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“The Engine Cooling System” ISBN 0-9720927-1-4 TTS Publication No. 109 List Price US $39.95 Everything you always wanted to know about cooling systems but couldn’t find anywhere. Until now! The most comprehensive, easy to use technical summary. Available now! |
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INTRODUCTION Heat rejection to the coolant Distribution of the waste heat Cooling the engine HEAT TRANSFER MECHANISMS Convection Conduction Radiation Conductivity of substances Convective heat transfer Convective heat transfer, with and without boiling Boiling regimes Radiation heat transfer HEAT TRANSFER WITHIN THE ENGINE Intake and compression strokes Spark ignition and combustion Gas temperature and pressure rise during combustion Compression ignition and combustion The power stroke The exhaust stroke QUANTIFYING THE HEAT REJECTION TO THE COOLANT Engine heat rejection curves Approximations maximum heat rejection Estimating heat rejection Factors that affect the heat ejection Spark advance Fuel/air ratio Exhaust emissions Heat rejection to the lubricating oil Diesel engine heat rejection Rule of thumb factors for heat rejection Basic Engine cooling systems Once thru cooling systems Closed cooling systems Why not just air cool it? THE WATER CIRCUIT Cylinder head water jackets Cylinder block water jackets Intake manifold water jackets Coolant transfer ports V & flat opposed engine water circuit Conventional flow water circuit Reverse flow water circuit Inlet & outlet side thermostat configurations By-pass circuit Fixed pass circuit Compound thermostat & variable pass circuits The heater circuit Schematic representations of the water circuit and its branches WATER PUMPS Pump inlet passages Pump discharge passages Pump bearing assembly Pump seal assembly Seal materials and failure modes Centrifugal pumping action Pump efficiency & power consumption Flow characteristics of centrifugal pumps Pump inlet and discharge pressures Pump mounting configurations THERMOSTATS Temperature control of the coolant flow rate Orientation of the sensing element to the flow Cold start, warm-up & light throttle operation Operation at high engine speeds/loads Typical thermostat installations Thermostat construction Control element (wax motor) Types of thermostats Balanced valve Compound valve Air bleed Temperature control settings Valve diameter vs. flow, pressure drop Stroke vs. flow, pressure drop Common failure modes COOLING SYSTEM PRESSURIZATION Pressurization due to thermal expansion of the coolant Thermal expansion, system rigidity and gas to liquid ratio Pressurization vs. amount of entrapped gas Pressurization due to boiling Dynamic pressurization Pump flow and pressure head Pump cavitation Pressure-temperature profile Differences in pressure profile outlet and inlet side thermostat configurations Typical system pressure-temperature profile Using the pressure-temperature profile to identify problem areas |
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PRESSURE RELIEF & REGULATION Types of radiator caps, construction Normally open (vented) partial pressure cap Normally closed (sprung) full pressure cap Vent and fill cap Manually vented cap System pressurization Reference and final temperatures for static pressure build-up Pressurization with the partial pressure cap Pressurization with the full pressure cap System deaeration and degassing Deaeration with the partial pressure cap Deaeration with the full pressure cap Coolant level sensitivity Effect of cap selection for various drive modes Reference pressures for mountainous operation Accuracy of stamped pressure relief setting Cap pressure retention and decay rates COOLANT RECOVERY SYSTEMS Un-pressurized (atmospheric) cold bottle recovery systems Pressurized cold bottle recovery systems Constant pressure hot bottle systems Other systems Summary of pressure cap/recovery system benefits and drawbacks RADIATORS Heat exchanger-basic concepts Heat balance Heat transfer characteristics of water and air Thermal and physical properties of water, coolant solutions and air Measuring heat (thermal units) Radiator design configurations Serpentine fin and tube Plate fin and tube (oval and round tube) Mounting configurations Radiator materials Thermal conductivity considerations Mechanical limitations of the flat tube Structural considerations of the radiator assembly Coolant and air velocity considerations Fluid viscosity Boundary layer Laminar, transition and fully developed turbulent flows Effect of turbulence on heat transfer Tube turbulence enhancements Fin turbulence enhancements Effect of coolant flow rate on heat transfer, deposits and corrosion Temperature profile along the tube Effect of fin pitch (fin density) on heat rejection Effect of tube spacing / fin height and width on heat rejection Effect of air velocity on heat transfer and resistance to flow Effect of grille bumper and structural obstructions on velocity and distribution Effect of recirculation on air temperature distribution and heat transfer efficiency Effect of fan spacing to radiator Effect of off-center, aggressive fans Effect of A/C condenser on air temperate and resistance Effect of flow vortices in the hot tank Effect of coolant flow distribution in the tube array Radiator selection Radiator characterization, calorimeter Inlet temperature differential (IT) Production radiator charts Typical radiator heat rejection ranges Correction factors to radiator chart data Tube length Tube fouling Low flow velocity Physical packaging restraints Characterization of airside heat transfer, pressure drop and distribution Characterization of waterside heat transfer and pressure drop HOSES AND CLAMPS Standard and heavy duty hose Effect of coolant inhibitors on hose tube Hose to nipple fit Clamping loads Types of hose clamps |
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TABLE OF CONTENTS FOR “THE ENGINE COOLING SYSTEM” |
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