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ISRO Refrigeration and Air Conditioning 2018 Official

Option 4 : 63%

ISRO Scientist ME 2020 Paper

1504

80 Questions
240 Marks
90 Mins

__Concept:__

Boiler efficiency is calculated by the following formula

\(\eta = \frac{m\;\times\;Δ h}{m_{coal}\;\times\;C.V}\)

where, m = water supplied per hour, Δh = rise in enthalpy, m_{coal} = mass of fuel, CV = calorific value

__Calculation:__

__Given:__

m = 205 kg/hr, m_{coal} = 23 kg/hr, Δh = 145 kJ/kg, CV = 2050 kJ/kg

\(\eta = \frac{m\;\times\;Δ h}{m_{coal}\;\times\;C.V}\) = \(\frac{205\;\times\;145}{2050\;\times\;23}\)

η = 0.6304 or 63.04% \(\approx\) 63%