Is this heat transfer realistic?!
Is this heat transfer realistic?!
(OP)
Hi all,
Just after some advice on whether or not some heat transfer values are realistic.
I have a piston, whose upper and lower crown temperatures are shown below:

Underneath the piston, there is a chamber (not shown), filled with engine oil, which has zero flow rate.
I have calculated the heat flow through the crown:


I now want to calculate the rise in temperature of the oil as a result of this heat flow. I have used the following equation, where the mass is equal to the volume of the oil in the chamber x density.


This suggests then that the oil heats up by 284 'C in one second! I can't quite get my head round such an increase in that time-frame....
Any advice/comments greatly appreciated.
Thanks
Just after some advice on whether or not some heat transfer values are realistic.
I have a piston, whose upper and lower crown temperatures are shown below:

Underneath the piston, there is a chamber (not shown), filled with engine oil, which has zero flow rate.
I have calculated the heat flow through the crown:


I now want to calculate the rise in temperature of the oil as a result of this heat flow. I have used the following equation, where the mass is equal to the volume of the oil in the chamber x density.


This suggests then that the oil heats up by 284 'C in one second! I can't quite get my head round such an increase in that time-frame....
Any advice/comments greatly appreciated.
Thanks





RE: Is this heat transfer realistic?!
RE: Is this heat transfer realistic?!
Your heat flow through the crown may be essentially moot, since the oil is not directly in contact with the bottom side of the crown, except, perhaps, through splashing oil. In fact, the low deltaT indicates that your model has air in contact with the bottom of the crown, so the heat flow is buffered by natural convection of air. The heat flow then has to travel through the air, and the convect into the oil. Or something like that, since you've not really defined where everything is and what's touching what and when.
TTFN

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RE: Is this heat transfer realistic?!
There is an inner piston and outer piston. The outer piston moves axially relative to the inner, depending on the volume of oil present in the upper chamber. There should be no air present in the upper chamber.
RE: Is this heat transfer realistic?!
Assuming that the piston is in intimate, continuous, contact with the oil would mean that bottom piston must remove heat as fast as the heat is introduced from the top piston, otherwise, boiling, vaporized oil would result.
TTFN

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RE: Is this heat transfer realistic?!
There is a check valve (not shown in diagram), through which oil flows into the upper chamber. There is also a discharge valve (pressure relief valve), through which oil leaves the chamber.
RE: Is this heat transfer realistic?!
TTFN

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