scholarly journals Power units with full CO2 utilization

2022 ◽  
Vol 2150 (1) ◽  
pp. 012024
Author(s):  
O O Milman
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Steam Turbine ◽  
Co2 Capture ◽  
High Speed ◽  
Fossil Fuels ◽  
Initial Mixture ◽  
Hydrogen Energy ◽  
Steam Boiler

Abstract The forecasts for the development of renewable energy and conventional energy with fossil fuels have significant discrepancies in quantitative indicators, but agree on the need to reduce CO2 emissions. In this direction, a great number of developments are associated with hydrogen energy. Alternative proposals are cycles on methane-oxygen fuel with CO2 capture from the concentrated stream at the outlet of the condenser-separator: high-temperature gas-steam turbine unit of CJSC SPC «Turbocon», Allam, and JIHT RAS cycle. A 100 kW gas-steam turbine with an initial mixture temperature of up to 800° C has been developed and tested. To develop a method for calculating steam condensers from a mixture with CO2 (common to all three schemes), tests were carried out on a special stand; the heat transfer coefficient experimental data have been used to design a highly efficient steam condenser from a mixture with a converging flow path to maintain its high speed, a heat transfer coefficient of 2700 W/m2K was achieved. It is planned to create a prototype installation containing a steam boiler, a gas-steam turbine and a steam condenser with CO2 capture from the concentrated stream at the compressor outlet.

Research on Precision Correcting for Heat Transfer Coefficient of Steam Turbine

2014 ◽  
Author(s):  
Yan Zhou ◽  
Danmei Xie ◽  
Yongxing Feng ◽  
Shi Liu
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Steam Turbine ◽  
High Speed ◽  
Thermal State ◽  
Turbine Rotor ◽  
Transfer Coefficients ◽  
Empirical Formulas ◽  
Steam Turbine Rotor

As a high-speed rotating part, forced convection of the surface of rotor is high-intensity when steam turbine is running. The thermal state of the rotor directly affects the distribution of the stress and vibration characteristics. In order to effectively monitor and control the thermal state of the rotor, heat transfer coefficient must be quickly and accurately calculated. Typically, different manufacturers select different empirical formulas and the calculated values vary greatly. Combining with empirical formulas, the accuracy of steam turbine rotor surface heat transfer coefficient is improved, so that the results become closer to the numerical calculation values, then also result in analyzing the thermal state of rotor more precisely. Taking a certain 300MW turbine rotor as an application, the heat transfer coefficients of rotor are analyzed and calculated. And the improved method can be also applied in a 600MW steam turbine rotor.

A Photographic Study of Flow Boiling Stability on a Plain Surface With Tapered Manifold

2015 ◽  
Author(s):  
Ankit Kalani ◽  
Satish G. Kandlikar
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
High Speed ◽  
Flow Boiling ◽  
High Heat ◽  
Bubble Nucleation ◽  
High Heat Transfer ◽  
Plain Surface ◽  
High Heat Transfer Coefficient

Flow boiling in microchannels offers many advantages such as high heat transfer coefficient, higher surface area to volume ratio, low coolant inventory, uniform temperature control and compact design. The application of these flow boiling systems has been severely limited due to early critical heat flux (CHF) and flow instability. Recently, a number of studies have focused on variable flow cross-sectional area to augment the thermal performance of microchannels. In a previous work, the open microchannel with manifold (OMM) configuration was experimentally investigated to provide high heat transfer coefficient coupled with high CHF and low pressure drop. In the current work, high speed images of plain surface using tapered manifold are obtained to gain an insight into the nucleating bubble behavior. The mechanism of bubble nucleation, growth and departure are described through high speed images. Formation of dry spots for both tapered and uniform manifold geometry is also discussed.

Subcooled Boiling of Surfactant Solutions

2000 ◽  
Author(s):  
G. Hetsroni ◽  
M. Gurevich ◽  
A. Mosyak ◽  
R. Rozenblit ◽  
L. P. Yarin
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
High Speed ◽  
Heated Surface ◽  
Pure Water ◽  
Video Camera ◽  
Subcooled Boiling ◽  
Bubble Behavior ◽  
Boiling Hysteresis

Abstract During subcooled boiling of pure water and water with cationic surfactants, the motion of bubbles and the temperature of the heated surface were recorded by both a high-speed video camera and an infrared radiometer. The results show that the bubble behavior and the heat transfer mechanism for the surfactant are quite different from those of clear water. Bubbles formed in Habon G solutions were much smaller man those in water and the surface was covered with them faster. Boiling hysteresis is found for degraded solutions. Dependencies of heat transfer coefficient for various solutions were obtained and compared. The boiling curves of surfactant are quite different from the boiling curve of pure water. Experimental results demonstrate that the heat transfer coefficient of the boiling process can be enhanced considerably by the addition of a small amount of Habon G. The experiments show that the limitations of the ER technique with respect to frequency response are outweighed by its unique capacity to measure wall temperature distribution with high spatial resolution over an area encompassing many nucleation sites and over long periods.

Shellside Vacuum Condensation With a Noncondensable Gas

2016 ◽  
Author(s):  
Susan N. Ritchey
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Atmospheric Pressure ◽  
High Speed ◽  
Process Conditions ◽  
Transfer Data ◽  
Noncondensable Gas ◽  
Overall Heat Transfer Coefficient ◽  
Vacuum Condensation

Shell-and-tube vacuum condensers are present in many industrial applications such as chemical manufacturing, distillation, and power production [1–3]. They are often used because operating a condenser under vacuum pressures can increase the efficiency of energy conversion, which increases the overall plant efficiency and saves money. Typical operating pressures in the petrochemical industry span a wide range of values, from one atmosphere (101.3 kPa) down to a medium vacuum (1 kPa). The current shellside condensation methods used to predict heat transfer coefficients are based on data collected near or above atmospheric pressure, and the available literature on shellside vacuum condensation generally lacks experimental data. The accuracy of these methods in vacuum conditions well below atmospheric pressure has yet to be validated. Recently, HTRI designed and constructed the Low Pressure Condensation Unit (LPCU) with a rectangular shellside test condenser. To date, heat transfer data have been collected in the LPCU for shellside condensation of a pure hydrocarbon and of a hydrocarbon with noncondensable gas at vacuum pressures ranging from 2.8 to 45 kPa (21 to 338 Torr). Traditional condensation literature methods underpredict the overall heat transfer coefficient by 20.8% ± 20.4% for the pure condensing fluid; whereas they overpredict heat transfer by 36.8% ± 40.0% with the addition of the noncondensable gas. Over or under predicting the overall heat transfer coefficient in the presence of noncondensable gases leads to inefficient condenser designs and the inability to achieve desired process conditions. With the addition of the noncondensable gas, the measured heat exchanger duty was significantly reduced compared to the pure fluid, even at inlet mole fractions below 5%. In one case, a noncondensable inlet mole fraction of 0.63% was estimated to reduce the duty by approximately 10%. Analysis of the acquired high-speed videos shows that the film thickness changes significantly from the top row to the bottom. The videos also display condensate drainage patterns and droplet interactions. The ripples and splashing of the condensate observed in the videos indicates that the Nusselt idealized model is not appropriate for analysis of a real condenser. This article presents the collected heat transfer data and high-speed images of shellside vacuum condensation flow patterns.

One Dimensional Model for Rotating Channels in the Turbine System: Part 2 — Formulation and Validation for Film Condensation

2013 ◽  
Author(s):  
Murali Krishnan R. ◽  
Zain Dweik ◽  
Deoras Prabhudharwadkar
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Steam Turbine ◽  
Compressible Flow ◽  
Saturation Temperature ◽  
Film Condensation ◽  
Bulk Temperature ◽  
Dimensional Model ◽  
One Dimensional

This paper provides an extension of the previously described [1] formulation of a one-dimensional model for steady, compressible flow inside a channel, to the steam turbine application. The major challenge faced in the network simulation of the steam turbine secondary system is the prediction of the condensation that occurs during the engine start-up on the cold parts that are below the saturation temperature. Neglecting condensation effects may result in large errors in the engine temperatures since they are calculated based on the boundary conditions (heat transfer coefficient and bulk temperature) which depend on the solution of the network analysis. This paper provides a detailed formulation of a one-dimensional model for steady, compressible flow inside a channel which is based on the solution of two equations for a coupled system of mass, momentum and energy equations with wall condensation. The model also accounts for channel area variation, inclination with respect to the engine axis, rotation, wall friction and external heating. The formulation was first validated against existing 1D correlation for an idealized case. The wall condensation is modeled using the best-suited film condensation models for pressure and heat transfer coefficient available in the literature and has been validated against the experimental data with satisfactory predictions.

Thermal Response Characteristics of Flat Plate Heated by High Temperature and High Speed Flow

2013 ◽  
Vol 448-453 ◽  
pp. 3316-3319
Author(s):  
Chuang Sun ◽  
Yang Zhao ◽  
De Fu Li ◽  
Qing Ai ◽  
Xin Lin Xia
Keyword(s):  
Heat Transfer ◽  
Temperature Field ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Flat Plate ◽  
High Speed ◽  
Convection Heat Transfer ◽  
Thermal Response ◽  
Convection Heat ◽  
Convection Heat Transfer Coefficient

According to the view of heat transfer, the process of the fluid flow with high temperature and high speed over a flat plate may be considered as the heat transfer process within a compressible thermal boundary layer. Based on the numerical results of thermal isolation assumption, combining the temperature comparison with modification method, a coupled method of convection heat transfer coefficient with temperature field of the plate is established, and the characteristics of the thermal response for the flat plate is dominated. Take some ribbed plates as instances, the convection heat transfer coefficient and temperature field of the plate are simulated through the provided coupled method. The results show that, not only the position and materials of the plate influence the convection heat transfer coefficient, but also the time.

Thermal Investigation of Integrated Combustor Vane Concept Under Engine-Realistic Conditions

2016 ◽  
Author(s):  
Simon Jacobi ◽  
Budimir Rosic
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Gas Turbines ◽  
High Speed ◽  
Secondary Flows ◽  
Experimental Measurements ◽  
Thermal Investigation ◽  
Nozzle Guide ◽  
The Heat Transfer Coefficient

This paper presents a thermal investigation of the Integrated Combustor Vane concept for power generation gas turbines with individual can combustors. This concept has the potential to replace the high-pressure turbine’s first vanes by prolonged combustor walls. Experimental measurements are performed on a linear high-speed cascade consisting of two can combustors and two integrated vanes. The modularity of the facility allows for the testing at engine-realistic high turbulence levels, as well as swirl strengths with opposing swirl directions. The heat transfer characteristics of the integrated vanes are compared to conventional nozzle guide vanes. The experimental measurements are supported by detailed numerical simulations using the inhouse CFD code TBLOCK. Experimental as well as numerical results congruently indicate a considerable reduction of the heat transfer coefficient (HTC) on the integrated vanes surfaces and endwalls caused by a differing state of boundary layer thickness. The studies furthermore depict a slight, non-detrimental shift in the heat transfer coefficient distributions and the strength of the integrated vanes secondary flows as a result of engine-realistic combustor swirl.

The Deformation Rule of the Cooled U75V Heavy Rail Caused by the Different Heat Transfer Coefficient

2011 ◽  
Vol 299-300 ◽  
pp. 1005-1011 ◽  
Author(s):  
Ming Xin Gao ◽  
Pei Long Wang ◽  
Hao Jia ◽  
Shan Hu Tong ◽  
Hua Song ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
High Speed ◽  
Reference Value ◽  
Ansys Software ◽  
Cooling Process ◽  
Technological Parameters ◽  
The Heat Transfer Coefficient ◽  
Heavy Rail

When rolled heavy rail is on the cooling bed for natural cooling, the heat transfer coefficient has important effect on the bending and section sizes of cooled heavy rail. In the paper, the heat-stress couple module ofANSYS software is adopted to carry on numerical simulation on the cooling process of 60kg/m U75V heavy rail, and we obtain the change rule that heat transfer coefficient has effect on bending curvature and section sizes of cooled heavy rail. This study is of great reference value on cooling bed design and the formulation of cooling technological parameters for high speed heavy rail.

scholarly journals THE STUDY OF TEMPERATURES IN A TUNGSTEN ELECTRODE AT REVERSE POLARITY ARCING

2021 ◽  
pp. 69-79
Author(s):  
V. P. Sidorov ◽  
◽  
D. E. Sovetkin ◽  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
High Speed ◽  
B Value ◽  
Limiting Current ◽  
Reverse Polarity ◽  
Start Time ◽  
Tungsten Electrode ◽  
Good Coincidence

The paper considers the features of energy release in a tungsten electrode under the reverse polarity TIG welding. The study substantiates the statement that the chemical composition of an electrode does not significantly affect the transfer of anode power to it. The specific effective power of an electrode is substantiated and taken as 6 W/A. The authors analyzed the features of arcing on the flat tip of a 3 mm diameter electrode using high-speed video. The analysis identified that at limiting currents ensuring tip melting, the tip heating is uniform over the cross-section. As a design scheme, the authors selected a continuous flat heat source on the semi-infinite rod surface with surface heat transfer. The authors obtained averaged values for volumetric heat capacity сρ=3.2 J/(cm3∙°С) and heat transfer coefficient а=0.3 cm2/s. The current at which the tip melting temperature is reached was taken as a limiting current. Using the limiting current value and start time of the electrode tip melting, the authors calculated the electrode heat transfer coefficient value b. The calculated melting depth for the over-limiting current welding mode showed good coincidence with an experiment. The authors recalculated the b value for the electrodes of 4-, 5-, and 6-mm diameter and calculated limiting currents for these diameters. The design limiting currents for these diameters also showed good coincidence with experimental results. The study showed that the increase of a coefficient up to 0.4 cm2/s does not cause changes in temperature and limiting currents at simultaneous сρ adjustment according to the constant thermal and physical properties сρа0.5. As a result, the authors obtained temperature dependencies for the electrode over time and length. Time dependence of the electrode tip heating allows calculating limiting currents with the decrease in arcing time.

scholarly journals Steady state CFD analysis of heat transfer coefficient in pressurised pipes of super-heater of OP210 steam boiler

2018 ◽  
Vol 240 ◽  
pp. 05008 ◽  
Author(s):  
Mariusz Granda
Keyword(s):  
Heat Transfer ◽  
Boundary Condition ◽  
Heat Transfer Coefficient ◽  
Steady State ◽  
Transfer Coefficient ◽  
Saturated Steam ◽  
Steam Boiler ◽  
Cfd Analysis ◽  
Convergence Criteria ◽  
Super Heater

The aim of the paper is Computational Fluid Dynamics (CFD) analysis of Wall Heat Transfer Coefficient (WHTC) of pressurized pipe as a part of super-heater of the OP210 boiler. The object of the investigation is convection from saturated steam to the wall of the pipe, which works under high pressure and high temperature. The analysis is an approach to obtain exact solutions of WHTC according to the third type boundary condition compared to direct results from CFD analysis. The paper consists of three-step approach typical for CFD analysis: (i) Pre-Processing, the most elaborated part of the analysis where knowledge about super-heaters, turbulence, velocity profile is important to 3D model, mesh and boundary condition definition. (ii) Simulation of steady state turbulent flow until convergence criteria are met. (iii) Post-Processing where different approaches to the WHTC are shown in comparison. Also, the investigation includes two different types of meshes (where a different number of inflation layers are used) and comparison between k-epsilon and Solid Shear Stress (SST) turbulence model.

Sign in / Sign up

Export Citation Format

Share Document