Thermal treatment Flashcards
What is the Fouriers equation?
Thermal diffusivity x time / thickness^2
What is Fouriers equation in symbols?
at/x^2
What is the equation for thermal diffusivity?
a=k/density cp
What is the symbol cp?
Specific heat capacity
What is the equation for sensible heat?
Q= cp x mass x change in temperature
What is the definition of conductance?
Sum of the resistances to heat flow
What is the equation for conductance?
1/Resistance
What is the definition of heat transfer coefficient?
Measure of how easily heat can travel through a material
Why can conductance not be summed?
It is limited to its lowest value
How does liquid behave at low flow rates?
In layers
What is the difference between ‘layers’ at the centre vs at the surface?
Centre layers are moving faster whereas surface layers are virtually stationary
How can flow rate be measured?
Reynolds’s number
What happens if Re<2000?
Streamline
What happens if Re>4000?
Turbulent flow
What happens in heat exchangers?
Cool fluid flows opposite to hot fluid to cool it
