jet fuel specific heat vs. density -- correlation?
jet fuel specific heat vs. density -- correlation?
(OP)
Trying to determine whether I can infer anything about the specific heat of jet fuel if I know the density (and temperature). Not talking about specific energy, but specific heat as the fuel is used as a coolant in heat transfer.
Of course specific heat and density are predictable over temperature, but I need to know if there is there any correlation between the two, or are they completely independent? Referring to Jet-A, Jet-B, JP-4, -5, -7, -8.
Any advice appreciated!
Of course specific heat and density are predictable over temperature, but I need to know if there is there any correlation between the two, or are they completely independent? Referring to Jet-A, Jet-B, JP-4, -5, -7, -8.
Any advice appreciated!





RE: jet fuel specific heat vs. density -- correlation?
Fuels are usually blended for specific properties and the density is not one of them but a consequence of whatever refinery processing went on before and whatever feedstocks were used.
One of the problems with aviation fuel reception into storage is to segregate the fuels simply because the density can vary so much from one bridger to another and density is very important to the all-up weight of the aircraft. In other words, density is not a controlled variable.
JMW
www.ViscoAnalyser.com
RE: jet fuel specific heat vs. density -- correlation?
There is a direct correspondence to Density.
RE: jet fuel specific heat vs. density -- correlation?
SpHeat = (0.6811-0.308*SG+(0.000815-0.000306*SG)*CRF)*(0.055*CRF+0.35) Btu/Lbm-Fº
SG = specific gravity
RE: jet fuel specific heat vs. density -- correlation?
RE: jet fuel specific heat vs. density -- correlation?
A question to BigInch. If the SG is fixed at 60oF, where is the correlation with temperature ?
I second jmw's answer. Any formula would be so roughly approximate that you may as well take the Cp tabulated values of C9H20 or C10H22, since these represent about the midpoint components of various kerosine jet fuels. I consider errors would be no more than ±10%
To get a general idea visit:
http:/
RE: jet fuel specific heat vs. density -- correlation?
You are also probably correct approximating the Cp by using the midpoint values of the tabulated chains, but I usually don't know what chemicals are in any given hydrocarbon I'm pumping. I usually only get a SG at 60F and have to convert that to actual SG at flowing pressure and temperature to get a mass rate, so I prefer to correlate to SG at any temp.
As for visco's comments, I don't know of any attempt to segrate one jet fuel from another when being received into storage. Gasoline, kerosene and diesel, yes, but not between light and heavy kerosene. Its all kerosene. You can download your Chevron material data sheets for Aviation Turbine Fuel and JP-8 from this page, http://ww
These pages show there is essentially no density difference between Aviation Turbine Fuel and JP-8 or kerosene, which is what we actually batch (usually) between diesel batches.
For av turbine fuel,
http:/
you see that they give a Density: 0.75 - 0.84 g/ml @ 15°C (59°F)
Open JP-8 and they give a Density: 0.755 - 0.84 g/ml @ 15 ºC
From a pipeline perspective, as well as what Chevron calls "Kerosene" in this MHS, can basically be anything between (our) endpoint gasoline cut + interface + beginning kero cut, and ending kero cut, interface and beginning point diesel cut between continuous serial directly interfaced batch loadings into the pipeline of all three. We distinguish batch changes by densitometer signals, not viscosity, and direct various products to either gas, jet or diesel (or interface) tanks. What we can't distinguish is cut out entirely and put in an interface tank, wich is later reblended back into the diesel, maintaining ppm limits. My understanding is that, after "kerosene" gets to the aviation terminal, they turn it into Jet A-1 or JP-8 by basically running which is really nothing more than some QA/QC tests a run through some filters, maybe adding anti-static, deicer and whatever else they need to do with it before they can call it JP or A-1.
RE: jet fuel specific heat vs. density -- correlation?
RE: jet fuel specific heat vs. density -- correlation?
RE: jet fuel specific heat vs. density -- correlation?
JP-4 (NATO F-40) WIDE CUT GASOLINE TYPE SG = 0.751-0.802
JP-5 (NATO F-44) KEROSENE TYPE SG = 0.788 - 0.845
JP-8 (NATO F-34/F-35) KEROSENE TYPE 0.755 - 0.840
Jet A-1 is the Commercial Equivalent of JP-8
VISCOSITY IS 8.5 cSt for JP-5 (Navy jet fuel), 8.5 for JP-8 & Jet A-1
Differences between these are primarily freeze point is lower for JP-4 (because JP-4 is a slightly wider cut at about 50-60% gasoline and, since 1996, is no longer used due to high flamability, JP-4 higher antioxidant content, JP-5 has lower volatility and higher flash point (60 vs 38ºC for JP-8)for shipboard operations, and JP-8 lower sulfur limits, JP-8+100 has cleaning additives.
JP-1, JP-2, JP-3 have not been used for 30 years or more. JP-6 has not been used since the XB-70 Bomber was cancelled.
JPTS is interesting. Its a U-2 and TR-1 specific fuel, no data on that, but my guess is it allows higher vapor pressure for high cold flights. And another interesting one, JP-7 is for SR-71 only and is not a distillate fuel at all, but composed of "speciality blending stocks" allowing for a very clean burn, low sulfur, low nitrogen and low oxygen impurities. A special additive for lubrication must be added to that one.
So, apparently I have confirmed our operating practice ... proving there is no difference between SG or viscosity between JP-8 and Jet A-1 as they are the same fuels. There can be as much as a 0.5% difference in limits for JP-5 vs JP-8/A-1 but most of the time there will be no difference.
Viscoanalyzer, is your experience any different?
RE: jet fuel specific heat vs. density -- correlation?
I also was associated with a tank truck meter application where the density meter was specifically adapted for truck duty.
Now I'm not saying any of these things went ahead or how far ahead they went but they were oil company initiatives.
You quote:
JP-4 (NATO F-40) WIDE CUT GASOLINE TYPE SG = 0.751-0.802
JP-5 (NATO F-44) KEROSENE TYPE SG = 0.788 - 0.845
JP-8 (NATO F-34/F-35) KEROSENE TYPE 0.755 - 0.840
and these show, to me, quite significant density tolerances - a 50kg/m3 spread is significant when you can easily measure online to 0.1-0.15kg/m3.
Sorry, I don't recall the density spread for commercial aviation fuels I was quoted, but I thought the spread was more. Of course, it could be they were quoting the spread across different grades (some time back).
JMW
www.ViscoAnalyser.com
RE: jet fuel specific heat vs. density -- correlation?
OK, just wondering if you thought it might be a current practice somewhere so that I wouldn't be caught flat-footed. As long as you're not doing it today, I guess I'm OK. Thx.
RE: jet fuel specific heat vs. density -- correlation?
This is typically how multi product pipeline transfer can use density to discriminate between different grades of gasolene, diesel etc.
Of course, part of the need to measure density is because fuel is sold by mass, not volume.
Re-reading I see that the original question did say "if I know the density"... and my comments were based on the fact that density can vary... sorry.
JMW
www.ViscoAnalyser.com
RE: jet fuel specific heat vs. density -- correlation?
No problem. As we've found out,... density can vary.