FLASH TANK ECONOMIZER CYCLE CONTROL

摘要

A flash tank economizer includes a sensor for sensing a condition indicative of pressure in the flash tank, and when that pressure is found to equal or exceed the critical pressure of the particular refrigerant being used, a controller responsively closes a valve in the economizer vapor line to shut off the economizer. A sensor is also provided to sense the pressure at the compressor mid-stage, and if that pressure is found to exceed the pressure in the flash tank, the controller causes the flow control device to function so as to prevent the flow of refrigerant from the compressor mid-stage to the flash tank. Provision is also made for selectively draining refrigerant from the flash tank to reduce the pressure therein from a supercritical to a subcritical condition.