US 4,060,997 AGranted

Water chiller control

AssigneeApplication Engineering Corporation

InventorsGilbert F. Shultz, Ronald W. Bailey

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Abstract

A control system for a water chiller comprising a heat exchanger, a pump for circulating a coolant comprising water or other process fluid through a path including the heat exchanger, a process apparatus, and a reservoir, and a compressor for circulating refrigerant through a path including the heat exchanger and a condenser; the control system includes electronic sensors for sensing the water supply pressure to the process apparatus, the refrigerant pressures at the compressor inlet and outlet, the water level in the reservoir, and the water temperatures at the heat exchanger inlet and outlet. The control system further includes logic and control circuits which de-activate the pump for conditions of inadequate (or excessive) water pressure or inadequate water in the reservoir, which vary the refrigerant circulation to maintain the water temperature essentially constant at a preset level, and which protect the chiller against over or under-pressure refrigerant conditions and against excessive cooling, affording precision control and continuous monitoring of all chiller operations.

Claims16

Dependent claims

In a water chiller comprising:

a principal heat exchanger having first and second separate fluid paths extending therethrough in heat-exchanging relationship;
pump means for circulating process fluid through a process fluid path including, in series, a process apparatus and the first heat exchanger path;
and compressor means for circulating a refrigerant fluid through a refrigerant path including, in series, a condenser and the second heat exchanger path;
a control system comprising:
a process fluid pressure sensor, connected to the process fluid path, for developing an electrical process fluid pressure signal having an amplitude indicative of the pressure at a given point in the process fluid path;
a process fluid pressure reference circuit for developing a reference signal of preset amplitude representative of a predetermined pressure;
process fluid pressure comparator means for comparing the process fluid pressure signal and the reference signal to develop a process fluid pressure cut-off signal indicative of a deviation of the process fluid pressure in a given sense from the predetermined pressure;
and control circuit means, coupled to the process fluid pressure comparator means and to the pump means, for deactivating the pump means in response to the process fluid pressure cut-off signal.

5 more elements

In a water chiller comprising:

a principal heat exchanger having first and second separate fluid paths extending therethrough in heat-exchanging relationship;
pump means for circulating process fluid through a process fluid path including, in series, a process apparatus and the first heat exchanger path;
and compressor means for circulating a refrigerant fluid through a refrigerant path including, in series, a condenser and the second heat exchanger path;
a control system comprising:
a process fluid pressure sensor;
a process fluid temperature sensor;
a refrigerant pressure sensor;
each sensor developing an electrical parameter signal having an amplitude indicative of the operating parameter sensed;
a process fluid pressure reference circuit;
a process fluid temperature reference circuit;
a refrigerant pressure reference circuit;
each reference circuit developing a reference signal representative of a predetermined value for the reference parameter;
a process fluid pressure comparator means;
a process fluid temperature comparator means;
a refrigerant pressure comparator means;
each comparator means comparing the associated parameter signal with the related reference signal to develop a cut-off signal indicative of a deviation of its parameter signal in a given sense from the related reference signal;
compressor control circuit means, coupled to each of the comparator means and to the compressor means, for deactivating the compressor means in response to any of the cut-off signals;
and pump control circuit means for deactivating the pump means in response to a cut-off signal from either of the process fluid pressure comparator means and the process fluid temperature comparator means.

15 more elements

Dependencies are inferred from the claim text.