R400-series: Zeotrope mixtures of refrigerants that do not have a evaporation point but rather a evaporation range. Evaporation takes place not on a fixed temperature but during the increase of temperature with a few degrees
R500-series: Azeotrope mixtures with a fixed evaporation point.
R600-series: Other organic refrigerants.
R700-series: Inorganic refrigerants.
Refrigerants for heat pumps
Below, several frequently used refrigerants in heat pumps are described.
R134a is used as a refrigerant for medium sized or large heat pump systems. As compared to refrigerants R407c and R410a its efficiency is much higher. However, as compared to refrigerant NH3 its efficiency is lower. The pressure in R134 is fairly low. Due to this the volume that needs to be swept by the compressor is rather high and therefore higher investments are needed for installation.
R407c and R410a are frequently used in small to medium sized heat pump systems. These refrigerants are regularly used in installations that have the dual function of both air conditioning and heating. R410a is supercritical above a temperature of 71 °C. Above this temperature a difference between gaseous and liquid phase can no longer be made. R410a can be applied in low temperature heat pump systems. As compared to R134a the volume that can be swept by the compressor is smaller; implying lower investment costs. On the other hand: its efficiency as compared to R134a is lower as well.
R600 (butane) and R600a (isobutene) are used for refrigeration installations. These refrigerants are also suitable for use in a heat pump, especially for temperatures higher than 80 °C. Many refrigerants give high pressures at these temperature levels. For R600 and R600a the increase of pressure with temperature is much lower. Because of a fire and explosion hazard, installations with R600 and R600a should meet safety requirements of NPR-7600.
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