problem 1: Differentiate between impulse and reaction turbines.
problem 2: A single phase single acting reciprocating air compressor has a bore of 20 cm and a stroke of 30 cm. The compressor runs at 600 rpm. The clearance volume is 4% of the swept volume and index of compression and expansion is 1.3. The suction conditions are 0.97 bar and 27o C and delivery pressure is 5.6 bar. The atmospheric conditions are at 1.01 bar and 17o C. Find out:
a) The free air delivered in m3/min
b) The volumetric efficiency referred to the free air conditions.
c) The indicated power.
problem 3: 2 kg/s of air enters the LP cylinder of a two phase reciprocating air compressor. The total pressure ratio is 9. The air at inlet to compressor is at 100 kPa and 35o C. The index of compression in each cylinder is 1.3. Find out the intercooler pressure for perfect inter-cooling. Also, find out the minimum power needed for compression, and percentage saving over single phase compression. Tame R = 0.287 kJ/kg K and Cp = 1 kJ/kg K.
problem 4: A three phase reciprocating air compressor compresses air from 1 bar and 17oC to 35 bar. The law of compression is pv1.25 = c. The law is same for all phases of compression. Find out the minimum power required to compress 15 m3/min of free air. Also find out the intermediate pressures. Suppose that the perfect inter cooling and neglect the clearance.
problem 5: A four cylinder, double acting compressor is needed to compress 30 m3/min of air at 1 bar and 25o C at a pressure of 15 bar. Find out the capacity of motor needed and cylinder dimensions if the following data are given.
a) Speed of the compressor = 310 rpm
b) Clearance volume = 3.5%
c) Stroke to bore ratio = 1.2
d) Mechanical efficiency = 82%
e) Index of compression 1.3
problem 6: One kg or air at 35o C DBT and 60% RH is mixed with 2 kg of air at 20o C DBT and 13o C dew point temperature. Compute the vapors pressure and dew point temperature of stream one, enthalpy of both streams and specific humidity of the mixture.
problem 7: With a schematic diagram, describe the requirement of a winter air conditioning system.
problem 8: Define the term Specific Humidity, Dry Bulb Temperature, Relative Humidity and Wet Bulb Temperature.
problem 9: 100 m3 of air per minute at 15o C DBT and 80% RH are heated till its temperature is 20o C. Compute heat added to air per minute, RH of the heated air and wet bulb temperature of the heated air.
problem10: prepare down the merits and demerits of vapor absorption system over a vapor compression system.