor, and the cooling of the flow path is performed by supplying one or two intermediate steam extractions from the extractions of the neighboring turbine. The first stages of the high-pressure cylinder run on steam from the front seals. The noted specificity of the purpose and operating conditions of the turbine in low-steam modes imposes additional requirements on the mathematical model. When developing models of a turbine stage in a motor mode, the physical media included in the object were taken into account: the steam of the flow path passing through the nozzle and working discs, participating in the conversion of its thermodynamic and kinetic energy into mechanical energy of the rotor rotation;vapor leakage into the space between the discs;steam leakage through the rotor-guide vane seal;metal of rotating devices (working disks and turbine rotor);and metal of the stator and exhaust pipes. Multipoint models are obtained with lumped parameters distributed along the length of the flow channel with values that vary depending on the ordinal number of the stage. The main part of the step models are eight ordinary differential equations or partial differential equations of physical media. The developed models are necessary for computer modeling and investigating the temperature distribution of the turbine flow path. Based on the research results, it is proposed to create a real automatic control system that ensures the implementation of restrictions on metal heating and the generation of added power.

关键词： turbine low steam and motor modes thermal processes multipoint models distributed parameter model partial differential equations lumped parameter model ordinary differential equations

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Nonlinear model Predictive Control for the Superfluid Helium Cryogenic Circuit of the Large Hadron Collider

Nonlinear Model Predictive Control for the Superfluid Helium...

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IEEE International Conference on Control Applications Part of 2010 IEEE Multi-Conference on Systems and Control

作者： Noga, Rafal Ohtsuka, Toshiyuki de Prada Moraga, Cesar Vinuela, Enrique Blanco Cubillos, Juan Casas Osaka Univ 1-3 Machikaneyama Osaka 5608531 Japan Univ Valladolid E-47011 Valladolid Spain CERN European Org Nuclear Res CH-1211 Geneva Switzerland

ISBN: (纸本)9781424453634

Superfluid helium is used in the cryogenic circuit that cools down and stabilizes temperature of more than 1600 high performance, main superconducting magnets of the Large Hadron Collider (LHC) - the new particle accelerator at European Organization for Nuclear Research (CERN). This paper presents a simulation study of the application of Nonlinear model Predictive Control (NMPC) to the Superfluid Helium Cryogenic Circuit. First, the new first principles, distributed parameter model of the circuit to be used in online optimization is reviewed. Then stabilization of the superconducting magnets temperature using NMPC based on the model and Continuation/Generalized Minimum Residual (C/GMRES) algorithm is described. Finally the small computational cost of C/GMRES solution/approximation method and resulting real-time feasibility are highlighted.

关键词： European Organization for Nuclear Research accelerator control systems accelerator magnets circuit optimisation continuation-generalized minimum residual algorithm cryogenic electronics distributed parameter model distributed parameter systems large hadron collider liquid helium nonlinear control systems nonlinear model predictive control online optimization particle accelerators predictive control superconducting magnet superconducting magnets superfluid helium cryogenic circuit superfluidity synchrotrons temperature control

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A multi-loop vibration control of a torsional plant

A multi-loop vibration control of a torsional plant

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IEEE International Conference on Mechatronics (ICM)

作者： Kang, BS Oloomi, H Purdue Univ Ft Wayne IN 46805 USA

ISBN: (纸本)0780389980

This paper addresses the problem of suppressing torsional vibration induced by a disturbance torque in a high performance two-disk system. The plant consists of two inertia disks connected by a weakly damped link and is driven by a brushless DC motor connected to one of the disks. A distributed parameter model of the system is developed and a lumped parameter model including the dominant torsional modes is then extracted. A multi-loop controller is designed on the basis of the lumped parameter model and is shown to be capable of suppressing the vibration to a reasonable level and over a wide frequency range.

关键词： torsional plant vibration control distributed parameter model multi-loop control disturbance suppression

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Study of Transient Spectrum in Transmission Lines

Study of Transient Spectrum in Transmission Lines

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General Meeting of the IEEE-Power-and-Energy-Society

作者： Wang, X. G. Huang, S. F. Liu, Q. K. N China Elect Power Univ Key Lab Power Syst Protect & Dynam Secur Monitori Minist Educ Beijing Peoples R China

ISBN: (纸本)9781424419050

When faults occur in transmission lines, the high frequency signals are caused by fault generated traveling waves and the spectrum is a series of harmonic in frequency domain. This paper utilizes lumped and distributed parameter models to express transmission tines respectively, analyzes the character of nature frequencies. Different influencing factors including different fault conditions, source impedance, bus capacitance, series compensated capacitance and shunt reactor are discussed in this paper. The results have been proven by ATP procedure in a typical 500-kv power transmission line.

关键词： Transmission line Nature frequencies High frequency signals Traveling wave Lumped parameter model distributed parameter model Spectrum

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