scholarly journals Determination of allowable fluid temperature during start-up operation of outlet header under the assumption of constant and temperature-dependent material properties

2013 ◽  
Vol 34 (3) ◽  
pp. 3-14
Author(s):  
Dariusz Rząsa ◽  
Piotr Duda
Keyword(s):  
Power Plants ◽  
Operation Time ◽  
Optimum Operating ◽  
Working Fluid ◽  
Fluid Temperature ◽  
Temperature Dependent ◽  
Allowable Limit ◽  
Heating And Cooling ◽  
Start Up ◽  
Operation Cycle

Abstract Modern supercritical power plants operate at very high temperatures and pressures. Thus the construction elements are subjected to both high thermal and mechanical loads. As a result high stresses in those components are created. In order to operate safely, it is important to monitor stresses, especially during start-up and shut-down processes. The maximum stresses in the construction elements should not exceed the allowable stresses that are defined according to boiler regulations. It is important to find optimum operating parameters, that can assure safe heating and cooling processes. The optimum parameters define temperature and pressure histories that can keep the highest stresses within allowable limit and reduce operation time as much as possible. In this paper a new numerical method for determining optimum working fluid parameters is presented. In this method, properties of steel can be assumed as constant or temperature dependent. The constant value is taken usually at the average temperature of the operation cycle. For both cases optimal parameters are determined. Based on these parameters start-up operations for both cases are conducted. During entire processes stresses in the heated element are monitored. The results obtained are compared with German boiler regulations - Technische Regeln fur Dampfkessel 301.

scholarly journals A new method for determining allowable medium temperature during transient operation of thick-walled elements in a supercritical power plant

2010 ◽  
Vol 31 (3) ◽  
pp. 55-72
Author(s):  
Piotr Duda ◽  
Dariusz Rząsa
Keyword(s):  
Power Plant ◽  
Power Plants ◽  
New Method ◽  
Optimum Operating ◽  
Transient Operation ◽  
Medium Temperature ◽  
Heating And Cooling ◽  
Optimum Parameters ◽  
Start Up ◽  
Working Parameters

A new method for determining allowable medium temperature during transient operation of thick-walled elements in a supercritical power plantConstruction elements of supercritical power plants are subjected to high working pressures and high temperatures while operating. Under these conditions high stresses in the construction are created. In order to operate safely, it is important to monitor stresses, especially during start-up and shut-down processes. The maximum stresses in the construction elements should not exceed the allowable stress limit. The goal is to find optimum operating parameters that can assure safe heating and cooling processes [1-5]. The optimum parameters should guarantee that the allowable stresses are not exceeded and the entire process is conducted in the shortest time. In this work new numerical method for determining optimum working parameters is presented. Based on these parameters heating operations were conducted. Stresses were monitored during the entire processes. The results obtained were compared with the German boiler regulations - Technische Regeln für Dampfkessel 301.

scholarly journals Determination of Transient Fluid Temperature and Thermal Stresses in Pressure Thick-Walled Elements Using a New Design Thermometer

Energies ◽  
2019 ◽  
Vol 12 (2) ◽  
pp. 222 ◽  
Author(s):  
Magdalena Jaremkiewicz ◽  
Dawid Taler ◽  
Piotr Dzierwa ◽  
Jan Taler
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Critical Pressure ◽  
Thermal Stresses ◽  
Thermal Inertia ◽  
Internal Surface ◽  
Transient Temperature ◽  
Fluid Temperature ◽  
Start Up

In both conventional and nuclear power plants, the high thermal load of thick-walled elements occurs during start-up and shutdown. Therefore, thermal stresses should be determined on-line during plant start-up to avoid shortening the lifetime of critical pressure elements. It is necessary to know the fluid temperature and heat transfer coefficient on the internal surface of the elements, which vary over time to determine transient temperature distribution and thermal stresses in boilers critical pressure elements. For this reason, accurate measurement of transient fluid temperature is very significant, and the correct determination of transient thermal stresses depends to a large extent on it. However, thermometers used in power plants are not able to measure the transient fluid temperature with adequate accuracy due to their massive housing and high thermal inertia. The article aims to present a new technique of measuring transient superheated steam temperature and the results of its application on a real object.

scholarly journals STUDI AWAL KARAKTERISTIK TEMPERATUR DAN TEKANAN PADA ALIRAN SIRKULASI ALAM DI FASILITAS UJI UNTAI FASSIP-02 MENGGUNAKAN SIMULASI CFD

POROS ◽  
2018 ◽  
Vol 16 (1) ◽  
Author(s):  
Ainur Roidi Rosidi
Keyword(s):  
Flow Rate ◽  
Power Plants ◽  
Heat Dissipation ◽  
Cfd Simulation ◽  
Reactor Core ◽  
Heat Removal ◽  
Test Facility ◽  
Working Fluid ◽  
Fluid Temperature ◽  
Heating Section

TFASSIP-02 loop is a test facility that is used for research and development of safety technologies for future nuclear power plants based on natural law. This test facility is designed to study natural circulation phenomena caused by differences in fluid density due to temperature differences in the one-phase heat dissipation system during the simulation of heat removal from the reactor core when an accident occurs. FASSIP-02 loop consists of piping components, water heating tanks, water cooling tanks and expansion tanks. The purpose of this study was to understand the conditions of temperature change and pressure of water working fluid based on temperature changes in the heater section which were simulated on the loop geometry FASSIP-02. The research method was carried out in a simulation of Computational Fluid Dynamics using FLUENT 6.3 software. The working fluid in the FASSIP-02 loop uses water with a temperature of 27°C, the flow rate is varied 0.3 m/s and 0.45 m / s, while the temperature in the heating section is 70°C. CFD simulation results show that the increase in the working fluid temperature of the water with a flow rate of 0.3 m/s after passing through the heating section is 39°C, while the temperature increase of the working fluid of the water with a flow rate of 0.45 m/s is 36.6°C. Pressure drops at flow rates of 0.3 m/s and 0.45 m/s each occur in water working fluid before entering through WHT and after passing through the heating section. 

Integration Between Gas Turbines and Concentrated Parabolic Trough Solar Power Plants

2012 ◽  
Author(s):  
Roberto Cipollone ◽  
Andrea Cinocca
Keyword(s):  
Gas Turbines ◽  
Power Plants ◽  
Solar Power ◽  
Electrical Energy ◽  
Energy Generation ◽  
Heat Transfer Fluid ◽  
Working Fluid ◽  
Fluid Temperature ◽  
Parabolic Trough ◽  
Solar Power Plants

Parabolic Trough Concentrating Solar Power plants (PT-CSP) technology has the capability to give, in the mean future, a strong contribution to the electrical energy generation. In the long term, inside a new framework of relationships concerning energy production, many aspects would justify a significant contribution to the phase out of fossil sources use. The paper concerns about a theoretical modeling aimed at improving the performances of CSP which approaches the energy generation from a system point of view. Thanks to it, the attention is focused on the use of gases as heat transfer fluid inside the solar receivers and on the possibility to use it as working fluid inside unconventional gas turbines for a direct electricity generation. The success of this concept is related to the possibility to increase the fluid temperature above the actual maximum values: this requires that the receiver efficiency has to be recalculated as a function of the fluid temperature. An innovative integration between the solar field and the gas turbine power plant, modified in order to maximize thermal energy conversion, is discussed.

scholarly journals Assessment of Hydrostatic Temperature Conditions Machine Plate Supports

2019 ◽  
pp. 1-6
Author(s):  
Almokhammad A. Mokhammad ◽  
Evgeny A. Sorokin ◽  
Maksim V. Brungardt
Keyword(s):  
Support System ◽  
Metal Cutting ◽  
Experimental Studies ◽  
Hydraulic Drive ◽  
Operation Time ◽  
Operating Conditions ◽  
Working Fluid ◽  
Fluid Temperature ◽  
Operational Conditions ◽  
Temperature Deformations

The working fluid temperature in the hydrostatic support system of the metal working machine plate is determined as a function of the drive operation time under different operating conditions. Temperature deformations of parts, units and assemblies of metal cutting machines are greatly influenced by the temperature of hydraulic drive working fluid, so the issues of optimization of working fluid temperature are given more attention. Experimental studies of the operating fluid temperature of the hydraulic support system of the faceplate and parameters affecting its changes were carried out under conditions close to operational conditions. Parts of different mass (0.5-3.8 t) were processed at different speeds of plate rotation

scholarly journals Structural and Parametric Optimization of S–CO2 Nuclear Power Plants

Entropy ◽  
2021 ◽  
Vol 23 (8) ◽  
pp. 1079
Author(s):  
Nikolay Rogalev ◽  
Andrey Rogalev ◽  
Vladimir Kindra ◽  
Ivan Komarov ◽  
Olga Zlyvko
Keyword(s):  
Carbon Dioxide ◽  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Parametric Optimization ◽  
Maximum Efficiency ◽  
Working Fluid ◽  
Fluid Temperature

The transition to the use of supercritical carbon dioxide as a working fluid for power generation units will significantly reduce the equipment′s overall dimensions while increasing fuel efficiency and environmental safety. Structural and parametric optimization of S–CO2 nuclear power plants was carried out to ensure the maximum efficiency of electricity production. Based on the results of mathematical modeling, it was found that the transition to a carbon dioxide working fluid for the nuclear power plant with the BREST–OD–300 reactor leads to an increase of efficiency from 39.8 to 43.1%. Nuclear power plant transition from the Rankine water cycle to the carbon dioxide Brayton cycle with recompression is reasonable at a working fluid temperature above 455 °C due to the carbon dioxide cycle′s more effective regeneration system.

A Numerical Model for Off-Design Performance Prediction of Parabolic Trough Based Solar Power Plants

2011 ◽  
Vol 134 (1) ◽  
Author(s):  
Giampaolo Manzolini ◽  
Andrea Giostri ◽  
Claudio Saccilotto ◽  
Paolo Silva ◽  
Ennio Macchi
Keyword(s):  
Numerical Model ◽  
Performance Prediction ◽  
Power Plants ◽  
Solar Power ◽  
Operating Conditions ◽  
Working Fluid ◽  
Design Calculation ◽  
Fluid Temperature ◽  
Parabolic Trough ◽  
Design Algorithm

This paper deals with the development and testing of an innovative code for the performance prediction of solar trough based concentrated solar power (CSP) plants in off-design conditions. Off-design calculation starts from data obtained through the on-design algorithm and considers steady-state situations. The model is implemented in flexible software, named patto (parabolic trough thermodynamic optimization): the optical-thermal collector model can simulate different types of parabolic trough systems in commerce, including a combination of various mirrors, receivers and supports. The code is also flexible in terms of working fluid, temperature and pressure range, and can also simulate direct steam generation (DSG) plants. Solar plant heat and mass balances and performance at off-design conditions are estimated by accounting for the constraints imposed by the available heat transfer areas in heat exchangers, as well as by the characteristic curve of the steam turbine. The numerical model can be used either for single calculation in a specific off-design condition or for complete year simulation, by generating energy balances with an hourly resolution. The model is tested with a view to real applications and reference values found in literature: results show an overall yearly efficiency of 14.8% versus the 15% encountered in the Nevada Solar One. Moreover, the capacity factor is 25%, i.e., equal to the value predicted by sam®. Code potential in the design process reveals two different aspects: it can be used not only to optimize plant components and layout in feasibility studies but also to select the best control strategy during individual operating conditions.

scholarly journals Action and Entropy in Heat Engines: An Action Revision of the Carnot Cycle

Entropy ◽  
2021 ◽  
Vol 23 (7) ◽  
pp. 860
Author(s):  
Ivan R. Kennedy ◽  
Migdat Hodzic
Keyword(s):  
Heat Engine ◽  
Working Fluid ◽  
Field Energy ◽  
Carnot Cycle ◽  
Gibbs Potential ◽  
Atmospheric Gases ◽  
Temperature Dependent ◽  
Expansion Phase ◽  
Heat Engines ◽  
The Difference

Despite the remarkable success of Carnot’s heat engine cycle in founding the discipline of thermodynamics two centuries ago, false viewpoints of his use of the caloric theory in the cycle linger, limiting his legacy. An action revision of the Carnot cycle can correct this, showing that the heat flow powering external mechanical work is compensated internally with configurational changes in the thermodynamic or Gibbs potential of the working fluid, differing in each stage of the cycle quantified by Carnot as caloric. Action (@) is a property of state having the same physical dimensions as angular momentum (mrv = mr2ω). However, this property is scalar rather than vectorial, including a dimensionless phase angle (@ = mr2ωδφ). We have recently confirmed with atmospheric gases that their entropy is a logarithmic function of the relative vibrational, rotational, and translational action ratios with Planck’s quantum of action ħ. The Carnot principle shows that the maximum rate of work (puissance motrice) possible from the reversible cycle is controlled by the difference in temperature of the hot source and the cold sink: the colder the better. This temperature difference between the source and the sink also controls the isothermal variations of the Gibbs potential of the working fluid, which Carnot identified as reversible temperature-dependent but unequal caloric exchanges. Importantly, the engine’s inertia ensures that heat from work performed adiabatically in the expansion phase is all restored to the working fluid during the adiabatic recompression, less the net work performed. This allows both the energy and the thermodynamic potential to return to the same values at the beginning of each cycle, which is a point strongly emphasized by Carnot. Our action revision equates Carnot’s calorique, or the non-sensible heat later described by Clausius as ‘work-heat’, exclusively to negative Gibbs energy (−G) or quantum field energy. This action field complements the sensible energy or vis-viva heat as molecular kinetic motion, and its recognition should have significance for designing more efficient heat engines or better understanding of the heat engine powering the Earth’s climates.

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