Abstract: A refrigeration system of the type having an economizer cycle is provided with a null cycle, in addition to heating and cooling cycles, without shutting a compressor prime mover down, to preserve air flow in a conditioned space. First, second and third controllable valves respectively: (1) select main and auxiliary condensers, (2) open and close a liquid line, and (3) open and close a line which provides a warm liquid to an economizer heat exchanger. The valves are controlled in at least one predetermined open/close pattern during a null cycle, and preferably in a plurality of selectable predetermined open/close patterns, to provide a null cycle at any instant which substantially matches the net heat gain or loss taking place in the conditioned space. Thus, the temperature of the served space will be more apt to remain in a null temperature range close to set point, providing smoother and more accurate control over the temperature of the conditioned space for longer shelf life of perishables stored therein.

Abstract: A refrigeration system of the type having an economizer cycle is provided with a null cycle, in addition to heating and cooling cycles, without shutting a compressor prime mover down, to preserve air flow in a conditioned space. First, second and third controllable valves respectively: (1) select main and auxiliary condensers, (2) open and close a liquid line, and (3) open and close a line which provides a warm liquid to an economizer heat exchanger. The valves are controlled in at least one predetermined open/close pattern during a null cycle, and preferably in a plurality of selectable predetermined open/close patterns, to provide a null cycle at any instant which substantially matches the net heat gain or loss taking place in the conditioned space. Thus, the temperature of the served space will be more apt to remain in a null temperature range close to set point, providing smoother and more accurate control over the temperature of the conditioned space for longer shelf life of perishables stored therein.

Abstract: A refrigeration system of the type having an economizer cycle is provided with a null cycle, in addition to heating and cooling cycles, without shutting a compressor prime mover down, to preserve air flow in a conditioned space. First, second and third controllable valves respectively: (1) select main and auxiliary condensers, (2) open and close a liquid line, and (3) open and close a line which provides a warm liquid to an economizer heat exchanger. The valves are controlled in at least one predetermined open/close pattern during a null cycle, and preferably in a plurality of selectable predetermined open/close patterns, to provide a null cycle at any instant which substantially matches the net heat gain or loss taking place in the conditioned space. Thus, the temperature of the served space will be more apt to remain in a null temperature range close to set point, providing smoother and more accurate control over the temperature of the conditioned space for longer shelf life of perishables stored therein.

Abstract: A refrigeration system of the type having an economizer cycle is provided with a null cycle, in addition to heating and cooling cycles, without shutting a compressor prime mover down, to preserve air flow in a conditioned space. First, second and third controllable valves respectively: (1) select main and auxiliary condensers, (2) open and close a liquid line, and (3) open and close a line which provides a warm liquid to an economizer heat exchanger. The valves are controlled in at least one predetermined open/close pattern during a null cycle, and preferably in a plurality of selectable predetermined open/close patterns, to provide a null cycle at any instant which substantially matches the net heat gain or loss taking place in the conditioned space. Thus, the temperature of the served space will be more apt to remain in a null temperature range close to set point, providing smoother and more accurate control over the temperature of the conditioned space for longer shelf life of perishables stored therein.

Abstract: A refrigeration system of the type having an economizer cycle is provided with a null cycle, in addition to heating and cooling cycles, without shutting a compressor prime mover down, to preserve air flow in a conditioned space. First, second and third controllable valves respectively: (1) select main and auxiliary condensers, (2) open and close a liquid line, and (3) open and close a line which provides a warm liquid to an economizer heat exchanger. The valves are controlled in at least one predetermined open/close pattern during a null cycle, and preferably in a plurality of selectable predetermined open/close patterns, to provide a null cycle at any instant which substantially matches the net heat gain or loss taking place in the conditioned space. Thus, the temperature of the served space will be more apt to remain in a null temperature range close to set point, providing smoother and more accurate control over the temperature of the conditioned space for longer shelf life of perishables stored therein.

Abstract: An oil flooded screw compressor including suction, rotor, and discharge sections having suction, intermediate pressure, and discharge ports, respectively, and an oil sump. The discharge section includes radially spaced internal and external housings, with the internal housing receiving an oil-gas stream from the rotor section. A filter is disposed to surround the internal housing, with the filter including a cylindrical, foraminate body portion, an end wall, and a filter pad against the end wall. The oil-gas stream from the rotor section exits the inner housing, via an opening which forms part of a first stage of oil removal. The oil-gas stream strikes the filter pad, removing oil as the oil-gas stream is forced to turn 90 degrees to exit the filter through the foraminate body portion, which also removes oil. The filter functions as second and third stages of oil removal.

Abstract: A refrigeration system of the type having an economizer cycle is provided with a null cycle, in addition to heating and cooling cycles, without shutting a compressor prime mover down, to preserve air flow in a conditioned space. First, second and third controllable valves respectively: (1) select main and auxiliary condensers, (2) open and close a liquid line, and (3) open and close a line which provides a warm liquid to an economizer heat exchanger. The valves are controlled in at least one predetermined open/close pattern during a null cycle, and preferably in a plurality of selectable predetermined open/close patterns, to provide a null cycle at any instant which substantially matches the net heat gain or loss taking place in the conditioned space. Thus, the temperature of the served space will be more apt to remain in a null temperature range close to set point, providing smoother and more accurate control over the temperature of the conditioned space for longer shelf life of perishables stored therein.

Abstract: A refrigeration system, and method of operating same, in which an economizer heat exchanger, normally used in conjunction with an intermediate port of a refrigerant compressor to cool the main refrigerant flow from a receiver to an evaporator to enhance the refrigerant cooling cycle, is caused to function as an evaporator during a hot gas heating cycle. The economizer heat exchanger is caused to function as an evaporator by adding heat thereto during a heating cycle, and by establishing an alternate liquid line, effective during a heating cycle, which includes the economizer heat exchanger. When the compressor is driven by an internal combustion engine, engine coolant may be used to add the necessary heat to the economizer heat exchanger during a heating cycle.