a. Why are commercial or any aircraft that fly at altitude, pressurized?
b. What is Pascal’s pressure assumption?
c. What are typical pressures used within commercial aircraft?
d. Explain air pressure and why it is higher at sea level than at high altitudes, support with diagrams if needed. (Hint, in a room is the cold air, it is at the floor. Is its density greater than hot air?)
In: Mechanical Engineering
A gas turbine operates as a cold-air standard Brayton cycle. Air enetrs the compressor at 300K and 100kPa and is compressed to 700kPa. During the heat addition process in the combustor, the temperature of the air increases to 1000K. The turbine and compressor can be assumed to be operating isentropically. Evaluate specific heat at 300K.
a. thermal efficiency of the cycle?
b. net work of the cycle (kj/kg)?
c. Back work ratio?
In: Mechanical Engineering
A counter-flow double-pipe heat exchanger is heating water from 20 to 80 C at a rate of 1.2 kg/s. The heating is provided by water at 160 C and a rate of 2 kg/s. The inner tube has a diameter of 1.5 cm, and the U is 640 W/m2 K. Use the effectiveness-NTU method to determine the length of the heat exchanger required.
In: Mechanical Engineering
List the Social and Economic issues of with respect to power plant
In: Mechanical Engineering
Derive the Friction Hill equation for open die forging of a cylindrical workpiece
In: Mechanical Engineering
How carbon affect hardness?? and Discuss the hardenability of each material.
1018 steel, 4140 steel, 1045 steel and 8620 steel
In: Mechanical Engineering
A new semi-automatic machine costs $ 80,000 and is expected to generate revenues of $ 40,000 per year for 6 years. It will cost $ 25,000 per year to operate the machine. At the end of 6 years, the machine will have a salvage value of $ 10,000. Evaluate the investment in this machine using all four methods (payback period, present worth, uniform annual cost (UAC), and rate of return). Neglect the salvage value for the payback period method and the rate of return methods.
Suppose, a completely automated machine is available for $ 140,000. The annual operating cost is $ 10,000 and the service life is expected to be 7 years. The salvage value of this equipment at the end of this period is $ 25,000. Revenues from this alternative too are $ 50,000 per year. Use the UAC method to compare this investment alternative with the semi-automatic machine investment.
Use a rate of return of 15 % where necessary.
In: Mechanical Engineering
Beer is to be pumped from a fermenting vessel to a racking tank at a velocity of 1.5 m/s through a 100 mm ID pipe, having an absolute roughness of 0.05 mm. The total length of the pipe, allowed for fitting and valves is equivalent to 10 m on the suction side of the pump and 60 m on the delivery. The pump is situated at 3 m below the constant level of beer in the fermenting vessel, which is at atmospheric pressure. Beer is discharged at the level 15 m above the pump in the racking tank. The pressure at the delivery point is 200kPa. The pump efficiency is 60%.
Make appropriate assumption and calculate the total head to be developed by the pump, its size and its required NPSH.
Given: beer viscosity = 0.001 Pa.s, beer density = 1.010 kg/l, vapour pressure = 2.3 kPa
In: Mechanical Engineering
A 20 degree Brix apple juice is being pumped from an open tank through a 1-in nominal diameter sanitary pipe into a second tank at a higher level. The mass flow rate is 1 kg/s through 30 m of straight pipe with two 90 degree standard elbows and one angle valve. The supply tank maintains a liquid level of 3 m and the apple juice leaves the system at an elevation of 12 m above the floor. Compute the power requirements of the pump.
Given: Juice density is 997.1 kg/m3 and viscosity is 2.1*10-3 Pa.s. Pump efficiency is 60%.
In: Mechanical Engineering
Air is compressed from 100 Kpa and 22 C to an outlet pressure 8 times greater. The compressor is not well insulated and loses heat at a rate of 120 kJ/kg. It is also note that there is a decrease in the entropy of the air of 0.4 kJ/kg-K between the inlet & the outlet. Assuming constant specific heats determine a) The outlet air temperature b) The required work input (kJ/kg) c) The entropy generation sgen (kJ/kg-K) during the compression process
In: Mechanical Engineering
. For each of edge, screw, and mixed dislocations:
(a) describe and make a drawing of the dislocation;
(b) note the location of the dislocation line;
(c) indicate the direction along which the dislocation line extends
In: Mechanical Engineering
Several types of thermoplastic elastomers were described in lecture and the textbook. Briefly describe the two phase model that explains the behavior of these polymers.
In: Mechanical Engineering
Describe a biomedical application of poly-methyl-methacrylate (PMMA) or PMMA containing polymers, copolymers or blends.
In: Mechanical Engineering
Describe and discuss:
The method required to specify inlet and outlet conditions for subsonic and supersonic flows.
The reasons for having different source and dissipation terms in regions close to the wall and away from the wall.
The meaning of apparent stresses.
Conditions for the law-of-the-wall to be adequate when studying turbulent flows.
In: Mechanical Engineering
Discuss:
How discrete momentum coefficients need particular modeling for the turbulent flows
The main reasons for limitations associated with algebraic turbulence models for recirculating flows
The differences between RANS and LES turbulence models.
In: Mechanical Engineering