Soal soal dibawah ini merupakan merupakan contoh penerapan dari konsep yang teah dijelaskan dalam

pertemuan ke 4 dan 5, baik substansi materi yang tertuang dalam e learning termo maupun saat

perkuliahan tatap muka di ruang kelas

EXAMPLE E3-1 At the exit of a nozzle (see accompanying

figure) a gas has the following properties: V1 = 95 m/s,

mdot2 = 0.5 kg/min, Jdot2 = 0.0635 kW. If the nozzle exit

diameter is 1 cm, determine (a) two thermodynamic

properties at the exit, and (b) the flow rate of enthalpy.

Neglect potential energy. [ Manual Solution] [TEST Solution]

Answers: (a) 0.895 m3/kg, 3.11 kJ/kg, (b) 0.02 kW

EXAMPLE E3-2 The specific volume of a gas in m3/kg is

experimentally related to the independent properties

temperature and pressure through the following functional

relationship: = 4.157 T/p, where T and p are expressed in K

and kPa respectively. Determine the change in , (a) exactly

and (b) approximately using Taylor's theorem for the

following change of state. State-1: p = 101 kPa, T = 1000 K;

State-2: p=100 kPa, T = 1005 K. [Manual Solution]

Answers: (a) 0.619m3/kg, (b) 0.615m3/kg

EXAMPLE E3-3 A piston-cylinder device contains steam at a

pressure of 1 MPa and a temperature of 300oC. Evaluate (a)

the difference between the left and right hand sides of the

first T-ds equation if the system comes to a new equilibrium

with its pressure decreasing by 1 kPa and temperature

increasing by 1oC. Use PC (Phase-Change) system state

daemon. (b) What-if-scenario: How would the answer

change if steam had velocities of 10 m/s and 100 m/s in the

two states? [Manual Solution] [TEST Solution]

Answers: (a) 5.3%, (b) 5.3%

EXAMPLE E3-4 A block of aluminum of mass 5 kg, initially at

equilibrium with the surroundings at 30oC and 100 kPa, is

placed in a pressurized chamber kept at a pressure of 10 MPa

and a temperature of 200oC. Determine the change in (a) the

internal energy, (b) enthalpy, (c) entropy of the block after it

comes to equilibrium with the chamber pressure and

temperature What-if-scenario: How would the answer in

part (a) and (c) change if the block were made of (e) copper,

(f) gold? [Manual Solution] [TEST Solution]

Answers: (a) 765 kJ, (b) 783.3 kJ, (c) 2.0 kJ/K, (d) 157.7 kJ, (e) 328.1 kJ, (f)

109.7 kJ

EXAMPLE E3-5 A pumping system delivers liquid water at a

higher pressure in an isentropic (constant entropy) manner.

At the inlet p1=100 KPa , V1 =10 m/s and z1 =0 and at the

exit p2 = 1000 KPa, V2 = 15 m/s and z2 = 5 m. Determine

the change in (a) specific internal energy, (b) specific stored

energy, (c) specific enthalpy, and (d) specific flow energy

between the inlet and exit. [Manual Solution] [TEST Solution]

Answers: (a) 0 kJ/kg, (b) 0.11 kJ/kg, (c) 0.90 kJ/kg, (d) 1.01 kJ/kg

EXAMPLE E3-6 Calculate the saturation temperature of (a)

water, (b) ammonia, (c) R-134a, and (d) nitrogen at 100

kPa. What-if-Scenario: How would the answers change if

the pressure were increased to 1 MPa? [Manual Solution] [TEST

Solution]

Answers:(a) 99.61oC, (b) -33.63oC, (c) -26.58oC, (d) -195oC, (e) 24.89oC

EXAMPLE E3-7 A pipe carrying refrigerant R-12 at 25oC as a

saturated liquid develops a small leak. Assuming the

atmospheric conditions to be 100 kPa and 25oC, determine

(a) the direction of flow at the leak, and (b) the temperature

of the refrigerant when exposed to the atmosphere. [Manual

Solution] [TEST Solution]

EXAMPLE E3-8 A tank contains superheated steam at 120

kPa. If the specific enthalpy is 2700 kJ/kg, determine the

temperature of the steam. [Manual Solution] [TEST Solution]

Answers: 112.86oC

EXAMPLE E3-9 A rigid tank with a volume of 0.02 m3 contains

0.5 kg of refrigerant ammonia (NH3) at 25oC. Determine the

phase composition. [Manual Solution] [TEST Solution]

Answers: Saturated Mixture

EXAMPLE E3-10 In the previous problem determine (a) x, (b)

u, and (c) the volume fraction y occupied by the liquid phase.

[Manual Solution] [TEST Solution]

Answers:(a) 35.12%, (b) 678.6 kJ/kg, (c) 540mL

EXAMPLE E3-11 The tank in the last example is heated until

all the liquid completely vaporizes. Determine (a) the

pressure, and (b) temperature in the tank. (c) What-if-

Scenario: How would the answers change if the tank were

heated until the liquid volume reduced to 200 mL? [Manual

Solution] [TEST Solution]

Answers: (a) 3148 kPa, (b) 67.8oC, (c) 2517 kPa

EXAMPLE E3-12 Saturated vapor of refrigerant R-134a flows

into an isentropic (constant entropy) compressor at a

pressure of 100 kPa. If the exit pressure is 1 MPa, determine

(a) the exit temperature. (b) Can you explain why entropy

remains constant despite an increase in temperature at the

exxit? [Manual Solution] [TEST Solution]

Answers:(a) 48.91oC, (b) 1.02 MPa

EXAMPLE E3-13 Water at 5 MPa and 140oC is pressurized at

constant entropy to a pressure of 10 MPa. Determine (a) the

change in temperature, and (b) enthalpy. Use the CL sub-

model for liquid water. (c) What-if-Scenario: How would

the results change if (c) the compressed liquid table or (d)

the solid/liquid model were used to model liquid water

instead? [Manual Solution] [TEST Solution]

Answers: (a) 0oC, (b) 5.79 kJ/kg, (c) 5.86 kJ/kg, 5.01 kJ/kg

EXAMPLE E3-14 A piston cylinder device having a volume of

2 L contains argon at a pressure of 1 atm and a temperature

of 550oR. The gas is heated to a temperature of 800oR in a

constant volume process. Determine (a) the mass of the gas,

and (b) the change in pressure, (c) entropy during the

process. Assume the atmospheric conditions to be 100 kPa

and 25oC. (e) What-if-Scenario: How would the answer in

part (c) change if the heating were carried out at a constant

pressure? [Manual Solution] [TEST Solution]

Answers:(a) 0.003 kg, (b) 46.1 kPa, (c) 0.0003 kJ/K, (d) 0.027 kJ, (e) 0.044 kJ

EXAMPLE E3-15 Superheated steam at a pressure of 10 kPa

and temperature 200oC undergoes a process to a final

pressure and temperature of 50 kPa and 300oC respectively.

Determine (a) Δv, (b ) Δu, (c) Δh, and (d) Δs, assuming

superheated steam to behave like a perfect gas. (e) What-

if-Scenario: How would these results change if the phase-

change model were used? [Manual Solution] [TEST Solution]

Answers:(a) -16.56m3/kg, (b) 141 kJ/kg, (c) 187.2 kJ/kg, (d) -0.38 kJ/kg.K,

(e) -16.54m3/kg

EXAMPLE E3-16 A tank of volume 10 m3 contains air at a

pressure of 100 kPa and a temperature of 300 K. The air is

heated to a temperature of 2000 K. Treating air as an ideal

gas, determine (a) the final pressure, and the change in the

total internal energy of air. (c) What-if-Scenario: How

would the answers change if the perfect gas model were

used? [Manual Solution] [TEST Solution]

Answers: (a) 667 kPa, (b) 17004 kJ, (c) 667 kPa

EXAMPLE E3-17 A tank of volume 10 m3 contains nitrogen at

a pressure of 3 MPa and a temperature of 125 K. Determine

the mass of nitrogen in the tank using the (a) ideal gas, (b)

real gas (Lee Kestler), and (c) real gas (Nelson-Obert)

models. What-if-Scenario: (c) How would the answers

change if the phase-change model were used? [Manual Solution]

[TEST Solution]

Answers: (a) 806 kg, (b) 1754 kg, (c) 1833 kg

EXAMPLE E3-18 (a) Predict the pressure of oxygen gas

having a temperature of 200 K and a specific volume of

0.001726 m3/kg using the real gas model. What-if-

Scenario: How would the answer change if we used (b) the

ideal gas equation of state, (c) the van der Waals equation,

(d) the BWR equation, or (e) the phase-change model is

used.? [Manual Solution] [TEST Solution]

Answers: (a) 21.33 MPa, (b) 29.55 MPa, (c) 24.57 MPa, (d) 19.5 MPa

EXAMPLE E3-19 Superheated steam at a pressure of 500 kPa

and temperature of 450oC undergoes an isothermal process

to a final pressure of 20 MPa. Determine the change in (a)

specific volume, and (b) enthalpy employing the real gas

model. What-if-Scenario: How would the answers change if

(c) the phase-change, (d) ideal gas, and (e) the perfect gas

model were used? [Manual Solution] [TEST Solution]

Answers: (a,c,d,e) -0.65 m3/kg, (b) -274.5 kJ/kg