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eggrobin

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Everything posted by eggrobin

  1. 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.
  2. 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).
  3. 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 }
  4. 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)...
  5. 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.
  6. 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.
  7. 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
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