Convection Coefficient 1

[Haf]

I once came across a useful equation for estimating the convection coefficient for calculating convective heat transfer from the combustion gases to the surroundings (i.e., piston and bore) in a diesel engine. The equation was of the form:

h = C*b^(m-1)*P^m*w^m*T^(0.75-1.62*m)

where

h is the convection coefficient
b is the bore diameter
P is pressure
w is the mean gas velocity (estimated as mean piston velocity)
T is temperature
C and m are constants

The reference also claimed that the overall heat transfer was 65% convection, 35% radiation.

I have used this equation and relation several times over the last two years with relatively good success. The embarassing thing is I can't find or remember where this equation and relation came from. Is anyone familiar with the above equation, and if so, could you provide the reference it comes from?

Thanks,

Haf

 

[mankas]

Jhon B. Heywood, 1988, Internal Combution Engine Fundamentals, McGRAW-HIll INTERNATIONAL EDITIONS, pp.679, equation 12.17

 

[ShaunT]

mankas: You have a SERIOUS memory, or way too much time on your hands!

Shaun TiedeULTRADYNE Arl,TX(stiede@ev1.net)

 

[Windsor377]

Is there a variation for a "gasoline" buring engine? Does the text fully explain the constants?

 

[mankas]

Haf was lucky, I was reading the book a couple of hours before geting in the forums. I am working now in piston heat transfer, so I was looking if I can find something interesting, I saw the question and I though "oh, I was just reading about that!!!"

Windsor, If I understood what you are asking, yes there are variations. Actually there are many equations adopted over the years which desrcibe heat transfer in the combustion chamber. Most of Internal combustion engines books, have a chapter about heat transfer. In the same book you can find a lot more of information.