Tutorial -3

1. If a barometer stands at 760 mm and condenser vacuum is at 710 mm and temperature is 30C, calculate the mass of air per kg of uncondensed steam.2. Steam enters a condenser at 36C and with barometer reading 760 mm. if the vacuum of 695 mm is produced, find the vacuum efficiency3. The outlet and inlet temperatures of cooling water to a condenser 37.5 C and 30 C respectively. If the vacuum in the barometer is 706 mm of mercury with barometer reading 760 mm determine efficiency.4. The surface condenser is designed to handle 16000 kg of steam per hour. The steam enters the condenser at 0.009 bar abs and 0.88 dryness fractions and the condensate leaves the condenser at the corresponding saturation temperature. Determine the rise in cooling water temperature if the cooling water flow rate is 8.96 105 kg/hr. Assume that the pressure is constant throughout the condenser.5. A surface condenser deals with 13625 kg of steam per hour at a pressure of 0.09 bar. The steam enters 0.85 dry and the temperature at the condensate and air extraction pipes is 36 C. the air leakage amount to 7.26 kg/hr. Determine 1) the surface required if the average heat transmission rate is 3.97 kJ/cm2 per second 2) the cylinder diameter of the dry air pump, if it is to be single acting at 60 r.p.m with a stroke to bore ratio of 1.25 and volumetric efficiency of 0.85.

Corrected vacuum in mm of Hg =(760-absolute pressure in mm of Hg)=(760-(Actual barometric height actual vacuum)Also, 760 mm of Hg =1.01325 bar1 mm of Hg =1.01325/760=0.001333 barVacuumBarometric pressure MercuryAbsolute pressureBarometric heightTorricelis vacuumVacuum gaugeCondenser shell