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9.3.- HEAT PUMPS
A heat pump is a thermal machine that exchanges energy in the form of heat from one space to another, from a cold source to a hotter one. Energy must be supplied for its operation since, due to the second law of thermodynamics, heat is spontaneously transferred from a hot source to a colder one.View more
The cycle of a heat pump is:
- Compression: the compressor transforms the electrical energy into heat and transfers it to a cooling fluid, raising its pressure and temperature.
- Condensation: the refrigerant goes from gaseous state to liquid state in a condenser that gives heat to the hot source.
- Expansion: the liquid expands, it is transformed into gas and cooled.
- Evaporation: heat is absorbed from the cold source and it is transferred to the refrigerant.
From this basic scheme, modifications can be made to increase the cycle performance or adapt it to specific requirements.
For greater performance, it is important to obtain the highest possible temperature of the environment (air, water, soil, groundwater …), which is the source of energy. Nevertheless, variables such as the initial investment and the authorization cost must be taken into account.
Since the thermodynamic cycle is the same, a heat pump can operate to heat or cool the ambient air. The function of the evaporator and the condenser is changed by a reversing valve, two check valves and an additional expansion valve.
Different evaporator designs are used depending on the needs:
- The direct evaporator, where the refrigerant takes the heat directly from the environment and the costs are reduced.
- The brine evaporator, where a circuit with liquid transfers the heat from the heat source to the evaporator to cover distances. It is used when heat is extracted from the groundwater, soils or waters. Since a pump is used for the brine circuit, the costs are high.
Heat pumps are used in conditioning systems for homes, hotels, offices, etc., although they are also used in other areas, such as heating swimming pools or in laundries.View Products