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
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 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
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
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 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 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 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 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
Problem 14.1
Steam enters the turbine of a Rankine cycle at 10 MPa and 480C and is expanded to a pressure
of 6 kPa. Water enters the pump as a saturated liquid. The turbine operates with an isentropic
efficiency of 80% and the pump operates with an isentr
Problem 13.1
Air at 400 kPa and 970 K enters a turbine operating at steady state and exits at 100 kPa and
670 K. Heat transfer from the turbine occurs at an average outer surface temperature of 315 K at
a rate of 30 kJ per kg of air flow. Assuming that ai
Problem 11.1
One kilogram of water in a piston-cylinder assembly, initially at 160C and 150 kPa, undergoes
an isothermal, internally reversible compression process to the saturated liquid state. Determine:
a. The heat transfer during the process, in kJ.
b
Problem 12.1
A 2.64-kg copper part, initially at 400 K, is plunged into a tank containing 4 kg of liquid water
that is initially at 300 K. The copper part and water reach a final equilibrium temperature of 310
K. Both the copper and water can be modeled a
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
Electricity Access in Haiti
Illegal Access to Electricity : 1.27 Million People
Legal Access to Electricity : 1.23 Million People
Illegal Access to Electricity : 1.27 Million People
Legal Access to Electricity : 1.23 Million People
No Access to Electricit
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
PRDBLEM 5-43-
A refrigeration cycle rejects Q = 500 Btu per cycle to
a hot reservoir at T = 540R, while receiving QC = 375
Btu per cycle from a cold reservoir at temperature TC. For
10 cycles ofloperation, determine (a) the net work went, in
Btu, and (b)
PROBLEM 3.13 l
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1.7 A person whose mass is 150 lb weights 144.4 lbf. Determine (a) the local acceleration of
gravity, in ft/sz, and (b) the persons mass, in 1b, and weight, in lbf, ifg = 32.174 ft/sz.
(a) Fgmv : mg
F . 2
g _ gmv _144.41bf 32.1741b ft/s _ 30.97 stz
PROBLEM 3.4
An open container of pure ethanol (ethyl alcohol) liquid is placed on a table in a room.
Evaporation occurs until all of the ethanol is gone. "Where did the alcohol go? che ethanol
liquid and the room air are taken to be a closed system= can t