Patent Application
20220325905
The present disclosure relates, in general, to an air handling unit and, more specifically relates, to a fan of the air handling unit.
An air conditioner is referred to as a split type air conditioner when an indoor unit and an outdoor unit thereof are located distant from one another. The outdoor unit in the split type air conditioner typically includes an axial fan as the air mover. The axial fan is located at a top portion of the cabinet and is received coaxially in a venturi. Generally, based on a layout of refrigerant tubes routed along a periphery of the outdoor unit, space available between an outer surface of the venturi and the refrigerant tubes routed through an upper portion of the outdoor unit, may be negligible. Such disposition of the axial fan and the venturi creates a narrow region for flow of air therebetween, thereby causing development of non-uniform pressure differential along a height of the outdoor unit and across refrigerant tubes guided along periphery of the outdoor unit. Since air tends to flow along a path of least resistance, such disposition of the venturi and the fan results in negligible flow of air across the refrigerant tubes located in the narrow region at the upper portion of the outdoor unit, thereby affecting heat exchange between the refrigerant tubes and air flowing therethrough.
In cases where the outdoor unit includes multiple circuits of refrigerant tubes, such disposition of the venturi and the fan may cause few circuits to be devoid of air, thereby developing an instance of airflow maldistribution along the height of the outdoor unit. Such instances of airflow maldistribution may be detrimental to an overall performance of the split type air conditioner.
According to one aspect of the present disclosure, a fan is disclosed. The fan includes a hub configured to rotate about an axis, and a plurality of fan blades coupled to the hub and located circumferentially along the hub. Each fan blade extends between a root and a tip edge thereof. The fan blade includes a first portion inclined at a first predefined angle with respect to the hub. The first portion is configured to induce an axial flow of air. In an embodiment, the first portion of the fan blade in non-planar. The fan blade further includes a second portion extending from the first portion and between a leading edge and a trailing edge of the fan blade. The second portion is configured as an airfoil defining an angle of attack to induce a radial inward flow of air. In some embodiments, each of the plurality of fan blades is made of one of plastic, metal, and composite material. A radius of curvature of a trailing edge segment of the second portion is less than a radius of curvature of a leading edge segment of the second portion. In an embodiment, a span of the second portion is less than a span of the first portion of the fan blade.
In some embodiments, the induced radial inward flow of air is in a range of about 5% to about 10% of the induced axial flow of air.
In an embodiment, the leading edge segment of the second portion is bent inward towards the hub to define the angle of attack of the fan blade. In an embodiment, a distance between the trailing edge segment of the second portion and a center of the hub is less than a distance between the leading edge segment of the second portion and the center of the hub. In some embodiments, the angle of attack at the tip edge of the fan blade is lower than the angle of attack at a base of the second portion, with respect to a radial direction of the fan blade.
In some embodiments, the angle of attack of the fan blade is in a range of about 3 degrees to about 15 degrees.
In an embodiment, a portion of the leading edge segment of the second portion extends perpendicular with respect to the first portion of the fan blade.
In an embodiment, each of the plurality of fan blades is a swept blade.
According to another aspect of the present disclosure, an air handling unit is disclosed. The air handling unit includes a cabinet, a motor housed within the cabinet, and a fan operably coupled to the motor. The fan is configured to allow a uniform inflow of air at an upper portion of the cabinet and direct the air from inside of the cabinet to outside of the cabinet. The fan includes a hub coupled to a shaft of the motor and configured to rotate about an axis. The fan also includes a plurality of fan blades coupled to the hub and located circumferentially along the hub. Each fan blade extends between a root and a tip edge thereof and includes a first portion inclined at a first predefined angle with respect to the hub. The first portion is configured to induce an axial flow of air. The fan blade also includes a second portion extending from the first portion and between a leading edge and a trailing edge of the fan blade. The second portion is configured as an airfoil defining an angle of attack to induce a radial inward flow of air. A radius of curvature of a trailing edge segment of the second portion is less than a radius of curvature of a leading edge segment of the second portion. In an embodiment, a portion of the leading edge segment of the second portion of the fan blade extends perpendicular with respect to the first portion of the fan blade.
In an embodiment, the leading edge segment of the second portion of the fan blade is bent inward towards the hub to define the angle of attack of the fan blade.
In an embodiment, the air handling unit includes a plurality of refrigerant tubes extending along a periphery of the cabinet. In such arrangement, the fan is configured to induce airflow over the plurality of refrigerant tubes to achieve heat exchange with respect to the plurality of refrigerant tubes.
According to yet another aspect of the present disclosure, an air handling unit is disclosed. The air handling unit includes a cabinet, a motor housed within the cabinet, and a bell mouth extending from the cabinet in a direction inward along a longitudinal axis of the cabinet. The bell mouth is configured to partially conceal the motor in a transverse direction of the cabinet. The air handling unit also includes a fan operably coupled to the motor. The fan is configured to allow a uniform inflow of air at an upper portion of the cabinet and direct the air from inside of the cabinet to outside of the cabinet through the bell mouth. The fan includes a hub coupled to a shaft of the motor and configured to rotate about the longitudinal axis of the cabinet. The fan also includes a plurality of fan blades coupled to the hub and located circumferentially along the hub. Each fan blade extends between a root and a tip edge. The fan blade includes a first portion inclined at a first predefined angle with respect to the hub. The first portion is configured to induce an axial flow of air. The fan blade also includes a second portion extending from the first portion and between a leading edge and a trailing edge of the fan blade. The second portion is configured as an airfoil defining an angle of attack to induce a radial inward flow of air. The second portion is partially concealed by the bell mouth in the transverse direction of the cabinet. A radius of curvature of a trailing edge segment of the second portion is less than a radius of curvature of a leading edge segment of the second portion.
In an embodiment, the induced radial inward flow of air is in a range of about 5% to about 10% of the induced axial flow of air.
In an embodiment, the air handling unit further includes a plurality of refrigerant tubes extending along a periphery of the cabinet. In such arrangement, the fan is configured to induce airflow over the plurality of refrigerant tubes to achieve heat exchange with respect to the plurality of refrigerant tubes.
In an embodiment, the air handling unit further includes a fan guard coupled to an outlet of the bell mouth.
These and other aspects and features of non-limiting embodiments of the present disclosure will become apparent to those skilled in the art upon review of the following description of specific non-limiting embodiments of the disclosure in conjunction with the accompanying drawings.
A better understanding of embodiments of the present disclosure (including alternatives and/or variations thereof) may be obtained with reference to the detailed description of the embodiments along with the following drawings, in which:
Reference will now be made in detail to specific embodiments or features, examples of which are illustrated in the accompanying drawings. Wherever possible, corresponding or similar reference numbers will be used throughout the drawings to refer to the same or corresponding parts. Moreover, references to various elements described herein, are made collectively or individually when there may be more than one element of the same type. However, such references are merely exemplary in nature. It may be noted that any reference to elements in the singular may also be construed to relate to the plural and vice-versa without limiting the scope of the disclosure to the exact number or type of such elements unless set forth explicitly in the appended claims.
As used herein, the terms “a”, “an” and the like generally carry a meaning of “one or more,” unless stated otherwise. Further, the terms “approximately”, “approximate”, “about”, and similar terms generally refer to ranges that include the identified value within a margin of 20%, 10%, or preferably 5%, and any values therebetween.
Aspects of the present disclosure are directed to a fan and an air handling unit implementing the fan. Specifically, the present disclosure provides constructional improvements to a fan blade of the fan to create air flow in a radial inward direction with respect to a hub of the fan in order to achieve uniform flow of air, for example inlet velocity of the air, in an upper portion of the air handling unit. Such uniform flow of the air aids reduction of airflow maldistribution in the air handling unit, such as an outdoor unit of a split type air conditioning system.
Referring to
Although not particularly illustrated, it will be understood that the indoor unit 104 includes an indoor heat exchanger supported within an indoor unit housing 110. Further, the indoor unit housing 110 may include an indoor air inlet, an indoor air outlet, an indoor refrigerant inlet, and an indoor refrigerant outlet.
Further, the cabinet 202 defines a plurality of openings 214 configured to allow inflow of ambient air “A” into the cabinet 202 from the environment. In such arrangement, the fan 208 is configured to induce airflow over the refrigerant tubes 212 to achieve heat exchange with respect to the refrigerant tubes 212. As such, in a cooling mode operation, the refrigerant flowing through the refrigerant tubes 212 loses heat to the ambient air “A” flowing across the refrigerant tubes 212. In a heating mode operation, the refrigerant flowing through the refrigerant tubes 212 absorbs heat from the ambient air “A” flowing across the refrigerant tubes 212. The fan 208 is configured to direct the air from within the cabinet 202 to the outside of the cabinet 202. As such, the inflow and outflow of air with respect to the cabinet 202 establishes a heat exchange relationship with the refrigerant tubes 212 of the outdoor unit 106. Since the outdoor unit 106 handles the flow of air into and out of the cabinet 202, the outdoor unit 106 is also referred to as “the air handling unit 106” in the present disclosure. In a cooling mode air conditioning operation, the refrigerant flowing through the refrigerant tubes 212 in the outdoor unit 106 loses heat to the air flowing across the refrigerant tubes 212 and is further guided to the indoor unit 104 to absorb heat from the predetermined indoor space 102. The refrigerant is then guided back to the outdoor unit 106 to complete an air conditioning cycle. In a heating mode air conditioning operation, the refrigerant flowing through the refrigerant tubes 212 in the outdoor unit 106 absorbs heat from the air flowing across the refrigerant tubes 212 and is further guided to the indoor unit 104 to dissipate heat to the predetermined indoor space 102.
In some embodiments, a span “S2” of the second portion 420 may be less than a span “S1” of the first portion 418 of the fan blade 406. In some embodiments, length of a chord “C2” in the second portion 420 may be equal to the length of the chord “C1” in the first portion 418. In some embodiments, length of the chord “C2” in the second portion 420 may be less than the length of the chord “C1” in the first portion 418. The second portion 420 is configured as an airfoil to define an angle of attack (α), with respect to the air flowing across the second portion 420, and to induce a radial inward flow of air (indicated by arrow “R” in
According to an aspect of the present disclosure, a radius of curvature of a trailing edge segment 422 of the second portion 420 is less than a radius of curvature of a leading edge segment 424 of the second portion 420. The radius of curvature of the trailing edge segment 422 creates a cambered airfoil profile that is associated with the angle of attack (α), such that the second portion 420 of the fan blade 406 induces the radial inward flow of air. In an embodiment, the leading edge segment 424 of the second portion 420 is bent inward towards the hub 402 to define the angle of attack (α) with respect to the air flowing across the leading edge segment 424 of the second portion 420.
In an embodiment, the angle of attack (α) of the fan blade 406 is in a range of zero degrees to about 10 degrees, and preferably in a range of about 3 degrees to about 10 degrees. In another embodiment, the angle of attack (α) may be in a range of about 5 degrees to about 8 degrees. In yet another embodiment, the angle of attack (α) may be in a range of about 6 degrees to about 7.5 degrees. In some embodiments, the angle of attack (α) may be predefined based on, but not limited to, a desired amount of radial flow of air, diameter of the fan 208, desired rotation speed of the fan 208, the length of the chord “C2” in the second portion 420 of the fan blade 406, and the span “S2” of the second portion 420 of the fan blade 406.
In an embodiment, a portion of the leading edge segment 424 of the second portion 420 extends perpendicular with respect to the first portion 418. Additionally, in some embodiments, a portion of the trailing edge segment 422 of the second portion 420 may extend perpendicular with respect to the first portion 418. In an embodiment, a distance between the trailing edge segment 418 of the second portion 420 and a center of the hub 402 may be less than a distance between the leading edge segment 424 of the second portion 420 and the center of the hub 402.
As can be seen in
In some embodiments, the tip edge 410 may be uncambered and may be associated with zero degree angle of attack. In alternate embodiments, the fan blade 406 may be designed to define lesser length of chord at the tip edge 410 when compared to lengths of chords downstream along the span “S2” of the second portion 420. Such design of the fan blade 406 may help reduce inward lift of air at the tip edge 410 and reduce losses at the tip edge 410, thereby enhancing efficiency of the fan blade 406. In some embodiments, the tip edge 410 may be parallel to the hub 402. Additionally, in some embodiments, a width “W1” of the tip edge 410 may be less than a width “W2” of the first portion 418 of the fan blade 406. As such, the fan blade 406 may have a trapezoidal shape along the span thereof.
During operation of the fan 208, the air present in the cabinet 202 and flowing across the first portion 418 of the fan blade 406 is guided along the longitudinal axis “L” of the cabinet 202 in a direction outward with respect to the cabinet 202. Further, the air flowing across the second portion 420 is guided in the radial direction of the fan blade 406 and subsequently guided outward, along with the axially flowing air, in the direction outward with respect to the cabinet 202. In such arrangement, a lift generated by the airfoil profile of the second portion 420 may be based on at least one of, but not limited to, shape of the second portion 420, the angle of attack with respect to the air flowing across the second portion 420, the length of the chord “C2” in the second portion 420, velocity of the air flowing across the second portion 420, and density of the air flowing across the second portion 420. In some embodiments, a desired lift (radial inward flow of the air) may be achieved by a combination of varied angles of attack and the length of the chord “S2” in the second portion 420 of the fan blade 406. In some embodiments, the desired lift may be achieved solely by varying the length of the chord “C2” in the second portion 420 of the fan blade 406. According to an aspect, vortex bound to the airfoil profile of the second portion 420 is guided towards the tip end 410 of the fan blade 406 to allow shedding of the vortex. As such, the second portion 420 allows in reduction of vortices in horizontal plane, thereby reducing induced drag and axial thrust of the fan 208. Additionally, the gradual reduction in the angle of attack towards the tip edge 410 reduces intensity of vortices.
Further, the second portion 420 of the fan blade 406 is partially concealed by the bell mouth 302 in the transverse direction of the cabinet 202. In some embodiments, the span “S2” of the second portion 420 may be designed to reduce length of the bell mouth 302 or eliminate requirement of the bell mouth 302, thereby allowing reduction in cost of manufacturing the cabinet 202 besides achieving the uniform flow of air in the upper portion 304 of the cabinet 202. In some embodiments, the motor 206 may be associated with higher RPM and the second portion 420 of the fan blade 406 may be associated with lesser angle of attack to achieve the uniform flow of air across the cabinet 202.
To this end, it will be understood that the fan blade 406 of the present disclosure, particularly the second portion 420 of the fan blade 406, improves the flow of air in the upper portion 304 of the cabinet 202, thereby reducing or eliminating airflow maldistribution which was otherwise caused due to layout of conventional cabinets including motor, axial fan, and venturi. Due to such uniform flow of air in the upper portion 304 of the cabinet 202, the refrigerant flowing through the refrigerant tubes 212 routed through the upper portion 304 is allowed to exchange heat with the air flowing across the refrigerant tubes 212, thereby enhancing heat exchange efficiency of the outdoor unit 106 and overall efficiency of the AC system 100. In an implementation, the fan 208 of the present disclosure may be deployed in a horizontally oriented outdoor unit of a split type air conditioning system.
While aspects of the present disclosure have been particularly shown and described with reference to the embodiments above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by the modification of the disclosed methods without departing from the spirit and scope of what is disclosed. Such embodiments should be understood to fall within the scope of the present disclosure as determined based upon the claims and any equivalents thereof.
