External surface temperature measurements for the heat transfer analysis of internally heated cylindrical clad-tubes subjected to external forced convection bulk water coolant thermal-hydraulic conditions

2020 ◽  
Vol 368 ◽  
pp. 110779
Author(s):  
K. Govinder ◽  
J.F.M. Slabber ◽  
J.P. Meyer
Keyword(s):  
Heat Transfer ◽  
Surface Temperature ◽  
Forced Convection ◽  
External Surface ◽  
Bulk Water ◽  
Temperature Measurements ◽  
Heat Transfer Analysis ◽  
Water Coolant ◽  
Hydraulic Conditions

scholarly journals Experimental Determination of the Heat Transfer Coefficient of Real Cooled Geometry Using Linear Regression Method

Energies ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 180
Author(s):  
Asif Ali ◽  
Lorenzo Cocchi ◽  
Alessio Picchi ◽  
Bruno Facchini
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Linear Regression ◽  
Surface Temperature ◽  
Transfer Coefficient ◽  
External Surface ◽  
Internal Surface ◽  
Regression Method ◽  
Thermal Transient

The scope of this work was to develop a technique based on the regression method and apply it on a real cooled geometry for measuring its internal heat transfer distribution. The proposed methodology is based upon an already available literature approach. For implementation of the methodology, the geometry is initially heated to a known steady temperature, followed by thermal transient, induced by injection of ambient air to its internal cooling system. During the thermal transient, external surface temperature of the geometry is recorded with the help of infrared camera. Then, a numerical procedure based upon a series of transient finite element analyses of the geometry is applied by using the obtained experimental data. The total test duration is divided into time steps, during which the heat flux on the internal surface is iteratively updated to target the measured external surface temperature. The final procured heat flux and internal surface temperature data of each time step is used to find the convective heat transfer coefficient via linear regression. This methodology is successfully implemented on three geometries: a circular duct, a blade with U-bend internal channel, and a cooled high pressure vane of real engine, with the help of a test rig developed at the University of Florence, Italy. The results are compared with the ones retrieved with similar approach available in the open literature, and the pros and cons of both methodologies are discussed in detail for each geometry.

scholarly journals Transient Thermal Analysis in an Intermittent Ceramic Kiln with Thermal Insulation: A Theoretical Approach

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Ricardo S. Gomez ◽  
Túlio R. N. Porto ◽  
Hortência L. F. Magalhães ◽  
Clotildes A. L. Guedes ◽  
Elisiane S. Lima ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Surface Temperature ◽  
Thermal Insulation ◽  
External Surface ◽  
Energy Gain ◽  
Ceramic Fiber ◽  
Microsoft Excel ◽  
Insulating Material ◽  
Transient Thermal ◽  
Thermal Insulations

Increasing the thermal efficiency of drying and firing processes of ceramic products plays an important role for industries that want to remain competitive in the market. Thus, this work aims to evaluate the influence of the type and thickness of thermal insulations, applied on the external sidewalls of an intermittent ceramic kiln, on heat transfer, temperature distribution in the insulating material, maximum external surface temperature, and energy gain, compared to the kiln without thermal insulation. All proposed mathematical formulations are based on the energy conservation, and mathematical procedures are implemented in Microsoft Excel software. Here, it was tested four types of thermal isolators: fiberglass, rockwool, calcium silicate, and ceramic fiber. Results indicate that the greater the thickness of the thermal insulation, the lower the maximum external surface temperature and the greater the energy gain when compared to the kiln without thermal insulation. In addition, fiberglass is the insulating material, among the four types analyzed, which provides greater energy gain and greater reduction in maximum external surface temperature.

Effects of Heat Generation in an Air Hydrostatic Journal Bearing

1970 ◽  
Vol 92 (4) ◽  
pp. 607-616
Author(s):  
R. E. Baker ◽  
K. G. Hornung
Keyword(s):  
Heat Transfer ◽  
Heat Generation ◽  
High Speed ◽  
Journal Bearing ◽  
Temperature Measurements ◽  
Heat Transfer Analysis ◽  
Hydrostatic Bearing ◽  
Thermal Deformations ◽  
The Subject ◽  
Viscosity Variation

A rather complete heat transfer analysis is carried out for a specific air hydrostatic bearing. The effects of viscosity variation and thermal deformations are included. The result is a prediction of film temperature of the bearing at high speed. Torque and temperature measurements are made on the subject bearing and show fair correlation with the theory.

The Measurement of Full-Surface Internal Heat Transfer Coefficients for Turbine Airfoils Using a Nondestructive Thermal Inertia Technique

2003 ◽  
Vol 125 (1) ◽  
pp. 83-89 ◽  
Author(s):  
Nirm V. Nirmalan ◽  
Ronald S. Bunker ◽  
Carl R. Hedlund
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Surface Temperature ◽  
Transfer Coefficient ◽  
External Surface ◽  
Internal Heat ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Turbine Airfoils ◽  
Internal Heat Transfer

A new method has been developed and demonstrated for the non-destructive, quantitative assessment of internal heat transfer coefficient distributions of cooled metallic turbine airfoils. The technique employs the acquisition of full-surface external surface temperature data in response to a thermal transient induced by internal heating/cooling, in conjunction with knowledge of the part wall thickness and geometry, material properties, and internal fluid temperatures. An imaging Infrared camera system is used to record the complete time history of the external surface temperature response during a transient initiated by the introduction of a convecting fluid through the cooling circuit of the part. The transient data obtained is combined with the cooling fluid network model to provide the boundary conditions for a finite element model representing the complete part geometry. A simple 1-D lumped thermal capacitance model for each local wall position is used to provide a first estimate of the internal surface heat transfer coefficient distribution. A 3-D inverse transient conduction model of the part is then executed with updated internal heat transfer coefficients until convergence is reached with the experimentally measured external wall temperatures as a function of time. This new technique makes possible the accurate quantification of full-surface internal heat transfer coefficient distributions for prototype and production metallic airfoils in a totally nondestructive and non-intrusive manner. The technique is equally applicable to other material types and other cooled/heated components.

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