US20180356106A1

US20180356106A1 - Heat Exchanger Elevated Temperature Protection Sleeve

Info

Publication number: US20180356106A1
Application number: US15/619,182
Authority: US
Inventors: Delbert Steven Christopher
Original assignee: Trane International Inc
Current assignee: Trane International Inc
Priority date: 2017-06-09
Filing date: 2017-06-09
Publication date: 2018-12-13

Abstract

A heating, ventilation, and/or air conditioning (HVAC) system may include a furnace having at least one heat exchanger tube with a temperature protection sleeve at least partially disposed in the heat exchanger tube. The temperature protection sleeve includes a flange, an elongated tubular portion extending from the flange, and a plurality of perforations disposed about the elongated tubular portion. The temperature protection sleeve protects the heat exchanger tube from high flame temperatures or elevated temperature flue products caused by rapidly combusting a pre-mixed air-fuel mixture within a burner of the furnace, thereby allowing the heat exchanger tube to comply with ANSI Z21.47. The furnace provides less than 14 Nanograms of oxides of nitrogen per Joule (Ng/J) of heat delivered to a temperature conditioned area and complies with SCAQMD Rule 1111.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

Not applicable.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO A MICROFICHE APPENDIX

Not applicable.

BACKGROUND

Heating, ventilation, and/or air conditioning (HVAC) systems used in commercial and residential applications often include a furnace having at least one heat exchanger configured to promote heat transfer with an airflow that contacts the heat exchanger to provide a heated airflow to condition an interior space. Traditional gas-fired heat exchangers used in furnaces may employ a long flame burner and/or multiple long flame burners to distribute heat over the heat exchanger slowly and/or evenly. However, this slow combustion process may produce excess emissions that do not comply with required standards for residential and/or commercial HVAC system applications.

SUMMARY

In some embodiments of the disclosure, a heat exchanger for a furnace is disclosed as comprising: at least one heat exchanger tube; and a temperature protection sleeve disposed at least partially within the heat exchanger tube.
In other embodiments of the disclosure, a furnace is disclosed as comprising: at least one burner; and a heat exchanger, comprising: at least one heat exchanger tube; and a temperature protection sleeve disposed at least partially within the heat exchanger tube.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure and the advantages thereof, reference is now made to the following brief description, taken in connection with the accompanying drawings and detailed description:

FIG. 1 is a schematic diagram of an HVAC system according to an embodiment of the disclosure;

FIG. 2 is a schematic diagram of air circulation paths of a structure conditioned by two HVAC systems of FIG. 1 according to an embodiment of the disclosure;

FIG. 3 is a schematic view of a furnace comprising a heat exchanger tube and a temperature protection sleeve according to an embodiment of the disclosure;

FIG. 4 is partial detailed view of the heat exchanger tube and the temperature protection sleeve of FIG. 3 according to an embodiment of the disclosure;

FIG. 5 is a detailed view of the temperature protection sleeve of FIGS. 3 and 4 according to an embodiment of the disclosure; and

FIG. 6 is a schematic diagram of the temperature protection sleeve of FIG. 5 according to an embodiment of the disclosure.

DETAILED DESCRIPTION

Referring now to FIG. 1, a schematic diagram of an HVAC system 100 according to an embodiment of this disclosure is shown. HVAC system 100 comprises an indoor unit 102, an outdoor unit 104, and a system controller 106. In some embodiments, the system controller 106 may operate to control operation of the indoor unit 102 and/or the outdoor unit 104. As shown, the HVAC system 100 is a so-called heat pump system that may be selectively operated to implement one or more substantially closed thermodynamic refrigeration cycles to provide a cooling functionality and/or a heating functionality. In alternative embodiments, the HVAC system 100 may comprise a type of air-conditioning system that is not a heat pump system.
Indoor unit 102 comprises an indoor heat exchanger 108, an indoor fan 110, and an indoor metering device 112. Indoor heat exchanger 108 is a plate fin heat exchanger configured to allow heat exchange between refrigerant carried within internal tubing of the indoor heat exchanger 108 and fluids that contact the indoor heat exchanger 108 but that are kept segregated from the refrigerant. In other embodiments, indoor heat exchanger 108 may comprise a spine fin heat exchanger, a microchannel heat exchanger, or any other suitable type of heat exchanger.
The indoor fan 110 is a centrifugal blower comprising a blower housing, a blower impeller at least partially disposed within the blower housing, and a blower motor configured to selectively rotate the blower impeller. In other embodiments, the indoor fan 110 may comprise a mixed-flow fan and/or any other suitable type of fan. The indoor fan 110 is configured as a modulating and/or variable speed fan capable of being operated at many speeds over one or more ranges of speeds. In other embodiments, the indoor fan 110 may be configured as a multiple speed fan capable of being operated at a plurality of operating speeds by selectively electrically powering different ones of multiple electromagnetic windings of a motor of the indoor fan 110. In yet other embodiments, the indoor fan 110 may be a single speed fan.
The indoor metering device 112 is an electronically controlled motor driven electronic expansion valve (EEV). In alternative embodiments, the indoor metering device 112 may comprise a thermostatic expansion valve, a capillary tube assembly, and/or any other suitable metering device. The indoor metering device 112 may comprise and/or be associated with a refrigerant check valve and/or refrigerant bypass for use when a direction of refrigerant flow through the indoor metering device 112 is such that the indoor metering device 112 is not intended to meter or otherwise substantially restrict flow of the refrigerant through the indoor metering device 112.
Outdoor unit 104 comprises an outdoor heat exchanger 114, a compressor 116, an outdoor fan 118, an outdoor metering device 120, and a reversing valve 122. Outdoor heat exchanger 114 is a spine fin heat exchanger configured to allow heat exchange between refrigerant carried within internal passages of the outdoor heat exchanger 114 and fluids that contact the outdoor heat exchanger 114 but that are kept segregated from the refrigerant. In other embodiments, outdoor heat exchanger 114 may comprise a plate fin heat exchanger, a microchannel heat exchanger, or any other suitable type of heat exchanger.
The compressor 116 is a multiple speed scroll type compressor configured to selectively pump refrigerant at a plurality of mass flow rates. In alternative embodiments, the compressor 116 may comprise a modulating compressor capable of operation over one or more speed ranges, the compressor 116 may comprise a reciprocating type compressor, the compressor 116 may be a single speed compressor, and/or the compressor 116 may comprise any other suitable refrigerant compressor and/or refrigerant pump.
The outdoor fan 118 is an axial fan comprising a fan blade assembly and fan motor configured to selectively rotate the fan blade assembly. In other embodiments, the outdoor fan 118 may comprise a mixed-flow fan, a centrifugal blower, and/or any other suitable type of fan and/or blower. The outdoor fan 118 is configured as a modulating and/or variable speed fan capable of being operated at many speeds over one or more ranges of speeds. In other embodiments, the outdoor fan 118 may be configured as a multiple speed fan capable of being operated at a plurality of operating speeds by selectively electrically powering different ones of multiple electromagnetic windings of a motor of the outdoor fan 118. In yet other embodiments, the outdoor fan 118 may be a single speed fan.
The outdoor metering device 120 is a thermostatic expansion valve. In alternative embodiments, the outdoor metering device 120 may comprise an electronically controlled motor driven EEV, a capillary tube assembly, and/or any other suitable metering device. The outdoor metering device 120 may comprise and/or be associated with a refrigerant check valve and/or refrigerant bypass for use when a direction of refrigerant flow through the outdoor metering device 120 is such that the outdoor metering device 120 is not intended to meter or otherwise substantially restrict flow of the refrigerant through the outdoor metering device 120.
The reversing valve 122 is a so-called four-way reversing valve. The reversing valve 122 may be selectively controlled to alter a flowpath of refrigerant in the HVAC system 100 as described in greater detail below. The reversing valve 122 may comprise an electrical solenoid or other device configured to selectively move a component of the reversing valve 122 between operational positions.
The system controller 106 may comprise a touchscreen interface for displaying information and for receiving user inputs. The system controller 106 may display information related to the operation of the HVAC system 100 and may receive user inputs related to operation of the HVAC system 100. However, the system controller 106 may further be operable to display information and receive user inputs tangentially and/or unrelated to operation of the HVAC system 100. In some embodiments, the system controller 106 may comprise a temperature sensor and may further be configured to control heating and/or cooling of zones associated with the HVAC system 100. In some embodiments, the system controller 106 may be configured as a thermostat for controlling supply of conditioned air to zones associated with the HVAC system 100.
In some embodiments, the system controller 106 may selectively communicate with an indoor controller 124 of the indoor unit 102, with an outdoor controller 126 of the outdoor unit 104, and/or with other components of the HVAC system 100. In some embodiments, the system controller 106 may be configured for selective bidirectional communication over a communication bus 128. In some embodiments, portions of the communication bus 128 may comprise a three-wire connection suitable for communicating messages between the system controller 106 and one or more of the HVAC system 100 components configured for interfacing with the communication bus 128. Still further, the system controller 106 may be configured to selectively communicate with HVAC system 100 components and/or other device 130 via a communication network 132. In some embodiments, the communication network 132 may comprise a telephone network and the other device 130 may comprise a telephone. In some embodiments, the communication network 132 may comprise the Internet and the other device 130 may comprise a so-called smartphone and/or other Internet enabled mobile telecommunication device.
The indoor controller 124 may be carried by the indoor unit 102 and may be configured to receive information inputs, transmit information outputs, and otherwise communicate with the system controller 106, the outdoor controller 126, and/or any other device 130 via the communication bus 128 and/or any other suitable medium of communication. In some embodiments, the indoor controller 124 may be configured to communicate with an indoor personality module 134, receive information related to a speed of the indoor fan 110, transmit a control output to an electric heat relay, transmit information regarding an indoor fan 110 volumetric flow-rate, communicate with and/or otherwise affect control over an air cleaner 136, and communicate with an indoor EEV controller 138. In some embodiments, the indoor controller 124 may be configured to communicate with an indoor fan controller 142 and/or otherwise affect control over operation of the indoor fan 110. In some embodiments, the indoor personality module 134, or any other suitable information storage device, may comprise information related to the identification and/or operation of the indoor unit 102 and/or a position of the outdoor metering device 120.
In some embodiments, the indoor EEV controller 138 may be configured to receive information regarding temperatures and pressures of the refrigerant in the indoor unit 102. More specifically, the indoor EEV controller 138 may be configured to receive information regarding temperatures and pressures of refrigerant entering, exiting, and/or within the indoor heat exchanger 108. Further, the indoor EEV controller 138 may be configured to communicate with the indoor metering device 112 and/or otherwise affect control over the indoor metering device 112.
The outdoor controller 126 may be carried by the outdoor unit 104 and may be configured to receive information inputs, transmit information outputs, and otherwise communicate with the system controller 106, the indoor controller 124, and/or any other device 130 via the communication bus 128 and/or any other suitable medium of communication. In some embodiments, the outdoor controller 126 may be configured to communicate with an outdoor personality module 140 that may comprise information related to the identification and/or operation of the outdoor unit 104. In some embodiments, the outdoor controller 126 may be configured to receive information related to an ambient temperature associated with the outdoor unit 104, information related to a temperature of the outdoor heat exchanger 114, and/or information related to refrigerant temperatures and/or pressures of refrigerant entering, exiting, and/or within the outdoor heat exchanger 114 and/or the compressor 116. In some embodiments, the outdoor controller 126 may be configured to transmit information related to monitoring, communicating with, and/or otherwise affecting control over the outdoor fan 118, a compressor sump heater, a solenoid of the reversing valve 122, a relay associated with adjusting and/or monitoring a refrigerant charge of the HVAC system 100, a position of the indoor metering device 112, and/or a position of the outdoor metering device 120. The outdoor controller 126 may further be configured to communicate with a compressor drive controller 144 that is configured to electrically power and/or control the compressor 116.
The HVAC system 100 is shown configured for operating in a so-called cooling mode in which heat is absorbed by refrigerant at the indoor heat exchanger 108 and heat is rejected from the refrigerant at the outdoor heat exchanger 114. In some embodiments, the compressor 116 may be operated to compress refrigerant and pump the relatively high temperature and high pressure compressed refrigerant from the compressor 116 to the outdoor heat exchanger 114 through the reversing valve 122 and to the outdoor heat exchanger 114. As the refrigerant is passed through the outdoor heat exchanger 114, the outdoor fan 118 may be operated to move air into contact with the outdoor heat exchanger 114, thereby transferring heat from the refrigerant to the air surrounding the outdoor heat exchanger 114. The refrigerant may primarily comprise liquid phase refrigerant and the refrigerant may be pumped from the outdoor heat exchanger 114 to the indoor metering device 112 through and/or around the outdoor metering device 120 which does not substantially impede flow of the refrigerant in the cooling mode. The indoor metering device 112 may meter passage of the refrigerant through the indoor metering device 112 so that the refrigerant downstream of the indoor metering device 112 is at a lower pressure than the refrigerant upstream of the indoor metering device 112. The pressure differential across the indoor metering device 112 allows the refrigerant downstream of the indoor metering device 112 to expand and/or at least partially convert to a gaseous phase. The gaseous phase refrigerant may enter the indoor heat exchanger 108. As the refrigerant is passed through the indoor heat exchanger 108, the indoor fan 110 may be operated to move air into contact with the indoor heat exchanger 108, thereby transferring heat to the refrigerant from the air surrounding the indoor heat exchanger 108. The refrigerant may thereafter reenter the compressor 116 after passing through the reversing valve 122.
To operate the HVAC system 100 in the so-called heating mode, the reversing valve 122 may be controlled to alter the flowpath of the refrigerant, the indoor metering device 112 may be disabled and/or bypassed, and the outdoor metering device 120 may be enabled. In the heating mode, refrigerant may flow from the compressor 116 to the indoor heat exchanger 108 through the reversing valve 122, the refrigerant may be substantially unaffected by the indoor metering device 112, the refrigerant may experience a pressure differential across the outdoor metering device 120, the refrigerant may pass through the outdoor heat exchanger 114, and the refrigerant may reenter the compressor 116 after passing through the reversing valve 122. Most generally, operation of the HVAC system 100 in the heating mode reverses the roles of the indoor heat exchanger 108 and the outdoor heat exchanger 114 as compared to their operation in the cooling mode.
Referring now to FIG. 2, a schematic diagram of air circulation paths of a structure 250 conditioned by two HVAC systems 100 is shown. In this embodiment, the structure 250 is conceptualized as comprising a lower floor 222 and an upper floor 224. The lower floor 222 comprises zones 226, 228, and 230 while the upper floor 224 comprises zones 232, 234, and 236. The HVAC system 100 associated with the lower floor 222 is configured to circulate and/or condition air of lower zones 226, 228, and 230 while the HVAC system 100 associated with the upper floor 224 is configured to circulate and/or condition air of upper zones 232, 234, and 236.
In addition to the components of HVAC system 100 described above, in this embodiment, each HVAC system 100 further comprises a ventilator 146, a prefilter 148, a humidifier 150, and a bypass duct 152. The ventilator 146 may be operated to selectively exhaust circulating air to the environment and/or introduce environmental air into the circulating air. The prefilter 148 may generally comprise a filter media selected to catch and/or retain relatively large particulate matter prior to air exiting the prefilter 148 and entering the air cleaner 136. The humidifier 150 may be operated to adjust a humidity of the circulating air. The bypass duct 152 may be utilized to regulate air pressures within the ducts that form the circulating air flowpaths. In some embodiments, air flow through the bypass duct 152 may be regulated by a bypass damper 154 while air flow delivered to the zones 226, 228, 230, 232, 234, and 236 may be regulated by zone dampers 156.
Still further, each HVAC system 100 may further comprise a zone thermostat 158 and a zone sensor 160. In some embodiments, a zone thermostat 158 may communicate with the system controller 106 and may allow a user to control a temperature, humidity, and/or other environmental setting for the zone in which the zone thermostat 158 is located. Further, the zone thermostat 158 may communicate with the system controller 106 to provide temperature, humidity, and/or other environmental feedback regarding the zone in which the zone thermostat 158 is located. In some embodiments, a zone sensor 160 may communicate with the system controller 106 to provide temperature, humidity, and/or other environmental feedback regarding the zone in which the zone sensor 160 is located.
While the HVAC systems 100 are shown as so-called split systems comprising an indoor unit 102 located separately from the outdoor unit 104, alternative embodiments of an HVAC system 100 may comprise a so-called package system in which one or more of the components of the indoor unit 102 and one or more of the components of the outdoor unit 104 are carried together in a common housing or package. The HVAC systems 100 are shown as a so-called ducted system where the indoor unit 102 is located remote from the conditioned zones, thereby requiring air ducts to route the circulating air. However, in alternative embodiments, an HVAC systems 100 may be configured as non-ducted systems in which the indoor unit 102 and/or multiple indoor units 102 associated with an outdoor unit 104 are located substantially in the space and/or zone to be conditioned by the respective indoor units 102, thereby not requiring air ducts to route the air conditioned by the indoor units 102.
Furthermore, the system controllers 106 may be configured for bidirectional communication with each other and may further be configured so that a user may, using any of the system controllers 106, monitor and/or control any of the HVAC system 100 components regardless of which zones the components may be associated. Further, each system controller 106, each zone thermostat 158, and each zone sensor 160 may comprise a humidity sensor. As such, it will be appreciated that structure 250 is equipped with a plurality of humidity sensors in a plurality of different locations. In some embodiments, a user may effectively select which of the plurality of humidity sensors is used to control operation of one or more of the HVAC systems 100. In some embodiments, the HVAC systems 100 may further comprise a furnace 170 configured to burn fuel such as, but not limited to, natural gas, heating oil, propane, and/or any other suitable fuel, to generate heat and/or provide heated air to at least one zone 226, 228, 230, 232, 234, 236 conditioned by an HVAC system 100.
Referring now to FIG. 3, a schematic view of a furnace 170 is shown according to an embodiment of the disclosure. In this embodiment, the furnace 170 may be configured as a non-condensing gas-fired furnace. Furnace 170 generally comprises a furnace cabinet 172, a partition panel 173 that defines an interior space 188 of the furnace 170, a burner box 174 comprising at least one or more burners configured to receive and rapidly combust a pre-mixed air-fuel mixture, and a draft inducer system 184 configured to draw the at least partially combusted air-fuel mixture from the burner box 174 through at least one heat exchanger tube 200 before ejecting the at least partially combusted air-fuel mixture through an exhaust 186. Additionally, as will be discussed later herein in more detail, the furnace 170 and/or the heat exchanger tube 200 may also comprise a temperature protection sleeve 250 disposed within the heat exchanger tube 200.
The heat exchanger tube 200 generally comprises an inlet 201 configured to receive hot gases produced from at least partially combusting the air-fuel mixture, a first pass 202, a second pass 204, a third pass 206, a fourth pass 208, and an outlet 209 coupled to the partition panel 173 and/or the draft inducer system 184. The first pass 202 is coupled to the second pass 204 by a first bend 203, the second pass 204 is coupled to the third pass 206 by a second bend 205, and the third pass 206 is coupled to the fourth pass 208 by a third bend 207 to form a continuous internal fluid flow path that extends from the inlet 201 associated with an open end of the first pass 202, through internal passages of each of the first pass 202, first bend 203, second pass 204, second bend 205, third pass 206, third bend 207, and fourth pass 208, to an outlet 209 associated with an open end of the fourth pass 208. Furnaces with greater than 80% AFUE may incorporate secondary heat exchangers replacing pass 208 comprised of materials capable of extended exposure to products of combustion including mildly acidic liquids which are the result of products of combustion reaching temperatures lower than dew point (saturation).
It will be appreciated that the passes 202, 204, 206, 208 generally may comprise substantially straight tubes that may be oriented substantially parallel to each other, such that the bends 203, 205, 207 generally comprise 180 degree U-shaped bends. Accordingly, each heat exchanger tube 200 may generally pass multiple times across the interior space 188 of the furnace 170. However, the first pass 202 may or may not generally comprise tapered swage joints at each end that taper into a larger diameter or alternative geometry tube of the first pass 202. Accordingly, the first pass 202 may comprise a first tapered swage joint 202 a that extends from the inlet 201 to a constant diameter portion 202 b of the first pass 202 and a second tapered swage joint 202 c that extends from the constant diameter portion 202 b to the first bend 203. Additionally, the interior space 188 of the furnace 170 may be configured to receive an incoming airflow 190 generated by a blower of the furnace 170 and/or the indoor fan 110 of the indoor unit 102 of FIG. 1, so that the incoming airflow 190 may contact each of the passes 202, 204, 206, 208 and/or bends 203, 205, 207 to promote heat transfer between fluid and/or hot gases within the internal passages of the heat exchanger tube 200 and the incoming airflow 190.
While only one heat exchanger tube 200 is shown, additional heat exchanger tubes 200 may be utilized to increase an overall heating capacity. Thus, a plurality of heat exchanger tubes 200 may receive hot gases produced by at least partially combusting the air-fuel mixture within the burner box 174 and/or each of the burners associated with the burner box 174. In some embodiments, a plurality of heat exchanger tubes 200 may receive the hot gases produced by at least partially combusting the air-fuel mixture from an associated and/or dedicated burner of the burner box 174, so that multiple parallel hot gas flow paths may be formed through the heat exchanger tubes 200 of the furnace 170. However, in other embodiments, the burners may feed at least one manifold configured to distribute the hot gases to the plurality of heat exchanger tubes 200. Further, the flow of the hot gases through the heat exchanger tubes 200 produced from at least partially combusting the air-fuel mixture may be provided by the draft inducer system 184 before ejecting the hot gases through the exhaust 186. Still further, while the furnace 170 is disclosed as a so-called non-condensing furnace comprising at least one heat exchanger tube 200, alternative furnace 170 embodiments may be a so-called condensing furnace and comprise at least one heat exchanger tube 200 and at least one secondary heat exchanger connected to the heat exchanger tube 200 by a hot header.
Referring now to FIGS. 4 and 5, a partial detailed view of the heat exchanger tube 200 and the temperature protection sleeve 250 of FIG. 3, and a detailed view of the temperature protection sleeve 250 of FIGS. 3 and 4 are shown, respectively, according to an embodiment of the disclosure. As stated, the burner box 174 is configured to receive a pre-mixed air-fuel mixture. The pre-mixed air-fuel mixture may generally combust within the burner box 174 very rapidly. The rapid, almost instant combustion occurs because the pre-mixed air-fuel mixture enhances atomization of the fuel, thereby producing a very rapid combustion process. As a result of the rapid combustion process, heat released from the combusted fuel also occurs rapidly, producing flame temperatures that are significantly higher as compared to other burners that employ external secondary forms of aeration or that mix the air and fuel during combustion. The quick heat release and increased flame temperatures may cause damage to joints (tapered swage joints 202 a, 202 c) of the heat exchanger tube 200 and/or the heat exchanger tube 200 itself. Accordingly, heat exchanger tube 200 comprises a temperature protection sleeve 250 configured to protect the heat exchanger tube 200 from the quick heat release and increased flame temperatures produced as a result of the rapid combustion of the pre-mixed air-fuel mixture.
The temperature protection sleeve 250 comprises an inlet 252, a flange 254, an elongated tube 256 that extends from the flange 254, and an outlet 258. Additionally, in some embodiments, the temperature protection sleeve 250 may also comprise a plurality of perforations 260 disposed about the elongated tube 256. Most generally, the temperature protection sleeve 250 may be disposed locally to the combustion process to provide the greatest amount of protection to the heat exchanger tube 200. In this embodiment, the temperature protection sleeve 250 may be disposed at least partially within the inlet 201 of the heat exchanger tube 200. The temperature protection sleeve 250 may comprise a compression and/or an interference fit with the inlet 201 of the heat exchanger tube 200 to retain the temperature protection sleeve 250 within the heat exchanger tube 200. Additionally, when the temperature protection sleeve 250 is captured inside the inlet 201 of the heat exchanger tube 200, the flange 254 of the temperature protection sleeve 250 may be rolled, formed, and/or otherwise manipulated around the inlet 201 of the heat exchanger tube 200 to secure the temperature protection sleeve 250 to the heat exchanger tube 200.
The temperature protection sleeve 250 may generally be formed from a material that promotes a gradual distribution of heat. Accordingly, the temperature protection sleeve 250 may generally be formed a composite material. In some embodiments, the temperature protection sleeve 250 may be formed from an alumina-fiber material (e.g. high grade fiberglass material). However, in other embodiments, the temperature protection sleeve 250 may be formed from a carbon fiber and/or any other metallic fiber composite suitable for subjection to significant flame temperatures produced by rapid combustion of a pre-mixed air-fuel mixture. Accordingly, the temperature protection sleeve 250 may be configured to shield the inlet 201, the vulnerable tapered swage joints 202 a, 202 c of the first pass 202, and/or the constant diameter portion 202 b of the first pass 202 from the increased flame temperatures produced by rapid combustion of a pre-mixed air-fuel mixture.
In some embodiments, the temperature protection sleeve 250 may protect the vulnerable areas of the heat exchanger tube 200 by promoting gradual heat transfer in those areas. Further, in some embodiments, the temperature protection sleeve 250 may prevent the high temperature flame from directly contacting the first tapered swage joint 202 a between the partition panel 173 and the constant diameter portion 202 b of the first pass 202. Thus, in some embodiments, the protection provided by the temperature protection sleeve 250 may be a result of diffusing the local high temperature flame and/or released heat caused by rapidly combusting the pre-mixed air-fuel mixture. As such, in some embodiments, the local high temperature flame and/or released heat may be passed through the internal passage of the temperature protection sleeve 250, where it may slowly diffuse and/or pass through the perforations 260 of the temperature protection sleeve 250. Additionally, in some embodiments, tertiary air, such as non-combustion air may be introduced into the temperature protection sleeve 250 through the perforations 260 to aid in the heat distribution provided by the temperature protection sleeve 250. By slowly diffusing the heat produced, the first pass 202 of the heat exchanger tube 200 may experience a more gradual, even, and/or uniform temperature distribution across the length of the first pass 202, thereby increasing and/or maximizing heat transfer with the incoming airflow 190 that contacts the first pass 202. Further, by the temperature protection sleeve 250 distributing the heat more evenly throughout the first pass 202, the heat may also be distributed more evenly throughout the entire heat exchanger tube 200, thereby increasing the overall heat transfer properties of the entire heat exchanger tube 200.
As a result of slowly and/or more evenly distributing and/or diffusing the heat throughout the heat exchanger tube 200 caused by the temperature protection sleeve 250, the temperature protection sleeve 250 enables the heat exchanger tube 200 and/or furnace 170 to maintain temperatures compliant with applicable heat standards for gas-fired furnaces, such as ANSI Z21.47-2016 CSA 2.3 2016 section 5.16-18 and referenced section 4.2.7 Table 1. At least in some part, the material selection of the temperature protection sleeve 250 contributes to the heat exchanger tube 200 complying with ANSI Z21.47. Furthermore, because of the rapid combustion of the pre-mixed air-fuel mixture, the combustion results in extremely low Nitrogen Oxide (NOx) emissions. In some embodiments, the NOx emissions may be less than 14 Nanograms of Nitrogen Oxides (calculated as Nanograms per Joule (Ng/J) of useful heat delivered to the temperature conditioned area. Accordingly, a furnace 170 comprising the heat exchanger tube 200 and the temperature protection sleeve 250 may comply with SCAQMD Rule 1111.
Referring now to FIG. 6, a schematic diagram 300 of the temperature protection sleeve 250 of FIGS. 3-5 is shown according to an embodiment of the disclosure. The schematic diagram 300 illustrates that by providing the temperature protection sleeve 250 in the heat exchanger tube 200, the heat exchanger tube 200 and/or the furnace 170 is compliant with the ANSI Z21.47 material temperature standard since the temperature protection sleeve 250 protects the heat exchanger tube 200 from the high temperature flame that typically would damage heat transfer components when a pre-mixed air-fuel mixture is rapidly combusted. Additionally, because the rapid combustion produces low NOx emissions (at least less than 14 Ng/J), the furnace 170 also complies with SCAQMD Rule 1111. As such, heat transfer between the heat exchanger tube 200 and the incoming airflow 190 may be maximized to provide an efficiently heated airflow to at least one of the temperature conditioned areas (e.g. zones 226, 228, 230, 232, 234, 236). Thus, the temperature protection sleeve 250 enables compliance of the furnace 170 with both the ANSI Z21.47 material temperature standard and SCAQMD Rule 1111.
At least one embodiment is disclosed and variations, combinations, and/or modifications of the embodiment(s) and/or features of the embodiment(s) made by a person having ordinary skill in the art are within the scope of the disclosure. Alternative embodiments that result from combining, integrating, and/or omitting features of the embodiment(s) are also within the scope of the disclosure. Where numerical ranges or limitations are expressly stated, such express ranges or limitations should be understood to include iterative ranges or limitations of like magnitude falling within the expressly stated ranges or limitations (e.g., from about 1 to about 10 includes, 2, 3, 4, etc.; greater than 0.10 includes 0.11, 0.12, 0.13, etc.). For example, whenever a numerical range with a lower limit, R_l, and an upper limit, R_u, is disclosed, any number falling within the range is specifically disclosed. In particular, the following numbers within the range are specifically disclosed: R=R_l+k*(R_u−R_l), wherein k is a variable ranging from 1 percent to 100 percent with a 1 percent increment, i.e., k is 1 percent, 2 percent, 3 percent, 4 percent, 5 percent, . . . , 50 percent, 51 percent, 52 percent, . . . , 95 percent, 96 percent, 97 percent, 98 percent, 99 percent, or 100 percent.
Unless otherwise stated, the term “about” shall mean plus or minus 10 percent of the subsequent value. Moreover, any numerical range defined by two R numbers as defined in the above is also specifically disclosed. Use of the term “optionally” with respect to any element of a claim means that the element is required, or alternatively, the element is not required, both alternatives being within the scope of the claim. Use of broader terms such as comprises, includes, and having should be understood to provide support for narrower terms such as consisting of, consisting essentially of, and comprised substantially of. Accordingly, the scope of protection is not limited by the description set out above but is defined by the claims that follow, that scope including all equivalents of the subject matter of the claims. Each and every claim is incorporated as further disclosure into the specification and the claims are embodiment(s) of the present invention.

Claims

What is claimed is:

1. A heat exchanger for a furnace, comprising:

at least one heat exchanger tube; and

a temperature protection sleeve disposed at least partially within the heat exchanger tube.

2. The heat exchanger of claim 1, wherein the temperature protection sleeve comprises a flange and an elongated tube extending from the flange.

3. The heat exchanger of claim 2, wherein the temperature protection sleeve comprises a plurality of perforations disposed about the elongated tube of the temperature protection sleeve.

4. The heat exchanger of claim 3, wherein the temperature protection sleeve is configured to shield at least a portion of the heat exchanger tube from at least one of a flame and an elevated temperature flue product produced from combusting a pre-mixed air-fuel mixture within the furnace.

5. The heat exchanger of claim 3, wherein the temperature protection sleeve is configured to dissipate heat generated from combusting a pre-mixed air-fuel mixture.

6. The heat exchanger of claim 2, wherein the flange of the temperature protection sleeve is disposed between a burner of the furnace and an inlet of the at least one heat exchanger tube.

7. The heat exchanger of claim 6, wherein the flange of the temperature protection sleeve is mounted to a partition panel of the furnace.

8. The heat exchanger of claim 7, wherein at least a portion of the inlet of the at least one heat exchanger tube is captured by the flange of the temperature protection sleeve.

9. The heat exchanger of claim 3, wherein the at least one heat exchanger tube complies with ANSI Z21.47.

10. The heat exchanger of claim 9, wherein the furnace is configured to emit less than 14 Nanograms of oxides of nitrogen per Joule (Ng/J) of heat delivered to a temperature conditioned area.

11. The heat exchanger of claim 10, wherein the furnace complies with SCAQMD Rule 1111.

12. A furnace, comprising:

at least one burner; and

a heat exchanger, comprising:

at least one heat exchanger tube; and

13. The furnace of claim 12, wherein the temperature protection sleeve comprises a flange and an elongated tube extending from the flange.

14. The furnace of claim 13, wherein the temperature protection sleeve comprises a plurality of perforations disposed about the elongated tube of the temperature protection sleeve.

15. The furnace of claim 14, wherein the temperature protection sleeve is configured to shield at least a portion of the heat exchanger tube from at least one of a flame and an elevated temperature flue product produced from combusting a pre-mixed air-fuel mixture within the furnace.

16. The furnace of claim 14, wherein the temperature protection sleeve is configured to dissipate heat generated from combusting a pre-mixed air-fuel mixture with the at least one burner.

17. The furnace of claim 12, wherein at least a portion of the inlet of the at least one heat exchanger tube is captured by the flange of the temperature protection sleeve, and wherein the flange of the temperature protection sleeve is disposed between the at least one burner of the furnace and an inlet of the at least one heat exchanger tube.

18. The furnace of claim 14, wherein the at least one heat exchanger tube complies with ANSI Z21.47.

19. The furnace of claim 18, wherein the furnace is configured to emit less than 14 Nanograms of oxides of nitrogen per Joule (Ng/J) of heat delivered to a temperature conditioned area and wherein the furnace complies with SCAQMD Rule 1111.

20. The furnace of claim 19, wherein the furnace is a component of a heating, ventilation, and/or air conditioning (HVAC) system.