So it comes down to. .
How cold does the intercooler get while cruising at speed? If "wind chill" cools the intercooler enough to pull significant heat out of the charge air, then could it get below ambient?
We're talking about charge air that has been compressed and sliding across warm components all the way to the intake valves. The intercooler would have to be VERY efficient to outcool all the warming factors. Its not happening. .
Added after reading Gary's comment above: Agreed, and Im with you on this one. Dont see how the charge air can be lower than ambient without some kind of cooling mist or added factor. It would be helpful to know what the air temps are at say 30psi. .
You are correct in your thinking, almost. In your case, with higher humidity it is because the water in the air improves the heat transfer ability of the air and therefore the heat transfer ability of the IC. Remember, the higher air flow as well as
the higher the density of the air and the greater the temperature difference the more heat will be transfered. Air flow is on both sides of the IC, just as it is for the temperatures. So as the truck goes faster the IC effecientcy will increase, because air flow on both sides of the IC is greater. Greater IE means effectively that the IC outlet temperature will decrease.
Basically the Heat Transfer rate formula goes something like:
(air flow outside * density factor / air flow inside * density factor) * ((temperature outside - temperature inside)*funny factor) * ((Heat Transfer co-efficient of the metal of the IC)*(contact area of the the IC)*(another funny factor))
It can get really complicated, with so many variables in the real world to make my head spin. I only have an inkling of calculus background, so the actual calculation is way beyond me. Thats why it is easiest to use a nominal value for IE of for example 73%.
Where:
T3 = T2 * IE
Case 4
T1 = 85F
P1 = 14. 69psia (sea level)
P2 = 75psia
CE = 75%
IE = 73%
T2 = 489F
T3 = 194F
Case 7
T1 = 85F
P1 = 14. 69psia (sea level)
P2 = 75psia
CE = 75%
IE = 85%
T2 = 489F
T3 = 145F
The concept of
Wind Chill exists only for warm blooded creatures and weather forcasts. Where you end up with a "feels like" temperature, as opposed to an actual temperature. The laws of heat transfer i have described above hold true. With higher winds heat is being removed from your body faster, your body tries to hold the temperature inside constant so it feels colder. For example, water will not freeze at 34F (ASL) wether the wind is blowing 10mph or 50mph. However, if the temperature is 30F then the water will freeze at a much faster rate if the wind is blowing 50mph. An IC has no "feels like" temperature, it is only the actual temperatures that matter.
Jim
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