Hybrid continuous flow grain dryer

A continuous flow grain dryer comprising:

• a pair of grain flow paths through which the grain flows downwardly under the influence of gravity in a grain column;
• each grain flow path being defined by a pair of longitudinally extending side walls and a pair of transversely extending end walls;
• each grain flow path having an upper portion comprising:
• a plurality of upper elongated grain diverters extending transversely across the grain flow path between opposing inner faces of the pair of longitudinally extending side walls;
• an upper opening in the side walls associated with each upper grain diverter;
• each grain flow path having a lower portion comprising:
• a plurality of lower elongated grain diverters extending longitudinally along alternating sides of the grain flow path between opposing inner faces of the pair of end walls;
• a longitudinally extending lower opening in the side walls associated with each lower grain diverter;
• wherein the upper elongated grain diverters are aligned substantially perpendicular in plan view to the longitudinally extending side walls, and wherein the lower elongated grain diverters are aligned substantially parallel in plan view to the longitudinally extending side walls;
• a central air plenum positioned between the pair of grain flow paths;
• and
• a divider separating the central air plenum into a positive pressure plenum and a negative pressure plenum;
• wherein the upper portion of each grain flow path comprises a mixed flow dryer configuration, and wherein airflow passing from the positive pressure plenum through the upper portion of the pair of grain flow paths creates a preheat zone in the upper portion of the pair of grain flow paths during operation;
• and wherein the lower portion of each grain flow path comprises an undulating flow dryer configuration, and wherein airflow passing from the positive pressure plenum through the upper portion of the pair of grain flow path creates a heat zone in the pair of adjacent flow paths below the preheat zone during operation.