Thermodynamics

Question 1

Quality

Answer 1

fraction of total mass that is vapor

x=m_g/(m_g+m_f)

Question 2

Specific Enthalpy

Answer 2

h=u+pv

h=h_f+xh_fg

Question 3

Molar Enthalpy

Answer 3

H=mh

Question 4

Internal Energy

Answer 4

U=H-pV

u=u_f+xu_fg

delta u = c_v*delta T

Units: kj/kg

Question 5

Gibbs Function

Answer 5

g=h-Ts=u+pv-Ts

Question 6

Heat Capacity (Specific Heat)

Answer 6

c_v - Constant Volume

c_p - Constant Pressure

Q=mc(T₂-T₁)

Q=heat energy

Question 8

First law of thermodynamics

Answer 8

Q=delta U + W

Question 9

conservation of energy for open systems

Answer 9

Question 10

Universal Constant: R

Answer 10

8314 m^3*Pa/(kmol*k)

Question 11

Ideal Gases undergoing Isentropic Processes

Answer 11

p_2/p_1=(v_1/v_2)^k

T_2/T_1=(v_1/v_2)^(k-1)

T_2/T_1=(p_2/p_1)^((k-1)/k)

k=c_p/c_v

Question 12

Entropy

Answer 12

delta s = integral ds = integral dq/T

Question 13

adiabatic process

Answer 13

A process in which no energy crosses the system boundary

Question 14

throttling process

Answer 14

An adiabatic process in which there is no change in enthalpy, but for which there is a significant pressure drop

Question 15

isochoric or isometric process

Answer 15

constant volume process

W=0

T/p=constant

Question 16

polytropic process

Answer 16

A process which obeys the polytropic equation of state. (pv^n) Gases always constitute the system in polytropic processes.

pv^n=constant

W=(p2v2-p1v1)/(1-n) - closed system

W=n(p2v2-p1v1)/(1-n) - closed system

Question 17

isentropic

Answer 17

pv^k=constant

W=(p2v2-p1v1)/(1-k)

=R(T2-T1)/(1-k)

=(RT/(k-1))*(1-(p2/p1)^(k-1)/k

Question 18

isothermal

Answer 18

pv=constant

W=RTln(v2/v1)=RTln(p1/p2) - closed system

W=RTln(v2/v1)=RTln(p1/p2) - open system

Question 19

Work

Answer 19

First assume some combination of Pdv