The vapor injection port is the core key structure of the EVI compressor, working as follows:
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After the refrigerant passes through the economizer, it is divided into two streams. One main stream continues to the evaporator for heat absorption; the secondary low-pressure, low-temperature vapor is guided into the middle injection port of the compressor cylinder, instead of only entering from the initial suction port like ordinary compressors.
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This supplementary cold vapor mixes with the compressed refrigerant midway in the compression stroke. It cools down the compressor compression chamber, reduces discharge temperature and lowers the overall compression ratio, effectively solving overheating and power drop in cold weather.
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Meanwhile, the injected vapor increases the total refrigerant circulation volume and system enthalpy. It supplements heating output, offsets severe capacity attenuation at ultra-low ambient temperatures.
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By adopting two-stage staged compression in one single compressor, the injection port enables stable operation even at -25°C to -30°C, maintaining high heating efficiency and reliable running performance in cold climates.