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Unformatted text preview: the piston head in °C.
The temperature difference (TC – TE) may be taken as 220°C for cast iron and 75°C for aluminium.
The heat flowing through the positon head (H) may be deternined by the following expression, i.e.,
H = C × HCV × m × B.P. (in kW)
where C = Constant representing that portion of the heat supplied to the engine
which is absorbed by the piston. Its value is usually taken
HCV = Higher calorific value of the fuel in kJ/kg. It may be taken as
45 × 103 kJ/kg for diesel and 47 × 103 kJ/ kg for petrol,
m = Mass of the fuel used in kg per brake power per second, and
B.P. = Brake power of the engine per cylinder Notes : 1. The thickness of the piston head (tH) is calculated by using equations (i) and (ii) and larger of the two
values obtained should be adopted.
2. When tH is 6 mm or less, then no ribs are required to strengthen the piston head against gas loads. But
when tH is greater then 6 mm, then a suitable number of ribs at the centre line of the boss extending ar...
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- Spring '11