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1. WO2013016404 - STARTUP LOGIC FOR REFRIGERATION SYSTEM

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[ EN ]

CLAIMS:

What is claimed is:

1. A refrigeration system comprising:

a compressor having a first stage and a second stage;

a heat rejecting heat exchanger having a fan drawing ambient fluid over the heat rejecting heat exchanger, the heat rejecting heat exchanger including an intercooler and a gas cooler, the intercooler coupled to an outlet of the first stage and the gas cooler coupled to an outlet of the second stage;

an unload valve coupled to an outlet of the intercooler and a suction port of the first stage;

a flash tank coupled to an outlet of the gas cooler;

a primary expansion device coupled to an outlet of the flash tank;

a heat absorbing heat exchanger coupled to an outlet of the primary expansion device, an outlet of the heat absorbing heat exchanger coupled to the suction port of the first stage; and

a controller for executing a startup process including at least one of:

controlling the fan speed to reduce refrigerant heat loss in the heat rejecting heat exchanger;

controlling the unload valve to direct refrigerant from the intercooler to the suction port of the first stage; and

controlling the primary expansion device to restrict flow of refrigerant to the heat absorbing heat exchanger.

2. The refrigeration system of claim 1 wherein:

the startup process includes at least two of:

controlling the fan speed to reduce refrigerant heat loss in the heat rejecting heat exchanger;

controlling the unload valve to direct refrigerant from the intercooler to the suction port of the first stage; and

controlling the primary expansion device to restrict flow of refrigerant to the heat absorbing heat exchanger.

3. The refrigeration system of claim 1 wherein:

the startup process includes all of:

controlling the fan speed to reduce refrigerant heat loss in the heat rejecting heat exchanger;

controlling the unload valve to direct refrigerant from the intercooler to the suction port of the first stage; and

controlling the primary expansion device to restrict flow of refrigerant to the heat absorbing heat exchanger.

4. The refrigeration system of claim 1 further comprising:

an economizer valve coupling the flash tank to an inlet of the second stage;

5. The refrigeration system of claim 4 wherein:

the startup process includes controlling the economizer valve to control flow of refrigerant from the flash tank to the inlet of the second stage.

6. The refrigeration system of claim 5 wherein:

controlling the economizer valve includes opening the economizer valve.

7. The refrigeration system of claim 1 further comprising:

a motor for driving the first stage and the second stage;

the startup process including applying direct current to the motor.

8. The refrigeration system of claim 1 wherein:

controlling the fan speed includes controlling fan speed in response to superheat.

9. The refrigeration system of claim 8 wherein:

the fan speed is proportional to the superheat.

10. The refrigeration system of claim 1 wherein:

controlling the unload valve includes opening the unload valve.

1 1. The refrigeration system of claim 1 wherein:

controlling the primary expansion device includes controlling primary expansion device in response to superheat.

12. The refrigeration system of claim 1 1 wherein:

controlling the primary expansion device incrementally opening the primary expansion device in response to increasing superheat.