Abstract: A system for modulating refrigerant flow from an evaporator of an air or gas drying apparatus wherein the air or gas drying apparatus has an evaporator shell with at least one exit orifice for return of refrigerant to an accumulator or compressor. The system comprising a flow metering structure connected to the at least one exit orifice, the structure having an internal tube with a vertical rise from an evaporator shell end to an accumulator or compressor end, the internal tube having at least one return orifice (a) which allows passage of liquid refrigerant outside the internal tube into the internal tube, and at least one return orifice (b) which allows passage of gas outside the internal tube into the internal tube.

Abstract: The present invention relates to a method and apparatus for effectively reducing/eliminating shut-downs while still allowing an air or gas dryer apparatus to operate even though the conditions, even extreme conditions, may be out of range. The present invention comprises a system and apparatus controlling a variable speed compressor system for an air or gas dryer, the system and apparatus comprising a set point value that causes system shut down when reached and an algorithm that operates using the set point value. A sensor that provides an input value to the algorithm whereupon the algorithm compares the input value to the set point value, a circuit carrying output of the algorithm, a controlled device responding to the output and a feedback circuit that operates to maintain a product value at a set point or within a set range where the algorithm operating to modulate or bypass the feedback circuit when the input value approaches the set point.

Abstract: The present invention relates to a method and apparatus for effectively reducing/eliminating oscillation of over and under shoot of superheat and refrigerant feed in an evaporator of compressed refrigerant of a gas/air dryer system. The feed makes use of a plurality of refrigerant expansion valves, sized in scaled manner, and adjusted inversely to the size of each, affording exact feed requirements to the evaporating vessel heat exchange. The system uses superheat feedback to respond rapidly or slowly to fill need for large or modest injections leading to stable, balanced operations. The operations ‘level-out’ to a smooth, even output of the gas/air dryer dew point temperature, relatively close to the dew point seat point without falling into an endless loop oscillation. The feed delivery of staged injection meters expanded refrigerant to demand while tracking superheat.