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Flashcards in Units Deck (9)
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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



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