Expansion valve control
AssigneeCarrier Corporation
InventorsMichel K. Grabon, Philippe Rigal, Ba-Tung Pham
Life of this patent
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Abstract
An expansion valve is controlled in response to sensing conditions at the outlet of at least one compressor within a refrigeration loop in a manner that achieves low suction superheat operation of the compressor. In particular, a discharge superheat is computed using data obtained from a specific mathematical model of the compression process corresponding to the current capacity stage of the compressor. The position of the expansion valve is controlled so as to result in an actual discharge superheat being within a predetermined dead band amount of the computed discharge superheat.
Claims24
A process for controlling an expansion device within a refrigerant loop of a cooling system, said process comprising the steps of:
- sensing temperature and pressure at the outlet of at least one compressor within the refrigerant loop;
- obtaining a saturated discharge temperature based upon the sensed pressure at the outlet of the at least one compressor;
- computing a discharge superheat at the outlet of the at least one compressor using the saturated discharge temperature;
- and
- controlling the expansion device within the refrigerant loop in response to the computed discharge superheat,
- wherein said step of computing a discharge superheat includes the step of generating a mathematical algorithm for computing the discharge superheat that is based upon the capacity of the at least one compressor within the refrigerant loop.
A system for controlling an expansion device within a refrigerant loop of a cooling system, said system comprising:
- a sensor for sensing temperature at the outlet of at least one compressor within the refrigerant loop;
- a sensor for sensing pressure at the outlet of the at least one compressor within the refrigerant loop;
- and
- a processor operative to obtain a saturated discharge temperature based upon the sensed pressure at the outlet of the at least one compressor, said processor being operative to commute a discharge superheat using the saturated discharge temperature, said processor being furthermore operative to control the expansion device within the refrigerant loop in response to the computed discharge superheat,
- wherein said processor is furthermore operative to generate a mathematical algorithm when computing the discharge superheat, the algorithm being based upon the current capacity of the at least compressor within the refrigerant loop.
Dependencies are inferred from the claim text.