| 摘要 |
A variable capacity compression type cooling system improves operating efficiency by modulating speed of the condenser pump motor and/or a cooling tower fan motor, in response to the loading level on the cooling apparatus. In contrast to known control strategies that rely on refrigerant gas pressure or temperature changes, the present system controls the heat rejection components in direct response to the current loading level on the cooling system. Cooling system loading is indicated, e.g,. by the current power ratio (percent of maximum) being utilized by the air conditioning compressor. The new strategy sets operation of the heat rejection components at a power setting that is a fixed ratio of the cooling system current power ratio (subject to limits). For a cooling tower, the control is applied to both the cooling tower fan(s) and the condenser pump(s). For small systems, a single variable-speed drive can be used for both the refrigerant compression device and the heat rejection component(s). The invention provides significant improvements in efficiency by reducing power consumed in operation of the various components of the system, particularly under reduced-loading conditions.
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