HEAT MANAGEMENT

Nearly all processes generate waste heat, this problem is particularly acute on spacecraft, where there are very high energy processes that create large amounts of heat, combined with being immersed in an environment which is essentially vacuum.

            There are further problems with heat management, first the heat has to be ‘collected’ whether by exchange with a working fluid, or by conduction to a cooling device. The other problem is that of removing the heat itself, most spacecraft hulls are extremely good insulators, this protects the internal volume from the massive changes in environment, unfortunately this also acts as a barrier to heat transfer to the surroundings.

            As space is essentially a vacuum, this limits the way in which heat can be lost, conduction and convection simply do not exist here, therefore if heat is to be transferred into the vacuum it can only be done so due to radiation of energy from its surface. It has already been said that the hull is highly impermeable to heat, this does hinder heat management, but if heat were to pass freely between exterior and interior then the crew risk chilling in the depths of interstellar space (not so much of a problem considering there is excess of heat), or being fried in close approaches to stars or other energetic objects (far more of a problem as you would have to remove even more heat against a flow).

A partial solution to the impermeability problem is an extension of an existing device for heat management. Throughout any spacecraft there lies and mesh of superconducting wires, this web of material is useful for a whole series of reasons, its first and most important role in energy distribution, though not for supplying power to ship components, but rather to distribute energy like a heat sink.

Superconductors have an unusual property in that the temperature anywhere along its length must be the same, this means if one was able to heat up part of it in a huge furnace and trail the rest of a cable of it many kilometers away, then all parts, no matter how distant, would share the same furnace heat.

In a ship this web of superconducting filaments helps to distribute energy and heat from internal process and also to distribute the energy from hull impacts, say from energetic weapons. This feature provides the ideal structure to extract heat from the ship, as chilling any part will reduce heat everywhere on the ship, and not just locally cool the area around the heat removal device. This application of superconductors has replaced more primitive cooling systems on every scale, first in providing effective heat sinks, and channeling heat flow, and cooling from microscale, such as in circuitry, to macroscale cooling of reactors.

If an internal superconducting network distributes heat inside a ship, then a similar surface on the hull could distribute heat to the vacuum, when these two separate networks, which lay on different sides of the hull are linked then a bridge can be formed across the insulating divide and heat can be transferred to external medium. However these bridges pose new problems, they must act as heat ‘diodes’ allowing heat to flow to hull when necessary, but not to allow external heat flooding the interior, with the advances made in conduction science this does not pose too much of a problem. Also the amount of heat that is bled to the outside needs to be controlled as well, as an equilibrium needs to be set.

Leaking heat from the hull surface is an easy and efficient method, however it is limited by the amount of heat it can remove, this may be fine for small craft but may prove insufficient for larger ships, this means new methods have to be employed. It is also important for military vessels to cut down, heat losses, and even be able to chill there hulls, for the heat output would reveal their presence, so sophisticated cooling systems are required for spacecraft to retain a degree of stealth.

One method is to remove the excess heat on laser light, heat can be transferred and emitted by specialized ‘heat lasers’ then the burden of extra heat can be pumped into the surroundings, however this is not an appropriate method for most craft, for military craft it would be like lighting a beacon to indicate where you were (however you could always point the output away from where you thought the enemy lies), and also would confuse sensor readings not only for the ship emitting (as the emitted heat would effect nearby objects) but also of other ships.

The main way of removing excess heat, is by transmutation into other forms, this has been most successfully been applied to driver coil material. The material that makes up driver coils has a property of extracting energy from the local environment and converting it into a change in gravitational field. When this material is being used to produce a distortion in space for propulsion purposes, vast amount of energy has to be supplied, and the driver coils transmute the vast thermal and radiative output of say a fusion reactor, into a cold distortion of space time. Driver coil material however can not consume all energy in an environment, this would lead the environment to be chilled to absolute zero, which in itself is a violation, however the material can chill things down to a few Kelvin, and the closer it gets to absolute the less efficient the transmutation of energy. However this material provides a way for handling excess heat in spacecraft by converting a greater part of it into work.

An elegant application of driver coil technology has been the production of artificial gravity for spacecraft, and this system being run by waste heat carried in the superconducting mesh. Good understanding of how the material behaves allows precisely defined gravitational fields to be produced which exert there effect only locally, and which do not exceed the confines of the ship.

However this process does consume quite a lot of energy, and if the superconducting mesh does not contain sufficient energy to run this application then part of the ship’s conventional power supply has to augment to sustain artificial gravity. On large ships there is generally enough waste heat to run this process, on smaller ships the amount of waste heat available is quite variable, and so gravity production relies on this duel supply method.

Further cooling can be afforded by putting even more driver coil material into the waste heat network. Blocks of driver coil material can be manufactured to leave no residual distortion of space, this means no corresponding increase in gravity of spatial distortion, this is very good for military craft as the heat can effectively disappear, and leaves no signature from which its position might be ascertained.

With advanced materials waste heat has become much less of burden, it has become a provider for artificial gravity and also a resource from which useful energy can be scavenged. Energy can be scavenged from differences in temperature, by having two superconducting networks, one ‘hot’ and one ‘cold’ energy can be extracted as energy is transferred between them. Advanced thermopiles (devices that extract electrical energy by temperature differences) can produce significant amounts of energy from a ‘hot-and-cold’ networked system, and provide small volume solutions, for auxiliary power production in small ships.

However as ships develop higher power equipment, and produce heat at a higher rate, heat management technology races to provide able management but at no greater loss to useful volume.