Hydrogen Fuel Cells - Question

[Randazzo]

I couldn't decide what the appropriate place to put this would be. I started to put it in the CRP thread but it's not really related to that.

I'm kicking around the idea of some hydrogen fuel cells and I got to looking in the CRP resource cfg for conversion rates, and I'm a touch confused now. PEMFC's create water as a result of the reaction taking place inside the cell, so naturally I want this cell to do the same, however I'm unsure of what the proper converstion rate from Hydrogen + Oxygen into Water would be.

Assuming I'm understanding the density correctly (the density listed equals one unit of the resource) would I simply add the density of the H₂ to half the density of the Oxygen to get one unit of water vapor or should I be using some different rate since the water is obviously a liquid and not a gas?

[Crzyrndm]

Water is H₂O, so we need twice as many molecules of hydrogen as we do oxygen (hydrogen and Oxygen both typically form in pairs, so we can ignore that). Per unit mass you get approx. 16 x as many hydrogen molecules as you do oxygen (molecular mass 1.00xxx vs. 15.99xxx). Ends up you need 8tons of oxygen per ton of hydrogen.

CRP is 1 unit = 1 litre.

Mass(kg) of 1 unit of oxygen => densityOx * 1000

Required mass(kg) of Hydrogen => densityOx * 1000 / 8

Required units of Hydrogen => densityOx * 1000 / (densityH * 1000 * 8) => densityOx / (densityH * 8)

Put in 1 for the oxy ratio and the final number for the hydrogen ratio and it should work out (assuming my math all checks out)

Edited June 26, 2015 by Crzyrndm

[Randazzo]

Water is H₂O, so we need twice as many molecules of hydrogen as we do oxygen (hydrogen and Oxygen both typically form in pairs, so we can ignore that). Per unit mass you get approx. 16 x as many hydrogen molecules as you do oxygen (molecular mass 1.00xxx vs. 15.99xxx). Ends up you need 8tons of oxygen per ton of hydrogen.

CRP is 1 unit = 1 litre.

Mass of 1 unit of oxygen => densityOx * 1000

Required mass of Hydrogen => densityOx * 1000 / 8

Required units of Hydrogen => densityOx * 1000 / (densityH * 1000 * 8) => densityOx / (densityH * 8)

Put in 1 for the oxy ratio and the final number for the hydrogen ratio and it should work out (assuming my math all checks out)

Assuming that's all correct (and I wouldn't know), and that I understand it:

0.00000141 / (0.00000008990 * 8) => 0.00000141 / 0.0000007192 = 1.96{05116796440489432703003337041} - I'll just snip this part off.

So either I don't understand what this is telling me, or it's telling me that I need 1 unit of oxygen and 2 units of hydrogen to get 1 unit of water.

I knew that

Perhaps I should clarify a touch.

Here's the converter "code"

MODULE
    {
         name = ModuleResourceConverter
         ConverterName = H2 Fuel Cell
         StartActionName = Start Fuel Cell
         StopActionName = Stop Fuel Cell
         FillAmount = 1
        AutoShutdown = true
        GeneratesHeat = true
        UseSpecialistBonus = false


         INPUT_RESOURCE
         {
            ResourceName = Oxygen
            Ratio = 0.0000141
            FlowMode = STAGE_PRIORITY_FLOW
         }
         INPUT_RESOURCE
         {
            ResourceName = Hydrogen
            Ratio = 0.000001798
            FlowMode = STAGE_PRIORITY_FLOW
         }
         OUTPUT_RESOURCE
         {
            ResourceName = ElectricCharge
            Ratio = 5
            DumpExcess = false
         }
         OUTPUT_RESOURCE
         {
            ResourceName = Water
            Ratio = ?
            DumpExcess = true
         }    
    }

That's 10 "units" of oxygen (as in, 10 of the density listed in the CRP resource config file) and 20 units of Hydrogen. What I'm looking for is the appropriate water output here. Unless of course that's entirely wrong as well.

And this is the density I'm referring to:

RESOURCE_DEFINITION
{
    name = Hydrogen
    density = 0.00000008990    <----
    unitCost = 0.000055836
    flowMode = ALL_VESSEL
    transfer = PUMP
    isTweakable = true

Which I presume to mean that is the mass of a single molecule.

I think I'm making this way more complicated than it needs to be.

Edited June 26, 2015 by Randazzo

[Crzyrndm]

If it turns out as 2:1, then it's 2:1. If the CRP resource definitions weren't standardised on some pressure it would have turned out differently. The density field is the mass of 1000 units (1m^3) in metric tons (1000kg) for CRP gases (or kg/L)

What you probably want for the converter is 1 Oxygen, 2 Hydrogen and ((densityOx + 2 * densityH ) / DensityWater => 0.00040455) Water. That is, 1 unit Ox per second, 2 units of H per second, and 0.00040455 H2O per second)

[Randazzo]

What you probably want for the converter is 1 Oxygen, 2 Hydrogen and ((densityOx + 2 * densityH ) / DensityWater => 0.00040455) Water. That is, 1 unit Ox per second, 2 units of H per second, and 0.00040455 H2O per second)

Yes! Precisely what I needed. I can't even begin to guess how many hours you saved me.