Patent Application
20220235944
The present disclosure relates generally to heat pump systems and, in particular, to air flow paths for heat pump systems.
Decreasing the energy consumption of water heaters can have a large impact on the energy usage of an overall household or other building. Some studies have found the water heater to be the second-most energy consuming appliance in a typical household, trailing only the heating and air conditioning system in the home. Particularly in heat pump water heater systems, increasing the heat transfer coefficient of the heat exchangers is desirable because increased efficiency of the heat pump will lead to increased efficiency of the overall water heater. When ambient air enters the heat pump to exchange heat with a thermal working fluid, a large portion of the heat transfer efficiency can be lost due to maldistribution of air (e.g., uneven distribution of air across the heat exchanger). Air recirculation and general turbulent flow can reduce the contact area of the heat exchanger that is available for heat transfer, thus reducing the heat transfer coefficient and efficiency of the system.
What is needed, therefore, are heat pump units that improve the quality and the volume of a flow of ambient air entering the heat pump to improve the heat transfer coefficient of the heat pump. The present disclosure addresses this need as well as other needs that will become apparent upon reading the description below in conjunction with the drawings.
The present disclosure relates generally to heat pump systems and, in particular, to air flow paths for heat pump systems.
The disclosed technology can include a heat pump system for a water heater. The heat pump system can comprise a housing defining an interior chamber, an air inlet, an air outlet, and an evaporator unit within the interior chamber. Air entering the interior chamber can transfer heat to the evaporator unit before flowing out of the air outlet. The air inlet can be included in a top pan which defines a top side of the interior chamber. The top pan can be configured to engage a top end of the heat pump system. The air outlet can be positioned on a side of the heat pump system. The air outlet can be configured such that an air flow path extends between the air inlet and the air outlet. The evaporator unit can be positioned in the air flow path, thereby creating a cross flow across the evaporator unit. The air flow path can be reversible, such that the air inlet is positioned on a side of the heat pump system and the air outlet is positioned on a top side of the interior chamber.
The heat pump system can also include a flue pipe positioned in the air flow path. The flue pipe cross-section can have a leading edge, a trailing edge, and a central portion between the leading edge and the trailing edge. A width of the leading edge can be less than or equal to a width of the central portion. The flue pipe can have an elliptical cross-section, wherein a major axis of the elliptical cross-section is parallel to the air flow path. The interior chamber can also be partitioned into a first interior chamber and a second interior chamber being fluidly separated, and the flue pipe can be positioned in the second interior chamber separate from the air flow path in the first interior chamber.
The heat pump system can also comprise side baffles positioned between the evaporator unit and the housing. Each of the side baffles can be disposed at an angle such that the side baffles direct the air flow path to the evaporator unit. Alternatively, or additionally, the air inlet can be a first air inlet and the housing can further comprise a second air inlet in fluid communication with the air flow path. The second air inlet can be positioned proximate to one of the side baffles to encourage air flow from the second air inlet to the air flow path.
The heat pump system can further include a curved elbow attached to the air inlet to direct the air flowing therethrough to the evaporator unit.
The disclosed technology can also include heat pump systems comprising a housing. The housing can have an internal volume and a partition defining a first interior chamber and a second interior chamber within the internal volume. The first interior chamber and the second interior chamber can be fluidly separated. The first interior chamber can also have an air inlet, and air outlet, and an air flow path extending therebetween. The heat pump system can also include an evaporator unit positioned at least partially in the air flow path in the first interior chamber. The evaporator unit can be curved thereby increasing a surface area of the evaporator unit exposed to the air flow path. The evaporator unit can be concave relative to the air flow path.
The disclosed heat pump systems can also comprise a condenser unit, a compressor, and a thermal expansion valve, all of which can form a fluid circuit. The fluid circuit can flow a heat transfer fluid therethrough.
These and other aspects of the present disclosure are described in the Detailed Description below and the accompanying figures. Other aspects and features of examples of the present disclosure will become apparent to those of ordinary skill in the art upon reviewing the following description of specific examples of the present disclosure in concert with the figures. While features of the present disclosure may be discussed relative to certain examples and figures, all examples of the present disclosure can include one or more of the features discussed herein. Further, while one or more examples may be discussed as having certain advantageous features, one or more of such features may also be used with the various examples of the disclosure discussed herein. In similar fashion, while examples may be discussed below as device, system, or method examples, it is to be understood that such examples can be implemented in various devices, systems, and methods of the present disclosure.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate multiple examples of the presently disclosed subject matter and serve to explain the principles of the presently disclosed subject matter. The drawings are not intended to limit the scope of the presently disclosed subject matter in any manner.
As described above, a problem with current water heaters is that ambient air flowing through heat pump systems, such as in the evaporator unit, is not evenly distributed across the heat exchanger. The fluid dynamics of current air flow paths tend to cause turbulent and/or obstructed flow, air recirculation, vortices, and other disruptive flow patterns. As a result, the amount of air contacting the heat pump working fluid is typically uneven, ineffective, or both. This can reduce the heat transfer coefficient of the heat exchanger and the overall efficiency of the heat pump, causing the system to waste additional time and energy to provide the necessary heat transfer.
Disclosed herein are heat pump systems comprising a housing defining an interior chamber, an air flow path extending through the interior chamber from an air inlet to an air outlet, and a heat exchanger (e.g., an evaporator unit) positioned in the air flow path. The heat exchanger can interact with the air flowing through the air flow path and across the heat exchanger to conduct a heat exchange between the air and a thermal working fluid flowing through an internal portion of the heat exchanger. If a flue pipe is also positioned in the air flow path, the flue pipe can have a shape (e.g., elliptical shape) to improve the aerodynamic flow around the flue pipe (e.g., a foil). The heat pump system can include side baffles to angle and direct air flow toward the heat exchanger, and/or the air inlet can include or be located proximate a curved elbow for similar reasons. Alternatively or in addition, the interior chamber can include one or more secondary air inlets leading into the air flow path to increase the air flow rate through the heat pump systems. These secondary air inlets can be located on or near the side baffles. Optionally, the air flow path can be partitioned away from other components of the heat pump system (e.g., the flue pipe) so that there are no obstructions in the air flow path (or a limited or reduced number thereof). The air inlet can be positioned on a top of the interior chamber, and the air outlet can be positioned on a side of the interior chamber, or vice versa.
While the present disclosure is described relating to heat pump systems for water heaters and evaporators for heat pump systems, it is understood that the technology described herein is not so limited. Indeed, unless otherwise explicitly stated, the present disclosure can be used in conjunction with any heat transfer unit configured to transfer latent heat (e.g., an evaporator or a condenser), sensible heat (a heat exchanger, a heater, or a chiller), or both from air to another working fluid. Additionally, unless otherwise explicitly stated, the present disclosure is not limited to use in water heating applications and can be used in heat pumps for any application.
Although certain examples of the disclosure are explained in detail, it is to be understood that other examples and applications are contemplated. Accordingly, it is not intended that the disclosure is limited in its scope to the details of construction and arrangement of components set forth in the following description or illustrated in the drawings. Other examples of the disclosure are capable of being practiced or carried out in various ways. Also, in describing the disclosed technology, specific terminology will be resorted to for the sake of clarity. It is intended that each term contemplates its broadest meaning as understood by those skilled in the art and includes all technical equivalents which operate in a similar manner to accomplish a similar purpose.
Herein, the use of terms such as “having,” “has,” “including,” or “includes” are open-ended and are intended to have the same meaning as terms such as “comprising” or “comprises” and not preclude the presence of other structure, material, or acts. Similarly, though the use of terms such as “can” or “may” are intended to be open-ended and to reflect that structure, material, or acts are not necessary, the failure to use such terms is not intended to reflect that structure, material, or acts are essential. To the extent that structure, material, or acts are presently considered to be essential, they are identified as such.
By “comprising” or “containing” or “including” is meant that at least the named compound, element, particle, or method step is present in the composition or article or method, but does not exclude the presence of other compounds, materials, particles, method steps, even if the other such compounds, material, particles, method steps have the same function as what is named.
It is also to be understood that the mention of one or more method steps does not preclude the presence of additional method steps or intervening method steps between those steps expressly identified.
The components described hereinafter as making up various elements of the disclosure are intended to be illustrative and not restrictive. Many suitable components that would perform the same or similar functions as the components described herein are intended to be embraced within the scope of the disclosure. Such other components not described herein can include, but are not limited to, for example, similar components that are developed after development of the presently disclosed subject matter.
Reference will now be made in detail to examples of the disclosed technology, some of which are illustrated in the accompanying drawings. Wherever convenient, the same references numbers will be used throughout the drawings to refer to the same or like parts.
The heat pump system 100 can have an air inlet 140 which can be an aperture in the housing 110 allowing air to flow from the external environment into the interior chamber 120. The evaporator assembly 100 can also include an air outlet 150, which can be another aperture in the housing 110 allowing air to flow out of the interior chamber 120. The air outlet 150 can guide egress of the air back to the external environment or into another chamber, another component of the water heater, or some other location.
The air inlet 140 can be positioned on a top side of the heat pump system 100, as shown. Such a top side can be referred to as a “top pan” that engages the heat pump system 100. The top pan can also define the top side of the interior chamber 120 (or a portion thereof) if the top side is not already defined by the housing 110. The air outlet 150 can be positioned on a side of the heat pump system 100, as shown. Alternatively, the air inlet 140 can be positioned on a side of the heat pump system 100, and the air outlet can be positioned on a top side of the heat pump system; in such a manner, the air flow from the air inlet 140 to the air outlet 150 can be reversed.
The air inlet 140 and the air outlet 150 can form an air flow path 160 extending therebetween along which air entering the heat pump system 100 flows from the air inlet 140 to the air outlet 150. The evaporator unit 130 can be positioned within the air flow path 160 to ensure that flowing air contacts the evaporator unit 130 to transfer heat. Increasing the average velocity along the air flow path 160, and therefore across the heat exchanger, can increase the Reynolds number of the air in contact with the evaporator unit 130. Without wishing to be bound by any particular scientific theory, increasing the Reynolds number of the air in contact with the evaporator unit 130 can increase the heat transfer coefficient of the evaporator unit 130.
Alternatively, if the air along the air flow path 160 is disrupted or uneven, the Reynolds number will decrease, thus decreasing the heat transfer coefficient of the evaporator unit 130. While uneven flow may result in higher local air velocities in certain locations along the evaporator unit 130, due to turbulence and air recirculation, others locations along the evaporator unit 130 can receive very little air flow and/or air flow having a low local air velocity, resulting in the total average air velocity along the evaporator unit 130 being lower than the higher local air velocities. Thus, there is an opportunity for improvement in the heat transferability of evaporator units in heat pumps. It is desirable to improve the air velocity distribution to thereby increase the Reynolds number of the air contacting the evaporator unit, as shown in Equation 1:
where Re is the Reynolds number, ρ is the fluid density, u is the fluid flow speed, L is the characteristic length, μ is the dynamic viscosity of the fluid, and v is the kinematic viscosity of the fluid.
Consequently, because the average heat transfer coefficient also has a proportional relationship with the rate of heat transfer ({dot over (Q)}) as shown in Equation 2, it follows that increasing the Reynolds number of the air flow path 160 can also increase the rate of heat transfer of the evaporator unit 130.
({dot over (Q)})=hAΔT (2)
As shown, {dot over (Q)} represents the heat transfer rate, h represents the average heat transfer coefficient, and ΔT represents the temperature difference of the air between the air inlet 140 and the air outlet 150. Additionally, as illustrated by Equation 4, the rate of heat transfer of the evaporator unit 130 can also be increased by increasing the heat transfer area (A). The heat transfer area can decrease if the air flow path 160 comprises flow disruptions, such as recirculation or vortices.
As shown in the top-down view of
The flue pipe 210 can have other shapes, such as shapes that have a leading edge with a width that is less than a width of the central portion. Furthermore, such shapes can have a leading edge with a width that is equal to a width of the central portion. Alternatively or in addition, at least a portion of the flue pipe 210 can have a shape in which the length of that portion of the flue pipe (i.e., generally perpendicular to a central axis of the flue pipe and/or generally parallel to the air flow path) is greater than the width. Alternatively, or additionally, for at least a portion of the flue pipe, the length of the flue pipe cross section “L” can be greater than the width of the flue pipe “W” as shown in
As shown in
The side baffles 310 are depicted as being located at either (or both) of the lateral ends of the evaporator unit 130. For example, as shown, each of the side baffles 310 can be angled from an outer wall of the interior chamber 120 toward an edge of the evaporator unit 130 to help direct air flow toward the evaporator unit and eliminate dead and/or recirculation areas adjacent to the evaporator unit 130. However, it is understood that the side baffles 310 can be similarly positioned above and/or below the evaporator unit 130 and angled upward and/or downward from a top or bottom of the interior chamber 120 to further direct air flow toward the evaporator unit 130. Indeed, the side baffles 310 can be positioned at any desirable angle to direct air flow into the evaporator unit 130.
Additionally, even though the side baffles 310 are depicted as rectangular, it should be understood that the side baffles 310 can take on any suitable shape to improve air flow into the evaporator unit 130. Indeed, the side baffles 310 can include fins, ridges, scallops, and other similar contouring to encourage smooth air flow over the side baffles 310. Additionally, the side baffles 310 themselves can be curved, angled, triangular, scooped, and other geometries to encourage air flow toward the evaporator unit 130.
Furthermore, the heat pump system 100 can include a secondary air inlet 320 in addition to the air inlet 140. The secondary air inlet 320 can include one or more apertures in the housing 110 in any position suitable to feed additional air into the air flow path 160. The secondary air inlet 320 can be positioned along the air flow path 160 (e.g., on a sidewall of the housing 110 at a position along the air flow path 160), or the secondary air inlet 320 can be positioned along the side baffles 310. As would be appreciated, if the secondary air inlet 320 was not along the air flow path 160, the side baffles 310 can help encourage air flow from the secondary air inlet 320 into either the air flow path 160 or the evaporator unit 130.
While the secondary air inlet 320 is shown as being rectangular in cross-sectional shape in
Alternatively, or additionally, the air inlet 140 can have a curved elbow 330, as shown in
As shown in
The partition 410 can cause the interior chamber 120 and the second interior chamber 420 to be divided into a variety of shapes. For example, the partition 410 can divide the housing into two semicircles. Alternatively, the partition 420 can be curved in a U-shape such that the air flow path 160 in the first interior chamber 120 can bend around the second interior chamber 420, as shown in
In
Furthermore, as described in reference to
While the various designs in
While the present disclosure has been described in connection with a plurality of example aspects, as illustrated in the various figures and discussed above, it is understood that other similar aspects can be used, or modifications and additions can be made to the described aspects for performing the same function of the present disclosure without deviating therefrom. For example, in various aspects of the disclosure, methods and compositions were described according to aspects of the presently disclosed subject matter. However, other equivalent methods or composition to these described aspects are also contemplated by the teachings herein. Therefore, the present disclosure should not be limited to any single aspect, but rather construed in breadth and scope in accordance with the appended claims.
