BACKGROUND

Heat exchangers are widely used to transfer heat from one fluid to another. Typically, to heat or cool a target fluid, the target fluid is passed through the heat exchanger, and within the heat exchanger is an array of heat exchanger tubes. To enhance heat transfer efficiency, fins are often installed along the heat exchanger tubes. A temperature-controlled fluid is passed through the heat exchanger tubes, and heat can thus be transferred between the target fluid and the temperature-controlled fluid via the heat exchanger tubes and the fins.

As a more specific example, gas furnaces can be used to provide heated air for a building. An air and fuel mixture is combusted, and hot combustion gases are routed through the heat exchanger tubes of the gas furnace's heat exchanger. A blower or fan can be used to force air to move across the heat exchanger, at which time heat is transferred from the hot combustion gases to the heat exchanger tubes and/or fins and from the heat exchanger tubes and/or fins to the passing air.

Recently, there has been an increase in demand for furnaces and other heat exchanging systems that have a decreased size and/or footprint. For example, there has been an increased demand for compact commercial rooftop gas furnaces.

Further, there is widespread demand for increased efficiency in furnaces and other heat exchanging systems. Unfortunately, traditional heat exchanger systems, and particularly those using traditional U-bend heat exchanger tubes, cause a large decrease in the pressure of the air passing over the heat exchanger. This can require larger blowers and/or fans, which can increase the overall cost of the system and can also decrease the overall efficiency of the system.

SUMMARY

These and other problems are addressed by the technologies described herein. Examples of the present disclosure relate generally to heat exchangers of heating, ventilation and air conditioning (HVAC) systems and, more specifically, to the configurations and arrangements of heat exchanger tubes for heat exchangers of HVAC systems.

The disclosed technology includes a heat exchanger that can include a first heat exchanger tube and a second heat exchanger tube. The first heat exchanger tube can include a first leg, a second leg, and a bend section. The bend section of the first heat exchanger tube can include three or more bends, and each of the three or more bends can have a corresponding angle (i.e., the degree of the corresponding bend, which can also be referred to as the “bend angle”) that is less than or equal to approximately 90 degrees. The second heat exchanger tube can include a first leg, a second leg, and a bend section. The bend section of the second heat exchanger tube can include three or more bends, and each of the three or more bends can have a corresponding angle that is less than or equal to approximately 90 degrees.

The three or more bends of the first heat exchanger tube can include a first bend having an angle of approximately 90 degrees, a second bend having a first acute angle, and a third bend having a second acute angle. The three or more bends of the second heat exchanger tube can include a first bend having an angle of approximately 90 degrees, a second bend having a first acute angle, and a third bend having a second acute angle.

The bend section of the first heat exchanger tube can include at least one substantially straight portion, and/or the bend section of the second heat exchanger tube can include at least one substantially straight portion.

The bend section of the first heat exchanger tube can include (i) a first substantially straight portion disposed between a first bend of the three or more bends and a second bend of the three or more bends and (ii) a second substantially straight portion disposed between the second bend of the three or more bends and a third bend of the three or more bends. The bend section of the second heat exchanger tube can include (i) a first substantially straight portion disposed between a first bend of the three or more bends and a second bend of the three or more bends and (ii) second substantially straight portion disposed between the second bend of the three or more bends and a third bend of the three or more bends.

The first leg of the first heat exchanger tube can be located at a height that is greater than a height of the second leg of the first heat exchanger tube, and the second leg of the second heat exchanger tube can be located at a height that is greater than a height of the first leg of the second heat exchanger tube.

Fins can be disposed along at least a portion of the first leg of the first heat exchanger tube and at least a portion of the second leg of the second heat exchanger tube.

Ridges can be disposed along at least a portion of the first leg of the first heat exchanger tube and at least a portion of the second leg of the second heat exchanger tube.

A length of the first leg of the first heat exchanger tube can be greater than a length of the second leg of the first heat exchanger tube, and a length of the second leg of the second heat exchanger tube can be greater than a length of the first leg of the second heat exchanger tube.

At least one of the first heat exchanger tube and the second heat exchanger tube can have a non-zero incline angle with respect to horizontal when viewed from a side of the first heat exchanger tube or the second heat exchanger tube.

The incline angle can be in a range between approximately 0.5 degree and approximately 5 degrees.

The incline angle of the first heat exchanger tube can be different from the incline angle of the second heat exchanger tube.

At least one of the first heat exchanger tube and the second heat exchanger tube can have a non-zero tilt angle with respect to vertical when viewed from an end of the first heat exchanger tube or the second heat exchanger tube.

The tilt angle can be in a range between approximately 0.5 degree and approximately 10 degrees.

The tilt angle of the first heat exchanger tube can be different from the tilt angle of the second heat exchanger tube.

The first heat exchanger tube can be one of a first plurality of heat exchanger tubes, and the second heat exchanger tube can be one of a second plurality of heat exchanger tubes. Each of the first plurality of heat exchanger tubes can be located such that none of the first plurality of heat exchanger tubes is adjacent to another of the first plurality of heat exchanger tubes. Each of the second plurality of heat exchanger tubes can be located such that none of the second plurality of heat exchanger tubes is adjacent to another of the second plurality of heat exchanger tubes.

The first heat exchanger tube can be one of a first plurality of heat exchanger tubes, and the second heat exchanger tube can be one of a second plurality of heat exchanger tubes. A U-bend heat exchanger tube can be disposed between each of the first plurality of heat exchanger tubes and the second plurality of heat exchanger tubes such that each of the first plurality of heat exchanger tubes is adjacent to at least one U-bend heat exchanger tube and each of the second plurality of heat exchanger tubes is adjacent to at least one U-bend heat exchanger tube.

The first heat exchanger tube and the second heat exchanger tube can be two of a plurality of heat exchanger tubes, and the plurality of heat exchanger tubes can be configured to redirect a substantial portion of an airflow from a generally vertical direction to a generally horizontal direction.

The first heat exchanger tube can be located at a height that is greater than a height of the second heat exchanger tube.

This disclosed technology includes a furnace include the heat exchanger.

The furnace can include a combustion chamber, a combustion blower configured to move combustion gases from the combustion chamber through the first heat exchanger tube and the second heat exchanger tube, and an indoor blower configured to move air toward the first heat exchanger tube and the second heat exchanger tube.

Further features of the disclosed design, and the advantages offered thereby, are explained in greater detail hereinafter with reference to specific examples illustrated in the accompanying drawings, wherein like elements are indicated be like reference designators.

