Chapter 11 Cooling Systems page 191
Cooling Systems Types Air cooling Liquid Cooling Mixture Air/Liquid
Principles of Engine Cooling Efficiency and life of engine Burned gasses 3600 F Loss of heat through cylinder walls 1200 F to 350 F 100 F by outer fins
COOLING SYSTEMS Heat Energy From Combustion 1. Cooling and Lubrication systems 33% 2. Exhaust system 33% Engine power 25% Frictional loss 5%
How Air Cooling Works heat passes through cylinder wall air passes by fins guided by baffles Conduction – through a material material Convection – solid to gas transfer Radiation – gives off heat
Parts of an Air Cooled system Fly Wheel Shrouds Fins
How Exhaust Cooling Works 1/3 heat lost through exhaust (muffler) 1200 F Blocked muffler Broken muffler
How Water Cooling Works Passage surrounds cylinder (water jacket) No fins water/antifreeze mixture protects freezing raise boiling point prevent corrosion
Parts of the Liquid Cooled System Radiator Water pump Water Jacket Hoses Fan Shroud Belt Thermostat
Radiator Tubes Fins Transfers heat coolant >air
Radiators Caries water through tubes Air travels through fins Together make RADIATIOR CORE Cross flow & Down flow
Water Pumps Moves coolant Boat at lower end of motor Driven by crankshaft Types sliding vane rotor plunger vari-volume
Radiator Cap Pressurize Pascal’s Law 1 psi = 3 F
Observing Thermostat Operation Opens at preset temp. Rating stamped on thermostat Holds coolant in block Opens to cool
Outboard Water Circulation Systems Pressure-vacuum water flow system propeller causes pressure & vacuum Centrifugal force no moving parts (propeller)
How Oil Cooling Works Oil collects dirt and particles Removes heat (5%)