This may shed some light on the subject:
Heat Value
The heat value of fuel is a general indication of how heat energy is supplied to an engine and how well the engine converts heat energy into work. The heat value can be found by testing with a calorimeter. With this test, a pre- measured amount of fuel is burned and the amount of heat emitted is carefully measured in Btus per pound of fuel. A British thermal unit (Btu) is the amount of heat required to raise the temperature of one pound of water one degree Fahrenheit. The metric equivalent of this unit is known as a joule. To convert Btus into joules, multiply by 1054.8.
Specific Gravity


The specific gravity of fuel is a ratio of the fuel density to the density of water. It is measured using a hydrom- eter. Specific gravity affects the fuel's spray penetration as it is injected into the combustion chamber. Because water is the standard, it has a specific gravity of one. Since oil floats on water, a diesel fuel's specific gravity is always less than one. Diesel fuel's specific gravity ranges from 0.8 to 0.94. Specific gravity is also a factor in measuring the heat value of the fuel. In general, heavier fuels usually have a greater heat value per gallon (Btus) than lighter fuels. Thus, specific gravity is a good indicator of the amount of heat (Btus) available in a given amount of fuel.
The American Petroleum Institute (API) employs another scale to determine specific gravity. Water has a specific gravity of 20 on the API gravity scale. Ten is the lowest value on this scale, the reverse of the system just described. Diesel fuels generally range from 20 to 45 on the API gravity scale, with most ranging between 34 to 36 at 60°F (15.5°C).
Excerpt from: http://www.g-w.com/PDF/SampChap/59070_7708_CH14.pdf ; Chapter 14, page 305
So it is my understanding that Btus are measured by weight, not by volume. Therefore, 1 gallon of diesel at 60* will have more Btus than 1 gallon of diesel at 100* since the 1 gallon of diesel is more dense at 60* and will weigh more than the 1 gallon of diesel at 100*.
Anyone Install a Fuel Cooler?
Discussion in 'Trucks [ Eighteen Wheelers ]' started by Cowpie1, Aug 3, 2012.
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Alot of truck built in Australia come with fuel coolers from factory. Well my 4 KW's did. They do it over here for cooling the engine. Common rail diesel engines really benefit from cool fuel and attributes to alot of the engines cooling.
This is the cooler mounted under the radiator, it is on the return line
CellNet Thanks this. -
If I may say, I don't know who is right/wrong, mistaken, overlooking something, miscalculating, or whatever, but anyone who would use the term "dumb truck driver" hasn't read some of the posts I have since I joined this forum a few months ago. Many very intelligent people in this business driving and wrenching (or technician-ing).
Y'all make me think I need to study engineering/chemistry/physics just to keep up! I know just enough to be dangerous. Thanks for all that you post and sharing with us who aren't quite there yet!
BTW, I may look into a cooler myself. -
IT don't hurt when some of us used to be engineers and such. I spent 4 years prior to getting back into the truck working as a mechanical/process engineer technician and also went to school to design roads in civil engineering/land survey. -
I guess then the idea of a fuel cooler also on the supply side direct to the head is a bad idea? Every mechanic I spoke with said to just do it on the return side like what all of you have said. My way of thinking on supply side cooler is that most of you guys have 379's and W9's with big tanks exposed to the direct heat and effects of sunlight on a hot day. Cowpie you have those kind of tanks on your truck and even worse your tanks are painted a dark color which causes them to absorb much more heat from the rays of the sun. I understand the fuel returning to the tanks is definietly going to be hotter and would benefit from a cooler, but what about when that cooler fuel gets to those tanks which are sitting out in the blazing hot sun? That's what makes me think a cooler on the supply side WOULD be beneficial as well. Now on a truck like mine or Dices with plastic side fairings it might not be all that much of a benefit at all, but I am just guessing here and don't really know. As far as winter time goes one could always just pull the coolers off for winter time trucking in really cold temps, but I somehow don't think gelling would be an issue, although I could be wrong..
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you would want it on the return side to keep the fuel in the tank cool. It's much easier to cool it in the line with a LOT more surface area than when you get it into a large mass like a tank.
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yes, I can see the benefit to it one on both sides.
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i could see a cooler on the return during the summer. but what would happen in the winter????
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