Temperature Rise Times in Pneumatic Tires

1976 ◽  
Vol 4 (3) ◽  
pp. 181-189 ◽  
Author(s):  
S. K. Clark
Keyword(s):  
Heat Transfer ◽  
Thermal Properties ◽  
Temperature Rise ◽  
Thermal Equilibrium ◽  
Transfer Coefficients ◽  
Pneumatic Tire ◽  
Heat Transfer Coefficients ◽  
Idealized Model ◽  
Pneumatic Tires

Abstract An idealized model is proposed for heating of a pneumatic tire. A solution is obtained for the temperature rise of such a model. Using known thermal properties of rubber and known heat transfer coefficients, the time to reach thermal equilibrium is estimated.

Investigation Into the Effect of Uncertainty in Thermal Properties on Turbomachinery Disc Heat Transfer Using Both a Monte Carlo Simulation Technique and a Taylor Series Uncertainty Propagation Method

2007 ◽  
Author(s):  
Adam Cooke ◽  
Peter Childs ◽  
Christopher Long
Keyword(s):  
Heat Transfer ◽  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Thermal Properties ◽  
Boundary Conditions ◽  
Taylor Series ◽  
Uncertainty Propagation ◽  
Outer Radius ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients

The effect of uncertainties in the thermal properties of components and surrounding fluids is often ignored in the field of experimental turbomachinery heat transfer. The work reported here uses two different methods of uncertainty analysis to help quantify these effects: 1) a stochastic Monte Carlo simulation and 2) a Taylor series uncertainty propagation. These two methods were used on a steady state free disc test case having a turbulent flow regime. The disc modelled was made from IMI 318 titanium and had an inner and outer radius of 0.115 m and 0.22 m respectively, representative of engine and test rig geometry. The disc thickness was 0.016 m. Convective boundary conditions were derived from the relevant equation for local Nusselt number. The applied boundary conditions resulted in local heat transfer coefficients in the range of approximately 120 W/m2 K to 170 W/m2 K. Uncertainties for these heat transfer coefficients were a near identical match between the two different uncertainty methods and were found to be ± 0.66%. Calculated heat flux values fell within the range of approximately 1500 W/m2 and 5200 W/m2. The Monte Carlo uncertainty method returned uncertainty values varying from ± 1.17% to ± 0.47% from the inner and outer radii respectively. An extended Taylor series of uncertainty propagation returned uncertainties varying from ± 1.82% to ± 0.96%, from the inner and outer radius respectively and increased and decreased a number of times in between. These differences are due to assumptions and simplifications which need to be made when using the Taylor series method and shows that a Monte Carlo simulation analysis offers a better way of quantifying the uncertainties associated with disc to air heat transfer as it is more realistic. Studying the magnitudes of uncertainty allows the analyst to understand the impact that uncertainties in thermal properties can have on calculated values of disc to air heat fluxes and heat transfer coefficients.

scholarly journals The influence of polyisocyanurate (PIR) facing on the heat transfer through the corners of insulated building partitions

2020 ◽  
Vol 172 ◽  
pp. 08008
Author(s):  
Tomas Makaveckas ◽  
Raimondas Bliūdžius
Keyword(s):  
Heat Transfer ◽  
Thermal Properties ◽  
Thermal Insulation ◽  
Insulation Material ◽  
Transfer Coefficients ◽  
Thermal Insulation Material ◽  
Heat Transfer Coefficients ◽  
Thermal Bridge ◽  
The Stability ◽  
Structural Solutions

Prefabricated products made of polyisocyanurate (PIR) thermal insulation material covered with cardboard, plastic, aluminium or composite facings are used for thermal insulation of building envelopes. The facing of these products is selected according to their conditions of use, and the effect of the facing on the declared thermal properties of the product depend only on water vapor diffuse properties of the facing. However, at the corners of the building where these products are joined, facings can be in the direction of the heat flux movement and significantly increase heat transfer through the longitudinal thermal bridge formed in the corner of the building. After analysing the solutions for installation of PIR thermal insulation products on the walls and roof corners of buildings, calculations of the heat transfer coefficients of the linear thermal bridges were made, and the influence of various facings and different structural solutions on the heat transfer coefficient value of the thermal bridge was determined. Aluminium foil facing have the greatest influence, but other facings must also be considered. The structural solutions with the greatest increase in the heat transfer due to the effect of the facing were selected, and the influence to the thermal and air tightness properties of the structural solution when facing is removed were analysed, the stability of thermal properties of the thermal insulation material were analysed as well. Proposals for joining PIR thermal insulation products with heat-conductive facings in the corners of buildings were prepared.

Heat Transfer Rig for Hydrogen-Cooled Generator Field Windings

1969 ◽  
Vol 184 (9) ◽  
pp. 31-40
Author(s):  
D. F. Davidson
Keyword(s):  
Heat Transfer ◽  
Temperature Rise ◽  
Direct Contact ◽  
Surface Heat ◽  
Maximum Output ◽  
Test Results ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Turbine Generators ◽  
Accurate Knowledge

The maximum output from large turbine generators is limited mainly by the temperature rise of the rotating field winding. Hydrogen at a pressure of several atmospheres is normally used to cool this winding by direct contact with the copper. Accurate knowledge of surface heat transfer coefficients is essential to ensure that the average winding temperature rise does not exceed the specified value. A heat transfer rig was built to test full-size rotor coils in hydrogen and to compare actual with predicted copper temperatures. The construction of the rig is described, together with details of its operation and the various problems which had to be overcome. Tests were carried out on two designs of rotor coil. In one case the flow is laminar, and in the other it is turbulent. The test results are compared and the various heat transfer coefficients evaluated.

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