Refrigeration is the process used in air conditioners: consists in producing cold, or better, to extract heat to produce cold since what is done is to carry heat from one place to another. So, the place to which he removes heat cools. As can exploit temperature differences to produce heat, to create differences of heat energy is required.
Usually the air conditioning refrigeration is produced by two systems: compression refrigeration or cooling by absorption.
Mini Split AC Units. Compression Refrigeration System.
The conventional cooling and the most used in the air conditioning, is the compression refrigeration system. Mechanical energy through a refrigerant gas is compressed. By condensing this gas emitted before the latent heat evaporates, it had absorbed the refrigerant to a lower temperature level.
To maintain this cycle employs mechanical energy, usually by electrical energy. Depending on the costs of electricity, this cooling process is very costly. Moreover, taking into account the efficiency of power plants, only a third of the primary energy is used in the process. Furthermore, the refrigerants employed nowadays belong to the fluorochlorocarbons, which on the one hand damage the ozone layer and on the other hand contribute to the greenhouse effect.
An alternative method is for absorption refrigeration. However, this absorption method is typically used only when there is a residual heat source or cheap, so cold production is much more economical and environmentally friendly, but their performance is significantly lower. In these systems the energy supplied is first thermal energy.
Ductless Mini-Split Air Conditioner. Absorption Refrigeration Cycle.
In the absorption refrigeration systems distinguishes between two circuits, the circuit of the refrigerant between thermal compressor, condenser and evaporator, the solvent and the circuit between the absorber and stripper. A remarkable advantage of absorption systems is that the refrigerant is not a fluoroclorocarbono.
The solvent mixture of refrigerant and air conditioning applications and for temperatures greater than 0 ° C is water and lithium bromide (LiBr). In applications for temperatures down to -60 ° C is ammonia (NH 3) and water. To date no other appropriate mixtures found for these applications, but are developing adsorption systems, in which the refrigerant is absorbed in solid matrices of zeolites.
