Chapter 11: Final Review & Key Terms

1.1. Key Terms

aeration A condition in which excessive amounts of air or steam bubbles are dissolved in coolant, diminishing the coolant’s effectiveness.

cavitation Erosion in cylinder block walls, heads, and liner sleeves as a result of the collapse of tiny water vapor bubbles formed when coolant vaporizes on hot cylinder wall surfaces.

coolant extender An additive package that is used only with ELC and is added at the midpoint of the coolant’s life.

diesel coolant additive (DCA) An additive used to treat cooling systems to reduce the effects of cavitation erosion.

electrolyte A substance that can conduct current.

ethylene glycol The base chemical from which the majority of antifreezes are made.

extended-life coolant (ELC) Several types of long-life coolant formulations containing an anticorrosion additive package that does not deplete; also known as long-life coolant (LLC).

heat exchanger A system of tubes and fins circulating coolant that transfers heat from coolant to the atmosphere.

heat rejection The transfer of heat into the cooling system from the combustion chamber.

hot-soak period The time period when a hot engine is cooling down after it is shut off. Coolant temperatures typically rise for a short time during this period.

hybridized cooling system A conventional cooling system with partial or complete electronic controls, such as an electronically controlled thermostat.

hybrid organic acid technology (HOAT) A combination of IAT and OAT with nitrites added, making it suitable for use in both LD and HD systems.

hydrostatic lock A condition in which the upward movement of a piston is stopped due to liquids in a cylinder; often caused when pressurized coolant is pushed through pin-size holes caused by cavitation erosion and into the cylinder during the engine’s hot-soak period.

inorganic additive technology (IAT) A diesel engine cooling system conditioner containing noncarbon-based corrosion inhibitors such as phosphates, borates, and silicate.

nitrited/nitrated organic acid technology (NOAT) An ELC using organic acid technology with nitrates added.

organic acid technology (OAT) An antifreeze additive technology that uses carbon-based molecules for corrosion inhibitors rather than inorganic-based inhibitors.

propylene glycol An antifreeze base that is nontoxic and environmentally friendly.

Rankine cycle A concept used by a heat exchanger to extract heat from low-temperature fluids or gases and then convert the heat of evaporation into another form of power. A Rankine cycle device frequently contains a fluid with a low boiling temperature that evaporates, and its energy is transferred to another device.

silicate dropout A dissolved sodium silicate in antifreeze begins to crystalize over time and form a precipitate that leaves a deposit of white, powdery material inside the cooling system. This is abrasive and plugs coolant passages.

supplemental coolant additive (SCA) An additive used to treat cooling systems to reduce the effects of cavitation erosion and optimize cooling system performance.

thermal efficiency The ability of an engine to convert the energy content of fuel into mechanical force.