ConcepTests in Chemical Engineering Thermodynamics

Note: Slides marked with JLF were adapted from the ConcepTests of John L. Falconer, U. Colorado. Cf. Chem. Eng. Ed. 2004,2007

1.3 What causes an azeotrope?

A. The components can’t be distilled.

B. The components have similar boiling temperatures.

C.The components like each other in the extreme.

D.The components dislike each other in the extreme.

Day1 Review

1.4 What’s the difference between a chemist and a chemical engineer?

A. Engineers like numbers.

B. About 20k$/yr.

C.Engineers care more about profits.

D.Engineers ask, “How does it work?”

Day1 Review

1.1 What is temperature?

A. “Hotness.”

B. A measure of heat.

C.A measure of kinetic energy.

D.What a thermometer says.

Day2 Preview

1.2 The picture below represents hard spheres colliding in a planar box (like an air hockey table). Which represents the area of the box that should be used to compute density?

A. The blue area.

B. The area inside the green (and grey) bars.

C.None of the above.

Day1 Review

2.1. Which of the following represents an ideal gas?

(a) (b)

(c) (d)

-10

-5

0

5

10

0 0.2 0.4 0.6 0.8r (nm)

u/k

(K

)

-10

-5

0

5

10

0 0.2 0.4 0.6 0.8r (nm)

u/k

(K

)

-40

-20

020

40

60

0 0.2 0.4 0.6 0.8r (nm)

u/k

(K

)

-1.5

-1

-0.5

0

0.5

1

0 1 2

Day2 Review

2.2 Which is characteristic of a liquid relative to a vapor?

A. Liquid molecules move slower.

B. Liquid has a higher pressure.

C.Liquid molecules collide more.

D.The liquid has more energy.

Day2 Review

2.3 For water at 375C and 10 MPa, find the internal energy (kJ/kg).

A. 2596.9

B. 2699.6

C.2766.0

D.2833.1

Day2 Review

2.4 The outlet from a turbine consists of steam at 100C and an entropy (S) of 7 kJ/kg-K. What is its quality?

A. 5%

B. 10%

C.90%

D.95%

E. 100%

Day2 Review

3.1 When running a turbine, you want to recover as much energy as work as possible. If the efficiency is, say, 75% then 25% of the possible work must be lost. The lost work must show up in the turbine outlet stream somehow, but how?

A. Its pressure is relatively higher.

B. Its velocity is relatively higher.

C. Its temperature is relatively higher.

D. Its enthalpy is relatively higher.

Day1 Review

3.2 What causes the efficiency of a turbine to be less than 100%?

A. Reversibility.

B. Pressure gradient.

C.Disorder.

D.Stirring.

Day3 Review

4.1 Two molecules are bouncing in 2D with molecular weight of 16g/mole. Their velocities (m/s) are given by:<555, -432>, < -555,432>. Estimate the temperature in the box (K).

A.

B.

C.

D.

Day4 begin

2 kg

gas

vacuum

1 kg

gas

vacuum

gas

vacuum

4.2 In these piston/cylinders, when the red stop is slipped out, the gas expands, and the piston moves until it hits the black stops. Each system is adiabatic. Each starts at 10 atm and 25oC and are ideal gases.Which has the largest lost work?JLF*

A B C

4.3 The curve represents an adiabatic reversible process for an ideal gas. Which regions cannot bereached by an adiabatic irreversible process? JLF

0

3

6

9

0.5 3.5 6.5

V

U

0

3

6

9

0.5 3.5 6.5

V

U

A

0

3

6

9

0.5 3.5 6.5

V

U

B

C. All regions canbe reached

4.4 High pressure steam flows through an adiabatic turbine to steadily produce work. Which is the best energy balance for solving this problem?

Day4 Preview

A.Hin*min – Hout*mout + W = d(mU)/dt

B. U = Q + W

C. H = Q + W

D. U = PV + W + mv2/2

4.5 High pressure steam flows into a piston-cylinder to produce work. Which is the most appropriate energy balance for solving this problem?

A.Hin*min – Hout*mout + W = d(mU)/dt

B. U = Q + W

C. H = Q + W

D. U = PV + W + mv2/2

Day4 Preview

6.1 Steam at 200 bars and 600C flows through a valve and out to the atmosphere. What will be the temperature after the expansion?

A.

B.

C.

D.

Day6 Preview

6.2 A gas is filling a rigid tank from a supply line. Which of the following represents the most appropriate energy balance?

A.H = Q + W

B. U = Q + W

C. d(nU)=Hdn

D. nU = Hn

Day6 Preview

6.3 A gas is leaking from a rigid tank into the air. Which of the following represents the most appropriate energy balance?

A.H = Q + W

B. U = Q + W

C. d(nU)=Hdn

D. nU = Hn

Day6 Preview

6.4 An ideal gas (Cp=3.5R) is adiabatically and reversibly compressed in a steady state process from 25C and 1bar to 10bar. What is the exit temperature (C)?

A.

B.

C.

D.

Day6 Preview

6.5 A ideal gas (Cp=3.5R) is adiabatically and reversibly compressed in a steady state process from 25C and 1bar to 10bar. What is the work requirement (J/mol)?

A.

B.

C.

D.

Day6 Preview

7.1 Two exit streams leave a turbine. One stream is given, the other can be inferred from the throttle. The turbine produces 100kW. Estimate the heat loss (kW).

A..

B.

C.

D.

Day7 Preview

3.5MPa

350 C

(1)1100kg/hr (2)

990 kg/hr

110 kg/hr

(3)0.8MPa

1.5MPa

1 bar

120 C

225 C

7.2 Which of the following represents the value for the following integral?

A.

B.

C.

D.

Day7 Preview

3

1

xdx

7.3 Which of the following represents the value for the following integral?

A.

B.

C.

D.

Day7 Preview

32

1

ln( )(1 0.5 )x x x dx

7.4 (Ex2.15) An insulated tank initially contains 500 kg of steam and water at 2.0 MPa. Half of the tank volume is occupied by liquid and half by vapor. The temperature (C) of the tank initially is closest to:

A.

B.

C.

D.

Day7 Preview

7.5 Steam at 150 bars and 600 C passes through a heater expander and emerges at 100 bars and 700 C. There is no flow of work into or out of the heater-expander, but heat is supplied. Using the steam tables, compute the flow of heat (kJ/kg) into the heater expander per mole of steam.

A.

B.

C.

D.

Day7 Preview

7.6 Steam at 150 bars and 600 C passes through a heater expander. Compute the (dimensionless) value of [H(150,600)-H(1,600)]/RT for steam at the inlet conditions.

A..

B. .

C. .

D. .

Day7 Preview

QQ1.1.1 What is the relationship for the force vs. distance, F(r), between two molecules according to the Lennard-Jones potential model?

12 6

4r r

12 6

4r r

12 64

12 6r r r

A.

B.

C.

D.

Day7 QikQiz

0

r

r

r

QQ1.1.2 Molecules A and B can be represented by the square-well potential. For molecule A, = 0.4 nm and = 20e-22 J. For molecule B, = 0.8 nm and = 10e-22 J. Which molecule would you expect to have the higher boiling temperature?

A.

B.

Day7 QikQiz

QQ1.1.3 Steam initially at 20 MPa, T = 366C, and H = 2421.6 kJ/kg is throttled to 1.0 MPa. What % of the expanded stream is liquid?

A.

B. 60

C.40

D.20

Day7 QikQiz

QQ1.1.4 Write the most appropriate energy balance for the following: A compressor is filling the Goodyear blimp. System: the blimp and its contents

A.U = Q + W

B. d(nU) = Hdn + W

C. nU) = Hn + Q + W

D. = Q + W

Day7 QikQiz

8.1 An insulated tank initially contains 500 kg of steam and water at 2.0 MPa. Half of the tank volume is occupied by liquid and half by vapor. 25 kg of moisture free vapor is vented from the tank so that the pressure and temperature are always uniform throughout the tank. Analyze the situation carefully and calculate the final pressure in the tank. E-bal?

A.U = Q + W

B. d(nU) = Hdn + W

C. nU) = Hn + W

D. = Q + W

Day8 Preview

8.2 In an old-fashioned locomotive an insulated piston+ cylinder is connected through a valve to a steam supply line at 3MPa and 300°C. The back side of the piston is vented to the atmosphere at the right side of the cylinder. The volume of the cylinder is 70 liters. When the valve opens the piston is touching the left side of the cylinder. As the piston moves to the right it accomplishes 108 kJ of work before it touches the right side of the cylinder. Then, the cylinder contains 0.5 kg of steam and the temperature remains at 300°C. A.U = Q + W

B. d(nU) = Hdn + W

C. nU) = Hn + W

D. = Q + W

Day8 Preview

8.3 Megan is half Kevin’s age. In six more years, she’ll be four-fifths Kevin’s age. In 10 years, she’ll be six-sevenths Kevin’s age. Neither is a teenager. How old is Megan now?

A.1

B. 2

C. 3

D. 4

Day8 Preview

8.4 Identify the engineer based on the following:

A.This room is a mess!

B. Would it be too much to ask for you to put your sox in their drawers?!

C. I know my calculator is in here somewhere!

D. The entropy in this room is 50 MJ/mol-K!

Day8 Preview

8.5 Two coins are tossed once each. If heads, the coin is placed in boxA. If tails, the coin is placed in boxB. What is the probability that one coin is in each box?

A.0%

B. 10%

C. 25%

D. 50%

Day8 Preview

8.6 Five coins are tossed once each. If heads, the coin is placed in boxA. If tails, the coin is placed in boxB. What is the probability that one coin is in boxA?

A.0%

B. 15%

C. 20%

D. 25%

Day8 Preview

9.1 Five coins are tossed once each. If heads, the coin is placed in boxA. If tails, the coin is placed in boxB. What is the probability that one coin is in boxA?

A.0%

B. 15%

C. 20%

D. 25%

Day9 Preview

9.2 Four coins are tossed once each. If heads, the coin is placed in boxA. If tails, the coin is placed in boxB. What is the probability that one coin is in boxA?

A.0%

B. 15%

C. 20%

D. 25%

Day9 Preview

9.3 Do not use a calculator to solve the following. Compute: log10(8000)-log10(4)-log10(2)=

A. 3

B. 2

C. 1

D. 0

Day9 Preview

9.4 Nitrogen at 300K and 10bar is adiabatically and reversibly expanded to 1bar. What is the final temperature (K)?

A.150

B. 200

C. 250

D. 300

Day9 Preview

9.5 Nitrogen at 300K and 10bar is throttled to 1bar. What is the final temperature(K)?

A.150

B. 200

C. 250

D. 300

Day9 Preview

9.6 Suppose two boxes but the one with NA particles is three times as large as the empty box. Then what is the change in entropy?

A.Rln(4/3)

B. Rln(3/4)

C. Rln(4/1)

D. Rln(1/4)

Day9 Preview

10.1 Three moles of N2 at 2 bars and 300K are expanded into a box that is 33.33% larger. Then what is the S?

A.Rln(4/3)

B. Rln(3/4)

C. 3Rln(4/3)

D. 3Rln(3/4)

Day10 Preview

10.2 One mole of O2 at 2 bars and 300K is expanded into a box that is four times larger. Then what is the S?

A.Rln(4/3)

B. Rln(3/4)

C. Rln(4/1)

D. Rln(1/4)

Day10 Preview

10.3 One mole of O2 is mixed with 3 moles of N2 at 2 bars and 300K. Then what is the final pressure (bar)?

A.2

B. 0.5

C. 0.25

D. 1

Day10 Preview

10.4 One mole of O2 is mixed with 3 moles of N2 at 2 bars and 300K. Then what is the S?

A.Rln(4/3)

B. 3Rln(4/3)

C. Rln(4/1)+Rln(4/3)

D. Rln(4/1)+3Rln(4/3)

Day10 Preview

10.5 One mole of O2 is mixed with 3 moles of N2 at 2 bars and 300K. Then what is the S/R?

A..ln(4/3) + 0.67ln(1/3)

B. 0.25ln(0.25)+0.75ln(0.75)

C. -0.25ln(1/4)-0.75ln(3/4)

D. ln(4/1)+3ln(4/3)

Day10 Preview

10.6 (Closed book) Estimate Cv/R for He.

A..

B. 1.5

C. 2.0

D. 2.5

Day10 Preview

10.7 (Closed book) Estimate Cv/R for N2.

A..

B. 2.0

C. 2.5

D. 3.0

Day10 Preview

QQ1.2.1 Identify the most appropriate energy balance for the following situation. A pot of water brought to a boil from initially cold water in a pressure cooker on the oven with the pressure relief valve operating perfectly. System: the pot and its contents.

A.U = Q + W

B. d(nU) = Hdn + Q + W

C. nU) = Hn + Q + W

D. = Q + W

Day11 QikQiz

QQ1.2.1b A disk is initially at the position (0.2,0.2)nm in a box that is 5nm on a side with its lower left corner at the origin in Cartesian coordinates. The disk is 0.4 nm in diameter. The velocity of the disk is (543,456)m/s. Compute the time (ns) when the disk collides with the east wall.

A. 0.0101

B. 0.0085

C.0.0110

D.0.0088

Day11 QikQiz

QQ1.2.2 If I fill an empty helium cylinder adiabatically to 1800 psia from a line at 300K, then seal it and allow it to equilibrate with the surrounding air on a 300K day, what will be the final pressure in the cylinder (psia)?

A. 1080

B. 1350

C. 1800

D. 2100

Day11 QikQiz

QQ1.2.3 For a system of 6 particles distributed between two boxes, what is the % of distinguishable microstates corresponding to the macrostate with 4 particles in Box A and 2 particles in Box B?

A. 20%

B. 15%

C. 30%

D. 80%

Day11 QikQiz

QQ1.2.4 One mole of O2 is mixed with 4 moles of N2 at 2 bars and 300K. Then what is the S/R?

A. 0.2ln(0.2) + 0.8ln(0.8)

B. 0.25ln(0.25)+0.75ln(0.75)

C. -0.25ln(1/4)-0.75ln(3/4)

D. [ln(5/1)+4ln(5/4)]/5

Day11 QikQiz

12.1 Charlie was cleaning his living room. He lifted a sofa cushion and found an equal number of pennies, nickels, and dimes totaling $1.28. How many of each coin did he find?

A. 4

B. 5

C. 6

D. 7

Day12 Preview

12.2 A steam engine is to operate between 500C and 50C. Estimate its thermodynamic efficiency(%) according to the Carnot guideline.

A. 20

B. 40

C. 60

D. 80

Day12 Preview

12.3 A heat pump converts work into heat, extracting heat from a colder source and supplying it to the higher temperature sink. Suppose 30kW of heat is to be pumped to 80 from 30F. Estimate how much work (kW) is required if Carnot efficiency is achieved.

A. 30

B. 20

C. 10

D. 5

Day12 Preview

12.4 Steam is supplied to a steady state turbine at 10 MPa and 600°C. The discharge from the adiabatic, reversible turbine is at 25C. Determine the quality of the outlet steam (%).

A. 85

B. 90

C. 95

D. 100

Day12 Preview

12.5 Steam is supplied to a steady state turbine at 10 MPa and 600°C. The discharge from the adiabatic, reversible turbine is at 25C. Determine the work generated (kJ/kg).

A. 1500

B. 2000

C. 2500

D. 3000

Day12 Preview

13.1 Steam undergoes a state change from 450 C and 3.5 MPa to 150C and 0.3MPa. Determine S (kJ/kg-K) from (a) steam tables.

A. 0.01

B. 0.03

C. 0.07

D. 0.14

Day13 Preview

13.2 Steam undergoes a state change from 450 C and 3.5 MPa to 150C and 0.3MPa. Determine S (kJ/kg-K) from (b) IG assumption.

A. 0.01

B. 0.03

C. 0.07

D. 0.14

Day13 Preview

13.3 Steam undergoes a sudden state change from 600K and 1 MPa to double the volume. Determine Tf (C) from (b) steam tables.

A. 300

B. 321

C. 327

D. 333

Day13 Preview

13.4 Instead of burning gas directly to get heat, it is proposed to run a heat engine (HE) that runs a heat pump (HP). Qh =40kJ/h. TF =800K;TS =263; Th =293. HE exhausts to TS. Compute QF (kJ/h)

A. 10

B. 6

C. 4

D. 3

Day13 Preview

13.5 1mol/min air enters at 500K, 2bar and exits at 350K, 1bar. The process produces 2000J/min of work. It also exchanges heat with a reservoir at 300K. Estimate Sgen.

A. -1.2

B. 0

C. 1.2

D. 3.3

Day13 Preview

14.1 A process produces as much work as possible from a turbine operating between 10MPa and exhausting at 40C, sat vapor. Estimate the entropy at the outlet.

A. 8.35

B. 8.25

C. 7.68

D. 0.57

Day14 Preview

14.2 A process produces as much work as possible from a turbine operating between 10MPa and exhausting at 40C, sat vapor. Estimate the work (kJ/kg).

A. 5200

B. 2625

C. 2573

D. 2406

Day14 Preview

14.3 A process heats saturated liquid water from 40C to steam at 10MPa and 1225C. Estimate the heat required (kJ/kg).

A. 5200

B. 5000

C. 2625

D. 167.5

Day14 Preview

14.4 A process produces as much work as possible from a turbine operating between 10MPa and exhausting at 40C, sat steam. The process condenses the vapor and pumps it to 10MPa (Wp~0) then reheats to steam at the turbine inlet conditions. Estimate the thermal efficiency (W/QH) of this cycle.

A. 0.50

B. 0.45

C. 0.40

D. 0.35

Day14 Preview

14.5 A process produces as much work as possible from a turbine operating with a max pressure of 10MPa and exhausting at 40C, sat steam. The boiler temperature is constrained by the softening temperature of steel. If you lower the temperature entering the turbine, the quality exiting will ____.

A. Increase

B. Decrease

Day14 Preview

14.6 A process produces as much work as possible from a turbine operating between 10MPa and exhausting at 40C, sat steam. The process condenses the vapor and pumps it to 10MPa (Wp~0) then reheats to steam at the turbine inlet conditions. Compute the thermodynamic efficiency of a Carnot cycle operating in the same temperature range.

A. 0.50

B. 0.65

C. 0.80

D. 0.95

Day14 Preview

15.1 A turbine compresses Freon134a (Cp/R=10.2, MW=102) from sat vapor at 0.126MPa to 0.789MPa. Estimate the minimal work requirement (kJ/kg) assuming the ideal gas law. (Hint: p654 for Tsat)

A. 50

B. 45

C. 40

D. 35

Day15 Preview

15.2 A valve throttles Freon134a (Cp/R=10.2, MW=102) from sat Liq at 0.789MPa to 0.126MPa. Estimate the enthalpy (kJ/kg) at the outlet. (Hint: p654)

A. 415

B. 385

C. 245

D. 175

Day15 Preview

15.3 A valve throttles Freon134a (Cp/R=10.2, MW=102) from sat Liq at 0.789MPa to 0.126MPa. The fluid from the valve is heated to saturated vapor. Estimate the ratio of this heat divided by the work of compressing the ideal gas from 0.126 to 0.789MPa (QL/W).

A. 4.5

B. 3.5

C. 2.5

D. 1.5

Day15 Preview

15.4 A turbine compresses Freon134a (Cp/R=10.2, MW=102) from sat vapor at 0.126MPa to 0.789MPa. Estimate the minimal work requirement (kJ/kg) using the chart on p653.

A. 50

B. 45

C. 40

D. 35

Day15 Preview

16.h1 The optimal intermediate pressure for continuous two-stage adiabatic compression of an ideal guess is:

A. P*=(P1+P2)/2

B. P*=(P1+P2)/3

C. P*=(P1+P2)/4

D. P*=(P1*P2)½

Day15 Preview

16.h2 HW3.17. The work produced (J/g) is:

A. 800

B. 1000

C. 1200

D. 1400

Day15 Preview

16.h2 HW3.27. The work required for compressor 1 (J/g) is:

A. 140

B. 120

C. 100

D. 80

Day15 Preview

16.h4 HW3.33. The initial can pressure (bar) is:

A. 190

B. 180

C. 160

D. 150

Day15 Preview

16.1 Which system will have the largest entropy change when the blue partition is removed? JLF

The gases are ideal.

3 atmN2

3 atm N2

2 atmN2

Vacuum

A

1 atm O2

Vacuum

B2 atm

N2

1 atmO2

C D

16.2 Which of the following processes could run under continuous operation? JLF

A. 1 + 2 B. 3 + 4 C. 4 D. 3 E. 1 + 3

WQH

1

hot

coldQC

WQH

2

hot

coldQC

WQH

4

hot

coldQC

WQH

3

hot

coldQC

16.3 This picture shows a DNA molecule on a surfacewith vertical pillars on half the surface. What willthe DNA do? JLF

A. Move into the pillars moreB. Move out onto the open areaC. Stay where it is

16.4 Adiabatic expansions and compressions are shown. One is reversible and one irreversible in each figure. Which are the irreversible curves? JLF

A. 1 & 3 B. 1 & 4 C. 2 & 3 D. 2 & 4

12P

T

start

34

P

T

start

T

S

1 4

2 3

T

S

1 4

2 3

T

S

1 4

4 3

T

S

1 4

2 3

A B

C D

16.5 Which diagram corresponds to a Carnot heat pump in which both adiabatic steps in the cycle are irreversible? JLF

QQ1.3.1 A process produces as much work as possible from a turbine operating between 5MPa and exhausting at 45C, sat steam. The process condenses the vapor and pumps it to 5MPa (Wp~0) then reheats to steam at the turbine inlet conditions. Compute the work generated by the turbine (kJ/kg).

A. 2000

B. 2250

C. 2500

D. 2750

Day 16 QikQiz 3

QQ1.3.2 A process produces as much work as possible from a turbine operating between 5MPa and exhausting at 45C, sat steam. The process condenses the vapor and pumps it to 5MPa (Wp~0) then reheats to steam at the turbine inlet conditions. Compute the thermodynamic efficiency of this Rankine cycle.

A. 0.60

B. 0.55

C. 0.50

D. 0.45

Day 16 QikQiz 3

QQ1.3.3 A process produces as much work as possible from a turbine operating between 5MPa and exhausting at 45C, sat steam. The process condenses the vapor and pumps it to 5MPa (Wp~0) then reheats to steam at the turbine inlet conditions. Compute the thermodynamic efficiency of a Carnot cycle operating in the same temperature range.

A. 0.65

B. 0.70

C. 0.75

D. 0.80

Day 16 QikQiz 3

QQ1.3.4 A turbine operates between 5MPa, 550C and 45C, sat steam. Compute the efficiency of this turbine.

A. 0.65

B. 0.70

C. 0.75

D. 0.80

Day 16 QikQiz 3

17.1 An adiabatic turbine is supplied with steam at 2.0 MPa and 600C and it exhausts at 98% quality and 24C. Compute the work output (kJ/kg).(15)

A. 3691

B. 2496

C. 1259

D. 1194

Day 17 PracTest (cf. 1993)

17.2. An adiabatic turbine is supplied with steam at 2.0 MPa and 600C and it exhausts at 98% quality and 24C. Compute the efficiency of the turbine.(20)

A. 0.76

B. 0.80

C. 0.84

D. 0.88

Day 17 PracTest (cf. 1993)

17.3. An ordinary vapor compression cycle is to be operated on R134a (Cp/R=10.2,MW=102) to cool a chamber to 260K. Heat will be rejected to air at 308K. The temperatures in the coils are 256K and 312K. Estimate the compressor work (J/g). (Hint: Use IG estimate )(10)

A. 4400

B. 420

C. 250

D. 43

Day 17 PracTest (cf. 1993)

A. 3.3

B. 3.1

C. 2.9

D. 2.7

Day 17 PracTest (cf. 1993)

17.4. An ordinary vapor compression cycle is to be operated on R134a (Cp/R=10.2,MW=102) to cool a chamber to 260K. Heat will be rejected to air at 308K. The temperatures in the coils are 256K and 312K. Estimate the COP.(10)

A. 0.2707

B. 0.3108

C. 1.2150

D. 1.3350

Day 18 QQ1.4

QQ1.4.1. An ordinary vapor compression cycle is to be operated on propane (Cp/R=8.85,MW=44) to cool a chamber to 260K. Heat will be rejected to air at 308K. The temperatures in the coils are 256K and 312K. Estimate the pressure in the condenser.

TK PMPa HL(J/g) HV(J/g) SL(J/g) SLJ/gK

256 0.2707 482 879 4.131 5.682

260 0.3108 490 883 4.158 5.669

308 1.2150 619 935 4.585 5.611

312 1.3350 624 942 4.600 5.619

A. 45

B. 50

C. 85

D. 90

Day 18 QQ1.4

QQ1.4.2. An ordinary vapor compression cycle is to be operated on propane (Cp/R=8.85,MW=44) to cool a chamber to 260K. Heat will be rejected to air at 308K. The temperatures in the coils are 256K and 312K. Estimate the work of compression (J/g).

TK PMPa HL(J/g) HV(J/g) SL(J/g) SLJ/gK

256 0.2707 482 879 4.131 5.682

260 0.3108 490 883 4.158 5.669

308 1.2150 619 935 4.585 5.611

312 1.3350 624 942 4.600 5.619

A. 3.1

B. 2.7

C. 2.2

D. 1.7

Day 18 QQ1.4

QQ1.4.3. An ordinary vapor compression cycle is to be operated on propane (Cp/R=8.85,MW=44) to cool a chamber to 260K. Heat will be rejected to air at 308K. The temperatures in the coils are 256K and 312K. Estimate the COP.

TK PMPa HL(J/g) HV(J/g) SL(J/g) SLJ/gK

256 0.2707 482 879 4.131 5.682

260 0.3108 490 883 4.158 5.669

308 1.2150 619 935 4.585 5.611

312 1.3350 624 942 4.600 5.619

End of File

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