Commercial starship lifeboat requirements

[PFVA63]

Your scenario is specifically about what to do when the situation is noticed and handled. So, no, not the same....

hi,

I disagree. Specifically I believe that I mentioned things like abandoning aircraft, boats, cars and houses and belongings in general specifically in response to the comments that had been made about the unlikelihood of people abandoning a multi-million credit starship. the specific case of abandoning an airplane in the event of the loss of life support that might exhibit an immediate threat to the crew onboard was another specific case.

...But, let's look at it: if they fail to correct the situation, how will bailing out improve the situation? In only one case could it - when the pilot dies or goes totally unconscious from hypoxia in some aircraft in which there is no ability to land the aircraft from the other seat. Even then, the aircraft would be flown to a lower altitude if possible, and an attempt to wake the pilot made, before abandoning the aircraft (likely only when fuel totally ran out). Again, however, this goes back not to a situation of "loss of cabin pressure" or even "loss of life support" - it goes back to an unrecoverable, out-of-control flight situation

Which is why you should listen to those who know what they are talking about. If they cannot descend to a lower altitude in time, then ejecting from the aircraft will surely kill them - since the ejection system will carry them through the same thin atmosphere ... and at a much slower rate than an emergency descent in an aircraft.

No jumping involved at all. I flew military aircraft for a number of years. I KNOW that this abstract is giving information which can only be deciphered by someone familiar with aircraft mishaps. You can look for more information on the internet if you so desire, but I don't understand why you would do so when you already have someone knowledgeable on the subject discussing it with you.

BTW, in case my opinion is inadequate, I polled three aircraft crewmembers in my office - their experience includes F4s, RF4s, KC-135s, B-52s and B1s - and every last one of them said the same thing: they would never leave an otherwise functioning aircraft if their sole problem was a loss of cabin pressure or a contaminated O2 system. Every last one of them had the same reaction I did concerning the abstract you quoted, and to the idea of ejecting because you couldn't reach a lower altitude quickly enough. If that's inadequate, I can go around the building and ask all the other fighter/bomber pilots/WSOs/OSOs/navigators who work here.

In this context, yes, you are - by definition - arguing about what should be done. I stated in the beginning that someone might do so, and they would be in trouble for doing so solely on the basis of a loss of cabin pressure. As to a "good reason", I explained there were good reasons - but they weren't loss of cabin pressure.....

With respect to such a situation, here is a link to a note on the internet about a Lockheed U-2A lost when "at 35,000 feet when he suffered an oxygen failure. As he began to pass out, the aircraft went out of control. Ericson managed to open the canopy, and parachute to a safe landing on the Navajo Indian Reservation in Arizona.' In this case it appears that the loss of life support onboard the aircraft put the pilot's life at risk and he 'abandoned' the aircraft and survived the ejection to land safely.

http://aviation-safety.net/wikibase/wiki.php?id=155918

...No. Read the rest of what I wrote - specifically, the fictional example from the Imperial Lancet.

Yes, it was proposed as an alternative to the lifeboat issue, since lifeboats don't make much sense in your scenario....

Actually in looking over the Mongoose High Guard they make mention of a 'Vault' which is described as a 'special armoured chamber in the heart of a spacecraft, designed to survive attacks that would annihilate the rest of the ship. ... A vault can contain cargo, staterooms or any other internal components equivalent up to 6 tons." As such, in some ways this seems a bit similar to the 'safe haven' that some others have described.

...And, it has been explained time and again that there are very few good reasons to abandon a spacecraft at all, and all of those involve actual destruction of the spacecraft such that existence in small, vulnerable, scattered units is preferable. Many of us have postulated that even those reasons (for civilian craft) are so infrequent that the carrying of lifeboats is economically unsound. ...

However, as I have noted lifeboats already exist in the Traveller universe in the form of the small craft that are already carried aboard many ships which can serve as lifeboats/lifepods in addition to their other duties. As such, to argue that "the carrying of lifeboats is economically unsound' actually doesn't really make much sense to me. Basically they already exist, although they are not specifically required by the rules.

As such, (as I have stated previously) to me the real questions are likely more along the lines of can other additional 'standardized' small craft or other rescue to options like lifepods also be included in in the game? In some respects Mongoose has broached this topic a little in providing 'escape bubbles' but other options may also be worth considering. And, in addition to this, is there any potential benefit to having certain specific ships (like passenger ships) being required to provide some form of back up lifepod/lifeboat capacity for the passengers?

...Oh, and stop tossing in "small craft". If we're talking lifeboats being carried, they are dedicated space that cannot be used for other purposes. A "small craft" is carried for other purposes, but could serve as a "lifeboat" in extremis. They are not the same thing when arguing whether they should be carried....

I disagree. Even for modern ocean going ships the craft that serve as 'lifeboats' can also have other functions. specifically, Wikipedia notes that;

" In the military, a lifeboat may double as a whaleboat, dinghy, or gig. The ship's tenders of cruise ships often double as lifeboats."

( http://en.wikipedia.org/wiki/Lifeboat_(shipboard) )

...Fine. Believe what you want - but it is a fallacy. If I call you a kumquat, that doesn't make you one, and it is a fallacy to believe otherwise.

With respect to this topic it may also be worth noting that in a recent period of high risk to the space station, the personnel onboard were relocated to the station's 'lifeboat' as a precaution in case the station needed to be abandoned quickly but it was not actually launched.

 

[PFVA63]

... Atpollard's 0.35, if I have it right, serves spaces like a hotel room or other setting where occupancy is light; that would be appropriate for passenger rooms and hallways....

Hi,

Taking a look at Table E-2 of the ANSI/ASHREA Standard 62-2001 entitled "Ventilation for Acceptable Indoor Air Quality" it appears that the "0.35 air changes per hour but not less than 15 cfm (7.5 L/s) per person' is actually the "outdoor air requirements for Ventilation of Residential Spaces" where "In using this table, the outdoor air is assumed to be acceptable".

As such I believe that this value represents the 'make up' air that is pumped into the house from the outside, and does not represent the number of times that the air within the house is recirculated through the enclosed space.

For a space ship or space station, outside make up air would not be available and as such I do not believe that this table is thus appropriate for our purposes.

http://www.google.com/url?sa=t&rct=...LF2SKfX_ZQ3cJh2Til8wijg&bvm=bv.50952593,d.aWc

 

[Carlobrand]

If alternate numbers are thought to be better those can be looked at.

Hmmm ... awkward since I'm moving away from the idea of using power plant heat (I much prefer compartmentalization), but others are still following that. Let's start by shaving it back to ten changes. I still think that's high by a factor of two, but it's a reasonable compromise. As to temp - I don't know. On-line articles are quoting CO2 decomposition temperatures at everything from 3500C with just heat to 1300C with some form of catalyst. Since we're preferring to kill two birds with one stone, we can try those figures, but we might want to play with a lower figure, on the assumption that CO2 breakdown is being accomplished by other means and the plant being used only for sterilization - HG's 800 degrees F figure translates as 700 Kelvin.

...I believe that I had noted this previously specifically noting how difficult/unlikely it would be to try and provide multiple sets of piping/ducting for given systems. ...

Why precisely would it be difficult to try and provide multiple sets of piping/ducting? I'm not seeing where that one comes from at all.

Look at the Supplement 7 deckplans for the Subsidized Liner. One distinct compartment comprising the forward passenger lounge and 7 staterooms (#s 3, 4, 7, 8, 9, 12 and 13). One distinct compartment comprising the galley and 6 staterooms (#s5, 6, 10, 11, 14 and 15). A distinct bridge compartment. A distinct engine room compartment. A distinct low berth compartment. A single very large cargo deck.

The cross-section on page 6 clearly shows use of the overhead space for ductwork and machinery of some kind. Maybe a fifth or a sixth of the volume of a living compartment is in this space. (I personally put more there; I like the home-like 7' ceiling, so my overheads take up about 3/10 of the volume.) So, for the typical 4 dTon stateroom allocation, perhaps 20% is ductspace.

MegaTrav offers some insight into details of the ship's infrastructure. Basic environment (heating and lighting) take up 1/2 percent of the volume. Basic life support (sealed environment, atmosphere and water) takes up 5%. Extended life support (food, waste recycling) takes up 0.3%. Grav plates are 1%, inertial compensators another 1%. In other words, the whole kit 'n kaboodle can be fit between decks with room to spare. Other than control wiring, there is no reason any compartment's equipment needs to extend into any other compartment, and it's actually best if they don't since this makes each compartment independently airtight, limiting the extent of damage in the event of a hull breach or life support failure.

So, on the subsidized liner, you have six distinct compartments. How well-served these compartments are, that would be something the gamemaster would decide: bridge and engine compartment might not have water or waste service, for example, and the cargo bay doesn't have the overhead space that the living areas do, so what air recycling it has is likely to be rudimentary and fed from the wall spaces near the drives. However, whatever the gamemaster might prefer, there's nothing in the layout that suggests the life support and other systems need to be interlinked, and there's no logical reason for a ship designer to make interlinked systems since these would only decrease the ship's odds of survival in the event of failure of one of the systems.

 

[Fritz_Brown]

I'm done. You've argued yourself out of a conversation, by being incredibly obstinate and constantly changing the basis of your arguments. You ignore actual experience and knowledge in favor of your pet ideas. So, you can have this discussion with yourself.

clear ether

 

[CosmicGamer]

here is a link to a note on the internet about a Lockheed U-2A lost when "at 35,000 feet when he suffered an oxygen failure. As he began to pass out, the aircraft went out of control. Ericson managed to open the canopy, and parachute to a safe landing on the Navajo Indian Reservation in Arizona.' In this case it appears that the loss of life support onboard the aircraft put the pilot's life at risk and he 'abandoned' the aircraft and survived the ejection to land safely.

It certainly can "appear" that way.

Picking little pieces that support one theory, one perhaps thinks
1) Life support failure
2) Pilot ejected and survived

when it's
1) Life support failure
2) Pilot stayed with aircraft as long as possible
3) The aircraft went out of control
4) Pilot ejected and survived

As stated before, ejecting and falling at high altitudes to an altitude with breathable air does not somehow provide a better life support solution than plane descending to a lower altitude with breathable air.

It's "the aircraft went out of control" that put the pilots life at greater risk than the loss of life support.

In traveler terms this would be
Total loss of all breathable atmosphere in a very short period, perhaps explosive decompression, during take off or landing with no backup systems like vaccsuits such that the crew will possibly pass out and the ship has no automated systems for landing and will crash. Do I have this right? So is the bridge itself a life boat that the crew can just pull the ejection lever and launch? Just me, but I think in this scenario having proper emergency gear like vacc suits is the safer and cheaper solution than trying to evacuate everyone onto life boats and let the ship crash.

However, as I have noted lifeboats already exist in the Traveller universe in the form of the small craft that are already carried aboard many ships which can serve as lifeboats/lifepods in addition to their other duties. As such, to argue that "the carrying of lifeboats is economically unsound' actually doesn't really make much sense to me. Basically they already exist, although they are not specifically required by the rules.

And Battle armor exists. I'd argue it is economically unsound to stock the entire locker with them instead of vacc suits in most cases.

 

[mike wightman]

Common canon civilian ships:
Safari Ship - 1x 20t launch
Yacht - 1x 30t ship's boat
*Sub merchant - 1x 20t launch
*Sub liner - 1x 20t launch
Free trader - no small craft
*Far trader - (air/raft)
Lab ship - 40t pinnace

It makes no economic sense to design the * ships with sub craft.

 

[PFVA63]

I'm done. You've argued yourself out of a conversation, by being incredibly obstinate and constantly changing the basis of your arguments. You ignore actual experience and knowledge in favor of your pet ideas. So, you can have this discussion with yourself.

clear ether

Hi,

Sorry you feel that way, but I don't see it that way at all.

So far I have tried to discuss something that appears to me to fit well within established Traveller Canon and I believe that I have been very clear upfront about the terms that I have been using, noting in posts long ago that in Canon Traveller had made mention of life boats and the fact that existing small craft could be used as lifeboats, etc.

Overall though, I would not describe anything as my 'pet theory' as I have noted, I have simply tried to look at things throughout Canon and make sense out of it and try and describe how I see it fitting together.
As such I do not believe that I have changed the basis of my argument. Rather, the only specific area that I think that I may have expanded a discussion was noting that it is not necessary to actually 'launch' a lifeboat/lifepod for it to be of use to the personnel onboard a ship, especially since this is not a possibility in 'jump space'. My thinking then was that in such a situation the personnel onboard a ship could use the 'lifeboat/lifepod/small craft' as a 'safe haven' until such time that they exit 'jump space', where they could then make the decision to detach or not. And, since this is a possibility in jump space, it naturally seemed to me that it was a concept that could also be applied in 'normal space' as well.

As for ignoring experience, I disagree as well. I listened to what you (and others) have had to say, but I have also made my own attempts to find additional information. And when that information has appeared to be different than what others have aid, I have noted it, typically with references to the source of my info (when I have had the info close at hand).

 

[PFVA63]

It certainly can "appear" that way.

Picking little pieces that support one theory, one perhaps thinks
1) Life support failure
2) Pilot ejected and survived

when it's
1) Life support failure
2) Pilot stayed with aircraft as long as possible
3) The aircraft went out of control
4) Pilot ejected and survived

....

Hi,

Along a similar vein, I don't believe that I ever argued a case where "an illness breakout onboard, everyone abandons ship" Rather, as I've tried to be clear on, I've noted that in cases where an illness breaks out and the personnel onboard are unable to contain and control it, and there is the fear that it may spread easily to others (such as it having contaminated the air and water supply) then you might consider segregating everyone, and depending on how things go you may end up launching the lifeboats, which may result in 'abandoning' the ship, but which also may instead mean that the sick remain on the ship with whoever is treating them (or whatever in the case where you may have some form of 'autobot' medic etc) while the remainder attempt to find help, fresh food, or supplies etc. A lot will likely depend on the specifics of the situation at hand.

As such, I think that you could also look at such a situation as 1) illness encountered, 2) personnel stay with parent ship as long as possible, 3) fear that life support system is compromised which may facilitate spread of disease, 4) personnel segregated, 5) decision eventually made to launch small craft or not. And, as noted above, launch may or may not imply the abandoning of the parent ship (depending on the status onboard it) and the small craft may be launching to 'deliver those onboard to somewhere safer', or 'it may be sent off to located supplies etc, or any one of a number of other options.

 

[PFVA63]

Common canon civilian ships:
Safari Ship - 1x 20t launch
Yacht - 1x 30t ship's boat
*Sub merchant - 1x 20t launch
*Sub liner - 1x 20t launch
Free trader - no small craft
*Far trader - (air/raft)
Lab ship - 40t pinnace

It makes no economic sense to design the * ships with sub craft.

Hi,

You bring up a good point that in some ways an air/raft does have some limited small craft and/or emergency craft use, in that (if I am understanding correctly) personnel from the ship can make use of it to travel from their ship, even in space if they are wearing their vacc suits and such (I think?).

 

[PFVA63]

...
Why precisely would it be difficult to try and provide multiple sets of piping/ducting? I'm not seeing where that one comes from at all.

Look at the Supplement 7 deckplans for the Subsidized Liner. One distinct compartment comprising the forward passenger lounge and 7 staterooms (#s 3, 4, 7, 8, 9, 12 and 13). One distinct compartment comprising the galley and 6 staterooms (#s5, 6, 10, 11, 14 and 15). A distinct bridge compartment. A distinct engine room compartment. A distinct low berth compartment. A single very large cargo deck.
....

It may well be worthwhile to also look at other ships as well. For instance, the various Scout/Couriers and Free Traders or Far Traders from the various rulesets. To get from the aft (typically machinery) spaces to forward spaces appear to often require going through the same general areas. If one of those areas is compromised/vented to vacuum then there is no longer any air in that space to maintain the warmth. As such, any piping or venting in the walls or overhead may be exposed to the temperatures of space.

As such, it would appear that unless either the pipes and vents, or the internal bulkheads, decks and overhead coverings, are protected to the same level of thermal protection/insulation etc as the outer hull then it is difficult to see how the air and water passing through these spaces and/or in deck deck/overhead structures in way of these spaces would be prevented from changing temperature, and even adjacent spaces, which appear to be separated only by internal bulkhead much thinner than the hull surface.

 

[aramis]

Vacuum is an insulator. Being in vacuum prevents most conductive cooling, restricting to blackbody radiation.

 

[Carlobrand]

It may well be worthwhile to also look at other ships as well. For instance, the various Scout/Couriers and Free Traders or Far Traders from the various rulesets. To get from the aft (typically machinery) spaces to forward spaces appear to often require going through the same general areas. If one of those areas is compromised/vented to vacuum then there is no longer any air in that space to maintain the warmth. As such, any piping or venting in the walls or overhead may be exposed to the temperatures of space.

Vacuum is an insulator. Being in vacuum prevents most conductive cooling, restricting to blackbody radiation.

As Aramis reminds us, the problem in space is not freezing. The problem is finding a way to get rid of heat. To put it in layman's terms, there are two ways to lose heat - well more than two, but two that apply to this situation. Blackbody radiation is when an object loses heat by giving off infrared light - it's why you can see people as little glowy forms in those neat infrared scopes and cameras. The other method involves the molecules of an object bumping up against the molecules of whatever it's up against and transmitting their energy kinetically - something like a bunch of billiard balls.

Space doesn't have much in the way of molecules, so cooling that way isn't possible in space. That's what makes your Thermos brand drink container so efficient at keeping your coffee warm - they put a vacuum between the inner liner and the outer shell, only point of heat transfer is where the inner liner's actually in contact with the outer shell.

You are correct that some layouts present a problem for the crew: unless you invent some IMTU method for collapsible emergency airlocks, the crew can't get from A to C if B suffers a decompression emergency. Awkward, but certainly preferable to having A, B, and C all suddenly finding themselves in vacuum.

 

[Carlobrand]

Hi,

Taking a look at Table E-2 of the ANSI/ASHREA Standard 62-2001 entitled "Ventilation for Acceptable Indoor Air Quality" it appears that the "0.35 air changes per hour but not less than 15 cfm (7.5 L/s) per person' is actually the "outdoor air requirements for Ventilation of Residential Spaces" where "In using this table, the outdoor air is assumed to be acceptable".

As such I believe that this value represents the 'make up' air that is pumped into the house from the outside, and does not represent the number of times that the air within the house is recirculated through the enclosed space.

What is "make-up" air? On what do you base this belief, other than the desire to see a higher value?

An interesting item I encountered dealt with a debate over some builders trying to circumvent the "outdoor air" requirement and reduce costs by installing CO2 filters and sensors to justify greater reliance on recirculated air within the building. The purpose of the "outdoor air" is to draw fresh air from outside into the building to replace "used" air, both to maintain acceptable O2 and CO2 levels and to ensure that odors and other contaminants get flushed out. In that capacity, it serves the exact same purpose that air outflow from a Traveller spaceship's air recycling system would serve.

https://www.google.com/url?sa=t&rct...=GdJWrOcN8c7jYd-uwkQQgQ&bvm=bv.50952593,d.aWc

 

[PFVA63]

What is "make-up" air? On what do you base this belief, other than the desire to see a higher value?

An interesting item I encountered dealt with a debate over some builders trying to circumvent the "outdoor air" requirement and reduce costs by installing CO2 filters and sensors to justify greater reliance on recirculated air within the building. The purpose of the "outdoor air" is to draw fresh air from outside into the building to replace "used" air, both to maintain acceptable O2 and CO2 levels and to ensure that odors and other contaminants get flushed out. In that capacity, it serves the exact same purpose that air outflow from a Traveller spaceship's air recycling system would serve.

https://www.google.com/url?sa=t&rct...=GdJWrOcN8c7jYd-uwkQQgQ&bvm=bv.50952593,d.aWc

Hi,

Make up air is air that has to be added to a system. This may include the need to "make up" for air that has escaped (ie the cool air that leaves your building through vents, or when you open doors, plus stuff that just leaks out naturally etc).

This site ( http://www.makeupair.info/pages/1/index.htm ) notes that;

"Makeup or compensating air is outside air which is introduced into the building to replace air that is exhausted from the building through ventilation or combustion processes."
In Heating/Ventilation and Air Conditioning (HVAC) systems units that supply "Make Up" air in volume appear to be called "Make-Up Air Units" as noted in this Wikipedia article.

http://en.wikipedia.org/wiki/Make-up_air_unit

The document below talks to the need for makeup air with regards to offsetting the air loss from "kitchen vent hoods" and how a MakeUp Air Unit can be used in that setting as an example.

www.fishnick.com/ventilation/.../CKV_Design_Guide_2_031504.pdf

From the link that you posted;

"Table 2 prescribes supply rates of acceptable outdoor air required for acceptable indoor air quality. These values have been chosen to control CO2 and other contaminants with an adequate margin of safety and to account for health variations among people, varied activity levels, and a moderate amount of smoking. Rationale of CO2 control is presented in Appendix D.""

In addition, from the document that I posted previously (which is actually Addendum n to the ASHREA 62-2001 spec and not the whole ASHREA 62-2001 spec as I think I inadvertantly indicated previously)

"6.2.4.1 Primary Outdoor Air Fraction. When Table 6.3 is used to determine system ventilation efficiency, the zone primary outdoor air fraction (Zp) shall be determined in accordance with Equation 6-5.

Zp = Voz/Vpz (6-5)

where Vpz is the zone primary airflow, i.e., the primary airflow to the zone from the air handler including outdoor air and recirculated return air. Note: For VAV systems, Vpz is the minimum expected primary airflow."

Where VAV appears to be a Variable Air Volume system.

Looking at Table E-2 from the Addendum n document you will see:



There you can see that it specifically notes that the 0.35 air changes per hour listed for Living Areas is the "Outdoor Air Requirements" for those spaces.

If you wish to consider a system with little or no make-up air (since we are talking about an enclosed starship and the only make-up air available would be from compressed air, and may be needed to make up for the hopefully small losses that may occur from using the airlocks and/or other hopefully small cases of leakage) that can be done. However, the 0.35 air changes per hour listed in the table above does not represent the total airflow that would be required for such a situation and should not be used as such.

PS. I'm not sure why you suggest that I may be arbitrarily trying to make the numbers look especially bad as I believe that they will come out that way any way.

If I were actually trying to do something along those lines though I could easily have selected a 200 dton Free Trader as an example, instead of a 100 dton Scout Courier type ship.

Since the 200 dton ship has the same power plant as a Scout/Courier, but carries less fuel (if I am recalling correctly based on my memeroies of the CT system) then the (200 dtons - 30 dtons of fuel) * and 85% permeability would give 144.5 net dtons (or 2023 cubic meters) of air that would have to be treated as opposed to the 714 cubic meters of the Scout/Courier type vessel (or 283% more air for the same sized power plant).

 

[CosmicGamer]

A lot will likely depend on the specifics of the situation at hand.

certainly

I don't believe that I ever argued a case where "an illness breakout onboard, everyone abandons ship"

That's not what I am suggesting. I hope you are not THAT unreasonable. :smirk: But it has seamed to me you were saying "if a disease corrupts life support you need a life boat to abandon ship". In the pilot scenario that you give it seams you suggest departing the plane because of a life support issue was appropriate and thus abandoning a functional ship that only has a life support issue is appropriate.

Instead, we point out that departing the plane was due to the plane being out of control and crashing was the danger and also suggest when a ship is fully functional except for life support (whatever the reason for life support issues, not just disease) the use of vacc suits, rescue baubles, and many other possibilities which allow providing oneself or a group of people alternate life support while still staying with the almost fully functional ship, it's longer range sensors and communication gear, it's supplies of medical and other items that might be needed, and so on.

and the small craft may be launching to 'deliver those onboard to somewhere safer', or 'it may be sent off to located supplies etc, or any one of a number of other options.

There actually is a thought to consider here which is something I've thought of from time to time. Something like a thrust 6 ships boat or other small craft which are much faster than the jump ship; not just for an emergency like running to get that part to repair the power plant, maneuver drive, life support or whatever but for many other reasons like getting the broker to the planet faster to start trying to find buyers and sellers for ships cargo so as soon as the ship lands it can offload and load up quicker, get passengers to their destination faster, and so on.

So yes, this fast boat might be used to offload the sick and get them to proper medical facilities faster than the ship or to go get medical professionals, equipment or supplies needed.

I'd still suggest that some out of control disease is not the reason for a life boat and instead almost a reason against it since folk could panic, fleeing and spreading a very dangerous disease.

 

[PFVA63]

Hi,

Sorry for the confusion. Sometimes I'm not as clear as I wish I could be.

 

[PFVA63]

Hi,

I've redone some quick calcs for a 100 dton ship assuming the air is heated from 297 K (about 75 deg F) to 800 K (about 980 deg F).

If I did the math right it looks like it would take 323.1MJ of energy to heat all the air onboard the ship from 'room temperature' to the 800 K value.

If we assume 10 air changes per hour (which I think would likely be the lowest number of air changes we would likely want to use) then we need to figure out how long we are assuming for heating this air.

If we assume the heating period will be for 1 minute of the 6 minute air refresh cycle then it will take 5.4 MW's of power to accomplish this, assuming 100% efficiency, and the amount of air onboard the ship being heated at any specific time would be 320.7 cubic meters (8.5 dtons).

To this we would also have to consider amount of time and volume needed to re-cool the air back down to room temperature. I haven't yet tried to figure that out yet but if it takes a similar amount of time as it took to heat the air the volume/amount of air in the process of being heated and cooled would be doubled.

Also you need to consider both the efficiencies involved and other items that might be required. For instance, in my calcs I have used the "Specific Heat Capacities" for heating at a constant volume. As such, this includes the assumption that since volume is being held constant pressure will go up. And since pressure would increase you would likely need something to force the air through the system into the region of higher pressure (beyond what would be required if the air were not heated). This will likely require additional power requirements as well.

With respect to efficiencies we would have to consider that the heat transfer will not be 100% from the heat source to the air as heat will also be transferred to the surroundings, piping/venting or enclosures, etc.

If instead we assume that the air is only heated for 30 seconds of its 6 minute refresh cycle then I believe that if I did the math right it would take 10.8 MW (at 100% efficiency and not including other loads for fans/pumps and such) but would only require 4.25 dtons of space (for the air that is, not including the machinery and such or the cooling side of the system).

Conversely If we assume that the air is only heated for 10 seconds of its 6 minute refresh cycle then I think it would take 32.3 MW (at 100% efficiency and not including other loads) and would require 1.42dtons of space (for the air).

As such, this seems to me to be a lot of power and a lot of volume needed for such a system just based on the heating side of such a system at 100% efficiency and not yet considering any additional power loads and space required for the actual machinery/physical parts of the system that may be required.

 

[atpollard]

These air change values are way too high. A 100 dTon ship has about 5000 square feet of floor area and 50,000 cubic feet of total volume. Treating all of that volume as air conditioned space and plugging it into HVAC estimator software as a super-insulated house (to maximize air circulation) yields about 2500 cfm required or about 3 air changes per hour.

Remember, however, that this is just air circulated to remove the latent moisture and heat from people and electric equipment. None of this air requires filtering for CO2 or indoor air pollutants. The 0.35 air changes per hour you referenced above serves exactly that purpose.

So the fan and condenser that removes the heat and moisture from the air requires a 2500 cfm fan and a 6 ton air conditioner and 3 air changes per hour to control waste heat and humidity in a 100 dTon living space. The air scrubbers that remove the CO2 and other nastiness, only requires one air change every 2.9 hours and a system capable of scrubbing about 300 cfm for a 100 dTon living space.

 

[PFVA63]

These air change values are way too high. A 100 dTon ship has about 5000 square feet of floor area and 50,000 cubic feet of total volume. Treating all of that volume as air conditioned space and plugging it into HVAC estimator software as a super-insulated house (to maximize air circulation) yields about 2500 cfm required or about 3 air changes per hour.

Remember, however, that this is just air circulated to remove the latent moisture and heat from people and electric equipment. None of this air requires filtering for CO2 or indoor air pollutants. The 0.35 air changes per hour you referenced above serves exactly that purpose.

So the fan and condenser that removes the heat and moisture from the air requires a 2500 cfm fan and a 6 ton air conditioner and 3 air changes per hour to control waste heat and humidity in a 100 dTon living space. The air scrubbers that remove the CO2 and other nastiness, only requires one air change every 2.9 hours and a system capable of scrubbing about 300 cfm for a 100 dTon living space.

Hi,

From the stuff I have read and am familiar with, I disagree. As noted previously the I believe the Space Shuttle, ISS and Skylab all appeared to have used a number tight around 10 changes per hour, and in those cases there either are no engines or power plants capable of putting out a large amount of power (and hence likely to produce a lot of waste heat) or in the case of the Space shuttle the main engines on the craft appear to be well separated fro the habitable spaces,and I also don't believe any of these craft/stations have the type of mess decks & galleys, sanitary spaces or the extensive types of electronics that appear to be in Traveller type designs.

Also as I've previously noted I believe that on surface ocean gong vessels numbers for air changes can typically be a fair bit higher than the 10 per hour used. Also, I previously also posted a link that indicated that for modern jet liners air changes on the order of 20 to 30 appear to be the norm.

As I posted a few posts up the ASHREA guide appears to indicate that the 0.35 air changes per hour is for "outside air" added into the system and not the recirculation rate form.

PS. I am currently looking for some of the sources that I think I recalled seeing these higher type air change rates suggested.

 

[Carlobrand]

...From the stuff I have read and am familiar with, I disagree. ...

Of course you do.

... I'm not sure why you suggest that I may be arbitrarily trying to make the numbers look especially bad as I believe that they will come out that way any way. ...

Because:

... You've argued yourself out of a conversation, by being incredibly obstinate and constantly changing the basis of your arguments. You ignore actual experience and knowledge in favor of your pet ideas. ...

Here's my thoughts:

You are a very patient person. You've kept your temper while others have lost theirs. You've stayed in here and pitched your thoughts persistently and calmly even while being criticized, sometimes sharply, from multiple fronts. However, your fund of knowledge seems to be limited to what you can find on the internet. That's not a criticism: outside of my own areas of expertise, a fair chunk of what I know comes from the internet - that, and Scientific American, and what I learn from the people here, who are really, really knowledgeable in their particular fields. When I was a kid - in the ancient pre-home-computer days - I used to enjoy myself reading random articles from Britannica (I was a very strange child), but those days are 40 years behind me and most of that information is ridiculously out of date.

At any rate, your knowledge base is weak in some areas. For example, your belief that freezing was a problem in space, or some of your ideas about disease organisms and their behavior, or your statements about "outside air," or a fair chunk of your discussion with Fritz.

Again, not a criticism - we all have our weak points. I've presented a number of what I thought were great ideas, only to have Aramis or someone else politely point out that they were scientifically absurd. Very embarrassing, but it's how we learn.

Your problem is you don't seem to be aware of the weakness. You hold forth on an argument even when people with professional experience in that area try politely and sometimes not so politely to point out that you're wrong. You seem to be convinced that the ideas and knowledge you've picked up in reading this or that article should carry as much weight as those of a professional who's been training in that field for years. As a consequence, you hear them, but you don't really listen to them - you just say you disagree and then repeat your argument.

This is a forum with many very knowledgeable people who are eager to share their knowledge with you. However, to learn from them, you must first start with an open mind, and an open mind starts with the self-admission that anything and everything you hold to be true might just be wrong.

That is in fact the basis of good science: every good scientist wakes up and goes to work each morning with the idea that something he knows to be true might just be proven wrong that day.