UPSC Mechanical Engineering PYQs 2018 | Vaidra

1Medium10 marks

Liquid air boiling at -153 °C is stored in a spherical container of diameter 320 mm. The container is surrounded by a concentric spherical shell of diameter 360 mm in a room at 27 °C. The space between the two spheres is evacuated. The surfaces of the spheres are flushed with aluminium of emissivity 0.03. Taking the latent heat of vaporization of liquid air as 210 kJ/kg, find the rate of evaporation of liquid air.

2Medium10 marks

Make a typical layout of steam power plant.

3Medium20 marks

In a laboratory test, a psychrometer recorded dry-bulb temperature as 35 °C and wet-bulb temperature as 28 °C. Calculate

(i) vapour pressure,

(ii) relative humidity,

(iii) specific humidity,

(iv) vapour density in air,

(v) dew point temperature and

(vi) enthalpy of mixture. Barometric pressure is 1.01325 bar. Do not use psychrometric chart. Saturation pressures of water vapour at 35 °C and 28 °C are 0.05628 bar and 0.03782 bar respectively. Saturation temperature at partial pressure of water vapour is 25.6 °C.

Mechanical Engineering UPSC PYQ 2018

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