Multizone air conditioning system and evaporators therefor

Claim 1

A multizone air conditioning system for cooling multiple zones by circulating refrigerant in a closed circuit through the system, the system comprising: at least one condensing unit containing a compressor and a condenser for condensing the refrigerant from a vapor to a liquid refrigerant, said condenser being in fluid connection with and downstream from said compressor; a plurality of evaporator units placed in parallel relationship with one another in the circuit and in fluid connection with and downstream from said condenser, each individual evaporator unit including at least one expansion device, heat exchange tubing having an input end downstream from said expansion device, and an output end in fluid connection with said compressor; control means for activating and deactivating at least one individual evaporator unit so that refrigerant flows through said evaporator unit when it is activated and does not flow through said evaporator when it is deactivated; and means including at least one automatically operated close off valve located in the heat exchange tubing of an individual evaporator unit between said input and output ends for retaining within a portion of the heat exchange tubing of an individual evaporator, when and if it is deactivated, an amount of liquid refrigerant that is, when evaporated, approximately equal to the amount of refrigerant that is in the individual evaporator unit when it is activated, whereby the refrigerant in each individual evaporator unit of the system remains essentially the same regardless of whether individual evaporator units are activated or deactivated.