October 31, 2020, 06:48:33 PM
Forum Rules: Read This Before Posting


Topic: Corrosivity of Decomposed RP-1 Help  (Read 204 times)

0 Members and 1 Guest are viewing this topic.

Offline burroht

  • Very New Member
  • *
  • Posts: 1
  • Mole Snacks: +0/-0
Corrosivity of Decomposed RP-1 Help
« on: October 16, 2020, 07:43:58 PM »
I'm doing a project on rocket fuels, part of which is the decomposition of the fuel made by liquid oxygen and dodecane. In the chart I'm using for the impact of sulfur impurities there's a column titled L* and I have no idea what it means. Any ideas what it could be?
The table is from kinetics.nist.gov/RealFuels/macccr/macccr20
08/Bruno2.pdf
And should be attached below

Offline chenbeier

  • Sr. Member
  • *****
  • Posts: 1173
  • Mole Snacks: +82/-20
  • Gender: Male
Re: Corrosivity of Decomposed RP-1 Help
« Reply #1 on: October 17, 2020, 06:50:39 AM »
The * should be explained somewhere below.

Offline Borek

  • Mr. pH
  • Administrator
  • Deity Member
  • *
  • Posts: 26074
  • Mole Snacks: +1699/-402
  • Gender: Male
  • I am known to be occasionally wrong.
    • Chembuddy
Re: Corrosivity of Decomposed RP-1 Help
« Reply #2 on: October 17, 2020, 08:26:22 AM »
https://en.wikipedia.org/wiki/CIELAB_color_space

(yes, it may seem unrelated, but it is about determining the color of the copper surface, and the CSCT, which is an ASTM Standard Test Method, is based on color judging).

2 minutes of gooling to find out.
ChemBuddy chemical calculators - stoichiometry, pH, concentration, buffer preparation, titrations.info, pH-meter.info

Offline Enthalpy

  • Chemist
  • Sr. Member
  • *
  • Posts: 3597
  • Mole Snacks: +295/-57
Re: Corrosivity of Decomposed RP-1 Help
« Reply #3 on: October 18, 2020, 08:48:17 AM »
I didn't grasp whether your fuel is RP-1 or dodecane.

Anyway, RP-1 is essentially free of sulphur, as your table confirms. It's also essentially free of multiple bonds. Manufacturers make efforts for that.

As RP-1 comprises alkanes and very little more, corrosion is not an issue, as long as any decomposition occurs without oxygen.

Neither do I see how decomposition could occur in a healthy rocket burning RP-1. The fuel is purified to avoid decomposition in the cooling jacket. If decomposition occurs, the launch will fail, and very much before corrosion can do anything.

If you plan to use RP-1 as a lubricant or a hydraulic fluid for years, corrosion may become interesting. In a rocket, I don't see the point.

==========

Be careful with the linked report. I dislike many aspects of it.

Aromatics and alkenes are removed from RP-1. If the authors found significant amounts, they should have discarded the sample.

Compressibility at 200bar can't be inferred from ultrasound measurements at 1atm. Same for the viscosity.

>1000kg/m3 from RP-1, I can't believe it.

5% additive make little sense in a rocket fuel. Certainly not additives like tetraline that release a gas. Bubbles are deadly in a cooling jacket. Polymers are deadly too, and aromatics from tetraline decomposition do make polymers.

==========

Possibly the project examines potential fuels for a hypersonic vehicle. I have no firm opinion in that field. My impression is that, here too, if RP-1 begins to decompose, other worries will happen much earlier than corrosion. And also, that additives are likely to worsen the behaviour. My limited understanding is that hypersonic fuels shall serve as a cooling agent too, hence the interest for RP-1.

If your dodecane is straight, you might want to check its melting point. -10°C isn't quite good for a rocket fuel, and completely unacceptable for usual aeroplanes. Synthetic fuels would be branched for that purpose, and their decomposition may differ from straight molecules. For instance Amyris produced farnesane some years ago, but apparently they target different markets now.

Sponsored Links