Assume you are making a compisite material airplane, which has ligter weight and more fuel effciency. Describe how your airplane will put pressure on a culture outside of America (Choose a specific country). How your airplane will affect their society, culture, economic, and envornment, etc?
In: Mechanical Engineering
Assume you are making an airplane to meet an application. For example, air dropping of supplies and carrying of small packages. Describe how your airplane will put pressure on a culture outside of America (Choose a specific country). How your airplane will affect their society, culture, economic, and envornment, etc?
In: Mechanical Engineering
Assume you are making an airplane to meet an application. For example, air dropping of supplies and carrying of small packages. Describe how your airplane will put pressure on a culture outside of America (Choose a specific country). How your airplane will affect their society, culture, economic, and envornment, etc?
In: Mechanical Engineering
What hydraulic fluid viscosity and temperature was used in preparing the performance data shown on this information sheet? Give specific examples of what changes would occur in the data if the viscosity and/or temperature was varied.
In: Mechanical Engineering
Hot water is transported from building A to building B through a
500-m-long, 2-inches steel-pipeline. The hot water is heated up to
90oC by an electric hot water boiler located in building A. The
efficiency of the boiler is 95% while the average ambient
temperature of the place is 20oC. In order to keep the water warm,
thermal insulation (fiberglass) can be installed around the pipe.
The purpose of this analysis is to determine the right amount of
insulation to be used.
1. Find the pipeline heat losses as a function of the insulation
thickness (assume any variable required for the calculation such as
convection heat transfer coefficients, surface finishing of the
insulation, etc.). Then, find the annual cost of the electricity
required to compensate the heat losses in the pipeline as a
function of the insulation thickness (again, assume any variable
required such as electricity cost).
2. Find the investment cost of the insulation as a function of the insulation thickness (you can assume that the installed fiberglass cost per unit volume is $150/m3 and multiply that cost times the total insulation volume required, if you find a more precise way to calculate the investment, it would be welcome). Then, annualize the investment cost by dividing total investment in 15 years of lifetime for the insulation (that way you are disregarding any elaborated financial calculation including, for example, interest rate, expected profit for the investment, residual cost, etc. Again, if you want to use a more precise way to calculate the annualized investment, it would be welcome).
3. Graph the total annual cost of the project against the thickness. The total annual cost can be found by adding the annual energy cost and the annualized investment cost. The graph should have a minimum value for some given thickness. Find such thickness (this is the optimal insulation thickness) and the corresponding total annual cost (this is the minimum total annual cost of the project).
4. For the optimal insulation thickness, find the temperature of the hot water reaching building B
5. What happens to the optimal thickness, the minimum total cost, and the temperature at building B if the average ambient temperature drops to -20oC?
6. What happens if the electric hot water boiler is replaced with a natural-gas-fueled hot water boiler with 85% efficiency (assume any required variable such as LHV or price for the natural gas)?
In: Mechanical Engineering
A mass of 5 kg of saturated water vapor at 150 kPa is heated at constant pressure until the temperature reaches 200°C, the the boundary work in KJ is done by the steam during this process is closest to?
In: Mechanical Engineering
If an engineer believes that a section of pipe is fully developed what are they claiming in terms of
a) fluid velocity?
b) fluid forces?
In: Mechanical Engineering
A system that dispenses fluid into a bottle currently uses a solenoid operated valve. This has the effect of a sudden opening of the valve and a sudden closing. The valve is open for a period of 1.5seconds and it opens the valve by 20mm (the flow rate is proportional to the distance the valve is opened).
Because the environment is so corrosive and humid, the electronic valve system keeps failing. Therefore, it has been decided to use an equivalent mechanical valve operated by a cam.
The profile for the cam will be a symmetrical triangle defined by the base (in seconds) and height (in mm).
A triangular profile is used because the cam moves slowly and the jerk is not a major issue. Still it is desired to keep all forces to a minimum.
The total time that the bottle sits under the valve is 18seconds. However, there is a fixing period of 5seconds that the valve must be closed for.
What is the height of the triangular profile in mm that corresponds to the lowest forces and the same amount of liquid being dispensed by the valve?
1% error is allowed for in your answer. Round to 1 decimal place.
Correct Answer:
[Correct] 4.6 ± 1%
In: Mechanical Engineering
which one is more prone to fatigue: ductile or brittle materials? why?
In: Mechanical Engineering
1-Why the material does not experience uniform elongation after necking tensile test?
2-Why the sprue is not designed straight / show your reasoning by using some formula?
In: Mechanical Engineering
A rod of diameter D = 25 mm and thermal conductivity of 60 W/m·K protrudes from a furnace with a wall temperature of 200ºC. The rod is welded to the furnace wall and is used as a hangar for instrumentation cables. To avoid damaging the cables, the surface temperature of last 100 mm of the rod must be kept below 100ºC. The ambient air temperature is 25ºC and the convection coefficient is 15 W/m2K. (a) Write the finite-difference equation for an internal node with ?x = 2 mm. (b) Write the finite difference equation for the node at the fin tip.
In: Mechanical Engineering
A component (pearlitic) is very weak. Describe a procedure of strengthening it.
In: Mechanical Engineering
Consider 4.0 pounds per minute of water vapor at 100 lbf/in2, 500oF, and a velocity of 100 ft/s entering a nozzle operating at steady state and expanding adiabatically to the exit, where the pressure is 40 lbf/in2. The isentropic nozzle efficiency is 95.0%.
(a) Determine the velocity of the steam at the exit, in ft/s.
(b) Determine the rate of entropy production, in Btu/min·oR.
In: Mechanical Engineering
Air of 0.5 kg mass is compressed in a piston-cylinder device from 300 K, 120 kPa to 500K, 940 kPa. (a) Determine the entropy change in kJ/K using (i) approximate analysis and (ii) exact analysis. (b) Determine the direction of heat transfer (into the device or out of the device).
In: Mechanical Engineering
An insulated, rigid tank whose volume is 0.5 m3 is
connected by a valve to a large vessel holding steam at 40 bar,
480°C. The tank is initially evacuated. The valve is opened only as
long as required to fill the tank with steam to a pressure of 20
bar.
Determine:
(a) the final temperature of the steam in the tank, in °C, the
final mass of the steam in the tank, in kg, and
(b) the amount of entropy produced, in kJ/K.
In: Mechanical Engineering