Week 5 Lecture 7

Question 2

Rate of entropy change =

Answer 2

Rate of entropy transfer + rate of entropy production

Question 3

At steady state the rate of entropy change is ____

Answer 3

0

Question 4

At steady state, the equation for rate of entropy is:

Answer 4

0 = rate of entropy transfer + rate of entropy production

Question 5

The rate of entropy transfer =

Answer 5

Σ(Qk/Tk) + Σmisi - Σmjsj

(Qk/Tk) represents the heat transfer occuring at temperature Tk
i and j refer to the inlet and outlet streams

Question 6

Rate of entropy production

Answer 6

S gen

Question 7

Rate of entropy transfer + Rate of entropy production equation

Answer 7

Σ(Qk/Tk) + Σmisi - Σmjsj + S gen = 0

Question 8

Entropy is not a ________ quantity

Answer 8

conserved

Question 9

If the process is irreversible, there maybe an ________

Answer 9

internal generation

Question 10

If the process is ________, there maybe an internal generation

Answer 10

irreversible

Question 11

Type of diagram used for Rankine cycle

Answer 11

T-S diagram

T is for temperature
S is for entropy

Question 12

enthalpy-entropy chart

Answer 12

h-s diagram

enthalpy-entropy chart

Question 13

p-h diagram

Answer 13

pressure enthalpy diagram

Question 14

constant entropy

Answer 14

isentropic

Question 15

isentropic conditions are shown by a ____ line on T-S and H-S diagrams

Answer 15

straight vertical

Question 16

example of a reversible heat engine

Answer 16

carnot cycle

Question 17

The two vertical steps on a carnot engine are ____ processes

Answer 17

adiabatic

Question 18

The two horizontal steps on a carnot engine are ____ processes

Answer 18

isothermal

Question 19

Carnot engine adiabatic compression equation for work

Answer 19

W = nCv(Th-Tc)

Question 20

Carnot engine adiabatic expansion equation for work

Answer 20

W = nCv(Tc-Th)

Question 21

Carnot engine isothermal expansion equation for work

Answer 21

W = nRT ln(P2/P3)

Question 22

Carnot engine isothermal compression equation for work

Answer 22

W = nRT ln(P1/P4)

Question 23

Net work of carnot cycle =

Answer 23

net work = W12 + W23 + W34 + W41
as W12 and W34 cancel, net work reduces to
net work = W23 + W41

Question 24

Type of diagram carnot cycle is shown on

Answer 24

P-V

Question 25

Result of carnot engine analysis shows that

Answer 25

- No engine can be more efficient than the Carnot engine - Net work extracted is the area inside the cycle

Question 26

Thermal or cycle efficiency, for a reversible process =

Answer 26

η = 1 - Tc/Th

Question 27

Reason why no engine can be more efficient than Carnot engine

Answer 27

irreversibility

Question 28

COP refrigeration

Answer 28

COP = Tc/ (Th - Tc)

Question 29

COP heat pump

Answer 29

COP = Th/ (Th - Tc)

Question 30

For a reversible heat engine:

Answer 30

W = Qh/Th (Th - Tc) Qh/Th = Qc/Tc

Question 31

Used to produce most forms of electricity

Answer 31

Vapour power cycle

Question 34

Rankine cycle components order

Answer 34

Pump Boiler Turbine Condenser ## Footnote Please Break The Chair

Question 35

In Rankine cycle, has input of work

Answer 35

Pump

Question 36

In Rankine cycle, has output of work

Answer 36

turbine

Question 37

Process over the pump in rankine cycle

Answer 37

reversible adiabatic compression (isentropic)

Question 38

Process over the turbine in rankine cycle

Answer 38

reversible adiabatic expansion (isentropic)

Question 39

Rankine cycle heat input/output

Answer 39

Heat input > condenser heat output

Question 40

Rankine cycle power input/output

Answer 40

Steam turbine power output >> pump power input

Question 41

Type of diagram Rankine cycle usually depicted on

Answer 41

T-S diagram

Question 42

High moisture content in the turbine leads to

Answer 42

Poor efficiency

Question 43

Step in Rankine cycle where Qh is added to the system

Answer 43

boiler

Question 44

Step in Rankine cycle where Qc exits the system

Answer 44

condenser