EP4636332A1

EP4636332A1 - Air handling unit with a heater assembly having stackable heating modules

Info

Publication number: EP4636332A1
Application number: EP25171402.8A
Authority: EP
Inventors: Dennis Blessing; Mark Hemphill
Original assignee: Carrier Corp
Current assignee: Carrier Corp
Priority date: 2024-04-18
Filing date: 2025-04-17
Publication date: 2025-10-22

Abstract

Disclosed herein is an air handling unit (100). The air handling unit comprises a housing duct (102), a blower (108) disposed inside the housing duct for moving air within the housing duct, and a heater assembly (106) comprising a plurality of heating modules (106-1 - 106-N) coaxially stacked over each other along a direction of the airflow, with the heater assembly coaxially disposed inside the housing duct along a direction of flow of the air. Each of the heating modules comprises a frame (202) formed by a mesh of rods (202-1 - 202-3), where the frame is configured to be removably disposed inside the housing duct, and a heating element (204) of a predefined shape and a predefined heating capacity removably attached to and supported on the frame. The predefined shape is selected based on an airflow pattern of the air flowing through the respective heating module such that the air flows through the corresponding heating element.

Description

BACKGROUND

The embodiments described herein relate to air handling units for HVAC systems.

SUMMARY

According to a first aspect of the invention there is provided an air handling unit for use with an air conditioning system. The air handling unit comprises a housing duct through which air is moved from an inlet to an outlet, a blower disposed inside the housing duct, configured for moving air within the housing duct, and a heater assembly comprising a plurality of heating modules coaxially stacked over each other along a direction of the airflow. The heater assembly is coaxially disposed inside the housing duct along a direction of flow of the air. Each of the heating modules comprises a frame formed by a mesh of rods, where the frame is configured to be removably disposed inside the housing duct, and a heating element of a predefined shape and a predefined heating capacity, removably attached to and supported on the frame, wherein the predefined shape is selected based on an airflow pattern of the air flowing through the respective heating module such that the air flows through the corresponding heating element.
Optionally, the heating modules are disposed downstream of the blower.
Optionally, the blower is a mixed airflow blower.
Optionally, the heating element associated with each of the heating modules is supported on the frame using one or more thermally and electrically insulative devices to electrically and thermally isolate the frame from the heating element, and wherein the frame is made of an electrically and thermally insulative material.
Optionally, the frame comprises a set of rods arranged parallelly, orthogonally, and/or diagonally to each other along a plane to form the mesh of rods defining the shape of the frame, wherein the formed mesh or the frame has an outer profile based on an inner profile of the housing duct.
Optionally, the heating element has a substantially circular ring-shaped profile, wherein the ring-shaped heating element has a predefined inner radius and predefined thickness based on the airflow pattern of the air flowing through the respective heating module.
Optionally, the radius and/or thickness of the heating element associated with each of the heating modules is different.
Optionally, the radius and/or thickness of the heating element associated with each of the heating modules decreases while moving downstream of the heater assembly.
Optionally, the radius and/or thickness of the heating element associated with at least two heating modules among the plurality of heating modules is different.
Optionally, the radius and/or thickness of the heating element associated with each of the heating modules is same.
Optionally, the heating element has a linear shape comprising one or more passes and turns.
Optionally, an area of the linear-shaped heater is circular or based on the airflow pattern of the air flowing through the respective heating module.
Optionally, the heating capacity of the heating element associated with each of the heating modules is different.
Optionally, the heating capacity of the heating element associated with at least two heating modules among the plurality of heating modules is different.
Optionally, the heating capacity of the heating element associated with each of the heating modules decreases while moving downstream of the heater assembly.
Optionally, the heating capacity of the heating element associated with each of the heating modules is same.
Optionally, the heating capacity of the heating element associated with at least one of the heating modules of the heater assembly is variable.
Optionally, the heating element is formed by an angular spiral wound electrical wire of a predefined resistance.
Optionally, the frame comprises at least one support plate connecting at least one end of each of the first set of rods, wherein the at least one support plate is configured to be removably attached to an inner wall of the housing duct to secure the corresponding heating module within the housing duct, wherein electrical terminals of the heating element extends through the at least one plate and an insulator is configured between the electrical terminals and the corresponding support plate.
Optionally, each of the heating modules comprises a controller operatively connected to the heating element and configured to control switching and adjust the heating capacity of the corresponding heating element based on an air-leaving temperature to be maintained downstream of the heating module or the heater assembly.
The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, features, and techniques of the invention will become more apparent from the following description taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a further understanding of the subject disclosure of this invention and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the subject disclosure and, together with the description, serve to explain the principles of the subject disclosure.
In the drawings, similar components and/or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label with a second label that distinguishes among the similar components. If only the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label.

FIG. 1 illustrates an exemplary schematic representation of an air handling unit with a heater assembly comprising stackable heating modules.
FIGs. 2A and 2B illustrate exemplary representations of an embodiment of one of the heating modules associated with the AHU of FIG. 1.
FIGs. 3A and 3B illustrate exemplary representations of another embodiment of one of the heating modules associated with the AHU of FIG. 1.

DETAILED DESCRIPTION

The following is a detailed description of embodiments of the disclosure depicted in the accompanying drawings. The embodiments are in such detail as to clearly communicate the disclosure. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the subject disclosure as defined by the appended claims.
Various terms are used herein. To the extent a term used in a claim is not defined below, it should be given the broadest definition persons in the pertinent art have given that term as reflected in printed publications and issued patents at the time of filing.
In the specification, reference may be made to the spatial relationships between various components and to the spatial orientation of various aspects of components as the devices are depicted in the attached drawings. However, as will be recognized by those skilled in the art after a complete reading of the subject disclosure, the components of this invention described herein may be positioned in any desired orientation. Thus, the use of terms such as "above," "below," "upper," "lower," "first," "second" or other like terms to describe a spatial relationship between various components or to describe the spatial orientation of aspects of such components should be understood to describe a relative relationship between the components or a spatial orientation of aspects of such components.
Air handling unit (AHU) associated with heating, ventilation, and air conditioning (HVAC) systems may be integrated with mixed airflow blowers to achieve a combination of airflow patterns. However, optimization and efficiency issues may arise when the AHU is paired with a supplemental heating module involving conventional heating elements. Traditionally, rod-style heating elements, often configured in 4 or 6 pass designs may be employed in the heating module. These elements may be designed to heat air directly as it passes over them, relying on a straightforward, linear airflow for effective heat transfer.
The effectiveness of the AHU is predicated on the ability of the heating element to uniformly transfer heat to the air moving over its surface. The mixed airflow blower has introduced a complex, non-linear airflow pattern that may not be well-matched with the simple, linear design of traditional rod-style heating elements. This mismatch may lead to several problems that may undermine the performance and efficiency of the AHU or the heating module. Primarily, the incompatibility between the heating elements and the airflow patterns may result in inefficient heat transfer. This inefficiency may manifest as uneven heating, with certain areas receiving less heat than intended, and the creation of hot spots within the HVAC unit and the associated ductwork. These hot spots may not only be a sign of energy waste but may also pose a risk to the reliability and lifespan of the system by potentially damaging the heating elements and other components through excessive thermal stress. In addition, the heating capacity of the supplemental heating module associated with the existing AHU is also limited, providing a limited range of air heating capabilities.
There is, therefore, a need to overcome the above-mentioned limitations and drawbacks, by providing an improved heating solution in air handling units which aligns with the airflow characteristics of the air flowing through the AHU to ensure efficient and evenly distributed heating of the air, and also provide a wide range of heating capacity.
Referring to FIG. 1, an air handling unit (AHU) 100 for use with an air conditioning system (not shown in figures) is disclosed. The AHU 100 may include a housing duct 102 fluidically coupling an inlet 102-1 and an outlet 102-2. Air may be moved through the housing duct 102 from the inlet 102-1 to the outlet 102-2 along direction 112 of the flow of air.
In one or more embodiments, the AHU 100 may further include a heat exchanger 104. The heat exchanger 104 may be disposed within the housing duct 102 along a direction 112 of the flow of the air, such that the air flowing through the housing duct 102 further flows through the heat exchanger 104. The heat exchanger 104 may be configured to facilitate the transfer of heat to and from the air moving through the housing duct 102. In some embodiments, the heat exchanger 104 may be configured to cool the air moving through the housing duct 102. In some other embodiments, the heat exchanger 104 may be configured to heat the air moving through the housing duct 102. In some embodiments, the heat exchanger 104 may include a primary heat exchanger 104 and other heat transfer devices (not shown). In some embodiments, the heat exchanger 104 may be a ducted fan coil unit (FCU). In some embodiments, the heat exchanger 104 may further be coupled with a humidifier to facilitate the air passing through the heat exchanger 104 to include predefined levels of moisture.
In some embodiments, the AHU 100 may further include a supplemental heater assembly 106. In some embodiments, the supplemental heater assembly 106 may be disposed within the housing duct 102, along the direction 112 of the flow of the air, such that the air flowing through the housing duct 102 flows through the heater assembly 106 and the heat exchanger 104, as shown in FIG. 1. The supplemental heater assembly 106 may be configured to heat the air passing through the housing duct 102. In some embodiments, the supplemental heater assembly 106 and the heat exchanger 104 may together be configured to heat the air and regulate the heated air temperature, respectively, that is flowing through the housing duct 102.
The AHU 100 may further include a blower 108 or a fan disposed inside the housing duct 102. In one or more embodiments, the blower 108 may be a mixed airflow blower 108 but is not limited to the like. The blower 108 may be configured to move the air through the housing duct 102, from the inlet 102-1 to the outlet 102-2. In some embodiments, the blower 108 may include an impeller operable by a motor. The motor may be a direct-drive motor. The motor may be operable with continuous speed control. The motor may be communicably coupled to the HVAC controls of an air conditioning unit. As the blower 108 rotates, it may pull in air through the inlet 102-1 and blow the air through the blower 108 and towards the outlet 102-2 through the housing duct 102. The blower 108 may have an axis of rotation that is in-line with the direction 112 of the flow of the air through the housing duct 102.
In some embodiments, the blower 108 may be positioned downstream relative to the heat exchanger 104. However, in some other embodiments, the blower 108 may be positioned upstream relative to the heat exchanger 104. In the illustrated embodiment of FIG. 1, the blower 108 is positioned downstream relative to the heat exchanger 104. Further, in the illustrated embodiment of FIG. 1, the blower 108 is positioned upstream relative to the supplemental heater assembly 106. However, in some other embodiments, the blower 108 may be positioned downstream relative to the supplemental heater assembly 106 without any limitation. Furthermore, in one or more embodiments, the heat exchanger 104 may be substantially V-shaped relative to the direction 112 of the flow of the air through the housing duct 102. However, in some other embodiments, the heat exchanger 104 may have any other configurations as well without any limitations and all such embodiments are well within the scope of the subject disclosure.
In one or more embodiments, the heater assembly 106 may be coaxially disposed within the housing duct 102 (about an axis A-A'), along the direction 112 of flow of the air, such that the air downstream of the blower 108 flows through the heater assembly 106, as shown in FIG. 1. In one or more embodiments, the heater assembly 106 may include a plurality of heating modules 106-1 to 106-N (collectively referred to as heating module, herein), each configured to be coaxially stacked over each other along a direction 112 of the airflow within the housing duct 102.
Referring to FIGs. 2A to 3B, in one or more embodiments, each of the heating modules 106 may include a frame 202 formed by a mesh of rods 202-1 to 202-3. The frame 202 may be configured to be removably disposed inside the housing duct 102. The heating module 106-1 to 106-N may further include a heating element 204 of a predefined shape and a predefined heating capacity, removably attached to and supported on the frame 202 such that the heating element 204 remains coaxially disposed inside the housing duct 102 upon coaxially positioning the heating module within the housing duct 102. The predefined shape of the heating element 204 associated with the heating modules may be selected based on an airflow pattern of the air (downstream of the blower 108) flowing through the heating modules such that the air flows through the heating element 204 of the heating modules, which may improve thermal interaction between the flowing air and the heating element 204s. Further, in one or more embodiments, the heating element 204 may have variable heating capacity, however, in other embodiments, the heating element 204 may also have a fixed heating capacity.
In one or more embodiments, as shown in FIGs. 2A and 2B, the heating element 204 of the heating module 106-1 to 106-N may have a substantially circular ring-shaped profile. Further, the ring-shaped heating element 204 may have a predefined inner radius and predefined thickness based on the airflow pattern of the air flowing through the respective heating module, such that the air (downstream of the blower 108) flows through the heating element 204. The heating element 204 may be formed by an angular spiral wound electrical wire of a predefined resistance based on the predefined heating capacity. Further, in one or more embodiments, multiple such spiral wound wires may be coaxially disposed along the same plane with a predefined gap therebetween to form the ring-shaped heating element 204.
In one or more embodiments, the radius and/or thickness of the heating element 204 associated with each of the heating modules 106-1 to 106-N in the heater assembly 106 may be different. Further, in some embodiments, the radius and/or thickness of the heating element 204 associated with at least two heating modules among the plurality of heating modules 106-1 to 106-N may be different. However, in other embodiments, the radius and/or thickness of the heating element 204 associated with each of the heating modules 106-1 to 106-N may also be the same, while the heating capacity of the heating modules 106-1 to 106-N may be different. It is to be appreciated by a person skilled in the art that the radius (same or different) of the heating element 204 associated with the heating modules 106-1 to 106-N is selected based on the airflow pattern of the air (downstream of the blower 108) flowing through the heating module 106-1 to 106-N, as a result, the major portion of the air downstream of the blower 108 may flow through the heating element 204 of the heating modules 106-1 to 106-N, which may improve thermal interaction between the flowing air and the heating element 204.
In one or more embodiments, the radius and/or thickness of the heating element 204 associated with each of the heating modules 106-1 to 106-N may decrease while moving downstream of the heater assembly 106. For instance, the radius and/or thickness of the heating element 204 associated with the heating module 106-1 may be more than that of the heating module 106-2, and the radius and/or thickness of the heating element 204 associated with the heating module 106-2 may be more than that of the heating module 106-3. However, in other embodiments, the radius and/or thickness of the heating element 204 associated with each of the heating modules 106-1 to 106-N may also increase while moving downstream of the heater assembly 106.
In one or more embodiments, as shown in FIGs. 3A and 3B, the heating element 204 of the heating module 106-1 to 106-N may have a linear shape having one or more passes or turns. For instance, but not limited to the like, the heating element 204 may have a linear shape comprising six passes as shown in FIG. 3A or four passes as shown in FIG. 3B. This heating element 204 may be formed by an angular spiral wound electrical wire of a predefined resistance having a typically linear shape, which may be turned or folded to define the passes and turns. Further, in one or more embodiments, an overall area of such heating element 204 may have a circular profile or other profile based on the airflow pattern of the air flowing through the respective heating module, such that the air (downstream of the blower 108) flows through the heating element 204.
Referring back to FIGs. 1 to 3B, in one or more embodiments, the heating capacity of the heating element 204 associated with each of the heating modules 106-1 to 106-N may be different. Further, in some embodiments, the heating capacity of the heating element 204 associated with at least two heating modules among the plurality of heating modules 106-1 to 106-N may be different. However, in other embodiments, the heating capacity of the heating element 204 associated with each of the heating modules 106-1 to 106-N may also be the same.
In one or more embodiments, the heating capacity of the heating element 204 associated with each of the heating modules 106-1 to 106-N may decrease while moving downstream of the heater assembly 106. For instance, the heating capacity of the heating element 204 associated with the heating modules 106-1 may be more than that of the heating module 106-2, and the heating capacity of the heating element 204 associated with the heating module 106-2 may be more than that of the heating module 106-3. However, in other embodiments, the heating capacity of the heating element 204 associated with each of the heating modules may also increase while moving downstream of the heater assembly 106.
Thus, the use of different heating modules 106-1 to 106-N having the same or different heating capacity may allow the heater assembly 106 to provide a wide range of heating capacity. Further, the heating modules 106-1 to 106-N may be accordingly switched and their heating capacity may also be adjusted to maintain the temperature of the corresponding heating elements 204 at a first predefined temperature and/or maintain the temperature of the air leaving the heating assembly 106 at a second predefined temperature, which may be further supplied out of the AHU 100 via the outlet 102-2 of the housing duct 102.
For instance, in a non-limiting example, a first heating module 106-1 of the heater assembly 106 may have a heating capacity of 10KW, a second heating module 106-2 of the heater assembly 106 may have a heating capacity of 3KW, and a third heating module 106-N of the heater assembly 106 may have a heating capacity of 1KW. Accordingly, the overall heater assembly 106 may provide a wide range of heating capacity ranging from 1KW to 14KW. Further, based on the heating modules being switched, the overall heater assembly 106 may provide heating capacities of 1KW, 3KW, 4KW, 5KW, 8KW, 10KW, 12KW, 15KW, 18KW, 20KW, and 25KW.
In another non-limiting embodiment, a first heating module 106-1 of the heater assembly 106 may have a variable heating capacity ranging from 5 to 10KW, a second heating module of the heater assembly 106 may have a heating capacity of 3KW, and a third heating module of the heater assembly 106 may have a heating capacity of 1 KW. Accordingly, the overall heater assembly 106 may provide a wide range of heating capacity ranging from 1KW to 14KW. However, based on the heating modules being switched, the overall heater assembly 106 may provide heating capacities of 1KW, 3KW, 4KW, 5KW, 8KW, 10KW, 12KW, 15KW, 18KW, 20KW, and 25KW.
In one or more embodiments, the heating element 204 may be supported on the frame 202 using one or more thermally and electrically insulative devices 206 to electrically and thermally isolate the frame 202 from the heating element 204. In one or more embodiments, the heating element 204 may be supported on the frame 202 using one or more ceramic holders 206 (also referred to as ceramic guides 206, herein) to electrically and thermally isolate the frame 202 from the heating element 204. Further, in some embodiments, the frame 202 may also be made of an electrically and thermally insulative material.
In one or more embodiments, the frame 202 may include a set of rods 202-1 to 202-3 arranged parallelly, orthogonally, and/or diagonally to each other along a plane to form the mesh of rods defining the shape of the frame 202. The rods 202-1 to 202-3 may be arranged to define the frame 202 based on an inner profile of the housing duct 102 such that an outer profile of the frame 202 allows the frame 202 or the heating modules to be coaxially fitted within the housing duct 102 without any hindrance.
In one or more embodiments, as shown in FIGs. 2A and 2B, the frame 202 may include a first set of rods 202-1 arranged parallelly to each other along a plane, a second set of rods 202-2 arranged orthogonally to the first set of rods 202-1, and a third set of rods 202-3 arranged diagonally with respect to the first and second set of rods 202-1, 202-2 to form the mesh of rods defining the shape of the frame 202. Further, these rods 202-1 to 202-3 may remain in contact via the ceramic holders or ceramic guides 206. Accordingly, the formed mesh or the frame 202 may have an outer profile based on the inner profile of the housing duct 102, allowing the frame 202 or the heating modules to be coaxially fitted within the housing duct 102 without any hindrance. However, in other embodiments, the rods 202-1 to 202-3 may be arranged in other fashions as well without any limitations to define the frame 202, as long as the frame 202 allows installation of the heating element 204 thereon and further allows installation of the frame 202 or heating modules coaxially within the duct 102 without any hindrance. Further, the parallelly arranged set of rods (or the first set of rods 202-1) may extend between opposite inner walls of the housing duct 102 to support and help secure the frame 202 or heating modules within the housing duct 102.
In addition, in one or more embodiments, the frame 202 may include a first support plate 208-1 connecting the first end of each of the first set of rods 202-1 and a second support plate 208-2 connecting the second end of each of the first set of rods 202-1. The first support plate 208-1 and the second support plate 208-2 may be configured to be removably attached to opposite inner walls of the housing duct 102, allowing the heating modules 106-1 to 106-N to be secured within the housing duct 102. However, in some embodiments, the frame 202 may only include the first support plate 208-1 connecting the first end of each of the first set of rods 202-1. In such embodiments, the first support plate 208-1 may be configured to be removably attached to an inner wall of the housing duct 102 and the second end of each of the first set of rods 208-1 may be configured to be removably attached to another wall, opposite to the first support plate 208-1, of the housing duct 102. Furthermore, in other embodiments (not shown), the frame 202 may include four support plates being connected in a substantially square or rectangular shape, with the rods extending between opposite plates and the heating element 204 supported on the rods 202-1 to 202-3. In such embodiments, the support plates may be configured to be removably attached to the inner walls of the housing duct 102.
In some embodiments, the AHU 100 may further include a packaged rooftop air management system that may be communicably coupled to the different components of the AHU 100, including, without limitations, the heat exchanger 104, the heating modules, the blower 108, and the motor. The AHU 100 may be implemented by a controller 110 configured to control the operations of the different components of the AHU 100 and control the heating modules. The controller 110 may include one or more processors coupled to a memory storing instructions executable by the processors, which may cause the controller 110 to perform the designated operations.
In one or more embodiments, electrical terminals 204-1 of the heating elements 204 may extend through the first support plate 208-1 and/or the support second plate 208-2 to allow the electrical connection of the heating modules to the controller 110 and a power source associated with the AHU 100. In such embodiments, slots may be formed in any of the support plates to allow extension of the terminals 204-1 therethrough. In addition, an insulator 210 may be configured between the electrical terminals 204-1 and the support plate(s) 208 to electrically and thermally isolate the electrical terminals 204-1 from the duct 102 as well as the frame 202. Further, in one or more embodiments, the controller 110 may be part of each of the heating module 106-1 to 106-N where the controller 110 may be removably secured on any of the support plates 208-1 or 208-2 associated with the heating module 106-1 to 106-N, thereby forming a stackable heating module 200A as shown in FIG> 2B which can be stacked and easily removably configured within the housing duct 102 of any AHU 100. Further, in some embodiments, the controller 110 may be a part of the HVAC controls of the air conditioning system as well.
Thus, this invention provides an improved heating solution in AHUs by providing the heater assembly having stackable heating modules that comprise a heating element having a shape/design based on the airflow characteristics of the air flowing through the AHU. This improves the thermal interaction between the air and the heating element, thereby ensuring efficient and evenly distributed heating of the air downstream of the blower/fan. As a result, the use of different heating modules having the same or different heating capacities may allow the heater assembly to provide a wide range of heating capacities. This may help control the temperature of the corresponding heating elements and/or further control and vary the temperature of the air leaving the heating elements.
In addition, the heating modules have a modular, stackable, and shock-proof design that may allow technicians to easily stack and install the heating modules within or remove the heating modules from the housing duct associated with existing AHUs. Moreover, the shock-proof and thermally safe design allows the heating modules to safely operate within the AHU without affecting the other components of the AHU.
While the invention has been described with reference to exemplary 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 invention as defined by the appended claims. Modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed, but that the invention includes all embodiments falling within the scope of the invention as defined by the appended claims.
In interpreting the specification, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms "comprises" and "comprising" should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced. Where the specification claims refer to at least one of something selected from the group consisting of A, B, C ....and N, the text should be interpreted as requiring only one element from the group, not A plus N, or B plus N, etc.

Claims

An air handling unit (100) for use with an air conditioning system, the air handling unit comprising:
a housing duct (102) through which air is moved from an inlet (102-1) to an outlet (102-2);

a blower (108) disposed inside the housing duct, configured for moving air within the housing duct; and

a heater assembly (106) comprising a plurality of heating modules (106-1 - 106-N) coaxially stacked over each other along a direction of the airflow, the heater assembly coaxially disposed inside the housing duct along a direction of flow of the air, wherein each of the heating modules comprises:
a frame (202) formed by a mesh of rods (202-1 - 202-3), the frame configured to be removably disposed inside the housing duct; and

a heating element (204) of a predefined shape and a predefined heating capacity, removably attached to and supported on the frame, wherein the predefined shape is selected based on an airflow pattern of the air flowing through the respective heating module such that the air flows through the corresponding heating element.
The air handling unit of claim 1, wherein the heating modules are disposed downstream of the blower.
The air handling unit of any one of claims 1 and 2, wherein the blower is a mixed airflow blower.
The air handling unit of any one of claims 1 to 3, wherein the heating element associated with each of the heating modules is supported on the frame using one or more thermally and electrically insulative devices (206) to electrically and thermally isolate the frame from the heating element, and wherein the frame is made of an electrically and thermally insulative material.
The air handling unit of any one of claims 1 to 4, wherein the frame comprises a set of rods arranged parallelly, orthogonally, and/or diagonally to each other along a plane to form the mesh of rods defining the shape of the frame, wherein the formed mesh or the frame has an outer profile based on an inner profile of the housing duct.
The air handling unit of any one of claims 1 to 5, wherein the heating element has a substantially circular ring-shaped profile, wherein the ring-shaped heating element has a predefined inner radius and predefined thickness based on the airflow pattern of the air flowing through the respective heating module.
The air handling unit of claim 6, wherein the radius and/or thickness of the heating element associated with at least two heating modules among the plurality of heating modules is different,
optionally wherein the radius and/or thickness of the heating element associated with each of the heating modules is different; and/or

optionally wherein the radius and/or thickness of the heating element associated with each of the heating modules decreases while moving downstream of the heater assembly.
The air handling unit of claim 6, wherein the radius and/or thickness of the heating element associated with each of the heating modules is same.
The air handling unit of any one of claims 1 to 5, wherein the heating element has a linear shape comprising one or more passes and turns.
The air handling unit of claim 9, wherein an area of the linear shaped heater is circular or based on the airflow pattern of the air flowing through the respective heating module,
The air handling unit of any one of claims 1 to 10, wherein the heating capacity of the heating element associated with at least two heating modules among the plurality of heating modules is different,
optionally wherein the heating capacity of the heating element associated with each of the heating modules is different, and/or

optionally wherein the heating capacity of the heating element associated with each of the heating modules decreases while moving downstream of the heater assembly.
The air handling unit of any one of claims 1 to 10, wherein the heating capacity of the heating element associated with each of the heating modules is same, or wherein the heating capacity of the heating element associated with at least one of the heating modules of the heater assembly is variable.
The air handling unit of any one of claims 1 to 12, wherein the heating element is formed by an angular spiral wound electrical wire of a predefined resistance.
The air handling unit of any one of claims 1 to 13, wherein the frame comprises at least one support plate (208-1 - 208-2) connecting at least one end of each of the first set of rods, wherein the at least one support plate is configured to be removably attached to an inner wall of the housing duct to secure the corresponding heating module within the housing duct, wherein electrical terminals (204-1) of the heating element extends through the at least one plate and an insulator is configured between the electrical terminals and the corresponding support plate.
The air handling unit of any one of claims 1 to 14, wherein each of the heating modules comprises a controller (110) operatively connected to the heating element and configured to control switching and adjust the heating capacity of the corresponding heating element based on an air leaving temperature to be maintained downstream of the heating module or the heater assembly.