Phase-change heat exchangers
Phase-change heat exchangers is to heating up or cooling down fluids in just a single phase, heat exchangers can be used either to heat a liquid to evaporate (or boil) it or used as condensor to cool a vapor and condense it to a liquid. In chemical plants and refineries ,reboilers used to heat incoming feed for distillation towers are often heat exchangers.
SETUP For Phase-change heat exchangers :
Distillation set-ups typically use condensers to condense distillate vapors back into liquid.
Power plants that use steam -driven turbines commonly use heat exchangers to boil water into steam. Heat exchangers or similar units for producing steam from water are often called boilers or steam generators.
Phase-change heat exchangers For USES:
In the nuclear power plants called pressurized water reactors , special large heat exchangers pass heat from the primary (reactor plant) system to the secondary (steam plant) system, producing steam from water in the process. These are called steam generators. All fossil-fueled and nuclear power plants using steam-driven turbines have surface condensers to convert the exhaust steam from the turbines into condensate (water) for re-use.
To conserve energy and cooling capacity in chemical and other plants, regenerative heat exchangers can transfer heat from a stream that must be cooled to another stream that must be heated, such as distillate cooling and reboiler feed pre-heating.
This term can also refer to heat exchangers that contain a material within their structure that has a change of phase. This is usually a solid to liquid phase due to the small volume difference between these states. This change of phase effectively acts as a buffer because it occurs at a constant temperature but still allows for the heat exchanger to accept additional heat. One example where this has been investigated is for use in high power aircraft electronics.
Heat exchangers functioning in multiphase flow regimes may be subject to the Ledinegg instability.