System and method to modulate refrigerant pressure

Abstract

The present disclosure relates to a system and method to modulate refrigerant pressure comprising: a first heat exchanger, a second heat exchanger, refrigerant, and a modulator valve, wherein the modulator valve is operable connected to the first heat exchanger and operatively connected to the second heat exchanger and is capable of regulating the amount of refrigerant in the first and second heat exchangers.

Description

SYSTEM AND METHOD TO MODULATE REFRIGERANT PRESSURE CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims benefit and priority to U.S. provisional patent application serial no. 63 / 623,294 filed January 21, 2024. The foregoing application is hereby incorporated by reference.FIELD OF DISCLOSURE

[0002] The present disclosure relates to a system and method to regulate the flow of refrigerant in an HVAC or refrigeration system between multiple heat exchangers, wherein the heat exchangers have differing surface areas, in order to regulate refrigerant pressure.BACKGROUND

[0003] Without sufficient head pressure, an HVAC or refrigeration system may not operate effectively. In instances where the head pressure is not sufficiently within the system’s operating range, the flow of refrigerant may lead to reduced heating or cooling capacity. This can also cause earlier failure of components within the system. In practice, head pressure may be insufficient where the system is rejecting heat to a heat sink at a relatively low temperature. This may lead the condensing pressure to drop below the preferred operating threshold.

[0004] Traditional methods to counteract this phenomenon include using a speed-controlled fan to limit the flow of air, reducing the impact of a the outer surface of the heat exchanger, or by reducing the effective internal heat transfer coefficient by filling up, or flooding, the heat exchanger with liquid refrigerant. Adjusting the fan speed results in inconsistent or intermittent air flow. Flooding the heat exchanger requires the system to hold more refrigerant just for when flooding is needed.

[0005] For example, in so-called Dedicated Outside Air Systems (DOAS) a constant air outflow is required, making traditional HVAC / refrigeration configurations and control schemes untenable. Likewise, because of environmental legislation pushed by concerns related to the ozone layer and global warming, several HVAC / refrigeration systems must now use dangerous refrigerants, such as A2L-class and A3 -class refrigerants which are flammable. Other refrigerants may be flammable, toxic, or act as greenhouse gases if released into the environment. For these reasons, many refrigerants, including A2L and A3 -class refrigerants, are preferably used in smaller volumes and keep under lower pressures, to reduce the risks of accidental leakage or humanexposure. As a result, in many circumstances, these inconsistent or intermittent air flow outputs and increased refrigerant amounts are ineffective, not possible, or dangerous.

[0006] Therefore, there is a need for a HVAC / refrigeration system which provides constant air flow (such as a DOAS) and utilizes a lower quantity of refrigerant, while still being able to modulate refrigerant pressure and refrigerant flow as required to maintain the HVAC / refrigeration system within its proper operating parameters.SUMMARY

[0007] The present disclosure relates to a system and method to modulate refrigerant between two different heat exchangers in order to maintain a constant airflow out of the HVAC / refri eration system while simultaneously maintaining the pressure of the HVAC / refrigeration system with reduced refrigerant amounts.

[0008] Unlike traditional methods to modulate system pressure, which relied on modulating the speed of the fan to force more or less air through the heat exchanger or flooding a portion of the refrigerant surface, the present disclosure allows a system to effectively lower or raise pressure without interrupting airflow and without the need for higher volumes of refrigerant.

[0009] To modulate pressure in a system which requires constant airflow (such as a DOAS), a second heat exchanger is arranged in parallel with regards to refrigerant flow and parallel or series, either first or second, with regards to airflow, with a first heat exchanger. In the preferred embodiment, the second heat exchanger has a lower surface area than the first heat exchanger. In this way, in order to lower the pressure of the system without a reduction in airflow output, refrigerant can be directed to the heat exchanger with a higher relative surface area. Conversely, to raise pressure of the system, refrigerant can be directed to the heat exchanger with a lower surface area. By directing the flow of refrigerant to the larger or smaller heat exchanger, the HVAC / refrigeration system can effectively modulate the pressure in the system without a disruption to airflow output. Likewise, because the system will be less dependent on flooding and / or filling techniques to modulate the pressure of the refrigerant, a smaller volume of total refrigerant will be required. This is advantageous because less refrigerant will lower costs and is particularly desirable when the refrigerant is harmful because lower quantities are required.

[0010] A modulating valve modulates the flow of refrigerant between the smaller heat exchanger and the larger heat exchanger.

[0011] Accordingly, it is an object of the disclosure not to encompass within the disclosure any previously known product, process of making the product, method of using the product, or method of treatment such that Applicants reserve the right and hereby disclose a disclaimer of any previously known product, process, or method. It is further noted that the disclosure does not intend to encompass within the scope of the disclosure any product, process, or making of the product or method of using the product, which does not meet the written description and enablement requirements of the USPTO (35 U.S.C. §112, first paragraph) or the EPO (Article 83 of the EPC), such that Applicants reserve the right and hereby disclose a disclaimer of any previously described product, process of making the product, or method of using the product disclosed herein.

[0012] It is noted that in the present disclosure and particularly in the claims and / or paragraphs, terms such as “comprises,” “comprised,” “comprising” and the like can have the meaning attributed to them in U.S. patent law; e g., they can mean “includes”, “included”, “including”, and the like; and that terms such as “consisting essentially of’ and “consists essentially of’ have the meaning ascribed to them in U.S. patent law, e.g., they allow for elements not explicitly recited, but exclude elements that are found in the prior art or that affect a basic or novel characteristic of the invention.

[0013] These and other embodiments are disclosed or are obvious from and encompassed by the following Drawings and Detailed Description.BRIEF DESCRIPTION OF THE DRAWINGS

[0014] FIG. 1A depicts a first embodiment of a line diagram of the system and method of modulating refrigerant pressure in an HVAC system.

[0015] FIG. IB depicts a second embodiment of a line diagram of the system and method of modulating refrigerant pressure in an HVAC system.

[0016] FIG. 2 depicts a third embodiment of a line diagram of the system and method of modulating refrigerant pressure in an HVAC system.

[0017] FIG. 3 is a flow diagram depicting the operation of the method of modulating refrigerant pressure in an HVAC system.DETAILED DESCRIPTION

[0018] FIGs. 1 A and IB depicts an embodiment of a system and method to regulate refrigerant between multiple heat exchangers 100. The system and method 100 may comprise an HVAC orrefrigeration system 110 having a first heat exchanger 120, a second heat exchanger 130, a modulator valve 140, refrigerant, refrigerant tubing 150 and a controller 160. The system and method 100 allows an HVAC or refrigeration system 110 to regulate the flow of refrigerant 150 between multiple heat exchangers 120, 130 to ensure that pressure remains within the system’s operational envelope and that a constant outflow of air in maintained.

[0019] The controller 160 is operatively connected to the modulator valve 140 and provides instructions to the modulator valve 140 to regulate the flow of refrigerant 150 and direct a desired amount of refrigerant to the desired heat exchanger 120, 130.

[0020] In the preferred embodiment, the heat exchangers 120, 130 are arranged in parallel with regards to refrigerant flow 150 and are arranged in series or parallel with regards to airflow 1000. With regards to airflow 1000, either heat exchanger 120, 130 may be the first in series.

[0021] To increase the pressure in the system, the modulator valve 140 may increase the flow of refrigerant 150 into a second heat exchanger 130 which is larger in size than the first heat exchanger 120. Because the smaller heat exchanger 120 has a smaller surface area, the total pressure of the refrigerant will increase. In an embodiment, the surface area of the second heat exchanger 130 is between 1 and 6 times as large as the surface area of the first heat exchanger 120. In a preferred embodiment, the surface area of the second heat exchanger 130 is approximately four times as large as the surface area of the first heat exchanger 120.

[0022] In another embodiment, the surface area of the second heat exchanger 130 is between 1 and 2 times as large as the surface area of the first heat exchanger 120. In another embodiment, the surface area of the second heat exchanger 130 is between 2 and 2.5 times as large as the surface area of the first heat exchanger 120. In another embodiment, the surface area of the second heat exchanger 130 is between 3 and 3.5 times as large as the surface area of the first heat exchanger 120. In another embodiment, the surface area of the second heat exchanger 130 is between 3.5 and 4 times as large as the surface area of the first heat exchanger 120. In another embodiment, the surface area of the second heat exchanger 130 is between 4 and 4.5 times as large as the surface area of the first heat exchanger 120. In another embodiment, the surface area of the second heat exchanger 130 is between 4.5 and 5 times as large as the surface area of the first heat exchanger 120. In another embodiment, the surface area of the second heat exchanger 130 is between 5 and 5.5 times as large as the surface area of the first heat exchanger 120. In another embodiment, the surface area of the second heat exchanger 130 is between 5.5 and 6 times as large as the surfacearea of the first heat exchanger 120. In another embodiment, the surface area of the second heat exchanger 130 is between 3.5 and 3.75 times as large as the surface area of the first heat exchanger 120. In another embodiment, the surface area of the second heat exchanger 130 is between 3.75 and 4 times as large as the surface area of the first heat exchanger 120. In another embodiment, the surface area of the second heat exchanger 130 is between 4 and 4.25 times as large as the surface area of the first heat exchanger 120. In another embodiment, the surface area of the second heat exchanger 130 is between 4.25 and 4.5 times as large as the surface area of the first heat exchanger 120. In another embodiment, the surface area of the second heat exchanger 130 is between 1.5 and 2 times as large as the surface area of the first heat exchanger 120. In another embodiment, the surface area of the second heat exchanger 130 is between 3.75 and 4.25 times as large as the surface area of the first heat exchanger 120.

[0023] Comparatively, to decrease the pressure of the system, the modulator valve 140 can increase the flow of refrigerant 150 to the relatively larger second heat exchanger 130. Because the larger heat exchanger 130 comprises a larger surface area, the total pressure of the refrigerant will decrease.

[0024] The refrigerant 150 travels through each of the components of the system 100 via a series of tubes. In an embodiment, the tubing is made of a flexible material. In alternative embodiments, other suitable materials are considered.

[0025] Because there are at least two heat exchangers 120, 130 of differing sizes, the HVAC or refrigeration system 110 may modulate the pressure of the refrigerant more effectively, allowing a more consistent outflow of air, and without the need to regulate the airflow of a fan 1002 or to rely on heat exchanger flooding to alter the pressure of the refrigerant. This allows the system 100 to operate without higher levels of refrigerant and increases the ability of the system 100 to modulate the pressure of the system without changing air outflow. This is beneficial when the ambient temperature is relatively cold, but the disclosed system and method 100 can be utilized for an HVAC / refrigeration system under any environmental conditions.

[0026] FIG. 2 depicts an alternative embodiment of a system and method to regulate refrigerant between multiple heat exchangers 200. The system and method 200 may comprise an HVAC or refrigeration system having a compressor 202, evaporator(s) 206 (and optionally an expansion device or devices), pressure sensors 204a, 204b, small heat exchanger 220, large heat exchanger 230, modulator valves 240a, 240b, refrigerant tubing, and a controller 260. In general,the system 200 allows an HVAC or refrigeration system to regulate the flow of refrigerant 250 between multiple heat exchangers 220, 230 to ensure that pressure remains within the system’s operational envelope and that a constant outflow of air is maintained.

[0027] The controller 260 is operatively connected to modulator valves 240a and 240b and regulates the flow of refrigerant 250 which directs a desired amount of refrigerant to and from the desired heat exchanger 220, 230. A first modulator valve 240a is located prior to the heat exchangers 220, 230 and regulates the flow of refrigerant 250 into the modulator valve 240a. A second modulator valve 240b is located after the heat exchangers 220, 230 and regulates the flow of refrigerant 250 from the heat exchangers 220, 230 to the evaporators 206. In the preferred embodiment, only one modulator valve 240a, 240b is active at any one time.

[0028] In the preferred embodiment, the heat exchangers 220, 230 are arranged in parallel with regards to refrigerant flow 250 and are arranged in series or parallel with regards to airflow 1000. With regards to airflow, either heat exchanger 220, 230 may be the first in series.

[0029] To increase the pressure in the system 200, the modulator valve 240a may increase the flow of refrigerant 250 into the small heat exchanger 220. Because the smaller heat exchanger 220 has a smaller surface area, the total pressure of the refrigerant will increase. Alternatively, the second modulator valve 240b may increase the flow of refrigerant received from the small heat exchanger 220 to the evaporator 206.

[0030] In an embodiment, the surface area of the second heat exchanger 230 is between 1 and 6 times as large as the surface area of the first heat exchanger 220. In a preferred embodiment, the surface area of the second heat exchanger 230 is approximately four times as large as the surface area of the first heat exchanger 220.

[0031] In another embodiment, the surface area of the second heat exchanger 230 is between 1 and 2 times as large as the surface area of the first heat exchanger 220. In another embodiment, the surface area of the second heat exchanger 230 is between 2 and 2.5 times as large as the surface area of the first heat exchanger 220. In another embodiment, the surface area of the second heat exchanger 230 is between 3 and 3.5 times as large as the surface area of the first heat exchanger 220. In another embodiment, the surface area of the second heat exchanger 230 is between 3.5 and 4 times as large as the surface area of the first heat exchanger 220. In another embodiment, the surface area of the second heat exchanger 230 is between 4 and 4.5 times as large as the surface area of the first heat exchanger 220. In another embodiment, the surface area of the second heatexchanger 230 is between 4.5 and 5 times as large as the surface area of the first heat exchanger 220. In another embodiment, the surface area of the second heat exchanger 230 is between 5 and 5.5 times as large as the surface area of the first heat exchanger 220. In another embodiment, the surface area of the second heat exchanger 230 is between 5.5 and 6 times as large as the surface area of the first heat exchanger 220. In another embodiment, the surface area of the second heat exchanger 230 is between 3.5 and 3.75 times as large as the surface area of the first heat exchanger 220. In another embodiment, the surface area of the second heat exchanger 230 is between 3.75 and 4 times as large as the surface area of the first heat exchanger 220. In another embodiment, the surface area of the second heat exchanger 230 is between 4 and 4.25 times as large as the surface area of the first heat exchanger 220. In another embodiment, the surface area of the second heat exchanger 230 is between 4.25 and 4.5 times as large as the surface area of the first heat exchanger 220. In another embodiment, the surface area of the second heat exchanger 230 is between 1.5 and 2 times as large as the surface area of the first heat exchanger 220. In another embodiment, the surface area of the second heat exchanger 230 is between 3.75 and 4.25 times as large as the surface area of the first heat exchanger 220.

[0032] To decrease pressure of the system 200, the modulator valve 240a can increase the flow of refrigerant 250 to the larger heat exchanger 230. Because the large heat exchanger 230 comprises a larger surface area, the total pressure of the refrigerant will decrease. Alternatively, the second modulator valve 240b may increase the flow of refrigerant received from the large heat exchanger to the evaporator 206.

[0033] The controller 260 activates the modulator valves 240a, 240b based on data received from pressure sensors 204a, 204b. The first pressure sensor 204a is located after the compressor 202 and measures the pressure of the refrigerant flow upon exiting the compressor 202. The second pressure sensor 204b is located proximate the evaporator 206 and measures the refrigerant flow 250 prior to entry of the evaporator (or expansion device(s) 206. In the preferred embodiment only one pressure sensor 204a, 204b is active at any one time.

[0034] The refrigerant 150 travels through each of the components of the system 100 via a series of tubes. In an embodiment, the tubing is made of a flexible material. In alternative embodiments, other suitable materials are considered.

[0035] Because there are at least two heat exchangers 220, 230 of differing sizes, the HVAC or refrigeration system may modulate the pressure of the refrigerant more effectively, allowing amore consistent outflow of air, and without the need to regulate the airflow of a fan or to rely on heat exchanger flooding to alter the pressure of the refrigerant. This allows the system 200 to operate at lower levels of refrigerant and increases the ability of the system 200 to modulate the pressure of the system without changing air outflow. This is beneficial when the ambient temperature is relatively cold, but the disclosed system and method 200 can be utilized for an HVAC or refrigeration system under any environmental conditions.

[0036] FIG. 3 is a flow chart depicting the method of modulating the flow of refrigerant through the HVAC system. First, a pressure sensor 204a, 204b takes a pressure reading from a refrigerant stream 150, 250 and the pressure sensor communicates the pressure reading to the controller 160, 260. Second, the controller 160, 260 compares the pressure reading to the upper and lower pressure thresholds set by a user.

[0037] Third, the controller 160, 260 directs the modulating valve 140, 240a, 240b to modulate the refrigerant flow to the heat exchangers 120, 130, 220, 230. However, if the pressure reading is within the upper and lower pressure thresholds, no action is taken and the method restarts at the first step.

[0038] If the pressure reading is higher than the upper pressure threshold, the controller 160, 260 directs the modulating valve 140, 240a, 240b to increase the flow of refrigerant 150, 250 through the second heat exchanger 130, 230. Then the method restarts at the first step.

[0039] If the pressure reading is lower than the lower pressure threshold, the controller 160, 260 directs the modulating valve 140, 240a, 240b to increase the flow of refrigerant 150, 250 through the second heat exchanger 130, 230. Then the method restarts at the first step.

[0040] The method restarts from step one after a desired interval of time set by the user and is continuous unless disabled by the user. In an embodiment, the desired interval between the third step and first step is up to 5 seconds. In an alternative embodiment, the desired interval between the third step and first step is between 6 and 10 seconds. In another alternative embodiment, the desired interval between the third step and first step is between 11 and 15 seconds. In another embodiment, the desired interval between the third step and first step is between 16 seconds and 30 seconds.

[0041] Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined in the appended claims.Having thus described in detail preferred embodiments of the present invention, it is to be understood that the invention defined by the above paragraphs is not to be limited to particular details set forth in the above description as many apparent variations thereof are possible without departing from the spirit or scope of the present invention.

Claims

CLAIMSWhat is claimed is:

1. A refrigeration system including a compressor, a condenser, and an evaporator connected in series by a plurality of tubular lines with a refrigerant disposed throughout, the system further comprising: a modulator valve disposed between the compressor and the condenser, wherein the condenser is configured as a first heat exchanger and a second heat exchanger in parallel fluid connection, and a controller operatively connected to the modulator valve to regulate the flow of refrigerant to the first heat exchanger and second heat exchanger, wherein the first heat exchanger has a surface area x and the second heat exchanger has a surface area y, the surface area y being greater than surface area x.

2. The HVAC system of 1, further comprising a pressure sensor operatively connected to the controller and located upstream of the modulator valve, wherein the pressure sensor communicates pressure measurements to the controller.

3. The HVAC system of 1, further comprising a pressure sensor operatively connected to the controller and located upstream of the evaporator and downstream of the modulator valve, wherein the pressure sensor communicates pressure measurements to the controller.

4. The HVAC system of 1, wherein an air stream flows across the first heat exchanger and second heat exchanger in parallel.

5. The HVAC system of 1, wherein an air stream flows across the first heat exchanger and second heat exchanger in series.

6. The HVAC system of 1, wherein surface area y is between 1 to 6 times greater than surface area x.

7. The HVAC system of 1, wherein surface area y is between 3.5 to 4 times greater than surface area x.

8. The HVAC system of 1, wherein the surface area y is between 4.5 to 5 times greater than surface area x.

9. The HVAC system of 1, wherein the surface area is between 3.5 to 4.5 times greater than surface area x.

10. The HVAC system of 1 , wherein the surface area y is approximately 4 times greater than surface area x.

11. A method of modulating head pressure control within a HVAC system, the HVAC system comprising a first heat exchanger, a second heat exchanger, a controller, a modulating valve, and refrigerant, the method of modulating head pressure comprising the steps of: installing the first heat exchanger in parallel refrigerant flow with the second heat exchanger, wherein the second heat exchanger has a greater surface area than the first heat exchanger; installing the modulating valve upstream of the first heat exchanger and second heat exchanger; and modulating flow of the refrigerant through the first heat exchanger and the second heat exchanger via the modulating valve, wherein: head pressure is reduced by increasing flow of refrigerant to the second heat exchanger; and head pressure is elevated by increasing flow of refrigerant to the first heat exchanger.

12. The method of modulating head pressure control of claim 11 further comprising the step of installing the first heat exchanger in parallel airstream flow with the second heat exchanger .

13. The method of modulating head pressure control of claim 11 further comprising the step of installing the first heat exchanger in series airstream flow with the second heat exchanger.

14. The method of modulating head pressure control of claim 11, wherein the surface area of the second heat exchanger is between 3.5 to 4.5 times greater than the surface area of the first heat exchanger.

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