# Mechanical Engineering Written Exam Questions (Part-2)

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⏩ Two identical bodies of constant heat capacity are at the same initial temperature T₁. A refrigerator operates between these two bodies until one body is cooled to temperature T₂. If the bodies remain at constant pressure and undergo no change of phase, find the minimum amount of work deeded to do this, in terms of T₄, T₂ and heat capacity.

⏩ Explain Rankine cycle with the help of P–V, T-S and h-S diagram.

⏩ Steam at 10 bar, 250ºC flowing with negligible velocity at the rate of 3 kg/min mixes adiabatically with steam at 10 bar, 0.7 quality, flowing also with negligible velocity at the rate of 5 kg/min. The combined stream of steam is throttled to 5 bar and then expanded isentropically in a nozzle to 2 bar. Determine,

(a) the state of steam after mixing

(b) the state of steam after throttling

(c) the increase in entropy due to throttling

(d) the exit area of the nozzle.

Neglect the kinetic energy of the steam at the inlet to the nozzle.

⏩ What is C. I. engine? Why it has more compression ratio compared to S.I. engines?

⏩ A diesel engine operating on Air Standard Diesel cycle operates on 1 kg of air with an initial pressure of 98 kPa and a temperature of 36ºC. The pressure at the end of compression is 35 bar and cut off is 6% of the stroke. Determine,

__Basic Mechanical Engineering Questions__

#### Part-1: Steam Boiler &Turbine

Part-2: Power Plant Engineering

⏩ A compound shaft is made up of a steel rod of 50 mm diameter surrounded by a closely fitted brass tube. When a torque of 9 kN-m is applied on this shaft, its 60% is shared by the steel rod for steel is 85 GPa and for brass it is 45 GPa. Calculate,

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