Thermo Flashcards
PV =
PV = mRT
R =
Rbar/M
PV/T (1) =
PV/T (1) = PV/T (2)
x =
x = mg/ (mg + mf)
or
x = (v - vf) / (vg-vf)
1-x =
1-x = mf / m
v =
v = vf + x vfg;
h = xfhf + xghg
or
v = V/m
Cv =
du/dt = Cp/k
Cp =
Cp = dh/dt; and Cp = Cv + R (ideal gases)
Power =
Work/time = KJ/s
Work =
Work = Pdv; Fdx; KJ
Enthalpy (h)
h = u + Pvfg)
Energy to vapourise (h)
Internal energy (u)
Energy to expand (Pvfg)
E =
U + Pe + Ke; = Q-W
Internal energy
dU =
dH = mCpdT Const pressure (Cp)
dU = mCvdT Const vol (Cv)
OR
dU = U2-U1; U = mfuf+mgug; m = V/v
dS (entropy) > 0 =?
An irreversible process
=0; reversible
Control Volume equation:
Q̇− Ẇ= ∑out ṁ (ℎ+Pe +ke)− ∑in ṁ(ℎ+Pe+ke)
=m ̇(dℎ+dpe +dke) (single stream)
Heat engine COP
η= 1 − QL/QH
Can sub q for T
Heat pump COP
B′= 1/η
Refrigerator COP
B=
1 /
(QH/QL) −1
Define an adiabatic system.
No heat or mass transfer across system boundary
Define a closed system.
No mass transfer. Energy transfer only.
Control mass method.
Define an open system.
Mass and energy transfer.
Control volume method.
What are 3 forms of energy?
Kinetic - movement of mass;
Potential - position of mass;
Internal energy: molecularmotion, latent (intermolecular forces and phase change) and chemical (bonds within a molecule).
First Law:
Energy can be transformed, not created or destroyed. E = Q-W
mass = (in terms of Vol)
m = V/v
What is the difference between the energy equation for a non-flowing fluid and a flowing fluid.
Nonflowing: e = u + ke + pe Flowing: e = (u+Pv) + ke + pe Pv = flow energy h = u+Pv e = h + ke + pe
What is the Kelvin Planck statement?
It is impossible to operate in a cycle and produce no effect other than work and heat exchange with a single reservoir.
e.g to do work you need a change in temp
Clausius statement:
It is impossible to transfer heat without work
