Development of a generalized thermal resistance model for the calculation of effective thermal conductivities in periodic open cellular structures (POCS)

2022 ◽  
Vol 183 ◽  
pp. 122083
Author(s):  
Konrad Dubil ◽  
Hannah Wolf ◽  
Thomas Wetzel ◽  
Benjamin Dietrich
Keyword(s):  
Thermal Resistance ◽  
Cellular Structures ◽  
Resistance Model ◽  
Thermal Conductivities

scholarly journals Thermal-wet model of knitted double jersey based on backpropagation algorithm of neural network

2020 ◽  
Vol 15 ◽  
pp. 155892501990083
Author(s):  
Xintong Li ◽  
Honglian Cong ◽  
Zhe Gao ◽  
Zhijia Dong
Keyword(s):  
Neural Network ◽  
Water Vapor ◽  
Thermal Resistance ◽  
Resistance Test ◽  
Training Algorithm ◽  
Backpropagation Algorithm ◽  
Optimal Network ◽  
Resistance Model ◽  
Hidden Layer ◽  
The Relationship

In this article, thermal resistance test and water vapor resistance test were experimented to obtain data of heat and humidity performance. Canonical correlation analysis was used on determining influence of basic fabric parameters on heat and humidity performance. Thermal resistance model and water vapor resistance model were established with a three-layered feedforward-type neural network. For the generalization of the network and the difficulty of determining the optimal network structure, trainbr was chosen as training algorithm to find the relationship between input factors and output data. After training and verification, the number of hidden layer neurons in the thermal resistance model was 12, and the error reached 10−3. In the water vapor resistance model, the number of hidden layer neurons was 10, and the error reached 10−3.

Piston-Liner Thermal Resistance Model for Diesel Engine Simulation: Part 1: Formulation and Tuning

1991 ◽  
Vol 205 (5) ◽  
pp. 343-352 ◽  
Author(s):  
Y Rasihhan ◽  
F J Wallace
Keyword(s):  
Heat Transfer ◽  
Diesel Engine ◽  
Thermal Resistance ◽  
Direct Injection ◽  
Transfer Model ◽  
Conductive Heat ◽  
Axially Symmetric ◽  
Engine Simulation ◽  
Axial Movement ◽  
Resistance Model

A simple, effective and computationally economical piston-liner thermal resistance model for diesel engine simulation is described. In the model, the detailed shape of the piston and its axial movement and interaction with liner nodes are all taken into account. An imaginary node within the piston provides the necessary temperature difference between the piston and the liner nodes for conductive heat transfer, which is expected to reverse its direction with liner insulation. In the liner, an axially symmetric two-dimensional heat-transfer model is used. Later the piston-liner model is tuned for the experimental single cylinder, direct injection, Petter PH 1W engine used at Bath University, against the experimental piston temperature and liner temperature distribution.

The thermal conductivity of solid helium

1952 ◽  
Vol 214 (1119) ◽  
pp. 546-563 ◽  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Resistance ◽  
Single Crystals ◽  
Liquid Helium ◽  
Solid Helium ◽  
Boundary Scattering ◽  
Conductivity Measurements ◽  
Helium Ii ◽  
Characteristic Temperatures ◽  
Thermal Conductivities

The thermal conductivities of crystals of solid helium at densities between 0⋅194 and 0⋅218 g/cm 3 have been measured at liquid-helium temperatures. In order to interpret the results, the specific heat of solid helium at these densities has been measured from 0⋅6 to 1⋅4° K. The range of densities employed is sufficient to allow the observation of Debye characteristic temperatures varying by 40 %, and of thermal conductivities varying by factors of over 10. It is shown that the conductivity measurements are in accord with the ‘umklapp’ type of thermal resistance derived by Peierls (1929, 1935). Further work was restricted by the difficulty of obtaining good single crystals in narrow tubes, but measurements of the conductivity at one density were obtained down to 0⋅3° K. In this region the conductivity is limited by boundary scattering and is higher than that observed by other authors for liquid helium II at similar temperatures.

A Simple Thermal Resistance Model for Open Cell Metal Foams

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Pradeep. M. Kamath ◽  
C. Balaji ◽  
S. P. Venkateshan
Keyword(s):  
Heat Transfer ◽  
Thermal Resistance ◽  
Contact Resistance ◽  
Convective Heat Transfer Coefficient ◽  
Vertical Channel ◽  
Metal Foams ◽  
Experimental Results ◽  
Actual Case ◽  
Open Cell ◽  
Resistance Model

This paper presents a methodology for obtaining the convective heat transfer coefficient from the wall of a heated aluminium plate, placed in a vertical channel filled with open cell metal foams. For accomplishing this, a thermal resistance model from literature for metal foams is suitably modified to account for contact resistance. The contact resistance is then evaluated using the experimental results. A correlation for the estimation of the contact resistance as a function of the pertinent parameters, based on the above approach is developed. The model is first validated with experimental results in literature for the asymptotic case of negligible contact resistance. A parametric study of the effect of different foam parameters on the heat transfer is reported with and without the presence of contact resistance. The significance of the effect of contact resistance in the mixed convection and forced convection regimes is discussed. The procedure to employ the present methodology in an actual case is demonstrated and verified with additional, independent experimental data.

Piston-Liner Thermal Resistance Model for Diesel Engine Simulation: Part 2: Application to various Insulation Schemes

1991 ◽  
Vol 205 (5) ◽  
pp. 353-361 ◽  
Author(s):  
Y Rasihhan ◽  
F J Wallace
Keyword(s):  
Diesel Engine ◽  
Temperature Distribution ◽  
Thermal Resistance ◽  
Heat Fluxes ◽  
Engine Simulation ◽  
Resistance Model

The piston-liner thermal resistance model, developed in Part 1, is applied to various piston and/or liner insulation schemes. The effects of insulation on piston-liner conduction and gas to wall heat fluxes and liner temperature distribution are examined. The small effect of insulation of the middle and lower parts of the liner is clearly shown.

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