GATE ME Applications PYQs & Answers — Page 5

Questions 41–50 of 61. Imported answers require independent review unless marked reviewed.

Topic practice 61 questionsPage 5 of 7

Which one of the following modifications of the simple ideal Rankine cycle increases the thermal efficiency and reduces the moisture content of the steam at the turbine outlet?

Your answerChoose one option.

Increasing the boiler pressure.

Decreasing the boiler pressure.

Increasing the turbine inlet temperature.

Decreasing the condenser pressure.

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An idealized centrifugal pump (blade outer radius of 50 mm) consumes 2 kW power while running at 300 rpm. The entry of the liquid into the pump is axial and exit from the pump is radial with respect to impeller. If the losses are neglected, then the mass flow rate of the liquid through the pump is ______ kg/s (round off to two decimal places).

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A steam power cycle with regeneration as shown below on the T-s diagram employs a single open feedwater heater for efficiency improvement. The fluids mix with each other in an open feedwater heater. The turbine is isentropic and the input (bleed) to the feedwater heater from the turbine is at state 2 as shown in the figure. Process 3-4 occurs in the condenser. The pump work is negligible. The input to the boiler is at state 5. The following information is available from the steam tables:

State	1	2	3	4	5	6
Enthalpy (kJ/kg)	3350	2800	2300	175	700	1000

The mass flow rate of steam bled from the turbine as a percentage of the total mass flow rate at the inlet to the turbine at state 1 is ______.

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An air standard Otto cycle has thermal efficiency of 0.5 and the mean effective pressure of the cycle is 1000 kPa. For air, assume specific heat ratio

and specific gas constant R = 0.287 kJ/kg·K. If the pressure and temperature at the beginning of the compression stroke are 100 kPa and 300 K, respectively, then the specific net work output of the cycle is _____ kJ/kg (round off to two decimal places).

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A gas turbine with air as the working fluid has an isentropic efficiency of 0.70 when operating at a pressure ratio of 3. Now, the pressure ratio of the turbine is increased to 5, while maintaining the same inlet conditions. Assume air as a perfect gas with specific heat ratio

=1.4. If the specific work output remains the same for both the cases, the isentropic efficiency of the turbine at the pressure ratio of 5 is ______ (round off to two decimal places)

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Select the correct statement for 50% reaction stage in a steam turbine.

Your answerChoose one option.

The rotor blade is symmetric.

The stator blade is symmetric.

The absolute inlet flow angle is equal to absolute exit flow angle.

The absolute exit flow angle is equal to inlet angle of rotor blade.

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For a Pelton wheel with a given water jet velocity, the maximum output power from the Pelton wheel is obtained when the ratio of the bucket speed to the water jet speed is ______ (correct to two decimal places).

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A standard vapor compression refrigeration cycle operating with a condensing temperature of 35°C and an evaporating temperature of −10°C develops 15 kW of cooling. The p-h diagram shows the enthalpies at various states. If the isentropic efficiency of the compressor is 0.75, the magnitude of compressor power (in kW) is ________ (correct to two decimal places).

Diagram for Mechanical Engineering question 43

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Ambient air is at a pressure of 100 kPa, dry bulb temperature of 30°C and 60% relative humidity. The saturation pressure of water at 30°C is 4.24 kPa. The specific humidity of air (in g/kg of dry air) is ________ (correct to two decimal places).

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A test is conducted on a one-fifth scale model of a Francis turbine under a head of 2 m and volumetric flow rate of 1 m

/s at 450 rpm. Take the water density and the acceleration due to gravity as

kg/m

and 10 m/s

, respectively. Assume no losses both in model and prototype turbines. The power (in MW) of a full sized turbine while working under a head of 30 m is ______ (correct to two decimal places).

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GATE ME Applications PYQs

Question 13

Question 48

Question 49

Question 49

Question 50

Question 11

Question 24

Question 43

Question 44

Question 45