Multi-stage refrigeration system

A method of providing multi-stage cooling, using a system having at least two independent cooling circuits with different capacities, said method comprising steps of:

• operating only a first of said at least two cooling circuits, thereby providing a first stage of cooling;
• operating only a second of said at least two cooling circuits, thereby providing a second stage of cooling greater than the first stage;
• and
• operating both the first and second cooling circuits, thereby providing a third stage of cooling.

A method of controlling a multi-stage cooling system, said method comprising the steps of:

• determining the cooling load on said cooling system;
• selecting a lead compressor to minimize compressor cycling for temperature control at said cooling load;
• and
• changing the lead compressor selection to provide additional latent cooling as required to maintain humidity at a desired set point.

A multi-stage cooling system for providing at least three stages of cooling, said cooling system comprising:

• a) at least two independently operable compressors having different capacities;
• b) a condenser structure comprising a plurality of individual condenser coils, each condenser coil comprising an independent refrigerant path receiving compressed refrigerant from one of said compressors;
• c) an evaporator structure comprising a plurality of individual evaporator coils, each evaporator coil comprising an independent refrigerant path receiving condensed refrigerant from a corresponding condenser coil via an expansion mechanism and returning refrigerant to an input of a corresponding compressor;
• and
• d) a control system operating said compressors to provide one of the at least three cooling stages corresponding to the heat load of a space to be cooled.

A method of providing multi-stage cooling, using a system having at least two independent cooling circuits with different capacities and a common control, said method comprising steps of:

• operating only a first of the at least two cooling circuits, thereby providing a first stage of cooling;
• operating only a second of the at least two cooling circuits, thereby providing a second stage of cooling greater than the first stage;
• and
• operating both the first and second cooling circuits, thereby providing a third stage of cooling.