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US 2009/0024257 A1Published application
Control system
AssigneeJohnson Controls Technology Company
InventorsCurtis Christian CRANE, Brian T. GALLUS
Life of this patent
Estimating the term…
Abstract
A pull-down control process for a chiller system is provided. The pull-down control process can override the capacity control process for the chiller system to pull-down the leaving chilled liquid temperature faster than the capacity control process. The pull-down control process can maintain pre-rotation vanes in a fully open position to pull-down the leaving chilled liquid temperature as quickly as possible to a predetermined setpoint.
Claims20
A method of lowering a temperature of a liquid exiting a heat exchanger in a vapor compression system, the method comprising:
- measuring a temperature of a liquid leaving a heat exchanger in a vapor compression system;
- comparing the measured temperature to a predetermined temperature;
- measuring a position of a flow control device configured to regulate flow of refrigerant to a compressor in the vapor compression system in response to the measured temperature being greater than the predetermined temperature;
- comparing the measured position to a predetermined position;
- measuring a current for a motor of the compressor in response to the measured position being in the predetermined position;
- comparing the measured current to a predetermined current;
- and
- maintaining the flow control device in the predetermined position in response to the measured supply current being greater than the predetermined current, wherein the maintaining of the flow control device in the predetermined position enables a rate of change of the measured temperature to remain substantially constant.
5 more elements
A system comprising:
- a compressor, first heat exchanger, expansion device and second heat exchanger connected in a closed loop;
- a motor configured and disposed to drive the compressor;
- the second heat exchanger comprising a return connection to receive a liquid from a cooling load and a supply connection to provide the liquid to the cooling load;
- a flow control device associated with the compressor and configured to regulate flow of a fluid into the compressor;
- and
- a control panel configured to provide output signals to the flow control device to maintain the flow control device in a predetermined position in response to a measured temperature of the liquid to be provided to the cooling load being greater than a predetermined temperature, a measured position of the flow control device being in a predetermined position and a measured current of the motor being greater than a predetermined current, wherein the maintaining of the flow control device in the predetermined position enables a rate of change of the measured temperature of the liquid to be provided to the cooling load to remain substantially constant.
3 more elements
Dependencies are inferred from the claim text.