A Method of the Inverse Evaluation for Heat Transfer Coefficient between Al-Cu Alloys and Cooling Water

2011 ◽  
Vol 189-193 ◽  
pp. 2294-2299
Author(s):  
Zhong Lin Hou ◽  
Ting Li ◽  
Jun Qiao ◽  
Sheng Li Li
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Cooling Water ◽  
Transfer Model ◽  
Inductive Heating ◽  
Measured Temperature ◽  
Cu Alloys ◽  
The Heat Transfer Coefficient ◽  
Peak Value

The heat transfer coefficient between the alloys and cooling water is affected by a lot of factors and hard to measure, a new method was investigated with a self-designed system ultilizing SP-15 high-frequency inductive heating unit. Based on measured temperature curves and Fourier heat transfer model, quantitative correlation between heat transfer coefficient and temperature was obtained by inverse algorithm method of iterative simulation and automatic optimization. The results showed that in submerged water-cooling process, the heat transfer coefficient reached to a peak value at the beginning and then decreased with increasing temperature. A decrease of cooling water temperature increased the peak value of the heat transfer coefficient, but did not change temperature range of the peak value from 200°C to 225°C . The heat transfer coefficient was mainly dependent of interfacial temperature between the Al-Cu alloys and the cooling water.The temperatures range from 200°C to 225°C gave the highest heat flux transfer.

Combustion and Heat Transfer in 300MW Oxy-Fired CFBB

2011 ◽  
Vol 354-355 ◽  
pp. 369-375
Author(s):  
Chun Bo Wang ◽  
Xiao Fei Ma ◽  
Jiao Zhang ◽  
Jin Gui Sheng ◽  
Hong Wei Li
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Particle Diameter ◽  
External Heat ◽  
Transfer Model ◽  
Heat Transfer Characteristics ◽  
Operation Condition ◽  
Transfer Capability ◽  
The Heat Transfer Coefficient

A combustion and heat transfer model in oxy-fired CFBB was set. Particle diameter, voidage of the bed ,etc, was analyzed with 30%, 50%, and 70% oxygen. Take a 300MW CFBB for example, the heat transfer characteristics in furnace were numerical simulated. In the sparse zone, heat transfer coefficient is proportional to oxygen concentration at the same voidage of the bed; under the same operation condition, the heat transfer coefficient in CFB increases with the voidage of the bed at first, then it decreases. It was found the heat transfer capability decrease due to the higher concentration of oxygen. It is necessary to set an external heat exchanger to keep a normal combustion

scholarly journals Experimental Investigation on Condensation of Vapor in the Presence of Non-Condensable Gas on a Vertical Tube

2018 ◽  
Author(s):  
Shengjun Zhang ◽  
Feng Shen ◽  
Xu Cheng ◽  
Xianke Meng ◽  
Dandan He
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Total Pressure ◽  
Mass Fraction ◽  
Heat Removal ◽  
Heat Transfer Process ◽  
Transfer Model ◽  
Operation Conditions ◽  
The Heat Transfer Coefficient

According to the operation conditions of time unlimited passive containment heat removal system (TUPAC), a separate effect experiment facility was established to investigate the heat transfer performance of steam condensation in presence of non-condensable gas. The effect of wall subcooling temperature, total pressure and mass fraction of the air on heat transfer process was analyzed. The heat transfer model was also developed. The results showed that the heat transfer coefficient decreased with the rising of subcooling temperature, the decreasing of the total pressure and air mass fraction. It was revealed that Dehbi’s correlation predicted the heat transfer coefficient conservatively, especially in the low pressure and low temperature region. The novel correlation was fitted by the data obtained in the following range: 0.20~0.45 MPa in pressure, 20% ~ 80% in mass fraction, 15°C ~ 45°C in temperature. The discrepancy of the correlation and experiment data was with ±20%.

Heat Transfer With Insulated Combustion Chamber Walls and Its Influence on the Performance of Diesel Engines

1988 ◽  
Vol 110 (3) ◽  
pp. 482-488 ◽  
Author(s):  
G. Woschni ◽  
W. Spindler
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Combustion Chamber ◽  
Fuel Consumption ◽  
Temperature Difference ◽  
Wall Temperature ◽  
Cooling Water ◽  
Great Expectations ◽  
The Heat Transfer Coefficient

Recently great expectations were put into the insulation of combustion chamber walls. A considerable reduction in fuel consumption, a marked reduction of the heat flow to the cooling water, and a significant increase of exhaust gas energy were predicted. In the meantime there exists an increasing number of publications reporting on significant increase of fuel consumption with total or partial insulation of the combustion chamber walls. In [1] a physical explanation of this effect is given: Simultaneously with the decrease of the temperature difference between gas and wall as a result of insulation, the heat transfer coefficient between gas and wall increases rapidly due to increasing wall temperature, thus overcompensating for the decrease in temperature difference between gas and wall. Hence a modified equation for calculation of the heat transfer coefficient was presented [1]. In the paper to be presented here, recent experimental results are reported that confirm the effects demonstrated in [1], including the influence of the heat transfer coefficient, which depends on the wall temperature, on the performance of naturally aspirated and turbocharged engines.

The Research on Heat Transfer Coefficient of Wheel Rims of Large Capacity Steam Turbines

2013 ◽  
Vol 744 ◽  
pp. 100-104
Author(s):  
Wei Min Han ◽  
Yan Zhou ◽  
Heng Liang Zhang ◽  
Dan Mei Xie
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Turbine Rotor ◽  
Transfer Model ◽  
Steam Turbines ◽  
Large Capacity ◽  
Quantitative Calculation ◽  
Calculation Results ◽  
The Heat Transfer Coefficient

Several models for calculating the heat transfer coefficient of wheel rims of large capacity steam turbines are presented. Taking a certain 600MW supercritical turbine rotor as an example, the heat transfer coefficient of wheel rim under cold start-up are analyzed and calculated, according to the and comparison, and the quantitative calculation results are given The results show that the heat transfer coefficient of rotor rims obtained by Sarkar method is close to the heat transfer coefficient obtained by a research institute based on a rib heat transfer model. In finite element analyses, the calculation results by mentioned method could provide the heat transfer boundary condition of temperature and thermal stress field calculations of supercritical and ultra-supercritical steam turbine rotors.

Bio Inspired Particle Enhanced Capillary Heat Exchanger

2008 ◽  
Author(s):  
Fatemeh Hassanipour ◽  
Jose´ Lage
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Red Blood Cells ◽  
Blood Cells ◽  
Exchange Process ◽  
Heat Fluxes ◽  
Measured Temperature ◽  
Lung Capillaries ◽  
The Heat Transfer Coefficient

This study proposes a new cooling concept using encapsulated phase-change material particles in mini-channels. This novel method is inspired by the gas exchange process in the lung capillaries. An important characteristic of capillary blood flow is that the red blood cells fit very snugly into the capillary opening. Hence, it is conjectured that using particles with diameter similar to the channel diameter, in a manner similar to red blood cells in lung capillaries, is likely to enhance the heat transfer coefficient, even under laminar flow. Preliminary tests are performed with encapsulated Octadecan paraffin (C18H38) in a low-conductivity thin melamine shell, flowing through a test module. The effect of flow rate on the heat transfer coefficient and also the effect of using particles on enhancement of Nusselt number has been measured. Temperature distribution on the chip has also been investigated under various particle concentrations, heat fluxes and Reynolds numbers.

scholarly journals A Heat Transfer Model for the Production of Semi-Solid Billets with the SEED Process

2006 ◽  
Vol 519-521 ◽  
pp. 1525-1532 ◽  
Author(s):  
Josée Colbert ◽  
Dominique Bouchard
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Computer Model ◽  
Heat Transfer Model ◽  
Transfer Model ◽  
Inverse Technique ◽  
Solid Aluminum ◽  
Semi Solid ◽  
The Heat Transfer Coefficient

A heat transfer model was built to predict the temperature evolution of semi-solid aluminum billets produced with the SEED process. An inverse technique was used to characterize the heat transfer coefficient at the interface between the crucible and the semi-solid billet. The effect of several process parameters on the heat transfer coefficient was investigated with a design of experiments and the coefficient was inserted in a computer model. Numerical simulations were carried out and validated with experimental results.

RESEARCH OF THERMAL AND MASS-EXCHANGE PROCESSES IN GAS-LIQUID FILM ABSORBERS IN SURFACE-ACTIVE TECHNOLOGY

2021 ◽  
pp. 3-16
Author(s):  
O. Dzevochko ◽  
M. Podustov ◽  
A. Dzevochko
Keyword(s):  
Mathematical Modeling ◽  
Heat Transfer ◽  
Mass Transfer ◽  
Heat Transfer Coefficient ◽  
Liquid Phase ◽  
Transfer Coefficient ◽  
Sulfur Trioxide ◽  
Cooling Water ◽  
Transfer Coefficients ◽  
The Heat Transfer Coefficient

The article states that surfactants have an asymmetrically constructed molecule that contains hydrophilic and hydrophobic groups. The main department of surfactant production is the process of sulfation of organic matter with gaseous sulfur trioxide. It is shown that the process of sulfation in gas-liquid film absorbers consists of the following stages: the process of mass transfer of sulfur trioxide from the gas stream to the liquid phase; the process of absorption of sulfur trioxide by organic matter with the passage of an exothermic chemical reaction; the process of heat exchange between the liquid phase and the gas stream; the process of heat exchange between the liquid phase and the flow of cooling water. Studies of heat and mass transfer processes at these stages make it possible to select the necessary equations for the calculation of heat transfer coefficients, heat transfer coefficients and mass transfer coefficient. It is recommended to calculate the heat transfer coefficient from liquid to gas by the equation when the diffusion and thermal Prandtl numbers are close to unity. The use of the classical equation to calculate the heat transfer coefficient from the liquid phase to the wall of the reaction tube did not give the desired result. Therefore, an equation was used that takes into account the properties of the gas-liquid flow as a whole. It is recommended to calculate the heat transfer coefficient from the reaction pipe wall to the cooling water flow according to the classical Nusselt equation. Experimental data processing data for calculating the density and dynamic viscosity of the reaction mass along the length of the reactor are presented. The equation for calculating the mass transfer coefficient was obtained by analyzing 6 equations of different authors who were engaged in the process of sulfation of organic substances. A mathematical description of the sulfation process in a film absorber was developed for analysis. During the development of the mathematical description, the balance equations of mass and heat transfer for the reaction tube were compiled. Based on the results of mathematical modeling, an equation was chosen that includes the tangential stress at the gas-liquid interface. The results of mathematical modeling were compared with Gutierrez's experimental data and the results of Dabir's mathematical modeling. The obtained results will be used in mathematical modeling of the sulfation process in a film absorber.

scholarly journals Experimental Verification of the Inverse Method of the Heat Transfer Coefficient Calculation

Energies ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1440
Author(s):  
Piotr Duda ◽  
Mariusz Konieczny
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Heat Balance ◽  
Inverse Method ◽  
Unknown Boundary ◽  
Laboratory System ◽  
Measured Temperature ◽  
Coefficient Distribution ◽  
The Heat Transfer Coefficient

The purpose of this work is to formulate a method which can be used to solve nonlinear inverse heat conduction problems and to calculate the heat transfer coefficient distribution on the unknown boundary. The domain under consideration is divided into control volumes in polar coordinates, and heat balance equations are written. Based on temperature transients measured in selected points on the outer surface, temperature values in other points of the domain are determined. Finally, the heat transfer coefficient distribution on the inner surface with the unknown boundary condition is calculated from the presented heat balance equation. The proposed inverse method was verified experimentally using a collector that is part of a semi-industrial laboratory system. This collector is a horizontal, cylindrical thick-walled tank with flat side walls with outlets that enable oil supply and removal. Each side wall has an additional connector to ensure venting. The calculations made it possible to identify the phenomena occurring inside the collector during the experiment. The transient temperature distribution identified by the proposed inverse method was verified by a comparison of the calculated and the measured temperature transients in points inside the collector wall. Very good agreement is observed between the calculated and the measured temperature transients, which confirms the correctness of the identification. This proposed inverse method of the temperature and the heat transfer coefficient calculation is fast enough to apply in online thermal state monitoring systems. The proposed algorithm presented in this paper can easily be implemented industrially.

Evaporation of lignin-lean black liquor

TAPPI Journal ◽  
2015 ◽  
Vol 14 (7) ◽  
pp. 441-450
Author(s):  
HENRIK WALLMO, ◽  
ULF ANDERSSON ◽  
MATHIAS GOURDON ◽  
MARTIN WIMBY
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Black Liquor ◽  
Salt Content ◽  
Solubility Limit ◽  
Lignin Removal ◽  
Kraft Black Liquor ◽  
Black Liquors ◽  
The Heat Transfer Coefficient

Many of the pulp mill biorefinery concepts recently presented include removal of lignin from black liquor. In this work, the aim was to study how the change in liquor chemistry affected the evaporation of kraft black liquor when lignin was removed using the LignoBoost process. Lignin was removed from a softwood kraft black liquor and four different black liquors were studied: one reference black liquor (with no lignin extracted); two ligninlean black liquors with a lignin removal rate of 5.5% and 21%, respectively; and one liquor with maximum lignin removal of 60%. Evaporation tests were carried out at the research evaporator in Chalmers University of Technology. Studied parameters were liquor viscosity, boiling point rise, heat transfer coefficient, scaling propensity, changes in liquor chemical composition, and tube incrustation. It was found that the solubility limit for incrustation changed towards lower dry solids for the lignin-lean black liquors due to an increased salt content. The scaling obtained on the tubes was easily cleaned with thin liquor at 105°C. It was also shown that the liquor viscosity decreased exponentially with increased lignin outtake and hence, the heat transfer coefficient increased with increased lignin outtake. Long term tests, operated about 6 percentage dry solids units above the solubility limit for incrustation for all liquors, showed that the heat transfer coefficient increased from 650 W/m2K for the reference liquor to 1500 W/m2K for the liquor with highest lignin separation degree, 60%.

Sign in / Sign up

Export Citation Format

Share Document