# US 2014/0151015 A1 · Termperature Control Logic For Refrigeration System

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- Number: US 2014/0151015 A1
- Document ID: US20140151015A1
- Status: Published application
- Kind: A1
- Application number: 14/234,712
- Filed: 2012-07-25
- Published: 2014-06-05
- Earliest claimed: 2011-07-26
- Assignees: Carrier Corporation
- Applicants: Carrier Corporation
- Inventors: Jian Sun; Hans-Joachim Huff; Aryn Shapiro; Gilbert B. Hofsdal; Minfei Gan; Wenhua Li
- Web page: https://patentgrep.com/patent/US20140151015A1

## CPC

- F25B 49/02: for compression type machines, plants or systems
- B60H 1/3228: {characterised by refrigerant circuit configurations}
- F25B 1/10: with multi-stage compression (with cascade operation F25B7/00)
- F25B 9/008: {the refrigerant being carbon dioxide}
- F25B 41/00: Fluid-circulation arrangements
- F25B 41/39: Dispositions with two or more expansion means arranged in series, i.e. multi-stage expansion, on a refrigerant line leading to the same evaporator
- F25B 2309/061: with cycle highest pressure above the supercritical pressure
- F25B 2400/072: Intercoolers therefor
- F25B 2400/13: Economisers
- F25B 2400/23: Separators
- F25B 2600/025: by controlling speed
- F25B 2600/11: Fan speed control
- F25B 2600/111: of condenser fans
- F25B 2600/21: Refrigerant outlet evaporator temperature
- F25B 2600/2501: Bypass valves
- F25B 2600/2509: Economiser valves
- F25B 2600/2513: Expansion valves
- F25B 2700/191: near an expansion valve
- F25B 2700/1933: Suction pressures
- F25B 2700/195: of the condenser
- F25B 2700/198: Intermediate pressures
- F25B 2700/2102: at the outlet of the gas cooler
- F25B 2700/21151: at the suction side of the compressor
- F25B 2700/21152: at the discharge side of the compressor
- F25B 2700/21163: of the refrigerant at the outlet of the condenser
- Y02B 30/70: Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating
- F25B: REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- B60H: ARRANGEMENTS OF HEATING, COOLING, VENTILATING OR OTHER AIR-TREATING DEVICES SPECIALLY ADAPTED FOR PASSENGER OR GOODS SPACES OF VEHICLES
- Y02B: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS

## Abstract

A refrigeration system includes a compressor having a first stage (20a) and a second stage (20b); a motor (22) driving the compressor; a heat rejecting heat exchanger having a fan (44) drawing ambient fluid over the heat rejecting heat exchanger, the heat rejecting heat exchanger including an intercooler (43) and a gas cooler, the inter-cooler coupled to an outlet of the first stage and the gas cooler (41) coupled to an outlet of the second stage; a flash tank (70) coupled to an outlet of the gas cooler; a primary expansion device (55) coupled to an outlet of the flash tank; a heat absorbing heat exchanger (50) 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 (100) for implementing a pulldown mode, a control mode and a staging logic mode.

## Claims

### Claim 1

A refrigeration system comprising:
a compressor having a first stage and a second stage;
a motor driving the compressor;
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;
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;
a controller for implementing a pulldown mode for cooling a space to a control temperature within a band of a control temperature setpoint, a control mode for maintaining the control temperature within the band of the control temperature setpoint and a staging logic mode for reducing system capacity while maintaining the control temperature within the band range of the control temperature setpoint.

### Claim 2 (depends on 1)

The refrigeration system of claim 1 further comprising:
a secondary expansion device positioned between the gas cooler and the flash tank;
the pulldown mode includes controlling the secondary expansion device to control discharge pressure at the compressor.

### Claim 3 (depends on 1)

The refrigeration system of claim 1 wherein:
the pulldown mode includes controlling the primary expansion device to control the heat absorbing heat exchanger superheat temperature.

### Claim 4 (depends on 1)

The refrigeration system of claim 1 wherein:
the control mode includes controlling drive signals to the motor to control the control temperature.

### Claim 5 (depends on 4)

The refrigeration system of claim 4 wherein:
the motor is a variable frequency drive (VFD) motor.

### Claim 6 (depends on 1)

The refrigeration system of claim 1 further comprising:
a secondary expansion device positioned between the gas cooler and the flash tank;
the control mode includes controlling the secondary expansion device to control discharge pressure at the compressor.

### Claim 7 (depends on 1)

The refrigeration system of claim 1 wherein:
the control mode includes controlling the primary expansion device to control the heat absorbing heat exchanger superheat temperature.

### Claim 8 (depends on 1)

The refrigeration system of claim 1 further comprising:
a heater;
the control mode includes controlling the heater to maintain the control temperature within the band of the control temperature setpoint.

### Claim 9 (depends on 1)

The refrigeration system of claim 1 wherein:
the staging logic mode includes modulating the fan to reduce system capacity.

### Claim 10 (depends on 1)

The refrigeration system of claim 1 further comprising:
an economizer valve coupling the flash tank to an inlet of the second stage;
wherein the staging logic mode includes closing the economizer valve.

### Claim 11 (depends on 1)

The refrigeration system of claim 1 further comprising:
an unload valve coupling an outlet of the intercooler to the suction port of the first stage;
wherein the staging logic mode includes opening the unload valve.

### Claim 12 (depends on 1)

The refrigeration system of claim 1 wherein:
the staging logic mode includes modulating the fan to control the control temperature.

### Claim 13 (depends on 1)

The refrigeration system of claim 1 wherein:
the controller implements an off integrator, the off integrator tracking an amount of error accumulated by the system when the control temperature is below the control temperature setpoint.

### Claim 14 (depends on 13)

The refrigeration system of claim 13 wherein:
the off integrator sums the difference between the control temperature and the control temperature setpoint over time.

### Claim 15 (depends on 14)

The refrigeration system of claim 14 wherein:
wherein when the sum difference exceeds an off integrator limit, the controller implements a shut down mode.