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The collection and transportation of heat:
The components and systems depend on the power density, the level of power, and the degree of temperature requirements for collection and transportation of heat.
Mechanical elements for TCS:
In general, collection of the heat dispersed by any type of device through its fixation elements and baseplate. With increasing power dissipation, the complete baseplate has to be in contact with the spacecraft panel. The transfer of heat depends on the parameters such as the surface finish, interface pressure, the types of materials involved in difficult to control and quantify. The way to increasing the conductivity through the interface surfaces include the use of synthetic mats or metallic, and the application of the thermal grease. This last solution has to be used with care because of the obvious potential contamination of difficulties.
Heat pipes:
The heat pipe is a device that allows efficient transport for thermal energy. It consists of a sealed metal tube with a capillary structure on the inside, and filled with a suitable working fluid. Heat is absorbed at one end by the evaporation of the fluid, and released at the other end by condensation of the vapour. The liquid is transported again back to the evaporator by the capillary forces.
The heat pipes commonly used on the spacecraft are an aluminium or ammonia type that allows optimal temperature control in the range of 0 to 40°C. The quantity of the heat transported by the pipe and it determined by its dimensions and design, the equivalent thermal conductance is constant and leading to the stable Conductance Heat Pipe.
Cooling loops:
For greater power dissipation or more stringent temperature requirements, other heat collection and transportation systems can be used. Various kinds of fluid loops have been proposed and applied to cope with these situations.
In single-phase loops, the refrigerating liquid absorbs the heat from the heat dispersing items by increasing its temperature, and transports it to the heat rejecting device where the fluid is cooled down. A mechanical pump is essential to provide the hydraulic energy needed for this process. The process of cooling loops, it has four types. There are Single phase loop, two phase capillary loop, two phase hybrid loop, and mechanically assisted two phase loop.
Thermo electric heat pumps:
Heat pumps have reversible mechanism that able to transfer the thermal energy from lower to higher temperature bodies using extra source of energy. Only this kind of heat pumps have been used in space, the basic feature of this pump is the Peltier element, and it’s the connection through the metallic tab of type p and type n semiconductor devices.

These kinds of heat pumps are normally used for the control of tight temperature of the low power devices and the facilities used for microgravity equipments. Many systems have been used and developed for both manned and unmanned spacecraft.