eggrobin

I'm confused... That means a new (life support) Hydrogen resource, the LiquidOxygen and LiquidHydrogen are already in MFS/RF. Do you mean additional liquid life support O2 and H2? That would be terribly complicated, you would have 3 kinds of oxygen and hydrogen (LS gas, LS liquid, propulsion liquid) and you would need converters between the 3. I was thinking about having 2 kinds of those: the life support variant (gas) and the existing liquid propellant. The problem is of course that some life support systems use LOX and LH2, but we can ignore that (just make tanks that have the right density). Boiloff shouldn't be too much of a problem for the life support O2/H2 if the Wikipedia article on Apollo 13 is to be believed:

I'm not sure what to think about that. On the one hand, there are projects to use hydrogen from electrolysis as fuel, and that would allow for accurate modeling of the Sabatier reaction. (It just has to produce LiquidMethane. There are plans to use that as fuel too.) On the other hand, you then need to use the Oxygen from the electrolysis as fuel too, so it should be LiquidOxygen, but that interferes with the nice kerbal*day numbers. Moreover, for most applications, you want to keep the O2 and H2 life support circuits separate from the propulsion system. You wouldn't want the fuel cells to start drawing from your transmunar injection fuel... I think the way forward is to keep O2 and H2 as separate resources, as they are used in fuel cells, kerbals etc., and to have a life support to propulsion interface that converts Oxygen to LiquidOxygen and Hydrogen to LiquidH2 (I think they are supposed to be gases in the TACLS system, so this could just model the liquefaction). Methane can be LiquidMethane without any harm. (Unless you want to model methane pyrolysis. Actually this is a very realistic alternative to the Bosch reaction for closed-circuit life support. We are doomed.)

The numbers look good. I'll check them in more detail (and finish my electrolyser model) when it is not 04:44.

Do not forget to rescale the ElectricCharge requirements (Also, I had not yet downloaded the latest version. I keep missing posts and edits in this conversation...)

It probably makes sense to match the outputs rather than the inputs for these. If you have a CO2 supply (on Duna) and a Bosch reactor rated for 3 kerbals, it would be embarrassing to have them suffocate, same if you are shipping water (as on the ISS).

Elektron is actually just the electrolyser. The ISS Water Recovery System is called the Water Recovery System (they plan to extend it. It will be called the Extended Water Recovery System), and Bosch reactors don't quite exist yet (in space). The conversion rate is too high if you just want to sustain three kerbals though: conversionRate=1 supplies 4.23 kerbals with oxygen, and is thus equivalent to Elektron. conversionRate=n is equivalent to n Elektrons. The water purifier should get between .8 and .94 Water out of 1 WasteWater, and the Waste should be the mass difference (the stuff you send down in a Progress). See http://forum.kerbalspaceprogram.com/threads/40667-0-22-WIP-TAC-Life-Support-0-6-8Dec?p=807493&viewfull=1#post807493. Edited to add: I'm almost done with my electrolyser model (see some WIP screenshots: http://forum.kerbalspaceprogram.com/threads/40667-0-22-WIP-TAC-Life-Support-0-6-8Dec?p=831724&viewfull=1#post831724). It's Elektron (12 electrolytic cells with a pump-driven KOH loop) without any of these fancy unkerbal safety features such as a blast-proof housing or a pressure hull with an inert atmosphere (what could go wrong with hot gaseous hydrogen and oxygen aboard a spacecraft anyway?).

I had not heard of their existence on the ISS, but hydrogen-oxygen fuel cells were in the Apollo and STS spacecrafts. I computed some specifications for fuel cells (and better specifications for the electrolyser) on page 33 of this thread, so it should be fairly easy to make this part yourself while waiting for Taranis to add it. Edit: Actually, the hydrogen on the ISS is vented, so I'm quite sure they don't use it to turn oxygen back to water (that would be a great way of throwing power out the metaphorical window).

The various models of Elektron have weighed between 150 kg and 110 kg (http://www.jamesoberg.com/elektron2_tec.html). Stuff outside of stock KSP is light! (Well, light considering it has a pressurised hull with an inert atmosphere and a blast-proof housing).

You used my numbers for the Electrolyser, so that was based on kerbals. If you want to replicate the performance of Elektron, your Water Electrolyser should read inputResources = Water, 1, ElectricCharge 86400, // 1 kW * 1 day outputResources = Oxygen, 4.229055504417308397, false // Assuming 100% oxygen recovery. Reduce to your liking. I think 4 would be fine. Elektron does this in a day, so if you want to go with the small parts approach, setting conversionRate=1 allows for fine tuning of the capacity of your station by adding the right number of electrolysers. Again, as Mir had 2 of those and the ISS has 3, this seems to be a nice way to partition stuff.

I edited my post while you were replying to it, so you missed the consumption for the Water Purifier: 1 775 kJ for 4l. The WasteWater is sewage and grey water (and sweat &c) I think. Standard TAC assumes 2 kerbals have the same requirements as 1 human.

I would advocate making small recyclers (3-4 kerbals, maybe some 1-kerbal units) and using several of these. This is what happens in real life: the ISS has 3 Elektron units which supply oxygen for 3-4 crewmembers each, the Apollo service module had 3 fuel cells, Mir had 2 Elektron units, the STS had 3 fuel cells, etc.

Some of it is It turns out that there is a bug in your CO2 density: A big kerbal day is 112 g, this should be 1.12 kg. Using the corrected density, the amount of O2 produced makes sense. Bear in mind that the efficiency is more that 90%, as the theoretical maximum here would be ~0.969, the respiratory exchange ratio of your kerbals (the ones from TACLS have a respiratory exchange ratio of ~0.866, I guess they work less). The amount of Waste should be 0.32407407407407407 to conserve mass. The electric consumption looks good. The name is inaccurate though: there is no Sabatier reaction (CO2 + 4H2 --> CH4 + 2H2O) going on here (It is also possible to run a closed circuit with the Sabatier process, but you need to pyrolyse the methane, CH4 --> C + 2H2, and I haven't done the calculations for that). This is just the Bosch reaction (CO2 + 2H2 --> C + 2H2O, requires higher pressures and temperatures than the Sabatier reaction), coupled with an electrolysis (2H2O --> O2 + 2H2).

It is probably a good idea to abstract the Bosch reactor+electrolyser in a single part for now (this works in closed circuit as far as hydrogen is concerned, and the waste is indeed graphite), but the power consumption for that is on the order of 43 000 kJ for 840 g of oxygen. Calculations: 9959 kJ to turn 1 standard kerbal day of CO2 into 0.232 standard kerbal days of H2O 51776 kJ to split 1 standard kerbal day of H2O rescaling factor for O2: 1 big kerbal day = 840/429 standard kerbal days (9959 kJ + 51 776 kJ * 0.232) * 840 / 429 = 43 000 kJ (rounded to 3 significant figures) Edit: answer to the edit H2 is complicated. I don't know of any instances where life support O2 or H2 were also used for propulsion (I think there are plans for that, but there are plans for just about everything), so I'm not sure they should be identified with the MFS/RF LiquidOxygen resp. LiquidH2. Using it later on in a fuel cell might make sense if you need a really big battery.

I may be misunderstanding something, but your electric consumptions for the recyclers seem to be all over the place (from reading the cfgs). The electrolyser needs a whopping 954 kW to sustain 8 crewmembers (one ISS Elektron unit sustains 3 to 4 and consumes ~1kW), while the water purifier uses only 3 W to sustain 8 crewmembers (for some reason, the one that sustains 16 crewmembers is half as efficient). Note that (with existing systems) CO2 to O2 cannot consume less than electrolysis for a given amount of oxygen, as both the Sabatier and Bosch processes produce water. You might want to look at the the calculations I did on the TACLS thread (electrolyser and fuel cell, Sabatier and Bosch reactors), these are just linearly scaled performances for existing devices. Realistic masses can be found at http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/40487/1/04-3358.pdf.

These are EC/day (1 EC/day = 11.57 mW under the usual assumption that 1 EC = 1 kJ). This means that the base consumption of a pod is 13.8 W, and that the additional consumption per kerbal is 27.7 W.

I don't think methanediol (methane-di-ol by the way, not methanedoil) makes much sense as Waste, considering that this mod assumes kerbals to be rescaled humans. Human solid waste is definitely not methanediol. Moreover, Waste encompasses more than this, as it also includes graphite from CO2 recycling, whatever remains from the reprocessing of waste water, etc. As far as methanogenesis is concerned, bear in mind that it produces methane, carbon dioxide, and water, not oxygen. Regarding methane though, you can get that from the Sabatier reaction (I gave the specs for a Sabatier reactor a couple of pages ago, just replace the Waste output with a [WhateverYourMethaneResourceIs] output). Remember to conserve mass. On an unrelated note, I made an electrolyser model inspired by Elektron (it's basically Elektron without any of that fancy blast-proof housing and inert atmosphere stuff, fitted awkwardly inside a cylinder). Suggestions and criticism are welcome (I have no experience with either modeling or texturing, so it's going to take a while to finish).

A 1-kerbal Sabatier CO2 reprocessing unit (source: http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/40487/1/04-3358.pdf). MODULE { name = TacGenericConverter converterName = Sabatier Reactor conversionRate = 1 inputResources = CarbonDioxide, 1, Hydrogen, 3.4623213297201505, ElectricCharge, 300 outputResources = Water, 0.23258488055756316, false, Waste, 3.313853064479525, true } The main problem for the Bosch reactor seems to be that the catalyst is fouled by the graphite deposit. Apparently, newer catalysts solve this. This paper does not mention power consumption, but the operating temperatures seem to be similar. I just reused the characteristics from the 1971 prototype, assuming they can be replicated with non-expendable catalysts. A 1-kerbal unit: MODULE { name = TacGenericConverter converterName = Bosch Reactor conversionRate = 1 inputResources = CarbonDioxide, 1, Hydrogen, 1.7311606648600752, ElectricCharge, 9959 outputResources = Water, 0.23258488055756316, false, Waste, 2.481022167311451, true }

They already do (they are modeled as half a human). The specifications I am computing take this into account: the electrolyser above supplies a bit more than 3 kerbals, while Elektron supplies a bit more 3 humans. Using the SM2A-03-Block II-(1) Apollo Operations Handbook, page 2.6-19/2.6-20, as a reference (H2O produced at a rate of 2.297E-2 lb/(A*h), voltage 29 V), producing one TACLS unit of Water yields 18014 kJ (18014 ElectricCharge), so if we want to supply one kerbal with water, we will produce 208 W = 0.208 ElectricCharge/s. Compare with the OX-STAT panel's 750 W under normal Kerbol exposure at Kerbin, or with the Mk-1 Pod's life support consumption of 41.6 W. This seems reasonable. This yields the following spec for a 1-kerbal fuel cell, MODULE { name = TacGenericConverter converterName = Fuel Cell conversionRate = 1 inputResources = Oxygen, 3.7215675, Hydrogen, 7.443135 outputResources = Water, 1, false, ElectricCharge, 18014, true } or the following for a 3-kerbal fuel cell. MODULE { name = TacGenericConverter converterName = Fuel Cell conversionRate = 3 inputResources = Oxygen, 3.7215675, Hydrogen, 7.443135 outputResources = Water, 1, false, ElectricCharge, 18014, true } Using the same Hydrogen resource, we can also update the spec of the electrolyser---also, new numbers based on computations with a ridiculous number of significant figures. I changed the density of Hydrogen very slightly. These numbers conserve mass well enough (the error is 1E-7): MODULE { name = TacGenericConverter converterName = Electrolyser conversionRate = 1 inputResources = Water, 1, ElectricCharge, 51776 outputResources = Oxygen, 3.7215675, false, Hydrogen, 7.443135, true } RESOURCE_DEFINITION { name = Hydrogen density = 0.0000270274 flowMode = ALL_VESSEL transfer = PUMP } Next up: Sabatier and Bosch! A remark concerning the power consumption of the pod (41.6 W for the Mk I): It seems okay. the Orlan spacesuit consumes a maximum of 54 W, but it's a spacesuit. We can handwave that a human spacesuit has the same volume/heat losses as a 1-kerbal pod. This also appears to work gameplay-wise. The 2.31 W consumption on EVA seems very low though. This means you can survive with 18 times less power by staying outside the pod (and resupplying every 12 h)...

I certainly would not mind if you used some of my numbers. Given that all foreseeable processes for CO2 reprocessing convert it and H2 to water + something else, the current CO2 -> O2 + waste converter is probably an abstraction a Bosch reactor (CO2 + 2H2 --> C(solid waste) + 2H2O) coupled with an electrolyser (2H2O --> O2 + 2H2), yielding a net CO2 --> C(solid waste) + O2. While the Bosch reaction is exothermic, the required compressors/heaters and controls mean you need to supply quite a bit of power to manage it. This 1971 paper mentions 950 W to sustain four (human) crewmembers. Moreover, we have to include the power requirements from the electrolyser (about 1 kW for four humans). I will investigate more recent papers. A seemingly more practical (in terms of the requisite pressures and temperatures) reaction is the Sabatier reaction (CO2 + 4H2 --> CH4 + 2H2O). This requires a supply of hydrogen, but hydrogen is light enough, and it produces methane as waste. As these two reactions give H2 an essential life support role, I think it is worth considering modeling it. This will also allow for life support systems based on of 2H2 + O2 cells, which were historically used in Apollo and STS for both water and power. I will now try to find specifications for Bosch and Sabatier Reactors, as well as for fuel cells. I have not found any instances where LOX/LH2 used for propulsion was also used in fuel cells or life support systems, so I think it is safe to base my calculations on a Hydrogen resource separate from the MFS LiquidHydrogen. For ease of computation, I shall use 1 unit of Hydrogen to represent as many molecules of hydrogen as there are molecules of oxygen in 1 unit of Oxygen (1 kerbal * day), namely 13.4067 mol. This means 2 units of Hydrogen will nicely react with 1 unit of Oxygen in a fuel cell to form 0.268764 units of Water. RESOURCE_DEFINITION { name = Hydrogen density = 0.0000270274 flowMode = ALL_VESSEL transfer = PUMP } It might be wise to call it LifeSupportHydrogen to avoid conflict with other mods (and general confusion), though this does not seem to have been necessary for Oxygen.

I wanted to make an electrolyser TacGenericConverter, and I found some interesting numbers. A standard kerbal (unmodified TACLS) consumes in one 24h day (rounded to 3 significant figures) : 1.79 kg of water (this is slightly less than half the daily recommended intake of adult human males), 316 g of food, 429 g of oxygen (that's 322 l at 20 °C, 1 atm, a bit more than half a human adult). That same kerbal produces during the same time: 1.98 kg of waste water (more than the water intake, but some of this comes from the food), 56.2 g of dry solid waste, 511 g of carbon dioxide (it follows that the kerbal's respiratory exchange ratio is on average 0.866, which makes sense). We shall now assume 1 kJ = 1 ElectricCharge, which seems to have become the consensus, e.g. http://forum.kerbalspaceprogram.com/threads/54327-Realism-Overhaul?p=731978&viewfull=1#post731978. The average power consumption by the ISS water recovery system is (http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20060047781_2006249861.pdf) 560 W. However, if we do not average over time, the consumption when in use seems to be 700 W (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1332000/). Using the figures from this last article, the ISS produces 1.5 gallons of water (5.68 l, or 3.46 kerbal * days) in one hour, using 2520 kJ in the process. It follows that the ISS WRS is 1.53 times more energy efficient than the TACLS WaterPurifier, and that 11.5 of the latter would be needed in order to replicate the functionality of the former. The apparatus would be more massive by a factor of 6.55, but everything is made of solid platinum in KSP. The 90% efficiency is alright, since they plan on 94% for the EWRS and the current systems are around 80%. Regarding CO2 reprocessing, we first need to consider that the ISS produces oxygen by electrolysis and vents carbon dioxide (these calculations will come in handy for CO2 reprocessing anyway, as both the Sabatier and the Bosch processes convert CO2 and H2 to water, which you still need to separate). Using the numbers found at http://www.jamesoberg.com/elektron2_tec.html, one comes to the following specifications for an electrolyser that replicates the functionality of Elektron scaled to 3 kerbals (this is actually slightly less efficient). There is some mass loss representing the vented hydrogen. if we want to keep it for use in a Sabatier or Bosch reactor (or more boosters ), this process produces 81.0789 g of hydrogen (that's about a litre if it's liquid, or 0.9 m^3 at atmospheric pressure) : MODULE { name = TacGenericConverter converterName = Electrolyser conversionRate = 1 inputResources = Water, 1, ElectricCharge, 51776 outputResources = Oxygen, 3.7215675, false, Hydrogen, 7.443135, true } All units are kerbal*days, that is, the electrolyser consumes a kerbal*day of water to produce 3.72 kerbal*days of oxygen, and does so in a day. The energy consumption is about 0.6 kW. Specifications for the Sabatier and Bosch reactors later, I need some sleep.

A wonderful BPC indeed, and a neat parachute. May I however suggest allowing surface attachments on the escape tower ---[tt] attachRules = 1,0,1,1,0 [/tt]---, thus enabling more control over the LES, e.g., through the use of Safer Development boosters as pitch control motors (no symmetry) and tower jettison motors (2-fold symmetry) ? My trials with this alteration yielded a highly reliable LES, the escape tower being more self-contained than in my previous model (Pod - NovaSilisko's Mk3 - Safer Decoupler - Sunday's Punch-out - Safer Structural, bearing the aforementioned motor setup - Safer Aeropart), which, unless subtly adjusted, would send the capsule crashing right into the ground during pad aborts... One could argue, though, that if an escape tower is frowned upon, jettison and pitch control motors would be rejected outright by Jebediah. Who would want to board a rocket without there being a chance of being crushed by the life-saving systems, or even landing a bit closer to that splendid explosion below? 8) Thanks for those good-looking parts, eggrobin