Thermo

Question 1

PV =

Answer 1

PV = mRT

Question 2

R =

Answer 2

Rbar/M

Question 3

PV/T (1) =

Answer 3

PV/T (1) = PV/T (2)

Question 4

x =

Answer 4

x = mg/ (mg + mf)
or
x = (v - vf) / (vg-vf)

Question 5

1-x =

Answer 5

1-x = mf / m

Question 6

v =

Answer 6

v = vf + x vfg;
h = xfhf + xghg
or
v = V/m

Question 7

Cv =

Answer 7

du/dt = Cp/k

Question 8

Cp =

Answer 8

Cp = dh/dt; and Cp = Cv + R (ideal gases)

Question 9

Power =

Answer 9

Work/time = KJ/s

Question 10

Work =

Answer 10

Work = Pdv; Fdx; KJ

Question 11

Enthalpy (h)

Answer 11

h = u + Pvfg)
Energy to vapourise (h)
Internal energy (u)
Energy to expand (Pvfg)

Question 12

E =

Answer 12

U + Pe + Ke; = Q-W

Question 13

Internal energy

dU =

Answer 13

dH = mCpdT
Const pressure (Cp)

dU = mCvdT
Const vol (Cv)

OR

dU = U2-U1; U = mfuf+mgug; m = V/v

Question 14

dS (entropy) > 0 =?

Answer 14

An irreversible process

=0; reversible

Question 15

Control Volume equation:

Answer 15

Q̇− Ẇ= ∑out ṁ (ℎ+Pe +ke)− ∑in ṁ(ℎ+Pe+ke)

=m ̇(dℎ+dpe +dke) (single stream)

Question 16

Heat engine COP

Answer 16

η= 1 − QL/QH

Can sub q for T

Question 17

Heat pump COP

Answer 17

B′= 1/η

Question 18

Refrigerator COP

Answer 18

B=

1 /
(QH/QL) −1

Question 19

Define an adiabatic system.

Answer 19

No heat or mass transfer across system boundary

Question 20

Define a closed system.

Answer 20

No mass transfer. Energy transfer only.

Control mass method.

Question 21

Define an open system.

Answer 21

Mass and energy transfer.

Control volume method.

Question 22

What are 3 forms of energy?

Answer 22

Kinetic - movement of mass;

Potential - position of mass;

Internal energy: molecularmotion, latent (intermolecular forces and phase change) and chemical (bonds within a molecule).

Question 23

First Law:

Answer 23

Energy can be transformed, not created or destroyed. E = Q-W

Question 24

mass = (in terms of Vol)

Answer 24

m = V/v

Question 25

What is the difference between the energy equation for a non-flowing fluid and a flowing fluid.

Answer 25

Nonflowing: e = u + ke + pe
Flowing: e = (u+Pv) + ke + pe
Pv = flow energy
h = u+Pv
e = h + ke + pe

Question 26

What is the Kelvin Planck statement?

Answer 26

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

Question 27

Clausius statement:

Answer 27

It is impossible to transfer heat without work