Abstract: A furnace heat exchanger with multiple parallel flow passages wherein the last flow passage extends downwardly from its plane as it approaches the outlet so as to result in a lower overall height of the heat exchanger. Preferably both the upper wall and the lower wall of the last passage extend downwardly such that the cross-sectional area of the last flow passage is not reduced and is preferably increased as it approaches the outlet. The bottom wall extension is preferably curvilinear and has substantially the same curvature as a return bend at the inlet of the penultimate flow passage.

Abstract: A furnace heat exchanger with multiple parallel flow passages wherein at least one flow passage has a cross-sectional shape which transitions from one form to another in a gradual manner so as to reduce the occurrence of stress therein. In one embodiment, the transition is from an oval shape to a wavy shape.

Abstract: In a fuel gas burner, a reduction of NOx emissions is brought about by the combined use of both a catalyst and a radiation baffle. The catalyst and baffle are located in serial flow relationship such that each contributes to the NOx reduction function without the creation of undesirable conditions. The catalyst is located upstream of the flame and the amount of primary air supplied to the burner is controlled so as to bring about a reduction of NOx emissions while at the same time not allowing the temperature of the catalyst to exceed a threshold limit, thereby ensuring an acceptably long life and durability of the catalyst. The radiation baffle is located in the flame to radiate heat away therefrom and lower the temperature thereof to reduce NOx emissions, with the mass of the baffle being limited such that no significant levels of CO are generated.

Abstract: In a gas burner for introducing a fuel/air mixture into a combustion chamber, a tube is provided for introducing a source of primary air into a core portion of the fuel air mixture. The resulting secondary flame that is produced within the primary flame causes a reduction of NOX gases, which can be attributed to the dispersion of combustion byproducts within the primary flame. In one embodiment, the air supply tube enters the area of the fuel air mixture radially and then turns and extends axially along an extended axis of the burner.

Abstract: In a fuel gas burner, a reduction of NOx emissions is brought about by the combined use of both a catalyst and a radiation baffle. The catalyst and baffle are located in serial flow relationship such that each contributes to the NOx reduction function without the creation of undesirable conditions. The catalyst is located upstream of the flame and the amount of primary air supplied to the burner is controlled so as to bring about a reduction of NOx emissions while at the same time not allowing the temperature of the catalyst to exceed a threshold limit, thereby ensuring an acceptably long life and durability of the catalyst. The radiation baffle is located in the flame to radiate heat away therefrom and lower the temperature thereof to reduce NOx emissions, with the mass of the baffle being limited such that no significant levels of CO are generated.

Abstract: The high side pressure of a vapor compression system is selected to optimize the coefficient of performance by measuring the heat sink inlet temperature with a temperature sensor. For any heat sink inlet temperature, a single optimal high side pressure is selected which optimizes the coefficient of performance. The optimal high side pressure for each heat sink inlet temperature is preset into a control and is based on data obtained by previous testing. A pressure sensor continually measures the high side pressure. If the high side pressure is not at the optimal value, the expansion device setting is adjusted to alter the high side pressure to the optimal value.

Abstract: In a gas burner for introducing a fuel/air mixture into a combustion chamber, a tube is provided for introducing a source of primary air into a core portion of the fuel air mixture. The resulting secondary flame that is produced within the primary flame causes a reduction of NOX gases, which can be attributed to the dispersion of combustion byproducts within the primary flame. In one embodiment, the air supply tube enters the area of the fuel air mixture radially and then turns and extends axially along an extended axis of the burner.

Abstract: A multipass heat exchanger with return bends between passes has its first return bend which varies in cross sectional area in the direction of the of the gas flow. The cross sectional area first increases so as to thereby reduce the velocity of the flue gas, decrease the flue side heat transfer coefficient and decrease the resulting hotspots. The cross sectional area is then increased in a more downstream portion of the return bend so as to not increase the overall height of the heat exchanger. The variation preferably occurs throughout the entire span of the return bend, with the increase in cross sectional area beginning at the start of the return bend.

Abstract: A furnace heat exchanger with multiple parallel flow passages with at least two of the passages being partially formed of a pair of opposed sidewalls having wavy cross-sectional shapes wherein the downstream passage has at least as many and preferably more waves than the upstream pass. The wavy shapes are preferably generally sinusoidal in form with the waves of the two sides being substantially in phase.

Abstract: A burner system for a furnace (10) includes an in-shot burner (20) having an axially elongated tubular nozzle (40) having an inlet end (42), an outlet end (44) and a venturi transition section (46) therebetween. At least a portion of a catalyst body (50) is disposed within the outlet end (44) of the burner (40). The catalyst body (50) supports a partial oxidization catalyst operative to catalyze the fuel in the primary air/fuel mixture to intermediate combustion species, including hydrogen and carbon monoxide, thereby reducing emissions such as nitrogen oxides.