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.

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.

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.

scholarly journals Determination for Thickness of the Multilayer Thermal Insulation Clothing Based on the Inverse Problems

2019 ◽  
Vol 2019 ◽  
pp. 1-7
Author(s):  
Bo Yu ◽  
Qiao Chang ◽  
Tingting Zhao ◽  
Linlin Wang
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Inverse Problems ◽  
Surface Temperature ◽  
Thermal Insulation ◽  
Transfer Model ◽  
Optimal Thickness ◽  
Fire Area ◽  
In Fire ◽  
High Temperature Operation

In this paper, the optimal thickness of multilayer special clothing material under the high temperature operation based on the inverse problems is studied. We analyze the parameters of the thickness of thermal insulation clothing material and the surface temperature of the dummy. Using the least-squares fitting, the function with the distribution of the dummy surface temperature is established. Then the heat transfer model and optimization model to obtain the optimal thickness of different clothing layers are built, respectively. Taking the true data as an example, we give the application of thermal insulation clothing in fire area, and the results show that the models are feasible.

Influence of External Surface Resistance and Thermal Insulation Level on Energy Need for Cooling

2016 ◽  
Vol 824 ◽  
pp. 445-452
Author(s):  
Ivan Chmúrny
Keyword(s):  
Heat Transfer ◽  
Thermal Insulation ◽  
Surface Resistance ◽  
External Surface ◽  
External Environment ◽  
Summer Season ◽  
Climate Conditions ◽  
Heating And Cooling ◽  
Current Climate ◽  
Resistance To Heat

The value of the external surface resistance on the outside of the structure in the summer season affects the energy need for cooling buildings. The paper analyzes the convection and radiation in the external environment for the current climate conditions of Slovakia in terms of their impact on the value of the external surface resistance to heat transfer in the months when it is expected cooling of buildings. Analysis of the external surface resistance to heat transfer on the outside of the structure for the monthly method of calculating the energy need for heating and cooling.

scholarly journals Influence of insulation defects on the thermal performance of walls. An experimental and numerical investigation

2018 ◽  
Author(s):  
Iole Nardi ◽  
Stefano Perilli ◽  
Tullio de Rubeis ◽  
Stefano Sfarra ◽  
Dario Ambrosini
Keyword(s):  
Heat Transfer ◽  
Numerical Investigation ◽  
Thermal Insulation ◽  
Thermal Performance ◽  
Comsol Multiphysics ◽  
Insulating Material ◽  
Damaged Material ◽  
Vertical Walls ◽  
Damaged Materials ◽  
Numerical Approaches

The addition of insulating layers on vertical walls of buildings is a common practice for providing a higher thermal insulation of the envelope. Workmanship defects, however, might influence the effectiveness of such insulation strategy. Damaged materials, incorrect installation, use of aged or weathered materials might alter the capability of reducing heat transfer through the envelope, whether vertical or sloped. In this work, drawbacks caused by the wrong installation of insulating material and by damaged material are assessed. A specimen wall was investigated by experimental and numerical approaches, the latter carried out by using COMSOL Multiphysics®. Results are compared and discussed.

An Inverse Analysis Method for Estimation of Heat Flux and Temperature-Dependence of Heat Transfer Coefficient

2011 ◽  
Author(s):  
Shiro Kubo ◽  
Seiji Ioka
Keyword(s):  
Heat Transfer ◽  
Surface Temperature ◽  
Inverse Method ◽  
Thermal Stresses ◽  
Temperature History ◽  
Inner Surface ◽  
History Of ◽  
Transient Thermal ◽  
The Relationship ◽  
Inverse Analysis Method

Transient thermal stresses develop in pipes during start-up and shut-down. In previous papers the present authors [1–4] proposed an inverse method for determining the optimum thermal inlet liquid temperature history which reduced the maximum transient thermal stress in pipes. The papers considered multiphysics including heat conduction, heat transfer, and elastic deformation. The inverse method used the relationship between inner surface temperature history, transient temperature distribution and transient thermal stresses. The coefficient of heat transfer plays an important role in the evaluation of thermal stress. In this study an inverse method was developed for estimating heat flux and temperature-dependence of the coefficient of heat transfer from the history of the outer surface temperature and the liquid temperature. The method used the relationship between the outer surface temperature and the inner surface temperature. For the regularization of solution the function expansion method was applied in expressing the history of flux on the inner surface. Numerical simulations demonstrated the usefulness of the proposed inverse analysis method. By examining the effect of measurement errors of temperature on the estimation, the robustness of the method was shown.

Sign in / Sign up

Export Citation Format

Share Document