UPSC Mechanical Engineering PYQs 2016 | Vaidra

1Medium10 marks

What is the function of an economiser in a thermal power plant? Why are the economiser tubes often provided with fins on the gas side? Explain.

2Medium10 marks

A company is planning to manufacture medical testing equipment. Three locations A, B and C are under consideration. The estimated fixed costs/annum and variable cost/unit at the locations are given in the table below: [2016]

Location A: Fixed cost/Annum = ₹300 Lakh, Variable cost/unit = ₹3000

Location B: Fixed cost/Annum = ₹500 Lakh, Variable cost/unit = ₹2000

Location C: Fixed cost/Annum = ₹250 Lakh, Variable cost/unit = ₹3500

The average sale price of the equipment may be taken to be ₹7,000 per unit.

(i) If the projected sales volume is 18000 units per year, which location should be chosen?

(ii) How much will be the profit per year?

3Medium20 marks

A steam pipe (inner diameter = 150 mm and outer diameter = 160 mm) having thermal conductivity 58 W/m K is covered with two layers of insulation of thicknesses 30 mm and 50 mm respectively and thermal conductivities 0.18 W/m K and 0.09 W/m K respectively. The temperature of inner surface of the steam pipe is 320 °C and that of the outer surface of the insulation layers is 40 °C.

(i) Determine the quantity of heat lost per metre length of the steam pipe and layer contact temperature.

(ii) If the condition of the steam is dry and saturated, find the quality of the steam coming out of one metre pipe assuming that the quantity of steam flowing is 0.32 kg/min. [ Use the data : At 320 °C saturation temperature h_f = 1463 kJ/kg, h_{fg} = 1240 kJ/kg, h_g = 2703 kJ/kg ]

Mechanical Engineering UPSC PYQ 2016

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