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VENTILATION SYSTEM. Why engine room need ventilation?. Engine must receive sufficient air for combustion Engine room should be cooled to acceptable temperature. Two modes in ventilation. At working engine – cooling and engine feeding At not working engine – moisture expelling.
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Why engine room need ventilation? • Engine must receive sufficient air for combustion • Engine room should be cooled to acceptable temperature
Two modes in ventilation • At working engine – cooling and engine feeding • At not working engine – moisture expelling
Engine room temperature Less than 45o – 50oC • Hot air getting engine cylinder decrease performance • Electrical system is sensitive to elevated temperature • Crew working in the engine room
Requirements • Supply enough air • Effective routing • Sound insulation • Water from sea and rain should not enter • Closing air access in case of fire • Minimum resistance in air pipes
Quantity Required (without combustion air) • Rough estimation – Change the air in the room every one or two minutes • 0.1 – 0.2 m3/min per installed horsepower
Calculate required air for your engine Velocity of the air in personnel working area: • Do not exceed 1.5 m/s
Combustion air Ducts • Quantity - 0.1m3 of air / min / kW 2.5 ft3 of air / min / bhp • Duct restriction – should not exceed 2.49 kPa (10 in of water) at engine full rated power • Velocity in duct should not exceed 610 m/min
Rules: • Fresh air should enter the ER as far from the sources of heat as practical • Fresh air should enter the ER as low as possible • Discharge air should leave ER at the highest point • Discharged air should leave ER above the heat source
Using Fans • Improve air supply • Location – most effective in suction line • Type – axial and centrifugal– the motor should be outside the direct flow • Sizing – name plate rating is higher than as-installed
Air Discharge • Avoid recirculation • Higher and aft ward than intake
Minimum Resistance • No more than three 90o elbows • More pipes – greater resistance • Longer pipes – greater resistance Resistance decreases efficiency
Crankcase Fumes Disposal • Could be digested by engine • Could require ventilation piping