Exemplary embodiments pertain to the art of heating, ventilation, air conditioning and refrigeration (HVAC&R) systems. More specifically, the present disclosure relates to shell-and-tube heat exchangers for HVAC&R systems.
Shell and tube heat exchangers are utilized in HVAC&R systems, particularly as evaporators in HVAC&R systems, to facilitate a thermal energy exchange refrigerant in the evaporator and a medium, often water, a brine or other solution, flowing through a number of tubes in the evaporator. The thermal energy exchange cools the medium and causes the refrigerant to boil.
In one embodiment, a heat transfer tube includes a tube having an internal tube wall, and a tube element extending along a tube length and radially inwardly from the internal tube wall. The tube element has a radial element height less than a hydraulic radius of the tube, and the radial element height is greater than a base element width at the internal tube wall.
Additionally or alternatively, in this or other embodiments the tube element extends helically along the tube length.
Additionally or alternatively, in this or other embodiments the tube element has a ratio of pitch to hydraulic diameter in the range of 1 to 20.
Additionally or alternatively, in this or other embodiments the tube element extends intermittently along the tube length.
Additionally or alternatively, in this or other embodiments the tube element includes a first element portion and a second element portion separate from the first element portion, the first element portion and second element portion overlapping along a lengthwise direction of the tube.
Additionally or alternatively, in this or other embodiments the tube element is configured to extend through a thermal boundary layer of a heat transfer medium flowing therethrough.
Additionally or alternatively, in this or other embodiments the tube element is a helical feature formed integral to the tube.
Additionally or alternatively, in this or other embodiments a single, unitary tube element extends radially inwardly from the internal tube wall at a cross-section perpendicular to the tube length.
Additionally or alternatively, in this or other embodiments the tube is formed from a first material, and the tube element is formed from a second material different from the first material.
Additionally or alternatively, in this or other embodiments the heat transfer tube includes one or more surface enhancements including one or more of axial, helical or crosshatched microfins or reentrant cavities.
In another embodiment, a tube and shell heat exchanger includes a housing and a heat exchanger tube extending through the housing and having a heat transfer medium flowing therethrough. The heat exchanger tube includes a tube having an internal tube wall and tube element extending along a tube length and radially inwardly from the internal tube wall. The tube element has a radial element height less than a hydraulic radius of the tube, and the radial element height is greater than a base element width at the internal tube wall. The heat exchanger includes a refrigerant inlet to flow a refrigerant over the heat exchanger tube, for thermal energy exchange between the refrigerant and the heat transfer medium.
Additionally or alternatively, in this or other embodiments the tube element extends helically along the tube length.
Additionally or alternatively, in this or other embodiments the tube element has a ratio of pitch to hydraulic diameter in the range of 1 to 20.
Additionally or alternatively, in this or other embodiments the tube element extends intermittently along the tube length.
Additionally or alternatively, in this or other embodiments the tube element includes a first element portion and a second element portion separate from the first element portion, the first element portion and second element portion overlapping along a lengthwise direction of the tube.
Additionally or alternatively, in this or other embodiments the tube element is configured to extend through a thermal boundary layer of a heat transfer medium flowing therethrough.
Additionally or alternatively, in this or other embodiments the tube element is a helical feature formed integral to the tube.
Additionally or alternatively, in this or other embodiments a single, unitary tube element extends radially inwardly from the internal tube wall at a cross-section perpendicular to the tube length.
Additionally or alternatively, in this or other embodiments the tube is formed from a first material, and the tube element is formed from a second material different from the first material.
Additionally or alternatively, in this or other embodiments, the heat exchanger tube includes one or more surface enhancements including one or more of axial, helical or crosshatched microfins or reentrant cavities.
The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike:
A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures.
A typical tube of a shell and tube heat exchanger may have features or “enhancements” to improve thermal energy transfer between the medium and the refrigerant. One such enhancement is a twisted tape inset that extends entirely across an inner diameter of the tube. These inserts however typically result in a high pressure drop penalty along a length of the tube.
Shown in
Referring now to
The evaporator 12 includes housing 52 with the evaporator 12 components disposed at least partially therein, including a separator 30 to separate liquid refrigerant 20 and vapor refrigerant 14 from the vapor and liquid refrigerant mixture 24. Vapor refrigerant 14 is routed from the separator 30 through a suction port 32 and toward the compressor 16, while the liquid refrigerant 20 is routed toward a distribution system 34 of the evaporator 12. The distribution system 34 includes a distribution box 36 having a plurality of openings 38 arrayed along a bottom surface 44 of the distribution box 36. Though in the embodiment of
Heat transfer medium 28 flows through the evaporator tubes 26 for thermal energy exchange with the liquid refrigerant 20. Referring now to
Referring now to
In an alternative embodiment, as shown in
Referring again to
In embodiments with circular inserts 68, insert diameter 74 is substituted for insert height 70. The insert height 70 is established to extend through the thermal boundary layer 64, while causing minimal disturbance to the core flow 66.
Referring again to
In some embodiments, such as shown in
Referring now to
While in some embodiments, the helical insert 68 is secured to the tube inner wall 62, such intimate contact along an entire length of the helical insert 68 is not necessary, as the primary purpose of the helical insert 68 is to provide flow mixing of the heat transfer medium 28 to enhance heat transfer through the heat transfer medium 28.
The helical insert 68 may be formed from the same material as the evaporator tube 26, such as aluminum or copper or alloys thereof, and further may be formed integral with the evaporator tube 26. In other embodiments, the helical insert 68 is formed separately from the evaporator tube 26, and is installed via a secondary operation. Further, the helical insert 68 may be formed from a material different from the material utilized to form the evaporator tube 26, such as a metal or polymer material.
The term “about” is intended to include the degree of error associated with measurement of the particular quantity based upon the equipment available at the time of filing the application.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, element components, and/or groups thereof.
While the present disclosure has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the essential scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this present disclosure, but that the present disclosure will include all embodiments falling within the scope of the claims.
Filing Document | Filing Date | Country | Kind |
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PCT/US2018/050409 | 9/11/2018 | WO | 00 |
Number | Date | Country | |
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62557828 | Sep 2017 | US |