GATE ME 9. Power Engineering and Turbomacinery Chapter Power Engineering and Turbomacinery Test 1 Mock Test Series 2022-23

Question 1
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Match List-I with List-II and choose the correct option.
List – I List – II
A) Pelton turbine                                1. Low head, high discharge
B) Francis turbine                              2. Medium head, medium discharge
C) Kaplan turbine                               3. High head, low discharge

A
A – 3, B – 2, C – 1

B
A – 2, B – 1, C – 3

C
A – 3, B – 1, C – 2

D
A – 2, B – 3, C – 1

Question 2
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In a gas turbine cycle, the turbine output is 600 kJ/kg, the compressor work is 400 kJ/kg, and the heat supplied is 1000 kJ/kg. the thermal efficiency of the cycle is:

A
20%

B
40%

C
30%

D
50%

Question 3
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A thermal electric power plant produces 1000 MW of power. If the coal releases 900 x 10⁷ kJ/h of energy, then what is the rate at which heat is rejected from the power plant?

A
500 MW

B
1000 MW

C
1500 MW

D
2000 MW

Question 4
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The thermal efficiency of a gas turbine cycle with ideal regenerative heat exchanger is

A
equal to work ratio

B
less than work ratio

C
more than work ratio

D
unpredictable

Question 5
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A turbine develops 7223 kW power under a bead of 25 m at 135 rpm. The specific speed of the turbine will be nearly

A
245 rpm

B
225 rpm

C
205 rpm

D
185 rpm

Question 6
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The efficiency of superheat Rankine cycle is higher than that of simple Rankine cycle because

A
The enthalpy of main steam is higher for superheat cycle

B
The mean temperature of heat addition is higher for superheat cycle

C
The temperature of steam in the condenser is high

D
The quality of stem in the condenser is low

Question 7
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Consider an actual regenerative Rankine cycle with one open feed water heater. For each kg steam entering the turbine, If m kg steam with a specific enthalpy of h1 is bled from the turbine, and the specific enthalpy of liquid water entering the heater is h2, then h3 specific enthalpy of saturated liquid leaving the heater Is equal to

A

B

C

D

Question 8
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The minimum and maximum temperatures in gas turbine cycle are 900 K and 1600 K respectively. The maximum possible work output is (kJ/kg) ____
(C_p = 1.005 kJ/kg.K)

A
100-101

B
1004-1011

C
1007-1016

D
1009-1012

Question 9
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In a steam power plant operating on the Rankine cycle, steam enters the turbine at 4 MPa, 350°C and exits at a pressure of 15 kPa. Then it enters the condenser and exits as saturated water. Next, a pump feeds back the water to the boiler. The adiabatic efficiency of the turbine is 90%. The thermodynamic states of water and steam are given in the table

h is specific enthalpy, s is specific entropy and v the specific volume; subscripts f and g denote saturated liquid state and saturated vapour state

The net work output (kJ kg-1) of the cycle is

A
498 kJ kg^-1

B
775 kJ kg^-1

C
860 kJ kg^-1

D
957 kJ kg^-1

Question 10
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A horizontal jet of water of cross-sectional area 2 cm² and velocity 10 m/s strikes a vertical plate moving towards the jet at 3 m/s. The force exerted by the jet on the plate is

A
28.4 N

B
33.8 N

C
30.6 N

D
40.9 N

Question 11
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In a two-stage reciprocating air-compressor with suction pressure of 2 bar and delivery pressure of 8 bar, the ideal intercooler pressure will be

A
10 bar

B
6 bar

C
4 bar

D
3 bar

Question 12
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A pump work against a head of 30 m while the one-third scale model is tested at head of 10 m and 600 rpm. The rated speed of actual pump (in rpm) is _______

A
346-347

B
3464-3471

C
3467-3476

D
3469-3472

Question 13
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The absolute atmospheric and vapour pressure at the location of a reaction turbine are 100 kPa and 25 kPa respectively. The net effective head of water is 10 m. Thoma’s cavitation index is 0.95. Assume specific weight of water as 10 kN/m³. The location of turbine setting w.r.t. tail race to avoid cavitation is___

A
6.55 m above tail water level

B
6.55 m below tail water level

C
2 m above tail water level

D
2 m below tail water level

Question 14
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A model turbine produces 0.5 kW under 4m head and runs at 780 rpm. The large turbine has to work under 49 meters head of water and produces 1.4 MW. The model scale ratio (D_p: Dm) approximately is _____ [D_p= diameter of prototype, D_m= diameter of model]

A
1 : 8

B
8 : 1

C
1 : 4

D
4 : 1

Question 15
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For a given set of operating pressure limits of a Rankine cycle, the highest, efficiency occurs for

A
Saturated cycle

B
Superheated cycle

C
Reheat cycle

D
Regenerative cycle.

Question 16
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In a Pelton wheel turbine, the ratio of the mean bucket speed to jet velocity is 60% that for the maximum efficiency. For shockless entry of fluid that is defected by 165°, the efficiency in % is ______.

A
82-83

B
824-831

C
827-836

D
829-832

Question 17
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A thermal power plant operates on a regenerative cycle with a single openfeed water heater, as shown in the figure. For the state points shown, thespecific enthalpies are: h1 = 2800 kJ/kg and h2 = 200 kJ/kg. The bleed to thefeed water heater is 20% of the boiler steam generation rate. The specificenthalpy at state 3 is

A
720 kJ/kg

B
2280 kJ/kg

C
1500 kJ/kg

D
3000kJ/kg

Question 18
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For two cycles coupled in series, the topping cycle has an efficiency of 30%and the bottoming cycle has an efficiency of 20%. The overall combinedcycle efficiency is

A
50%

B
44%

C
38%

D
55%

Question 19
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In a Rankine cycle, with the maximum steam temperature being fixed from metallurgical considerations, as the boiler pressure increases

A
The condenser load will increase

B
The quality of turbine exhaust will decrease

C
The quality of turbine exhaust will increase

D
The quality of turbine exhaust will remain unchanged

Question 20
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Which one of the following is correct? In ideal regenerative cycle the temperature of steam entering the turbine is same as that of

A
Water entering the turbine

B
Water leaving the turbine

C
Steam leaving the turbine

D
Water at any section of the turbine

Question 21
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A centrifugal compressor develops a pressure ratio of 5 and air consumption of 30 kg/s. The inlet temperature and pressure are 15°C and 1 bar respectively. For an isentropic efficiency of 0.85, the power required by the compressor will be nearly

A
5964 kW

B
5778 kW

C
5586 kW

D
5397 kW

Question 22
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Directions For Questions

Consider a steam power plant using a reheat cycle as shown. Steam leaves the boiler and enters the turbine at 4 MPa, 350°C (h3 = 3095 kJ/kg). After expansion in the turbine to 400 kPa (h4 = 2609 kJ/kg), the steam is reheated to 350°C (h5 = 3170 kJ / kg), and then expanded in a low pressure turbine to 10 kPa (h6= 2165 kJ/kg). The specific volume of liquid handled by the pump can be assumed to be .

...view full instructions

The thermal efficiency of the plant neglecting pump work is

A
15.8%

B
41.1%

C
48.5%

D
58.6%

Question 23
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In a Rankine power plant, dry saturated steam is supplied at 1.6 MPa. The condenser pressure is 0.3 bar and following data is obtained.
At 1.6MPa: Saturation Temperature = 198.27℃, Enthalpy = 2800 kJ/kg, Entropy = 6.5302 kJ/kgK
At 0.3 bar: Saturation temperature = 65.9 ℃, h_f= 218.2 kJ/kg, h_fg = 2300 kJ/kg, s_f = 1.026 kJ/kgK, s_fg = 6.6438 kJ/kgK
The second law efficiency of this Rankine cycle is ________ %

A
92-94

B
924-941

C
927-946

D
929-942

Question 24
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A steam plant has the boiler efficiency of 92%, turbine efficiency (mechanical) of 94%, generator efficiency of 95% and cycle efficiency of44%. If 6% of the generated power is used to run the auxiliaries, the overallplant efficiency is

A
34%

B
39%

C
45%

D
30%

Question 25
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A reciprocating compressor has clearance volume 7 % of total volume. The expansion and compression indices are 1.36 and 1.30 respectively, then the maximum pressure ratio that can be obtained is _______

A
37-38

B
374-381

C
377-386

D
379-382