Secondary heat exchanger for a furnace heat exchanger

Abstract

Secondary heat exchanger assembly for a heat exchanger unit comprising a hot header box configured to receive combustion gases from a primary heat exchanger assembly of the heat exchanger unit, a cold header box configured to transfer combustion gases to an induction assembly of a furnace unit the heat exchanger unit is part of and heat transfer zone located between the hot and cold boxes. The zone includes secondary heat conduction tubes coupled to the hot box to receive the combustion gases passing through the hot box, and, coupled to the cold box to deliver the combustion gases to the colder box. Air, when blown from a blower unit of the furnace unit through the zone, has a non-uniform velocity profile across a width of the zone, and, a heat transfer mass of the zone across the width is configured to have a substantially similar-shaped non-uniform heat transfer mass profile.

What is claimed is: 
     
         1 . A secondary heat exchanger assembly for a heat exchanger unit, comprising:
 a hot header box configured to receive combustion gases from a primary heat exchanger assembly of the heat exchanger unit;   a cold header box configured to transfer the combustion gases to an induction assembly of a furnace unit that the heat exchanger unit is part of;   a heat transfer zone located between the hot header box and the cold header box, the heat transfer zone including secondary heat conduction tubes coupled to the hot header box to receive the combustion gases passing through the hot header box, and, coupled to the cold header box to deliver the combustion gases to the colder header box, wherein,   air, when blown from a blower unit of the furnace unit through the heat transfer zone, has a non-uniform velocity profile across a width of the heat transfer zone, and, a heat transfer mass of the heat transfer zone across the width is configured to have a substantially similar-shaped non-uniform heat transfer mass profile.   
     
     
         2 . The assembly of  claim 1 , wherein the heat transfer zone further includes perimeter side walls located on either side of the secondary heat conduction tubes and each connected to the hot header box and the cold header box, the perimeter side walls configured to direct air from the blower unit of the furnace unit into the heat transfer zone. 
     
     
         3 . The assembly of  claim 1 , wherein the heat transfer zone includes a central subzone that is parallel and proximate to a central axis of the heat transfer zone, running from the hot header box to the cold header box and two peripheral subzones adjacent to the central subzone and parallel to and distal from the central axis, and wherein the heat transfer mass in the central subzone is greater than the heat transfer mass in any one of the peripheral subzones. 
     
     
         4 . The assembly of  claim 3 , wherein the central subzone, has an amount of the heat transfer mass of the secondary heat conduction tubes that is greater than an amount of the heat transfer mass of the secondary heat conduction tubes in either one of the peripheral subzones. 
     
     
         5 . The assembly of  claim 3 , wherein the central subzone, occupying about one-third of a total volume of the heat transfer zone, the amount of the heat transfer mass is about 10 percent or greater than the of the heat transfer mass in any one of the peripheral subzones, that each occupy about one-third of the total volume of the heat transfer zone. 
     
     
         6 . The assembly of  claim 3 , wherein the central subzone, occupying about one-third of a total volume of the heat transfer zone, has about 20 percent or greater of the heat transfer mass than the heat transfer mass in any one of the peripheral subzones that each occupy about one-third of the total volume of the heat transfer zone. 
     
     
         7 . The assembly of  claim 3 , wherein the central subzone, occupying about one-third of a total volume of the heat transfer zone has at least one more of the secondary heat conduction tubes than the secondary heat conduction tubes in any one of the peripheral subzones that each occupy about one-third of the total volume of the heat transfer zone. 
     
     
         8 . The assembly of  claim 7 , wherein the heat transfer zone including two centrally located and staggered rows of the secondary heat conduction tubes, a first one of the rows having nine of the tubes, and a second one of the rows having seven of the tubes. 
     
     
         9 . The assembly of  claim 3 , wherein the central subzone, occupying about one-third of a total volume of the heat transfer zone has at least two more of the secondary heat conduction tubes than either one of the peripheral subzones that each occupy about one-third of the total volume of the heat transfer zone. 
     
     
         10 . The assembly of  claim 9 , wherein the heat transfer zone including three centrally located and staggered rows of the secondary heat conduction tubes, first and second ones of the rows having nine of the tubes, and a third one of the rows having five of the tubes. 
     
     
         11 . The assembly of  claim 3 , wherein the central subzone, has fins and collars coupled to the secondary heat conduction tubes that provide an amount of the heat transfer mass that is greater than an amount of the heat transfer mass from the fins and the collars coupled to the secondary heat conduction tubes in any one of the peripheral subzones. 
     
     
         12 . The assembly of  claim 3 , wherein the central subzone, occupying about one-third of a total volume of the heat transfer zone has a same number of the secondary heat conduction tubes as in either one of the peripheral subzones, and, fins coupled to the secondary heat conduction tubes in the central zone provide an amount of the heat transfer mass that is greater than the heat transfer mass from the fins coupled to the secondary heat conduction tubes in any one of the peripheral subzones. 
     
     
         13 . The assembly of  claim 1 , wherein the assembly is part of the heat exchanger unit in the heating furnace. 
     
     
         14 . The assembly of  claim 14 , wherein the heating furnace is a component of a HVAC system. 
     
     
         15 . A method of manufacturing a secondary heat exchanger assembly for a heat exchanger unit, comprising:
 providing a hot header box configured to receive combustion gases from a primary heat exchanger assembly of the heat exchanger unit;   providing a cold header box configured to transfer the combustion gases to an induction assembly of a furnace unit that the heat exchanger unit is part of;   forming a heat transfer zone between the hot header box and the cold header box including the heat transfer zone including:
 coupling secondary heat conduction tubes to the hot header box so as to receive the combustion gases passing through the hot header box, and, 
 coupling the secondary heat conduction tubes to the cold header box so as to deliver the combustion gases to the colder header box, 
   wherein air, when blown from a blower unit of the furnace unit through the heat transfer zone, has a non-uniform velocity profile across a width of the heat transfer zone, and, a heat transfer mass of the heat transfer zone across the width is configured to have a substantially similar-shaped non-uniform heat transfer mass profile.   
     
     
         16 . The method of  claim 15 , wherein the heat transfer zone further includes connecting perimeter side walls to the hot header box and the cold header box such that the perimeter side walls are located on either side of the secondary heat conduction tubes, the perimeter side walls configured to direct air from the blower unit into the heat transfer zone. 
     
     
         17 . The method of  claim 15 , wherein the heat transfer zone includes a central subzone that is parallel and proximate to a central axis running from the hot header box to the cold header box and two peripheral subzones adjacent to the central subzone and parallel to and distal from the central axis, and forming the heat transfer zone includes providing an greater amount of the heat transfer mass in the central subzone than an amount of the heat transfer mass provided in any one of the peripheral subzones. 
     
     
         18 . The method of  claim 17 , wherein providing the greater amount of the heat transfer mass in the central subzone includes providing the central subzone with a greater amount of the heat transfer mass from the secondary heat conduction tubes than the amount of the heat transfer mass provided from the secondary heat conduction tubes in any one of the peripheral subzones. 
     
     
         19 . The method of  claim 17 , wherein forming the heat transfer zone further including connecting fins to the secondary heat conduction tubes such that the central zone has a greater amount of the heat transfer mass from the fins than an amount of the heat transfer mass from the fins coupled to the secondary heat conduction tubes in any one of the peripheral subzones. 
     
     
         20 . The method of  claim 17 , further including connecting collars to the secondary heat conduction tubes such that the central zone has a greater amount of the heat transfer mass from the collars than an amount of the heat transfer mass from the collars coupled to the secondary heat conduction tubes in any one of the peripheral subzones.