Units Flashcards
What do W and Ẇ indicate
W is total work done by the system
Ẇ is work done per unit of mass
What do Q, q and Q̇ indicate
Q indicates total quantity of heat (joules)
q (indicates rate of heat flow) power
Q̇ indicates rate of work flow per unit of mass
What is the units of entropy
kj/kg
What in the steam tables what is Hf Hg and Hfg
Hf is the enthalpy of a saturated fluid at a specific temperature. Hg is the Enthalpy of a saturated vapour at a specific temperature. Hfg is the difference between the two which is the specific enthalpy change of vapourisation. Hf is always m higher than Hg because most of the energy in steam is latent heat not sensible heat.
How is convective heat transfer calculated
Q = hA(delta T)
h =convection heat transfer coefficient, W/m2 °C
A =heat transfer surface area, m2
Ts =temperature of the surface, °C
T (infinity)=temperature of the fluid sufficiently far from the surface, °C
What is h with regards to convective heat transfer
It is the convective heat transfer coefficient
What is k with regards to heat transfer
thermal conductivity of the material W/m2
