Patent Application
20220099375
The present disclosure relates generally to heat exchangers and, in particular, to adjustable capacity heat exchangers.
Heat exchangers are widely used to transfer heat from one fluid to another, such as in heating, ventilation, and air conditioning (HVAC) applications. Typically, to heat or cool a target fluid, the target fluid is passed through the heat exchanger, which includes an array of heat exchanger tubes. To enhance heat transfer efficiency, fins are often installed along the heat exchanger tubes. A temperature-controlled fluid (e.g., heated, cooled) is passed through the heat exchanger tubes, and heat can thus be transferred between the target fluid and the temperature-controlled fluid via the heat exchanger tubes and the fins.
As a more specific example, air conditioners can utilize heat exchangers to provide cooled air for a building through the refrigeration cycle. A cold refrigerant is routed through the heat exchanger tubes of an evaporator. A blower or fan can be used to force ambient internal air to move across the heat exchanger, at which time heat is transferred from the warm internal air to the heat exchanger tubes and/or fins and from the heat exchanger tubes and/or fins to the flowing refrigerant.
Recently, there has been an increase in demand for air conditioning systems and other heat exchanging systems that have increased efficiency and versatility. Because many air conditioning systems have the ability to provide both heated and cooled air for a building, developments such as heat pump systems have greatly improved the efficiency, affordability, and versatility of existing air conditioning systems. Similarly, multi-speed air conditioning systems provide an increased level of efficiency and versatility over a wide range of temperatures.
A problem with heat pump systems, however, is that a refrigerant imbalance can be caused when there is a difference between an outdoor coil volume and an indoor coil volume. Moreover, for systems able to switch between a heating mode and a cooling mode, the necessary charge volume can change depending on the mode. That is, when switching between cooling and heating applications, refrigerant must be either added or taken away from the system to retain a proper heat exchange. To address this variance in charge required for operation, many systems include an additional component called a charge compensator, which is configured to store, or withdraw from circulation, an amount of refrigerant when the system is in heating mode and returning that amount of refrigerant back into circulation when the system is in cooling mode, or the opposite—withdrawing an amount of refrigerant from circulation when the system is in cooling mode and returning that amount of refrigerant back into circulation when the system is in heating mode—depending on the particular circumstances. Inclusion of the charge compensator can invite a host of problems, including the costs and inconvenience associated with purchasing, installing, and maintaining an additional device.
Additionally, most multi-speed systems are designed to operate at or near their capacity during high-speed operation, meaning that such systems are overdesigned for low and/or intermediate speed operation.
What is needed, therefore, are adjustable capacity heat exchanges that can have an increased efficiency when accommodating dissimilar outdoor and indoor volumes as well as variable speed operations. 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 exchangers and, in particular, to adjustable capacity heat exchangers. The disclosed technology can include a heat exchanger apparatus comprising a heat exchange tube configured to direct a refrigerant flow therethrough. The heat exchange tube can have an inlet valve, an outlet valve, and a tube portion being defined between the inlet valve and the outlet valve.
The heat exchanger apparatus can be configured to fluidly communicate with a refrigerant circuit. When the inlet valve and the outlet valve are open, the refrigerant flow can be permitted to flow through the tube portion such that the refrigerant circuit has a first amount of refrigerant circulating therethrough, and the heat exchanger apparatus can provide a first heat exchange surface area. When the inlet valve and the outlet valve are closed, the refrigerant flow can be prevented from flowing through the tube portion, and an amount of refrigerant can be stored in the tube portion such that the refrigerant circuit has a second amount of refrigerant circulating therethrough. The second amount can be less than the first amount, and the heat exchanger apparatus can provide a second heat exchange surface area that is less than the first heat exchange surface area.
The refrigerant flow can be permitted to flow through the tube portion when the inlet valve and the outlet valve are open. When the inlet valve and the outlet valve are closed, the refrigerant flow can be prevented from flowing through the tube portion. Closing the inlet valve and the outlet valve can reduce the effective heat exchange surface area of the heat exchanger apparatus. The heat exchange tube can further have an intermediate valve disposed at a position on the heat exchange tube that is between the inlet valve and the outlet valve. The intermediate valve can be a first intermediate valve and the bypass line can fluidly connect the first intermediate valve to the outlet valve via a second intermediate valve.
The heat exchange tube can include one or more hairpin bends, or the heat exchange tube can be in the form of a serpentine coil or a helical coil. The heat exchange tube can also have a predetermined length of line is between the inlet valve and the outlet valve, the predetermined length of line determining a predetermined amount of refrigerant to be stored in the heat exchange tube
The heat exchanger apparatus can include a first bypass line between the inlet valve and the outlet valve. The refrigerant flow can be routed through the bypass line when the inlet valve and the outlet valve are closed. The heat exchanger apparatus can also include a second bypass line fluidly connecting the intermediate valve to the outlet valve.
Also disclosed herein are heat exchangers comprising a plurality of heat exchange tubes. The plurality of heat exchange tubes can include a non-selectable heat exchange tube configured to permit a refrigerant to flow therethrough and a selectable heat exchange tube comprising a valve. The selectable heat exchange tube can be configured to permit the refrigerant to flow therethrough when the valve is open. The selectable heat exchange tube can be configured to prevent the refrigerant from flowing through at least a portion of the selectable heat exchange tube when the valve is closed, thereby reducing the effective heat exchange surface area of the heat exchanger. At least a portion of the selectable heat exchange tube can be configured to store a predetermined amount of refrigerant.
The valve can be located proximate an inlet of the selectable heat exchange tube. The valve can be a first valve and the selectable heat exchange tube can further comprise a second heat exchange tube located proximate an outlet of the selectable heat exchange tube. The valve can be located at a location on the selectable heat exchange tube that is between an inlet of the heat exchange tube and an outlet of the heat exchange tube.
The selectable heat exchange tube can further comprise a bypass line extending between the valve and a location nearer the outlet of the heat exchange tube than the inlet of the heat exchange tube. The valve can be a first valve, and the selectable heat exchange tube can further comprise a second valve located at the location nearer the outlet of the heat exchange tube than the inlet of the heat exchange tube.
Also disclosed herein are heat exchanger controllers comprising a processor and a memory. The memory can store instructions that, when executed by the processor, cause the heat exchanger controller to implement one or more methods disclosed herein.
The controller can receive a request to change an effective surface area of the heat exchanger apparatuses disclosed herein. The request can either be to decrease the effective heat exchange surface area or to increase the effective heat exchange surface area. Responsive to receiving the request to decrease the surface area, the controller can output instructions to transition the inlet valve and the outlet valve to a closed position thereby reducing the effective surface area of the heat exchanger. Responsive to receiving the request to increase the surface area, the controller can output instructions to transition the inlet valve and the outlet valve to an open position thereby increasing the effective surface area of the heat exchanger. The request can be indicative of one or more of: a change in temperature, a change in operating speed, or a change in operating mode.
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 air conditioning systems, particularly with heat pump systems, is that a refrigerant imbalance can be caused when there is a difference between an outdoor coil volume and an indoor coil volume. This can be caused because, in addition to volume differences, heat exchanger for multi-speed air conditioning systems are designed to operate at or near capacity during high-speed operation, with no method to correct the capacity during low-speed operation such that the heat exchangers are oversized for low-speed operation. Thus, a refrigerant imbalance can reduce system efficiency when switching between modes (e.g., from heating mode to cooling mode) and/or when switching between speeds (e.g., from low speed to high speed), which can ultimately increase operating costs for the user.
Disclosed herein, therefore, are heat exchanger apparatuses for use with HVAC systems. The heat exchangers can have multiple tubes through which refrigerant (or another working fluid) can flow, and the refrigerant can be used to exchange heat with air passing over the tubes. An inlet valve and an outlet valve can be attached to the tubes, with a bypass line passing therebetween, in order to partition a portion of the heat exchanger's tubes. As such, when the valves are closed, the refrigerant can flow through the bypass line and the heat exchange area can be reduced. Additionally, when the valves are opened, the refrigerant can flow through the partitioned tubes to increase the heat exchange area. In such a manner, the valves can afford a controller, or a user, additional control measures over the heat exchanger.
Additionally, the dynamically configurable tubing in the heat exchanger can act as a charge compensator by selectively storing refrigerant in partitioned tubes, removing the need for an external charge compensator component. Moreover, the disclosed technology provides an additional improvement over traditional charge compensators. Typically, conventional charge compensators are used only to adjust the active charge (i.e., refrigerant in circulation). In contrast, the disclosed technology can both adjust the active charge and change the heat transfer surface area by removing excess tubing from the active refrigerant circuit.
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.
While the examples illustrated and described herein are described relating to using a refrigerant as the working fluid in a heat exchanger, it is understood that any practical working fluid can be used to conduct a heat exchange. For example, combustion gases can flow through the heat exchanger when the ambient air in contact with the heat exchanger needs to be increased. Additionally, the term “refrigerant” can include any single phase heat transfer fluid, such as those designated as such by, and compliant with, the standards, rules, and regulations set forth by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) (e.g., ASHRAE Standard 34-2019). Other examples of refrigerants—which may or may not have a refrigerant designation per ANSI/ASHRAE-34-2019—can include any glycol (and water glycol mixtures), alcohol/water mixtures, and other natural and/or synthetic heat transfer fluids.
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.
Referring to
The first heat exchanger tube 110 can have an inlet valve 112 through which fluid can enter the heat exchanger apparatus 100 and an outlet valve 122 through which fluid can exit the heat exchanger apparatus. The heat exchanger apparatus 100 can have multiple similarly configured tubes to improve the efficiency of the heat exchange. Any number of tubes can be controlled by the inlet valve 112 and the outlet valve 122, such as the first heat exchanger tube 110 and the second heat exchanger tube 120. The inlet valve 112 and the outlet valve 122 can be placed such that fluid can pass through any number of heat exchanger tubes. For greater control, each heat exchanger tube can have its own inlet valve and outlet valve. In such a manner, the amount of tubes participating in the heat exchange can be varied, and the amount of refrigerant stored in inactive tubes can be altered.
The amount of refrigerant stored can be determined by the number of tubes 110, 120 outfitted with valves 112, 122 and the number of tubes 110, 120 that are removed from the refrigerant circuit by the valves 112, 122. For example, if the second heat exchanger tube 120, or a third heat exchanger tube (or any number of tubes), has an inlet valve 112 and an outlet valve 122, a greater amount of refrigerant can be stored within the tubes, which can correspond to a greater decrease in the effective heat exchange area of the heat exchanger apparatus 100. The amount of refrigerant can be altered based on the number of tubes 110, 120 that are removed from the refrigerant circuit.
The heat exchanger apparatus 100 can also be in the form of a singular tube 115, such as a coil, having multiple bend sections. The tube 115 or coil can be in a serpentine configuration, as depicted in
As shown in
That being said, an amount of refrigerant can be removed from circulation and stored in the tubing 115, even without the optional third valve. For example, the configuration illustrated in
When closed, the inlet valve 112 and the outlet valve 122 can store an amount of refrigerant in the portion of the tube 115 located between the inlet valve 112 and the outlet valve 122, thereby reducing the amount of the tube 115 that is able to provide heat transfer. Closing the inlet valve 112 and the outlet valve 122 can also cause the refrigerant to flow through the bypass line 130. When open, the inlet valve 112 and the outlet valve 122 can cause the refrigerant to flow through the first heat exchanger tube 110 and any additional predetermined length of tubing therebetween. For example, the refrigerant can flow through two or more bends in the tube 115, as shown. Alternatively, or additionally, any number of tubes, or any predetermined length of tubing, can be between the inlet valve 112 and the outlet valve 122.
Additionally, a predetermined amount of refrigerant can be stored between the inlet valve 112 and the outlet valve 122 when the bypass line 130 is in use. In such manner, a refrigerant charge can be stored between the inlet valve 112 and the outlet valve 122 for later circulation and use. For example, the stored refrigerant charge can be added or removed when transitioning the air conditioning system from heating mode to cooling mode, and vice versa. Such a configuration can eliminate the need for an external charge compensator and improve the efficiency of the overall air conditioning system. The amount of refrigerant stored can be determined by the positions of the inlet valve 112 and the outlet valve 122.
Furthermore, the tube 115 can include one or more intermediate valves located along the tube 115 between the inlet valve 112 and the outlet valve 122. For example, the tube 115 can include an intermediate valve located between the inlet valve 112 and the outlet valve 122 to define a first portion between the inlet valve 112 and the intermediate valve and a second portion between the intermediate valve and the outlet valve 122. The tube 115 can include the first bypass line 130 between the inlet valve 112 and the outlet valve 122, as shown in
This concept can be similarly extended to the U-bend tubes 110, 120 shown in
The heat exchanger apparatus 100 can include a tube plate 140 configured to maintain the heat exchanger tubes in a desired configuration, as shown in
The inlet valve 112 and the outlet valve 122 can be positioned at any point along the tube 115. The positions of the valves can be varied depending on the desired reduction in surface area and/or the desired volume of fluid to be stored in the tubes. The inlet valve 112 and the outlet valve 122 can also be positioned proximal one another (e.g., both on the u-bend side) or distal one another (e.g., on opposing u-bend sides).
The inlet valve 112 and the outlet valve 122 can be any valve configured to selectively permit fluid to pass, which can include, but is not limited to, ball valves, butterfly valves, choke valves, diaphragm valves, gate valves, globe valves, knife valves, needle valves, pinch valves, piston valves, plug valves, solenoid valves, spool valves, and the like. Other valves or other mechanical configurations to selectively permit refrigerant to flow can be used, such as rupture discs or regulators. Additionally, the inlet valve 112 and the outlet valve 122 need not be the same type of valve, though it is understood that the inlet valve 112 and the outlet valve 122 can be similar valves for consistency or other performance reasons.
While the present disclosure is discussed with respect to air conditioning systems for cooling air, as shown in
The gas furnace can include a heat exchanger apparatus 100 according to the instant disclosure, a combustion chamber to provide hot combustion gases through the heat exchanger apparatus 100, and a blower (e.g. a combustion blower) to force the combustion gases through the interior of the heat exchanger apparatus 100. The furnace can include an indoor to force air toward the heat exchanger tubes of the heat exchanger apparatus 100 such that heat can be transferred, via the heat exchanger tubes, from the hot combustion gases and to the flowing air. Heated air can thus be provided to a building, a portion of a building, or some other space. The furnace can include a controller, which can be configured to control the blower, the indoor blower, a fuel valve (not shown), and/or other components of the furnace.
As shown in
The one or more sensors 330 and/or transducers 340 can include, for example, a temperature sensor within the heat exchanger apparatus, a temperature sensor external to the heat exchanger apparatus, a flow sensor within the heat exchanger apparatus, a flow sensor outside the heat exchanger apparatus, a humidity sensor within an indoor space, a temperature sensor within an indoor space, and/or similar sensors placed in various locations.
The controller 300 can also be connected to and in communication with the inlet valve 112 and the outlet valve 122. The controller 300 can transition the inlet valve 112 and the outlet valve 122 between the open state and the closed state. The controller 300 can receive certain data inputs (e.g., from the one or more sensors 330 or from a user interface) and, in response, transition one (or both) of the inlet valve 112 and the outlet valve 122 between the open and closed states. For example, the controller can receive (e.g., from a temperature sensor) that an indoor temperature has been increased. As such, the controller 300 can determine that a capacity of the air conditioning system 200 should be increased. Therefore, the controller 300 can instruct both the inlet valve 112 and the outlet valve 122 to open, thus increasing the surface area of the heat exchanger apparatus 100. It should be understood that, in addition to the controller 300 controlling both the inlet valve 112 and the outlet valve 122, each of the inlet valve 112 and the outlet valve 122 can have its own respective controller.
The controller can also comprise an analog system. For instance, the controller can be connected to a temperature sensing bulb, such as a temperature sensing bulb in a thermal expansion valve. Other analog temperature and pressure sensors can be used in conjunction with analog systems to implement changes to the inlet valve 112, the outlet valve 122, or to other components of the heat exchanger apparatus 100. For example, the controller can comprise one or more hydraulic lines, pistons, actuators, solenoids, and the like.
As shown, in block 410, the controller 300 can receive a request to alter the surface area of the heat exchanger apparatus 100. The request can be to increase the surface area (e.g., if a higher compressor operating speed is desired) or to decrease the surface area (e.g., if a lower compressor operating speed is desired). The request can be received from an external source, such as a thermostat inside of a residential building. Alternatively, or additionally, the request can be related to a transition to a new operating mode for the heat exchanger apparatus 100, the air conditioning system 200, or the like. Alternatively, or additionally, the controller 300 can generate the request automatically upon analyzing received data (e.g., from the one or more sensors 330). If the request is to increase the surface area of the heat exchanger apparatus 100, the method can then proceed to block 420. If the request is to decrease the surface area of the heat exchanger apparatus 100, the method can then proceed to block 430.
In block 420, the controller 300 can instruct the inlet valve 112 and the outlet valve 122 to transition from closed to open. This can allow refrigerant (or other fluid) to flow through the first heat exchanger tube 110 and the second heat exchanger tube 120, thereby increasing the heat exchange area. The method 400 can terminate after block 420 or proceed on to other blocks of the method 400.
In block 430, the controller 300 can instruct the inlet valve 112 and the outlet valve to transition from open to closed. This can prevent refrigerant (or other fluid) from flowing through the first heat exchanger tube 110 and the second heat exchanger tube 120, thereby decreasing the heat exchange area. The method 400 can terminate after block 430 or proceed on to other blocks of the method 400.
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.
The following examples describe examples of a typical user flow pattern. They are intended solely for explanatory purposes and not limitation.
During the early morning, a user's air conditioning system may be operating under a low-speed configuration because the temperature inside the user's house has not heated up yet. As such, the heat exchanger in the air conditioning system can operate at a reduced surface area because less heat transfer is needed. The inlet and outlet valves can therefore be closed, and the bypass line can be in use to flow refrigerant through the heat exchanger.
As the day heats up the interior of the user's house, the thermostat measuring the temperature inside the house can indicate that additional cooling is needed. The thermostat can send the data to a controller of the air conditioning system. Upon receiving the request for additional cooling, the controller can determine that the surface area of the heat exchanger should be increased. The controller can then open the inlet valve and the outlet valve, allowing the refrigerant to flow through extra tubes in the heat exchanger thereby increasing the surface area.
