The high temperature inflammable gases of compressed and ignited fuel are dispersed as net horsepower used for engine output as well as exhaust and radiant heat loss and cooling water loss (e.g., net horsepower: 38%, exhaust and radiant heat loss: 35%, cooling water loss: 27%). Cooling water adjusts the amount of heat lost as cooling water loss. Accordingly, an appropriate temperature and amount of cooling water had to be circulated for the cylinder heads, cylinder liners, pistons, lubricated and other parts of the combustion chamber to achieve the right temperature.
Engine cooling water uses industrial/agricultural water, well water, river water, spring water, etc., in addition to tap water, often contain corrosive ions and ions which form scales. The factor which most affects corrosion is the concentration of sulfate ions and chlorine ions. Chlorine ions produce acid leading to pitting corrosion with the following reaction.
When the concentration of these corrosive ions is high, it is difficult to prevent corrosion, even with the addition of an anti-corrosive. Calcium and magnesium ions are given in terms of total rigidity, and as with silica, are highly corrosive. However, they have the shortcoming of forming scales when they precipitate. Calcium and silica scales can easily be checked with anti-freeze or corrosion registers, however, magnesium scales are difficult to prevent. Engine manufacturers have water quality recommendations which must be followed.
Corrosion can be divided into:
(1) Contact corrosion of different metals or galvanic cell corrosion caused by the precipitation of liquated metals.
(2) Local cell corrosion caused by variations in metal structure composition, e.g., intercrystalline corrosion.
(3) Oxygen concentration cells produced by variations in sulfuric acid concentration in the water.
(4) Corrosion caused by variations in the concentration of metal ions, e.g., erosion corrosion of metals such as copper.
(5) Passive-active cell corrosion in which a current runs between the membrane and the defect in a passive membrane.
(6) Stress-corrosion cracking which involves mechanical factors, cavitation pitting, and so forth.
Tap water is the ideal cooling water. The concentration of additives (e.g., coolants) must be controlled, the inside of the cooling system cleaned and additives replaced periodically.
