1) Explain how different engine operating conditions affect combustion ( ignition delay, temperatures, air fuel ratio, speed, heat transfer)?

2) What are the 3 sources of NOX formation, which is the least relevant, which is the most relevant, explain why?

What are austenitic steels? Write about their a) alloy principles b) effects of alloys (mechanical and radiation properties)

Provide references, please.

Many sports cars are convertibles. The air flow over such a car is significantly different depending on whether the convertible top is up or down. The engine of the 1000-kg car delivers 135 kW to the wheels, the car frontal area is 1.9 m² and rolling resistance is 2.5% of the car weight. The drag coefficient when the top is down is 0.43 and 0.31 when it is up. For 20 ºC air at one atmosphere, determine:

a. the maximum speed with the top up (in m/s)

b. the maximum speed with the top down (in m/s)

A design related question.

1)design a walk in refrigerator and freezer with 10 ton and 30 ton cooling capacity respectively.
2) freezer must be maintained between (24 to 15 deg celcius) and refrigerator between (3-7 deg celcius)
3)ambient condition ( 38 deg celcius) and refrigeration compressor efficiency assumed at 75%.
4)heat exchanger maintained at 11 deg celcius.
5) emphasis on reducing operating cost, so one compressor can be used and also flash chamber
6) reducing compressor work input and increasing coefficient of performance.
7) power consumption must be in Kilowatt ( KW).

how would you do this?
can you write why you went with the choice you went with...just summarize and justify your findings. it's a open ended question and there is no right or wrong answer.

thank you, looking forward to learning this.

A project requires weighing and dispensing of multiple hi-potent (ECL>3) pharmaceutical compounds in powder form for a blockbuster, commercially marketed drug, it’s a sterile processing plant. Provide your conceptual HVAC design description that include primary enclosures (only HVAC for handling and transfer devices) and secondary (room/HVAC) containments to protect product attributes (integrity, efficacy, purity), personnel from environmental exposures. Elegant, energy efficient, and least cost design URS solution are required criteria. A project requires weighing and dispensing of multiple hi-potent (ECL>3) pharmaceutical compounds in powder form for a blockbuster, commercially marketed drug, it’s a sterile processing plant. Provide your conceptual HVAC design description that include primary enclosures (only HVAC for handling and transfer devices) and secondary (room/HVAC) containments to protect product attributes (integrity, efficacy, purity), personnel from environmental exposures. Elegant, energy efficient, and least cost design URS solution are required criteria.

A combined cycle power system uses a simple gas-turbine Brayton cycle in conjunction with a simple Rankine cycle to produce a total power of 100 MW. In such configuration, the exhaust stream from the gas turbine is used as the heat source for the steam power cycle in a heat exchanger as shown in the figure. The following data are known for the gas-turbine cycle. Atmospheric air enters the compressor at 100 kPa and 20oC, the compressor pressure ratio is 8, the compressor isentropic efficiency is 85%, the maximum gas cycle temperature is 1100oC, and the gas turbine isentropic efficiency is 90%. Additionally, it is known that the gas stream leaves the heat exchanger at the saturation temperature of the steam flowing through it. The following data are known for the steam-turbine cycle. Steam flows through the heat exchanger with a pressure of 6000 kPa, leaving at 320oC, the steam-cycle condenser operates at 20 kPa, and the isentropic efficiency of the steam turbine is 90%.

(a) Schematically draw the complete system including all the equipment required for the analysis. Additionally, sketch the corresponding thermodynamic diagrams for the Brayton and Rankine cycles involved. Assign a different number to each stream and use such number in the diagrams.

(b) Find the power generation efficiency of the gas-turbine.

(c) Find the power generation efficiency of the Rankine cycle.

(d) Find the steam-turbine power, the gas-turbine power, and the total efficiency of the combined cycle.

For AISI 1050 Steel at 10 cm in diameter, use case hardening methods to produce a surface hardness of at least 60 HRC. Describe the method that will create a thin, carbon enriched surface layer in order to maintain the ductile properties of the core. Show calculations.

An air–fuel mixture enters a constant area combustion chamber at a velocity of 100 m/s a pressure of 70 kPa and a temperature of 150°C. Assuming that the fuel–air ratio is 0.04, the heating value of the fuel is 30 MJ/kg, and the mixture has the properties of air, calculate the Mach number in the gas flow after combustion is completed and the change of stagnation temperature and stagnation pressure across the combustion chamber. Neglect the effects of viscosity and assume that the properties of the gas in the combustion chamber are the same as those of air.

Air enters a constant diameter pipe at a pressure of 200 kPa. At the exit of the pipe the pressure is 120 kPa, the Mach number is 0.75, and the stagnation temperature is 330°C. Determine the inlet Mach number and the heat transfer per unit mass of air.

The power source in a particular welding setup generates 3119 watts that can be transferred to the work surface with a heat transfer factor of 0.65. The metal to be welded is low carbon steel. The melting factor in the operation is 0.4. A continuous fillet weld is to be made with a cross-sectional areas of 20 mm2. Determine the travel speed in mm/s at which the welding operation can be accomplished. Hint: See Table 28.2 for the melting temperature of low carbon steel.