Temperatures of gases inside the combustion chamber of a four stroke automobile

Question

Temperatures of gases inside the combustion chamber of a four stroke automobile engine can reach up to 1000 C degree. To remove this enourmous amount of heat the engine utilizes a closed liquid cooled system which relies on conduction to transfer heat from the engine block into the liquid and then into the atmosphere by flowing coolant around the outside surface of the cylinder. Let's assume we have a 6 cylinder engine and each cylinder has a diameter of 8.25 cm and height of 10.7 cm and is 3.46 mm thick. The temperature on the inside of the cylinders is 185.0 C degree whereas the temperature where the coolant passes is 134.2 C degree. The temperature of the liquid ( a mixture of water and antifreeze) is to be maintained at 101.3 C degree. Using the given parameters, What flow rate would need to be supplied by the water pump to cool this engine?

Explanation / Answer

you have not given the specificaation for the fluid (coolant). considering most of it to be water.

Specific heat = 4200 J/kg

Also, let the conductivity of the material of the cylinder, k = 17 W/mK {source - Internet, I have considered the material to be stainless steel}

Total area = 6*(2pi*r*h + 2pi*r*r) = 6*2*pi*r*(r+h) = 0.23 m2

Thickness = 0.0346 m

Heat/sec = k*A*(T2-T1)/x ; where x id the thickness

H/sec = 17*0.23*(185-134.2)/0.0346 = 5740.7 J/s

Heat removed by water = m*S*(T1-Tw) = m*4200*(134.2-101.3)

Mass of water req per sec = H/sec /4200*32.9

Mass / sec = 41.54 g/sec.

I have made certain assumptions, like material property and the water as coolant. You can always change those things in the equation. But the concept and procedure are the same.

Hope this helps.

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.