Fundamentals of Thermal-Fluid Sciences
Fundamentals of Thermal-Fluid Sciences
5th Edition
ISBN: 9780078027680
Author: Yunus A. Cengel Dr., Robert H. Turner, John M. Cimbala
Publisher: McGraw-Hill Education
bartleby

Videos

Question
Book Icon
Chapter 9, Problem 128P
To determine

The temperature at the inlet of each turbine and the thermal efficiency of the cycle.

Expert Solution & Answer
Check Mark

Explanation of Solution

Given:

Pressure of steam at the condenser (P1) is 20kPa.

Pressure of steam at the boiler (P3) is 5000kPa.

Pressure of steam at the reheat section (P4) is 1200kPa.

Temperature of water at the turbine inlet (T3) is 450°C.

Quality of steam at the exit of the turbines (x) is 0.96.

Calculation:

Draw the Ts diagram of the cycle as in Figure (1).

Fundamentals of Thermal-Fluid Sciences, Chapter 9, Problem 128P

The pressures are constant for the process 4 to 5 and process 6 to 1.

  P4=P5P6=P1

The entropies are constant for the process 3 to 4 and process 5 to 6.

  s3=s4s5=s6

Refer Table A-5, “Saturated water-Pressure table”, obtain the enthalpy and specific volume at state 1 corresponding to the pressure of 20kPa.

  h1=hf@20kPa=251.42kJ/kgv1=vf@20kPa=0.0010172m3/kg

Calculate the work done by the pump during process 1-2(wp,in).

  wp,in=v1(P2P1)=(0.0010172m3/kg)(5000kPa20kPa)=(0.0010172m3/kg)(5000kPa20kPa)(1kJ1kPam3)=5.065kJ/kg

Calculate the enthalpy at state 2(h2).

  h2=h1+wp,in=251.42kJ/kg+5.065kJ/kg=256.49kJ/kg

Refer Table A-5, “Saturated water-Pressure table”, obtain the following properties corresponding to the pressure of 1200kPa and quality of 0.96.

  hf=798.33kJ/kghfg=1985.4kJ/kgsf=2.2159kJ/kgKsfg=4.3058kJ/kgK

Calculate the enthalpy at state 4(h4).

  h4=hf+x4hfg=798.33kJ/kg+(0.96)(1985.4kJ/kg)=2704.3kJ/kg

Calculate the entropy at state 4(s4).

  s4=sf+x4sfg=2.2159kJ/kgK+(0.96)(4.3058kJ/kgK)=6.3495kJ/kgK

Refer Table A-6, “Superheated water”, obtain the enthalpy and temperature at state 3 corresponding to the pressure of 5000kPa and entropy of 6.3495kJ/kgK.

  h3=3006.9kJ/kgT3=327.2°C

Thus, the temperature at the inlet of the high-pressure turbine is 327.2°C.

Refer Table A-5, “Saturated water-Pressure table”, obtain the following properties corresponding to the pressure of 20kPa and quality of 0.96.

  hf=251.42kJ/kghfg=2357.5kJ/kgsf=0.8320kJ/kgKsfg=7.0752kJ/kgK

Calculate the enthalpy at state 6(h6).

  h6=hf+x6hfg=251.42kJ/kg+(0.96)(2357.5kJ/kg)=2514.6kJ/kg

Calculate the entropy at state 6(s6).

  s6=sf+x6sfg=0.8320kJ/kgK+(0.96)(7.0752kJ/kgK)=7.6242kJ/kgK

Refer Table A-6, “Superheated water”, obtain the enthalpy and temperature at state 3 corresponding to the pressure of 1200kPa and entropy of 7.6242kJ/kgK.

  h5=3436.0kJ/kgT5=481.1°C

Thus, the temperature at the inlet of the low-pressure turbine is 481.1°C.

Calculate the thermal efficiency of the cycle (ηth).

  ηth=1qoutqin=1h6h1(h3h2)+(h5h4)

  =12514.6kJ/kg151.42kJ/kg(3006.9kJ/kg256.49kJ/kg)+(3436.0kJ/kg2704.3kJ/kg)=12263.2kJ/kg3482.0kJ/kg=0.35=35%

Thus, the thermal efficiency of the cycle is 35%.

Want to see more full solutions like this?

Subscribe now to access step-by-step solutions to millions of textbook problems written by subject matter experts!

Chapter 9 Solutions

Fundamentals of Thermal-Fluid Sciences

Ch. 9 - Prob. 11PCh. 9 - Prob. 12PCh. 9 - Prob. 13PCh. 9 - Prob. 15PCh. 9 - Prob. 16PCh. 9 - Prob. 17PCh. 9 - Prob. 18PCh. 9 - Prob. 19PCh. 9 - Prob. 20PCh. 9 - Prob. 21PCh. 9 - Prob. 22PCh. 9 - Prob. 23PCh. 9 - Prob. 24PCh. 9 - Prob. 25PCh. 9 - Prob. 26PCh. 9 - Prob. 27PCh. 9 - Prob. 28PCh. 9 - Prob. 29PCh. 9 - Prob. 30PCh. 9 - Prob. 31PCh. 9 - Prob. 33PCh. 9 - Prob. 34PCh. 9 - Prob. 35PCh. 9 - Prob. 36PCh. 9 - Prob. 37PCh. 9 - Prob. 38PCh. 9 - Prob. 39PCh. 9 - Prob. 40PCh. 9 - Prob. 41PCh. 9 - Prob. 42PCh. 9 - Prob. 43PCh. 9 - Prob. 44PCh. 9 - Prob. 45PCh. 9 - Prob. 46PCh. 9 - Prob. 47PCh. 9 - Prob. 48PCh. 9 - Prob. 49PCh. 9 - Prob. 50PCh. 9 - Prob. 51PCh. 9 - Prob. 52PCh. 9 - Prob. 53PCh. 9 - Prob. 55PCh. 9 - Prob. 56PCh. 9 - Prob. 57PCh. 9 - Prob. 58PCh. 9 - Prob. 60PCh. 9 - Prob. 61PCh. 9 - Prob. 62PCh. 9 - Prob. 63PCh. 9 - Prob. 64PCh. 9 - Prob. 65PCh. 9 - Prob. 66PCh. 9 - Prob. 67PCh. 9 - A simple Brayton cycle using air as the working...Ch. 9 - Prob. 70PCh. 9 - Consider a simple Brayton cycle using air as the...Ch. 9 - Prob. 72PCh. 9 - Prob. 73PCh. 9 - Prob. 74PCh. 9 - A gas-turbine power plant operates on a simple...Ch. 9 - Prob. 77PCh. 9 - Prob. 78PCh. 9 - Prob. 79PCh. 9 - Prob. 80PCh. 9 - Prob. 81PCh. 9 - Prob. 82PCh. 9 - Prob. 83PCh. 9 - Prob. 84PCh. 9 - Prob. 85PCh. 9 - Prob. 86PCh. 9 - Prob. 87PCh. 9 - Prob. 89PCh. 9 - Prob. 90PCh. 9 - Prob. 91PCh. 9 - Prob. 92PCh. 9 - Prob. 93PCh. 9 - Prob. 94PCh. 9 - Prob. 95PCh. 9 - Prob. 96PCh. 9 - Prob. 97PCh. 9 - Prob. 98PCh. 9 - Prob. 99PCh. 9 - Prob. 100PCh. 9 - Prob. 101PCh. 9 - Prob. 102PCh. 9 - Prob. 103PCh. 9 - Prob. 104PCh. 9 - Prob. 105PCh. 9 - Prob. 106PCh. 9 - Prob. 107PCh. 9 - Refrigerant-134a is used as the working fluid in a...Ch. 9 - Prob. 109PCh. 9 - A simple ideal Rankine cycle with water as the...Ch. 9 - Prob. 111PCh. 9 - Prob. 112PCh. 9 - Prob. 113PCh. 9 - Prob. 114PCh. 9 - Prob. 115PCh. 9 - Prob. 116PCh. 9 - Prob. 117PCh. 9 - Prob. 119PCh. 9 - Prob. 120PCh. 9 - Prob. 121PCh. 9 - Prob. 122PCh. 9 - Prob. 123PCh. 9 - Prob. 124PCh. 9 - Prob. 125PCh. 9 - Prob. 127PCh. 9 - Prob. 128PCh. 9 - Prob. 129PCh. 9 - Prob. 130PCh. 9 - Prob. 131PCh. 9 - Prob. 132PCh. 9 - Why is the reversed Carnot cycle executed within...Ch. 9 - Prob. 134PCh. 9 - Prob. 135PCh. 9 - Refrigerant-134a enters the condenser of a...Ch. 9 - Prob. 137PCh. 9 - Prob. 138PCh. 9 - Prob. 139PCh. 9 - Prob. 140PCh. 9 - Prob. 141PCh. 9 - Prob. 142PCh. 9 - Prob. 143PCh. 9 - Prob. 144PCh. 9 - Prob. 145PCh. 9 - Prob. 146PCh. 9 - Prob. 148PCh. 9 - Prob. 149PCh. 9 - A commercial refrigerator with refrigerant-134a as...Ch. 9 - Prob. 151PCh. 9 - Prob. 153PCh. 9 - Prob. 154PCh. 9 - Prob. 155PCh. 9 - Prob. 156PCh. 9 - Prob. 157PCh. 9 - Prob. 158PCh. 9 - Prob. 159PCh. 9 - Refrigerant-134a enters the condenser of a...Ch. 9 - Prob. 161PCh. 9 - Prob. 162PCh. 9 - Prob. 164RQCh. 9 - Prob. 165RQCh. 9 - Prob. 166RQCh. 9 - Prob. 167RQCh. 9 - Prob. 168RQCh. 9 - A Brayton cycle with a pressure ratio of 12...Ch. 9 - Prob. 170RQCh. 9 - Prob. 171RQCh. 9 - Prob. 172RQCh. 9 - Prob. 173RQCh. 9 - Prob. 175RQCh. 9 - Prob. 176RQCh. 9 - Prob. 177RQCh. 9 - Prob. 178RQCh. 9 - Prob. 179RQCh. 9 - Prob. 180RQCh. 9 - Prob. 181RQCh. 9 - Prob. 182RQCh. 9 - Prob. 183RQCh. 9 - Prob. 184RQCh. 9 - Prob. 185RQCh. 9 - Prob. 186RQCh. 9 - A large refrigeration plant is to be maintained at...Ch. 9 - An air conditioner with refrigerant-134a as the...
Knowledge Booster
Background pattern image
Mechanical Engineering
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, mechanical-engineering and related others by exploring similar questions and additional content below.
Recommended textbooks for you
Text book image
Elements Of Electromagnetics
Mechanical Engineering
ISBN:9780190698614
Author:Sadiku, Matthew N. O.
Publisher:Oxford University Press
Text book image
Mechanics of Materials (10th Edition)
Mechanical Engineering
ISBN:9780134319650
Author:Russell C. Hibbeler
Publisher:PEARSON
Text book image
Thermodynamics: An Engineering Approach
Mechanical Engineering
ISBN:9781259822674
Author:Yunus A. Cengel Dr., Michael A. Boles
Publisher:McGraw-Hill Education
Text book image
Control Systems Engineering
Mechanical Engineering
ISBN:9781118170519
Author:Norman S. Nise
Publisher:WILEY
Text book image
Mechanics of Materials (MindTap Course List)
Mechanical Engineering
ISBN:9781337093347
Author:Barry J. Goodno, James M. Gere
Publisher:Cengage Learning
Text book image
Engineering Mechanics: Statics
Mechanical Engineering
ISBN:9781118807330
Author:James L. Meriam, L. G. Kraige, J. N. Bolton
Publisher:WILEY
Power Plant Explained | Working Principles; Author: RealPars;https://www.youtube.com/watch?v=HGVDu1z5YQ8;License: Standard YouTube License, CC-BY