Other

Arthur F Friday

Richard G Lord

Kenneth J Nieva

An improved cooler with level sensor for measuring variation in the liquid refrigerant level of a refrigerant within the cooler, comprises a cooler shell for holding the refrigerant, heat exchanger tubes for carrying the liquid to be cooled, and a liquid refrigerant level sensor comprising a probe extending to a point above the heat exchanger tubes, one or more thermistors; and a heating element. When the probe is totally within the vapor refrigerant above the heat exchanger tubes, the heater raises the temperature of the thermistors above the saturation temperature of the refrigerant. As the liquid refrigerant level begins to rise, the liquid refrigerant comes in contact with the outside of the probe. Since the heat transfer coefficient of the liquid refrigerant is significantly higher than that of the vapor refrigerant, the probe in that area is quickly cooled to the saturation temperature. This, in turn, increases the resistance of the nearby thermistor, causing the overall resistance of the thermistor circuit to increase. By measuring the resistance of the thermistor circuit, a porporant indication of the liquid refrigerant level can be obtained, and used to control an electronic expansion valve to adjust the liquid refrigerant level accordingly.

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Vienne, VA, United States of America

Arthur F Friday