2015 WINTER

Heating with Dehumidification process : By this process, specific humidity of air decreases and its dry bulb temperature increases. This type of process is suitable for industrial air conditioning where low relative humidity is required. This process is achieved by passing a stream of air over chemicals which have an affinity for water. The process is shown in figure. 

The major air pollutants emitted by petrol & diesel engines are CO2, CO, HC, NOx, SO2, smoke & lead vapour. Effect of CO:  Carbon monoxide combines with hemoglobin forming carboy hemoglobin ,which reduces oxygen carrying capacity of blood.  This leads to laziness, exhaustion of body & headache.  Prolong exposure can even leads to death.

In S.I. engine, the spark is timed to occur at a definite point just before the end of the compression stroke. If the ignition starts, due to any other reason, when the piston is still doing its compression stroke, it is known as pre – ignition.  Following factors are responsible for Pre – ignition 1) High compression ratio 2) Overheated spark plug 3) Incandescent carbon deposit in cylinder wall 4) Overheated exhaust valve 5) It may occur due to faulty timing of spark production

i] Compressor capacity:-  It is the volume of air delivered by the compressor in m3 per minute  It is express in m3 /min ii) FAD:-  It is the volume of air delivered by compressor under the intake conditions of temperature and pressure.  Capacity of compressor is generally given in terms of free air delivery.

1) To drive air motors in coal mines. 2) To inject fuel in air injection diesel engines. 3) To operate pneumatic drills, hammers, hoists, sand blasters. 4) For cleaning purposes. 5) To cool large buildings. 6) In the processing of food and farm maintenance. 7) For spray painting in paint industry. 8) In automobile & railway braking systems. 9) To operate air tools like air guns. 10) To hold & index cutting tools on machines like milling / cnc machines.

i) Deep Groove Ball bearing : Application: Electric Motor Reason: Capacity to take heavily axial load with high rotational speed ii) Taper roller bearing : Application: axle housing of automobile Reason: ability to take high radial load as well as thrust load iii) Thrust collar bearing: Application: Clutch of automobile Reason: ability to combine radial & axial load with min. speed iv) Needle roller bearing: Application: Differential of automobile Reason: takes less radial space. it has high radial load carrying capacity.