  # ISRO Scientist or Engineer Mechanical 2020

Instructions

For the following questions answer them individually

Question 11

# Air at $$27 ^\circ$$C and 100 kPa enters in a steady flow to a nozzle at a velocity of 100 $$\frac{m}{s}$$. If theinlet area of the nozzle is 0.5 $$m^{2}$$, what is the mass flow rate through the system Question 12

# Critical point of wateris Question 13

# In a shower mixer, cold water at 27 deg C, flowing at 5 kg/min is mixed with hot water at 77 deg C flowing at 15 kg/min.The exit temperature of the mixture is Question 14

# Which ofthe following uses a regenerator? Question 15

# Ratio of convective mass transfer to the massdiffusionrate is called? Question 16

# A gas is containedin a cylinder with a moveable piston of 100 kg mass. When 2500 J of heat flows into the gas, the internal energy of the gas increases by 1500 J. Whatis the distance through which the piston rises? Question 17

# A refrigerator with COP of 6 is used in a room at 300 K. Whatwill be the heat intake through a section of refrigerator wall of area $$100 cm \times 100 cm$$ with a thickness of 10 cm assuming only conduction? Value of thermal conductivity of the wall can be taken as 1 $$\frac{W}{cm}$$.K Question 18

# A Mass of 1Kg of air at $$27^\circ$$ and 0.98 atm is taken through a diesel Cycle. If the compression ratio of the the engine is 16,calculate the temperature of the air after compression ?(for calculation, take the ratio of the specific heats of air as 1.5) Question 19

# An aircraft is in its take off roll at sea level with ambient temperature of 18°C. What is the approximate speed of the aircraft if the temperature measured by a probe at the exist of the engine diffuser is $$36^\circ$$ C? (Assuming air Stagnation at diffuser outlet and $$C_{p}$$ of air as 1.0 $$\frac{kJ}{Kg.K}$$) Question 20

# The external surface of a wall of height 3m height ,5 m width and 0.5 m thickness is at a temperature of $$2^\circ$$ C.If a heat loss of 150 wfrom the room is measured across the wall ,find the inner wall temperature ?The thermal conductivity of wall material can be taken as 1 $$\frac{W}{m.k}$$ OR