A rigid, sealed container of R134a initially at -30°C and 40% quality is placed inside a room so that it heats up at 5°C/hr. If there is 3 kg of R134a in the container, determine:
a) The volume of the container
answer must be 0.2723 m3
b) The specific volume of the vapour when the R134a finishes converting into a gas
answer must be 0.09075 m3/kg
c) The pressure when all the R134a has finished converting into a gas
answer must be 222.8 kPa
d) The energy required to turn all the R134a into a gas
answer must be 399.6 kJ
e) How long it will take for all the R134a to become a gas
answer must be 4.52 hrs
In: Mechanical Engineering
A Diesel engine with a compression ratio of 16 has a cutoff ratio of 1.5. The state before polytropic compression (exponent 1.3) is 1700 cm3 , 96 kPa and 22°C and there is isentropic expansion.
(a) Sketch the P-v diagram for this cycle.
(b) Calculate the heat transfer in and heat transfer out.
answer must be Qin = 657 J or 724 J or 866 J, Qout = 291 J or 296 J or
(c) Determine the thermal efficiency.
answer must be 56% or 59.1% or 64.1%
(d) Calculate the mean effective pressure
answer must be 230 kPa or 268 kPa
In: Mechanical Engineering
A turbine flowmeter has a bore of internal diameter 150 mm. The
rotor consists of eight
blades, each of mean thickness 5 mm, mounted on a hub of mean
diameter 35 mm. The clearance
between each blade tip and the bore is 1 mm, and the inlet blade
angle at tip is 20°. Estimate
the meter factor K in pulses/m3.
In: Mechanical Engineering
If a dynamic pressure of 250 Pa was measured in a water tunnel using a pitot static tube and a mercury (denisty of 13650 kg.m ^ -3) manometer inckunded at 30 degrees, what is the velocity being measured in the water tunnel?
In: Mechanical Engineering
1- You need to analyze the operation and performance of a four-stroke, spark-ignition internal combustion engine (automobile engine).
a- Would you analyze the engine as an Open System or a Closed System?
b- How many properties of the engine exhaust would you need to measure in order to determine the Thermodynamic State of the exhaust gas?
c- Identify a set of properties of the exhaust gas that you might measure to establish its state.
d- Are these properties Intensive or Extensive?
In: Mechanical Engineering
Using the design of a kitchen blender and mixer: Apply several of the progressive methods to the product design and development. Explain how this benefits product development.
In: Mechanical Engineering
An ASTM A36 steel having a yield strength of 235 MPa, a tensile strength of 640 MPa, and an endurance limit of 210 MPa is subjected to a cyclic loading. Using the Goodman diagram, predict whether the material has an infinite fatigue life, or whether it will fail by yielding or fatigue, when the cyclic stress is between:
(i) 0 and 250 MPa.
(ii) 95 ± 220 MPa
In: Mechanical Engineering
Briefly describe methods used in recycling of Steel and Aluminum. Which product make use of such recycled Aluminum and Steel.
In: Mechanical Engineering
What is the difference between Thermoplastics and Thermoset polymers?
A)Thermoplastics can be moulded to shape, thermoset cannot.
B)Thermoplastics have covalent bonds that can be broken and reformed, thermoset does
not.
c. Thermoplastics have entangled polymerics units that can be untangled at elevated
temperature, thermoset does not.
d. Thermoset plastics are more flexible then thermoplastics.
Q )What is/are the benefit(s) of short fibre reinforcements?
A)Increased stiffness only.
B)Increased strength and increased Toughness.
C) Increased Toughness and increased flexibility.
D) None of the above.
What is apparent density?
a)Density as measured via suspension in water.
b)Density of materials without any pores.
c)Density of material calculated with the inclusion of ONLY open pores.
e)Density of materials calculated with the inclusion of ONLY close pores.
Q Plane strain fracture toughness is a fundamental material property which:
a) is valid when specimen thickness is much greater than crack dimensions.
b) increases with increasing strain rate and decreasing temperature.
c)usually increases with strengthening.
d)is not dependent on microstructure
Q)Nickel superalloys are selected for high-temperature gas turbine blades because of:
a)High modulus.
b)High creep strength.
c)High maximum working temperature.
d) b and c.
Q. The most important mechanical properties of metals include stiffness, strength, ductilityand toughness. Which of the following statements is true:
a. Both strength and stiffness are strongly dependent on microstructure and processing.
b. Strength is a measure of resistance to elastic deformation whereas toughness is a measure of resistance to fracture.
c. Ductility is a measure of the ability of a material to plastically deform.d. Increasing strength generally increases toughness.
In: Mechanical Engineering
List fabrication methods of composite Materials.
In: Mechanical Engineering
Mention some ways or examples to increase Heat Transfer in an internal flow?
In: Mechanical Engineering
How does gas mileage depend on the type of vehicle (2018 toyota and ford) based on speed, weight, horsepower and temperature? Provide a detailed answer.
In: Mechanical Engineering
Efficiency of an engine operating condition to Carnot cycle is equal to ? = 0.45. Temperature and specific volume of the gaseous working medium at the beginning of isentropic compression are T1 = 600 K and v1 = 0.5 m3/Kg respectively. Find the gas properties at all other characteristic points of the cycle and the amount of heat released during isothermal compression. Assume that the mass of 1Kg of the gas undergoes the sequence of processes corresponding to Carnot cycle. The specific volume of the gas at the end of isothermal expansion is doubled in comparison to specific volume at the end of the adiabatic compression. The particular gas constant and isentropic exponent of the gas is R = 287 KJ/KgK and K= 1.4 respectively. Draw the cycle on p-V and T-s diagram.
In: Mechanical Engineering
0.5 Kg of air at t1 = 327 0C and the specific volume v1 = 0.2 m3/Kg is enclosed in a cylinder under a piston. The gas slowly expands with no friction to the temperature t2 = 0 0C and the specific volume v2 =0.65 m3/Kg (polytrophic process). Find the work and heat of the process and change in internal energy of gas. Determine the initial and final pressure of the gas. The isentropic exponent and particular gas constant for air are equal to k=1.4 and R=287 J/KgK, respectively.
In: Mechanical Engineering
Please answer 3.
3. The airplane from Problem 2 has a maximum speed in steady level flight of 190 kts at 8,000 ft altitude. At this condition, the propeller efficiency is 0.75. Presuming a single reciprocating piston engine, and using the simple models for altitude lapse, compute the maximum shaft brake power in hp that the engine can produce at sea level.
2. Consider an airplane with a wing area of 240 ft2 , a span of 44 ft, an Oswald efficiency of 0.75, and a zero-lift drag coefficient of 240 counts (i.e., CD0=0.024). Presume that the airplane is operating at 8,000 ft altitude at a weight of 7,600 lbs.
In: Mechanical Engineering