Two-stage compression centrifugal unit and middle air supplementing control method therefor, and heating and ventilation device

Abstract

A two-stage compression centrifugal unit. The two-stage compression centrifugal unit includes: a two-stage centrifugal compressor; an evaporator and a condenser, a first-stage air suction port of the two-stage centrifugal compressor being connected to an air outlet of the evaporator, and a second-stage discharge port of the two-stage centrifugal compressor being connected to an air inlet of the condenser; an economizer and an air supplement valve, the economizer being connected between an air inlet of the evaporator and an air outlet of the condenser, and the economizer being connected to a first-stage discharge port and a second-stage air suction port of the two-stage centrifugal compressor by means of the air supplement valve; and a calculation module for calculating, according to operation parameters of the two-stage compression centrifugal unit, an actual air supplement amount and an optimal air supplement amount so as to adjust an opening degree of the air supplement valve.

Dependencies are inferred from the claim text.