Heat Transport Flashcards
Mechanisms of heat transfer:
– Conduction
– Convection
– Radiation
Heat conduction relation
Fourier’s law q = Q_dot/A = -k dT/dx
Heat flux
Heat flow per unit area in x direction
Thermal conductivity
k effectiveness of a material to transmit energy
Temperature
measure of the level of energy that determines the potential for transmitting thermal energy
Q
rate of energy flow, total amount of thermal energy transferred per unit time (W = J/s)
q and Q are constant if
The heat source produces a constant 𝑄, and the area
A through which heat flows is fixed and uniform.
What does Biot number tell us
For small BiotNumber, temperature difference in solid is small relative to that in fluid so we can treat the solid as being at a uniform temperature
cp
The term 𝑐_𝑝 represents the specific heat capacity at constant pressure. It is a thermodynamic property of the fluid that describes how much heat is required to raise the temperature of 1 kilogram of the fluid by 1 degree Celsius (or 1 Kelvin) at constant pressure (J/kgK)
what is alpha equal to
alpha = k/(rho*c_p)
semi infinite geo
A semi-infinite geometry is defined for a system when the dimension in the primary direction of heat flow is large enough that the thermal effects on one surface are not propagated to the opposite side
radial velocity
v_r = omega*r
