Write the Conservation of mass equation as it applies TO YOUR SYSTEM

• Write the Conservation of Energy equation as it applies TO YOUR SYSTEM

• List all the assumptions and idealizations for the process

Diesel cycle

Fuel being used is diesel

1 cylinder, four-stroke, water-cooled, air injection of fuel
Output: 14.7 kW (20 hp)
Fuel consumption: 317 g/kWh (238 g/hp-hr)
Efficiency: 26.2%
Number of revolutions: 172 min^-1
Displacement volume: 19.6 L
Bore: 250 mm
Stroke: 400 mm

A gas turbine power plant operates on a Brayton cycles has a pressure ratio of 7. Air enters the
compressor at 300 K. The energy in the form of heat is transferred to the air in the amount of 950
kJ/kg. Using a variable specific heat for air and assuming the compressor isentropic efficiency is
83 percent and turbine isentropic efficiency is 85 percent. Determine the followings:
(i) The highest temperature in the cycle [5 marks]
(ii) The net work output, in kJ/kg [10 marks]
(iii) The back work ratio [5 marks]
(iv) The thermal efficiency. [5 marks]
(v) Show the cycle on T-s diagram [5 marks]

Use your mechanical engineering skill. Explain in 200 - 250 words why DOE is important for a Mechanical Engineer using an example. In this section, it is not expected you implement DOE in one full example. The idea in that you reflect DOE understanding in a Mechanical field. Feel free to use any source but the answer must be thorough.

Please type, make it easy to understand.

Ideal Reheat Steam Cycle (10)

Consider a steam power plant operating on the ideal reheat Rankine cycle. Steam enters the high-pressure turbine at PH MPa and TH °C and is condensed in the condenser at a pressure of PL kPa. Assume the steam is reheated to the inlet temperature of the high-pressure turbine, and that pump work is NOT negligible. If the moisture content of the steam at the exit of the low-pressure turbine is not to exceed w% percent, determine:

(a) the pressure at which the steam should be reheated and show how you got the quality,

(b) the total turbine work ,

(c) the net work ,

(d) the total heat input , and

(e) the thermal efficiency of the cycle .

PH = 20 MPa, TH = 700 °C, PL = 10 kPa and w% = 12.9%.

Determine the adiabatic combustion temperature at constant pressure and at constant volume for two of the fuels of personal choice. Graphically show that this corresponds to the product temperature where the heat of reaction is zero.

At a point in a stressed body, the principal stresses are 100 MN/m2
(tensile) and 60 MN/m2
(compressive). Determine the normal stress and
the shear stress on a plane inclined at 50degree
counter clockwise to the axis
of minor principal stress. Also, calculate the maximum shear stress at the
point and draw the Mohr’s stress circle to verify the answers.
If the yield strength and Poisson’s ratio of the material in the above case
is 240 MPa and 0.3 respectively, check whether the failure will occur or
not according to (a) Maximum principal strain theory and (b) Maximum
shear strain energy per unit volume theory. If failure does not occur,
calculate the Factor of Safety.

An air-standard dual cycle has a compression ratio of 14. At the beginning of compression, p₁ = 14.5 lbf/in.², V₁ = 0.5 ft³, and T₁ = 50°F. The pressure doubles during the constant-volume heat addition process.


For a maximum cycle temperature of 3500°R, determine:

(a) the heat addition to the cycle, in Btu.

(b) the net work of the cycle, in Btu.

(c) the percent thermal efficiency.

(d) the mean effective pressure, in lbf/in.²

Question 1

(a)   For the nucleation process, explain the difference between homogeneous and heterogeneous nucleation. Why heterogeneous nucleation is more common than

homogeneous nucleation.

(b) (i) Sketch and label the cross-section view of common macrostructure of a metal ingot after solidification process.
(ii) If the molten metal is added with 2 wt% of grain refiner, explain how the grain refiner changes the macrostructure of this metal ingot.

(c)   What is the difference between point defect and line defect?

(d)   Briefly explain why vacancies and self-interstitials are considered as the crystal defects?

Name and explain three processes that done after printing the design to have it in its final state?

Do all technologies need those processes, which one needs minor after processing?  

3D printing

Saturated liquid refrigerant R-134a is throttled from 900 to 90 kPa at a rate of 0.32 kg/s. What is the rate of entropy generation for this throttling process? kW/K

Thirty-six grams of air in a piston–cylinder assembly undergo a Stirling cycle with a compression ratio of 7.5. At the beginning of the isothermal compression, the pressure and volume are 1 bar and 0.03 m³, respectively. The temperature during the isothermal expansion is 1200 K.


Assuming the ideal gas model and ignoring kinetic and potential energy effects, determine:

(a) the net work, in kJ.

(b) the percent thermal efficiency.

(c) the mean effective pressure, in bar.

A well insulated nozzle with a 0.005 m2 inlet cross section at 15 MPa and 673 K water vapor enters at a speed of 25 m / s. The pressure of the steam-liquid mixture, whose quality is 80% at the nozzle outlet, was measured as 4.688 MPa. Work done on the nozzle is neglected. So,

a) Speed at the nozzle outlet (m / s)

b) Mass flow (kg / s),

c) Calculate the exit cross section of the nozzle (m2)

We place a 3.4 cm-tall circular object in front of an unknown lens and observe a 2.4 cm-tall circular image on a screen. We move the object either towards or away from the lens. The circular image moves 2.2 cm either towards or away from the lens; the new image is 5.7 cm tall.

a) Is the lens converging or diverging? Do you move the object towards or away from the lens? Does the image move towards or away from the lens? Explain!

b) Use ray tracing to find the focal length of the lens and the location of the lens! use empty next page!

c) Use ray tracing to find the two locations of the object that produce the two images. How much do we move the object?

A 4 cylinder 4 stroke 2.3 L diesel engine with bore = 12.4 cm and stroke =11 cm. the crank radius is 6.2 cm and with a connecting rod length 15 cm. the compression ratio of the engine is 20 and the combustion efficiency is 97.3 %. If the average speed of the car over the running life of the engine is 56 km/h and the total traveled distance of the engine is 250000 km. note: use the engine speed as 2300 rpm whenever needed, mechanical efficiency is 73 %, indicated work produced from each cycle each cylinder is 1400J, and assume that the injection started 10 degrees bTDC and ends at 25 crank angle degree aTDC.

Determine:

1. The volume of the BDC.
2. The amount of the fuel that didn’t burned in the combustion chamber .
3. The rate of the air flow to the engine if the volumetric efficiency is 70 %.
4. The number of the exhaust strokes that have been happened during the engine life in one cylinder.
5. Indicated mean effective pressure.
6. The torque produced from the engine.
7. The time duration for the injection process.
8. The position of the piston at the end of the injection period.
9. The volume of the combustion chamber at the moment of the injection process.
10. If the mass floe rate of the fuel used if A/F is 19.3 kgair/kgfuel.
11. The specific power of the engine.
12. Based on the dimensions of the bore and the stroke, is this engine square engine or over or under square one?