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GATE 2020 Toppers quiz 5 (App update required to attempt this test)

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Question 1

At the inlet to a certain nozzle the enthalpy of fluid passing is 2800 kJ/kg, and the velocity is 50 m/s. At the discharge end the enthalpy is 2600 kJ/kg. The nozzle is horizontal and there is negligible heat loss from it. The inlet area is 900 cm2 and the specific volume at inlet is 0.187 m3/kg and the specific volume at the nozzle exit is 0.498 m3/kg, The velocity at exit of the nozzle is____m/s.

Question 2

Water at 90 flowing at the rate of 2 kg/s mixes adiabatically with another stream of water at 30 flowing at the rate of 1 kg/s . For an ambient temperature of 300 K, the exergy loss due to mixing is _____ kW

Question 3

The specific power output of a gas turbine is 336.5 kW/Kg and the exhaust gases leave the turbine at 700 K. If the value of CP and CV are 1 kJ/kg-K and 0.717 kJ/kg-K respectively, the turbine pressure ratio is

Question 4

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 γ = 1.4 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).

Question 5

A body of weight 20 N is resting on a horizontal surface. The coefficient of friction between the body and surface is 0.3 and a force of 5 N is acted upon on the body. Calculate the frictional force acting on the body_____?

Question 6

A hollow sphere is made up of two materials, first with k=70 W/m-K is having internal diameter of 10 cm and outer diameter of 30 cm and second with k=15 W/m-K forms the outer layer with outer diameter of 40 cm. The inside and outside temperature are 3000C and 300C. The rate of heat flow through the sphere assuming perfect contact between two materials is __________kW.

Question 7

A plane slab of thickness L and thermal conductivity k is heated with a fluid on one side and the other side is maintained at a constant temperature, TQ of 25°C, as shown in the figure. The fluid is at 45°C and the surface heat transfer coefficient, h, is The steady state temperature. TP (in °C) of the side which is exposed to the fluid is _________ (correct to two decimal places).

Question 8

A 1 cm diameter, 30cm long fin made of aluminum (k = 237 W/m-oC) is attached to a surface at 80oC. The surface is exposed to ambient air at 22oC with a heat transfer coefficient of 11 W/m2-oC. If the fin can be assumed to be very long, its efficiency is

Question 9

A vapour compression refrigerator system operating at an evaporator temperature of –5 °C and condenser temperature of 40 °C with mass flow rate of refrigerant is 21.0 kg/min. The refrigerant, R-12 is subcooled 5 °C before entering the expansion valve and vapour is superheated 6 ° C in evaporator coil. If the clearance is 2% then the piston displacement volume (in m3/min) is
Properties of R-12

(liquid)=0.963kJ/kgK
(vapour)=0.7035kJ/kgK

Question 10

The specific humidity of moist air is 0.0107 kg/kg of dry air . The total atmospheric pressure is 98.75 kPa. The saturation temperature (in °C) is______.(use linear interpolation if needed)
 
 Here Pis partial pressure of vapour and Tsat is corresponding Saturation temperature.
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