ME 231
Exam 1
09/29/2014
Exam rules
1. You have 50 minutes to complete the exam.
2. This exam is closed book
3. You can bring one A-4 size paper with information that could be relevant to the exam
4. You may not use
(a) Textbook (it is fine to use the tab
Problem 5.1
Fill in the table with the missing properties of water. Show any calculations that are required, but
you do not need to include the given, find, sketch or assumption sections.
p
(kPa)
200
T
(C)
h
(kJ/kg)
140
5000
700
Phase and quality
(if appl
PROBLEM 6.21
PROBLEM 6.39
PROBLEM 6.52
Figure P6.52 shows a piston-cylinder assembly containing 20 lb of water, initially a saturated
liquid at 20 lbf/in.2 in contact with a hot plate. Heat transfer occurs slowly from the hot plate to
the contents of the
ME 231
Homework 6 Chapter 6
(Total 35 points)
11/07/2014
1. One kg of water in a piston-cylinder assembly undergoes the two internally reversible
processes in series shown in Fig below. For each process, determine, in kJ, the heat
transfer and the work. (
1.21 A 2-lb sample of an unknown liquid occupies a volume of 62.6 in.3 For the liquid
determine (a) the specific volume, in ft3/lb, and (b) the density, in lb/ft3.
KNOWN: Volume and mass of an unknown liquid sample.
FIND: Determine (a) the specific volume
ME 231 Homework 3 Chapter 3 09/19/2014
1. Determine the phase or phases in a system consisting of H20 at the following conditions
and sketch Tv diagram showing the location of each state (6 points)
(a) p =10 bar, T = 150 °C
(b) T = 100 C, p = 0.5 bar
(0)
Sample Exam
09/22/2014
Important information: The in class problems and HW problems are important.
1. What is a thermodynamic cycle?
2. What are different types of thermodynamic cycles? Give the equation for the
performance co-efficient for each.
3. What
ME 231 Homework Set 9
Due by 9:15 am on Thursday, November 5, 2015
Remember to follow the solution format discussed in class (given, find, sketch,
assumptions, basic equations, solution). Start each problem on a separate piece of paper.
Only the three pro
ME 231 Homework Set 8
Due by 9:15 am on Thursday, October 22, 2015
Remember to follow the solution format discussed in class (given, find, sketch,
assumptions, basic equations, solution). Start each problem on a separate piece of paper.
Only the three pro
Problem 1
Figure 1 shows a piston-cylinder assembly fitted with a spring. The cylinder contains
water, initially at 1000F, and the spring is in a vacuum. The piston face, which has an
area of 20 in2, is initially at x1 = 20 in. The water is cooled until t
ME 231 Homework Set 6
Due by 9:15 am on Thursday, October 8, 2015
Remember to follow the solution format discussed in class (given, find, sketch, assumptions,
basic equations, solution). Start each problem on a separate piece of paper. The homework must
b
MEEN 3310 Homework Set 2
Due by 9:15 am on Tuesday, September 8, 2015
Remember to follow the solution format discussed in class (given, find, sketch,
assumptions, basic equations, solution). Start each problem on a separate piece of paper.
The homework mu
Problem 10.1
A power cycle receives energy QH by heat transfer from a hot reservoir at TH = 1500R and rejects
energy QC by heat transfer to a cold reservoir at TC = 500R . For each of the following cases,
determine whether the cycle operates reversibly, o
ME270 Project Charter: Interactive Exercise
Instructions: Save this form upon completion. Once you complete your module, return to your
Blackboard and submit this form in the Learning Modules folder for Week 2. Upon submission you
will receive your partic
Problem 6.1
A spherical balloon initially contains helium at 80F and 14.7 psia. If the balloon initially has a
diameter of 20 ft, determine:
a. The mass of helium in the balloon, in lbm,
b. The diameter of the balloon, in ft, after rising to an elevation
Problem 8.1
Air enters a horizontal pipe operating at steady state at 40C, 300 kPa and a velocity of 40 m/s. At
the exit, the temperature is 50C and the pressure is 240 kPa. The pipe diameter is 0.04 m.
Assuming the ideal gas model with cp = 1.005 kJ/kgK
Problem 7.1
Figure 1 shows a piston-cylinder assembly fitted with a spring. The cylinder contains water,
initially at 1000F, and the spring is in a vacuum. The piston face, which has an area of 20 in2,
is initially at x1 = 20 in. The water is cooled until
Problem 9.1
Ammonia enters an insulated compressor as saturated vapor at 125 kPa and exits at 1.2 MPa and
100C. If the compressor draws 800 kW of power, determine:
a. The mass flow rate through the compressor, in kg/s.
b. The volumetric flow rates at the
Problem 3.1
Air in a piston-cylinder assembly initially occupies a volume of 1 ft3 at a pressure of 80 psia. The air
undergoes a polytropic process (pVn = constant) during which the volume of the air is doubled and the
pressure decreases to 30 psia. Deter
Problem 2.1
A manometer that contains water is used to measure the vacuum pressure of air flowing through
a duct. The column height in the manometer is 8 cm and the surrounding atmospheric pressure
is measured to be 100 kPa. Calculate the absolute pressur
Problem 4.1
Determine the phase or phases in a system consisting of water at the following conditions and
sketch p-v and T-v diagrams showing the location of each state. On each plot, draw and label the
isobar and the isotherm that pass through the state.
Problem 1.1
A sled with a mass of 175 lbm is accelerated at a rate of 0.4 ft/s2.
a. Determine the magnitude of the applied force, in lbf,
b. Determine the magnitude of the applied force, in N.
Problem 1.2
A 7 kg object is subjected to an applied upward fo
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Illegal Access to Electricity : 1.27 Million People
Legal Access to Electricity : 1.23 Million People
No Access to Electricit
ME 231 Homework Set 5
Due by 9:15 am on Thursday, October 1, 2015
Remember to follow the solution format discussed in class (given, find, sketch, assumptions,
basic equations, solution). Start each problem on a separate piece of paper. The homework must
b
Chapter 3
Evaluating Properties part 2
ME 231 Engineering Thermodynamics I section C
Dr. Mirka Deza
Phase Change
Consider a closed system consisting of a unit mass of
liquid water at 20oC contained within a piston-cylinder
assembly.
This state is represen
Chapter 3
Evaluating Properties part 3
ME 231 Engineering Thermodynamics I section C
Dr. Mirka Deza
Evaluating Properties of Gases
Using the Compressibility Chart
!General p-v-T Relations
Ideal Gas Model
!P-v-T Relations for Ideal Gases
!Using specific he
Engineering Thermodynamics I
ME 231
Part 5
Prof. Sonal Padalkar
Department of Mechanical Engineering
Iowa State University, Ames, IA-50011
Fall semester 2014
1
Topics related to Chapter 5
1. Second law of thermodynamics
2. Statements of the second law
3.
Engineering Thermodynamics I
ME 231
Part 6
Prof. Sonal Padalkar
Department of Mechanical Engineering
Iowa State University, Ames, IA-50011
Fall semester 2014
1
Topics related to Chapter 6
1. Entropy change & Entropy balance
2. Defining entropy change
3. F