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The higher temperature object has molecules with more kinetic energy; collisions between molecules distributes this kinetic energy until an object has the same kinetic energy throughout. Thermal conductivity , frequently represented by k , is a property that relates the rate of heat loss per unit area of a material to its rate of change of ...
The SI unit for heat capacity of an object is joule per kelvin (J/K or J⋅K −1). Since an increment of temperature of one degree Celsius is the same as an increment of one kelvin, that is the same unit as J/°C. The heat capacity of an object is an amount of energy divided by a temperature change, which has the dimension L 2 ⋅M⋅T −2 ...
Most experimentally determined values of the thermal contact resistance fall between 0.000005 and 0.0005 m 2 K/W (the corresponding range of thermal contact conductance is 200,000 to 2000 W/m 2 K). To know whether the thermal contact resistance is significant or not, magnitudes of the thermal resistances of the layers are compared with typical ...
Authors in the paper [4] propose a reversible isobaric heating concept, in which the plotted heating data points and cooling data points line on the same curve. Authors [4] consider this heating and cooling process very close to the ideal isobaric. A cartoon plot of reversible heating/cooling proposed in paper [4] is shown as Fig. 3.
A second parameter, the Biot number arises in nondimensionalization when convective boundary conditions are applied to the heat equation. [2] Together, the Fourier number and the Biot number determine the temperature response of a solid subjected to convective heating or cooling.
These first Heisler–Gröber charts were based upon the first term of the exact Fourier series solution for an infinite plane wall: (,) = = [ + ], [1]where T i is the initial uniform temperature of the slab, T ∞ is the constant environmental temperature imposed at the boundary, x is the location in the plane wall, λ is the root of λ * tan λ = Bi, and α is thermal diffusivity.
Simple solutions for transient cooling of an object may be obtained when the internal thermal resistance within the object is small in comparison to the resistance to heat transfer away from the object's surface (by external conduction or convection), which is the condition for which the Biot number is less than about 0.1.
That is, the method assumes that the temperature within the object is completely uniform, although its value may change over time. In this method, the ratio of the conductive heat resistance within the object to the convective heat transfer resistance across the object's boundary, known as the Biot number, is calculated.