GATE MN topic:mine-ventilation PYQs & Answers — Page 3

Questions 21–30 of 37. Imported answers require independent review unless marked reviewed.

An underground AC plant requires the delivery of 250 US gpm (15.85 US gpm = 1.0 lps) of chilled water. For this purpose, ice-pellets at 0 °C temperature (latent heat of melting, 334 kJ/kg) are mixed with water at 20 °C (specific heat 4.18 kJ/kg°C) on the surface. The mixture is adiabatically transported to the underground location such that the water at 7°C becomes available for the AC plant. The requirement of ice-pellets in tonne/hr to meet the design condition, is ______. (round off to two decimal places)

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An intake shaft has resistance of 0.05 Ns²/m⁸ up to a depth of 400 m. The airflow rate is 100 m³/s and the average density is 1.2 kg/m³. A barometer reads 99.375 kPa when placed on surface. Considering acceleration due to gravity is 9.81 m/s², the reading of the barometer at the depth of 400 m, in kPa is ______. (round off to two decimal places)

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Given impeller diameter

, speed of rotation

and air density

, for geometrically similar fans, the fan pressure is proportional to

Your answerChoose one option.

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A coal mine operating in three shifts produces 400 tonnes of coal per day with a face OMS of 1.0 from panel A, and 200 tonnes of coal with face OMS of 1.0 from panel B. The panel A and panel B are in parallel with resistance 0.6 Ns²m⁻⁸ and 0.5 Ns²m⁻⁸, respectively. If the panels are supplied with minimum permissible quantity as per CMR 2018, the required regulator resistance to meet the conditions in Ns²m⁻⁸ is ______. [round off to 2 decimal places]

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The dry and wet bulb temperatures at the inlet of the airstream are 30 °C and 25 °C, respectively. The corresponding values at the outlet of the airstream are 26 °C and 25 °C, respectively. The psychrometric process that occurs in the airstream is described as

Your answerChoose one option.

latent cooling

sensible cooling

condensation

evaporative cooling

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Air enters from ambient atmosphere into a level duct of uniform cross-section area 0.2 m

at a flow rate of 2.0 m

/s and density of 1.2 kg/m

. The entry shock loss factor is 1.0 and the resistance of the duct per meter length is 1.0 Ns

. The static pressure measured at a distance of 20 m from the duct entrance in Pa, is ________ (round off to 1 decimal place).

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A diesel loader produces 60 l/s of exhaust fumes containing 500 ppm of CO. The incoming air has 10 ppm of CO. The minimum amount of air flow in m

/s that is needed at the loader to dilute CO to a permissible level of 50 ppm is ________ (round off to 1 decimal place).

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The purpose of rotating a whirling hygrometer in hygrometric survey is to

Your answerChoose one option.

wet the cotton wick with water thoroughly

maintain constant temperature of water in the container

create steady state evaporation of moisture from the wet bulb surface

prevent the heat produced by the cap lamp of the observer from affecting the readings

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Water is pumped through a steel pipe of diameter 200 mm at a flow rate of 30 l/s. If the dynamic viscosity of water is

Pa s, the Reynolds number of the flow is

Your answerChoose one option.

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The characteristic curves of two mine fans installed in series in a fan drift are

and

where P is pressure in Pa and Q is quantity in m

/s. If the mine quantity is 70 m

/s, the mine resistance, in Ns

(rounded off to two decimal places) is

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GATE MN topic:mine-ventilation PYQs

Question 59

Question 60

Question 19

Question 54

Question 11

Question 37

Question 39

Question 12

Question 27

Question 40