Abstract: The present invention is an enhanced tubular heat exchanger for a furnace. The tubes of the heat exchanger include an enhanced portion which has a smaller cross-sectional area than the flue portion, in the form of an elliptically shaped tube. The enhanced portion further includes turbulators to promote the heat exchange from the heated flue gases. Circulation of air around the exterior of the tubes is also facilitated because the enhanced portion is disposed at a small angle relative to the flue portion. A plurality of tubes are disposed within the heat exchanger so that the circulation air first flows over the enhanced portions then over and around the generally cylindrical portions. This lowers the initial pressure drop in the circulation air flow and thereby facilitates the circulation of and heat transfer to the air being heated.

Abstract: The present invention is an enhanced tubular heat exchanger for a furnace with the heat tubes of the heat exchanger having two straight sections connected by a bend. The tubes of the heat exchanger include an enhanced portion which has a smaller cross-sectional area than the flue portion, in the form of an elliptically shaped tube. The enhanced portion further includes turbulators to promote the heat exchange from the heated flue gases. Circulation of air around the exterior of the tubes is also facilitated because the enhanced portion is disposed at a small angle relative to the flue portion. A plurality of tubes are disposed within the heat exchanger so that the circulation air first flows over the enhanced portions then over and around the generally cylindrical portions. This lowers the initial pressure drop in the circulation air flow and thereby facilitates the circulation of and heat transfer to the air being heated.