63 replies to this topic

[Tickdoff Tank]

If I understand correctly, HPG Manifold is supposed to be in "Space", meaning that we are not fighting in an atmosphere. I presume that the installation is situated on a moon or large asteroid to account for the gravity.

However, if the map is supposed to represent a battle in a vacuum, then the heat dissipation should be severely curtailed. I could possibly see the heat scale starting at a lower point than normal, but mechs should have a harder time shedding heat on that map.

I know this will never happen, and I fully understand why, but it still bugs me.

[Trauglodyte]

It is a slightly cooler than normal map. The added dissipation isn't anything that you'd really notice.
Also, you're assuming that a vacuum means no heat, which isn't the case at all.

Edited by Trauglodyte, 02 April 2016 - 03:00 PM.

[Ex Atlas Overlord]

Tickdoff Tank, on 02 April 2016 - 02:51 PM, said:

However, if the map is supposed to represent a battle in a vacuum, then the heat dissipation should be severely curtailed.

Vacuums do not prevent heat transfer by radiation.

Edited by The Atlas Overlord, 02 April 2016 - 03:04 PM.

[Bishop Steiner]

Trauglodyte, on 02 April 2016 - 02:59 PM, said:

It is a slightly cooler than normal map. The added dissipation isn't anything that you'd really notice.
Also, you're assuming that a vacuum means no heat, which isn't the case at all.

i think you read him backwards, he is talking about mechs running hotter because of inferior heat transfer.

[Bishop Steiner]

The Atlas Overlord, on 02 April 2016 - 03:03 PM, said:

Vacuums do not prevent heat transfer by radiation.

true.

Radiation is still an effective means of heat transfer, even in a void.

The Cold of Space

Question: "NASA frequently refers to "the cold of space" and the extremes of temperature from the sunny side of the shuttle to the shaded side. If I remember my college physics and astronomy correctly, space is a vacuum. Doesn't a true vacuum have no temperature? It would seem that the only problem that the astronauts should have is getting rid of heat. The only form of heat dissipation would be radiational and that would not be enough to cool an astronaut in a space suit -- they must require some form of air conditioning. If I am incorrect, then how does a vacuum bottle keep things hot or cold?"


Answer: "You remember your college physics correctly. Space is a vacuum, and heat can only be exchanged through radiation. However, that is a quite powerful means of exchanging heat. Have you ever stood in front of a campfire on a very cold winter night? While facing the fire you may feel roasted in your face, while your back feels frigid. The fire radiates heat at you, and your back radiates heat into the cold night. Of course, the cold air around you plays a role, but if there is no wind, the major heat exchange is radiation.

In space this is turned to the extreme. Without any star or planet nearby the temperature of space (as defined by radiation) is 3 K (-270 centigrade), the temperature of the ubiquitous background radiation from the Big Bang, i.e. extremely cold indeed. A spacecraft is roasted on the side that faces the sun and very effectively cooled on the opposite side.

The amount of heat that a spacecraft radiates into space and receives from the Sun can be controlled by the makeup of its surface. And this is the second secret of the vacuum bottle (or thermos): while the vacuum suppresses heat exchanges by conduction and air convection, exchange by radiation is suppressed by the shiny metallic coating of the bottle. This shiny coating reflects the heat radiation like a mirror and keeps it either inside the bottle (if the content is hot) or outside (if the content is cold)."

Dr. Eberhard Moebius
(March 2003)

http://helios.gsfc.n...v/qa_sp_ht.html

covers the basic principles, even if not the exact scenario. I figure NASA might know a little something about heat transfer in a vacuum.

Edited by Bishop Steiner, 02 April 2016 - 04:30 PM.

[Ex Atlas Overlord]

Bishop Steiner, on 02 April 2016 - 03:04 PM, said:

i think you read him backwards, he is talking about mechs running hotter because of inferior heat transfer.

Radiation is the greatest contributor to heat loss.

Going into a vacuum doesn't give you "inferior" heat transfer.....unless you're trying to use a method that doesn't work in a vacuum.

So if the mechs were designed to ONLY cool via convection, then sure.

But since they're designed to go into space.... their heatsinks would be designed out of a material with a high radiation constant.

Then the only limit is the difference between objects..... since a vacuum has a temp near zero K.... it's quite of lot of energy loss.





If an hot object is radiating energy to its cooler surroundings the net radiation heat loss rate is:
q = ε σ (T_h⁴ - T_c⁴) A_c
T_h = hot body absolute temperature (K)
T_c = cold surroundings absolute temperature (K)
A_c = area of the object (m²)
ε σ= radiation constant

Edited by The Atlas Overlord, 02 April 2016 - 03:18 PM.

[Bishop Steiner]

The Atlas Overlord, on 02 April 2016 - 03:16 PM, said:

Going into a vacuum doesn't give you "inferior" heat transfer.....unless you're trying to use a method that doesn't work in a vacuum.

So if the mechs were designed to ONLY cool via convection, then sure.

But since they're designed to go into space.... their heatsinks would be designed out of a material with a high radiation constant.

Then the only limit is the difference between objects..... since a vacuum has a temp near zero K.... it's quite of lot of energy loss.


If an hot object is radiating energy to its cooler surroundings the net radiation heat loss rate is:
q = ε σ (T_h⁴ - T_c⁴) A_c
T_h = hot body absolute temperature (K)
T_c = cold surroundings absolute temperature (K)
A_c = area of the object (m²)
ε σ= radiation constant

I never said it did, I said that is what the OP implied. If you look at my answer above, it actually contains a quote from a NASA scientist explaining heat transfer in a void.
http://mwomercs.com/...ost__p__5115014

Edited by Bishop Steiner, 02 April 2016 - 03:20 PM.

[thehiddenedge]

Well it may be a "vacuum", but being that close to the surface there is going to be a great deal more matter in the surrounding air than you would get further out in what is considered space.

[Tickdoff Tank]

Trauglodyte, on 02 April 2016 - 02:59 PM, said:

It is a slightly cooler than normal map. The added dissipation isn't anything that you'd really notice.
Also, you're assuming that a vacuum means no heat, which isn't the case at all.

A vacuum means greatly reduced heat dissipation. There is convection (or at least very very little) to assist in the heat loss.. I am not assuming "no heat". Heat radiation is the primary way a "spacecraft" or in this case, a space bound mech, would dissipate the heat, but that does not quite seem to make sense to me on HPG. And with the extreme amount of heat generation that a mech has, I still think it should be more difficult to lower your heat on that map.

Again, I know why it was not put on that map, but I kinda wish it was. Would make for a rather interesting dynamic.

edit: I have read everything on the NASA site about heat radiation in a vacuum. It is also predicated on turning your vessel away from the heat source in order to assist in the radiation of heat. Which we do not really have in a mech. I am not saying that there should be NO heat dissipation, but it WOULD be less than on a planet.

Edited by Tickdoff Tank, 02 April 2016 - 03:40 PM.

[Bishop Steiner]

thehiddenedge, on 02 April 2016 - 03:19 PM, said:

Well it may be a "vacuum", but being that close to the surface there is going to be a great deal more matter in the surrounding air than you would get further out in what is considered space.

and again, even in a vacuum, one dissipates through radiation.

Tickdoff Tank, on 02 April 2016 - 03:19 PM, said:

A vacuum means greatly reduced heat dissipation. There is convection (or at least very very little) to assist in the heat loss.. I am not assuming "no heat". Heat radiation is the primary way a "spacecraft" or in this case, a space bound mech, would dissipate the heat, but that does not quite seem to make sense to me on HPG. And with the extreme amount of heat generation that a mech has, I still think it should be more difficult to lower your heat on that map.

Again, I know why it was not put on that map, but I kinda wish it was. Would make for a rather interesting dynamic.

http://mwomercs.com/...ost__p__5115014

[Ex Atlas Overlord]

Bishop Steiner, on 02 April 2016 - 03:20 PM, said:

and again, even in a vacuum, one dissipates through radiation.

I think the problem tends to be people see: Convection, Conduction, Raditation and assume that they each all transfer an equal amount of energy and ONLY that amount of energy......

[Bishop Steiner]

The Atlas Overlord, on 02 April 2016 - 03:28 PM, said:

I think the problem tends to be people see: Convection, Conduction, Raditation and assume that they each all transfer an equal amount of energy and ONLY that amount of energy......

I also think people get conduction and radiation confused, since atmosphere also transfer through conduction (and don't get that all 3 forms of trnafer occur in an atmosphere), whereas in a vacuum radiation becomes MORE efficient.

*shrugs*

[Ex Atlas Overlord]

Bishop Steiner, on 02 April 2016 - 03:31 PM, said:

I also think people get conduction and radiation confused, since atmosphere also transfer through conduction (and don't get that all 3 forms of trnafer occur in an atmosphere), whereas in a vacuum radiation becomes MORE efficient.

*shrugs*

Edited by The Atlas Overlord, 02 April 2016 - 03:33 PM.

[thehiddenedge]

Bishop Steiner, on 02 April 2016 - 03:20 PM, said:

and again, even in a vacuum, one dissipates through radiation.

I agree, I was simply stating that conduction would be more efficient near a surface than out in space due to more condensed matter.

[Bishop Steiner]

thehiddenedge, on 02 April 2016 - 03:34 PM, said:

I agree, I was simply stating that conduction would be more efficient near a surface than out in space due to more condensed matter.

possible. Would also depend on if it's a true vacuum, and any number of things. Science is cool, and can be fun, but there's a point where one just rides with the rule of cool (unless you are paul, who is against any form of heat neutral mechs... which is quite appropriately NOT COOL)

[Cyborne Elemental]

I've always been curious about this as well.

There is no wind nor atmosphere to absorb, distribute, or move that heat, what is the science behind heat transfer in a vacuum?

[Bishop Steiner]

Mister D, on 02 April 2016 - 03:49 PM, said:

I've always been curious about this as well.

There is no wind nor atmosphere to absorb, distribute, or move that heat, what is the science behind heat transfer in a vacuum?

My link lists some of it. It radiation transfer. With no particulates, the same vacuum that allows radio waves to radiate so cleanly and uninterrupted, actually makes for a very effective heat dispersal, through means of radiation.

[Ex Atlas Overlord]

Mister D, on 02 April 2016 - 03:49 PM, said:

There is no wind nor atmosphere to absorb, distribute, or move that heat, what is the science behind heat transfer in a vacuum?

If an hot object is radiating energy to its cooler surroundings the net radiation heat loss rate is:
q = ε σ (T_h⁴ - T_c⁴) A_c
T_h = hot body absolute temperature (K)
T_c = cold surroundings absolute temperature (K)
A_c = area of the object (m²)
ε σ= radiation constant (varies based on the material)

Edited by The Atlas Overlord, 02 April 2016 - 04:18 PM.

[Metus regem]

Too much science for a day off...

[Exilyth]

Using heat pumps to transfer heat from the internals to another medium, e.g. a gas, which is stored compressed, released into the heatsinks and then let out to the outside once heated up would solve this nicely.

Decompressing the gas even leads to an additional cooling effect.

Edited by Exilyth, 02 April 2016 - 05:09 PM.