Abstract: A heat exchanger for an air conditioner outdoor unit includes tubing of the microchannel type which is internally partitioned into separate, parallel refrigerant flow passages and a wrapping of heat conductive flexible heat transfer material, commonly known as spine fin. The heat exchanger provides for greater heat transfer and a more compact package. Further, such heat exchangers allow for a reduced refrigerant charge in the air conditioning unit in which they are used.

Abstract: A refrigeration system is disclosed which includes evaporator means of the type for producing chilled liquid and wherein a compressor of the centrifugal type is provided for compressing refrigerant which has been vaporized in the evaporator means. Both air cooled and liquid cooled condenser means are connected in parallel flow relationship to the compressor, whereby the heat of condensation and compression may be rejected either to a source of ambient air or recovered through heat exchange with a source of liquid, whereby a heated liquid is produced for use as desired.

Abstract: An air cooled centrifugal liquid chiller is disclosed which includes an air cooled condenser exposed to ambient conditions such that, during those times when the temperature of the ambient is at a relatively low level and the chiller is inoperative, refrigerant will tend to migrate to and condense in the air cooled condenser. If this accumulated condensed refrigerant is permitted to then flow by gravity to the evaporator of the chiller, the heat exchange liquid within the tubes thereof may freeze, causing possible damage. In order to prevent this occurrence, the conduit means connecting the air cooled condenser to the evaporator are provided with a trap portion disposed at a level above the maximum level of condensed refrigerant accumulation within the air cooled condenser, which trap portion is vented to a point in the air cooled condenser above said maximum level.