US20180106492A1

US20180106492A1 - Hvac/r system with auxiliary power source and method of operating an hvac/r system

Info

Publication number: US20180106492A1
Application number: US15/787,539
Authority: US
Inventors: Paul Papas; Parmesh Verma; Richard G. Lord; Larry D. Burns
Original assignee: Carrier Corp
Current assignee: Carrier Corp
Priority date: 2016-10-18
Filing date: 2017-10-18
Publication date: 2018-04-19

Abstract

An HVAC/R system configured to receive power from a main power source is provided. The HVAC/R system includes an HVAC/R component configured to contain a refrigerant and allow a refrigerant to flow therethrough, a detecting mechanism configured to detect a concentration of the refrigerant outside of the HVAC/R component, and a blower configured to operate under power from an auxiliary power source upon detection of the refrigerant above a predetermined refrigerant level during a main power source outage.

Description

TECHNICAL FIELD OF THE DISCLOSED EMBODIMENTS

The present application is an international patent application, which claims priority to U.S. patent application Ser. No. 62/409,795, filed Oct. 18, 2016, which is herein incorporated in its entirety.

TECHNICAL FIELD OF THE DISCLOSED EMBODIMENTS

The presently disclosed embodiments generally relate to heating, ventilation, air conditioning, and refrigeration (HVAC/R) systems, and more particularly, to a system and method of operating an HVAC/R system with an auxiliary power source.

BACKGROUND OF THE DISCLOSED EMBODIMENTS

Refrigeration systems, as used in HVAC/R applications, utilize a closed loop refrigerant circuit to condition air inside an interior space. Over the years, the HVAC industry has been using refrigerants with ozone depleting chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs); however, the use of ozone depleting refrigerants is currently being phased out of the industry.
New refrigerants have been developed to comply with environmental regulations relating to global warming potential (GWP). In order to comply with the proposed GWP regulations, hydrofluorocarbon (HFC) and hydrocarbon refrigerants with various levels of flammability are being developed and are being considered for use in HVAC/R systems.

SUMMARY OF THE DISCLOSED EMBODIMENTS

In accordance with an embodiment of the present disclosure, an HVAC/R system configured to receive power from a main power source is provided. The HVAC/R system includes an HVAC/R component configured to contain a refrigerant and allow a refrigerant to flow therethrough, a detecting mechanism configured to detect a concentration of the refrigerant within a gas volume outside of the HVAC/R component, and a blower configured to operate under power from an auxiliary power source upon detection of the refrigerant above a predetermined refrigerant level during a main power source outage, wherein the blower is in fluid communication with the gas volume.
The detecting mechanism may operate under power from the auxiliary power source at least during the main power source outage. The system may further include a return conduit operably coupled to the at least one HVAC/R component, the return conduit including an opening to allow airflow therethrough. The system may further include a mitigation damper operably coupled to the return conduit and positioned adjacent to the opening to selectively allow airflow through the opening upon detection of the refrigerant by the detecting mechanism. The system may further include a controller in electrical communication with the detecting mechanism and the blower. The controller may operate under power from the auxiliary power source at least during the main power source outage. The blower may be further configured to operate for a predetermined time period following detection of the refrigerant below the predetermined refrigerant level by the detecting mechanism. The predetermined refrigerant level may be a lower flammability limit of the refrigerant. The HVAC/R system may be disposed in an outdoor space. The HVAC/R system may be disposed in an indoor space. The auxiliary power source may include at least one battery. The auxiliary power source may include a distributed energy source. The auxiliary power source may include a renewable energy source. The detecting mechanism may be a sensor. The detecting mechanism may be a system control algorithm. The system may further include an enclosure which at least partially surrounds the gas volume and the HVAC/R component.
In accordance with an embodiment of the present disclosure, a method of operating an HVAC/R system configured to receive power from a main power source is provided. The method includes circulating a refrigerant through an HVAC/R component, detecting a concentration of the refrigerant outside of the HVAC/R component, and powering a blower with an auxiliary power source during a main power source outage if the concentration of refrigerant detected is above a predetermined refrigerant level.
The method may further include opening a mitigation damper if the concentration of refrigerant detected is above the predetermined refrigerant level. The mitigation damper may be operably coupled to a return conduit. The method may further include powering a detecting mechanism configured to detect a concentration of the refrigerant outside of the HVAC/R component with the auxiliary power source during the main power source outage. The method may further include controlling the blower with a controller electrically connected to a detecting mechanism, and powering the controller with the auxiliary power source during the main power source outage. The method may further include operating the blower for a predetermined time period following detection of a concentration of the refrigerant above the predetermined refrigerant level. The auxiliary power source may include at least one battery. The auxiliary power source may include a distributed energy source.

BRIEF DESCRIPTION OF DRAWINGS

The embodiments and other features, advantages and disclosures contained herein, and the manner of attaining them, will become apparent and the present disclosure will be better understood by reference to the following description of various exemplary embodiments of the present disclosure taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a schematic diagram of a HVAC/R system in accordance with one embodiment of the present disclosure;

FIG. 2 is a schematic diagram of a HVAC/R system in accordance with one embodiment of the present disclosure;

FIG. 3 is a schematic flow diagram of a method of operating an HVAC/R system;

FIG. 4 is a schematic diagram of a HVAC/R system in accordance with one embodiment of the present disclosure; and

FIG. 5 is a schematic diagram of a HVAC/R system in accordance with one embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE DISCLOSED EMBODIMENTS

For the purposes of promoting an understanding of the principles of the present disclosure, reference will now be made to the embodiments illustrated in the drawings, and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of this disclosure is thereby intended.
As with any system, there is a potential for flammable refrigerants used in HVAC/R applications to leak and migrate to undesirable areas in the vicinity of the HVAC/R system. When the flammable refrigerants, in the presence of air or another oxidizer, are exposed to an ignition source, the potential for a combustion event exists. If the mixture is above the lower flammability limit (LFL) and below the upper flammability limit (UFL), the propagation of a deflagration is possible resulting in the production of toxic combustion products such as HF and a harmful pressure rise. There is therefore a need for an HVAC/R system which mitigates the possibility of igniting a leaked refrigerant. However, during power outages, mitigation systems and methods may not receive energy supply for mitigation operation. Therefore, there further exists a need for an HVAC/R system and method capable of a mitigation operation during a main power outage.
FIG. 1 illustrates a schematic diagram of an embodiment of a heating, ventilation, air conditioning, and refrigeration (HVAC/R) system 10 in an embodiment of the present disclosure, indicated generally at 10. The system 10 is configured to receive power during its operation from a main power source (not shown). The main power source may be an electrical grid in accordance with one embodiment. The system 10 includes a blower 26 in electrical communication with a controller 25. The blower 26 of one embodiment includes a fan designed to operate under relatively low power, such as a fan configured or rated for operation between 100 watts and 1000 watts in one non-limiting example. The system 10 further includes a detecting mechanism, such as a sensor 42 in electrical communication with the controller 25, in one non-limiting embodiment. In one or more additional embodiments, the detecting mechanism includes a system control algorithm. In such embodiments, detection is accomplished through system controls that monitor one or more values, such as pressure(s) and superheat and subcooling signatures, to name a few non-limiting examples, of the system 10. In the illustrated embodiment, the sensor 42 and/or the controller 25 are also in communication with a mitigation damper 12 in one embodiment, as explained further below. The sensor 42 is configured to detect refrigerant. The sensor 42 and/or the controller 25 may determine if the refrigerant level sensed by the sensor 42 is above a predetermined refrigerant level. In an embodiment, a refrigerant level above a predetermined refrigerant level indicates a refrigerant leak in the system 10. The predetermined refrigerant level is the lower flammability limit (LFL) of the refrigerant in an embodiment. In non-limiting examples, the LFL of difluoromethane (R32) refrigerant is as high as 14.4%, and the LFL of hydrocarbons, such as propane R290, is about 2% percent volume to air concentration. In one embodiment, the predetermined refrigerant level is between 3% and 10% percent volume refrigerant to air concentration. In another embodiment, the predetermined refrigerant level is between 5% and 8% percent volume refrigerant to air concentration. In an embodiment, the predetermined refrigerant level is between 1% and 3% percent volume refrigerant to air concentration. In additional embodiments, the predetermined refrigerant level is below 3% or above 10% percent volume refrigerant to air concentration.
It will be appreciated that the detecting mechanism, such as the sensor 42, may be located internal and/or external to the system 10 and/or the one or more HVAC/R component 22. In an embodiment, the detecting mechanism, such as the sensor 42, detects a concentration of the refrigerant outside of the HVAC/R component(s) 22. In an embodiment, the detecting mechanism is configured to detect a concentration of the refrigerant within a gas volume outside of the HVAC/R component. Further, the blower 26 is in fluid communication with the gas volume in an embodiment.
As explained in further detail below, the blower 26, the controller 25, the sensor 42, and/or the damper 12 are electrically coupled to an auxiliary power source 40. The auxiliary power source 40 of an embodiment is different than and/or separate from the main power source (not shown). The auxiliary power source 40 is not electrically coupled to the main power source in one embodiment. In one or more additional embodiments, the auxiliary power source 40 includes one or more batteries, one or more distributed power sources, and/or one or more alternative and/or renewable energy sources, including such non-limiting examples as a solar energy source, a wind energy source, a water or wave energy source, and a thermoelectric energy source.
In one embodiment, the HVAC/R system 10 includes the mitigation damper 12 disposed within a return air conduit 14, wherein the return air conduit 14 includes an opening 15 adjacent to the mitigation damper 12. The mitigation damper 12 includes a first portion 16 operably coupled to a rotating component 20. In an embodiment, the first portion 16 is positioned to cover the opening 15 when the mitigation damper 12 is in a closed position. In another embodiment, as shown in FIG. 2, the mitigation damper 12 further includes a second portion 18 operably coupled to the rotating component 20. In this embodiment, the second portion 18 is located within the interior of the return conduit 14, and the first portion 16 is positioned to cover the opening 15 from the exterior of the return air conduit 14 when the mitigation damper 12 is in a closed position. In the embodiment of FIG. 1, the first and second portions 16, 18 of the mitigation damper 12 are the same. For example, the first and second portions, 16, 18 may be formed as a unitary piece from the same materials, have the same shape, thickness, etc. In the embodiment FIG. 2, the first and second portions 16, 18 of the mitigation damper 12 are different. The mitigation damper 12 is configured to rotate between a closed and an open position if a refrigerant leak is detected. In one embodiment, the rotating component 20 is selected from a group consisting of a motorized and non-motorized hinge. It will be appreciated that an example of a non-motorized hinge includes a spring loaded latching mechanism operable to rotate the mitigation damper 12 upon receiving an electrical signal. It will further be appreciated that the interior portion 16 and exterior portion 18 may be formed in any shape, and composed of any material suitable for blocking airflow, such as metal, plastic, wood, etc. to name a few non-limiting examples.
The system 10 further includes at least one HVAC/R component 22 operably coupled to the return air conduit 14, the at least one HVAC/R component 22 being configured to allow a refrigerant to flow therethrough. In one embodiment, the refrigerant may be a flammable refrigerant, such that the refrigerant has the ability to ignite and/or propagate a flame in the presence of air. The flammability of a refrigerant is evaluated at specific ambient conditions, including, but not limited to initial temperature, humidity, and pressure relevant to conditions of operation. In one embodiment, the flammable refrigerant includes difluoromethane (R32), and in another embodiment the flammable refrigerant includes 2,3,3,3-tetrafluoro-1-propene (R1234yf). It will be appreciated that other flammable refrigerants may be used within the HVAC/R system 10. In the illustrated, non-limiting embodiment, the at least one HVAC/R component 22 further includes a fan coil containing an evaporator coil 24 in electrical communication with the controller 25.
In normal operation to condition an interior space, a compressor (not shown) of the HVAC/R system 10 is fluidically coupled to the evaporator coil 24. Compressed refrigerant is configured to enter the evaporator coil 24 via a refrigerant supply line 28 and is configured to exit the evaporator coil 24 via a refrigerant return line 30. As the refrigerant flows through the evaporator coil 24, the blower 26 operates to circulate the conditioned air 32 through a supply conduit 34 to an interior space. Return air 36 from the interior space enters the at least one HVAC/R component 22 via the return conduit 14. In an embodiment, the at least one HVAC/R component 22 may be a combination of an evaporator coil and a furnace. In another embodiment, the at least one HVAC/R component 22 may be a refrigeration unit.
FIG. 3 illustrates a method 100 of operating an HVAC/R system 10 configured to receive power from the main power source. The method 100 includes circulating, at step 102, a refrigerant through the HVAC/R component 22. The method 100 further includes sensing, at step 104, a refrigerant level by the sensor 42. The method 100 further includes the sensor 42 and/or the controller 25 determining, at step 106, whether the refrigerant level is above the predetermined refrigerant level. If the refrigerant level is not above the predetermined refrigerant level, the system 10 continues normal operation at step 103. If the refrigerant level is above the predetermined refrigerant level, the controller 26 determines, at step 108, if the system 10 is currently experiencing a main power source outage. If the system 10 is not currently experiencing a main power source outage, the system 10 continues normal operation at step 103. If the system 10 is currently experiencing a main power source outage, the system 10 operates, at step 110, the blower 26 under power from the auxiliary power source 40. In an embodiment, the system 10 operates the blower 26 under power from the auxiliary power source 40 until the sensor 42 either no longer detects refrigerant or senses refrigerant at a refrigerant level below the predetermined refrigerant level. In an embodiment, the system 10 operates the blower 26 under power from the auxiliary power source 40 for a predetermined time period following the sensor 42 either not detecting refrigerant or sensing refrigerant at a refrigerant level below the predetermined refrigerant level. The predetermined time period is between one minute and one hour in one embodiment, between 10 and 45 minutes in another embodiment, and between 20 and 40 minutes in another embodiment. In additional embodiments, the predetermined time period is less than one minute or greater than one hour.
In an additional embodiment, the method 100 further includes operating the mitigation damper 12 from a closed position to an open position if the refrigerant level is above the predetermined refrigerant level, and such operation may be performed under power from the auxiliary power source 40. Further, the sensing of step 104 and any function of the controller 25 may be performed under power from the auxiliary power source 40, such as by the sensor 42 and/or the controller 25 being powered by the auxiliary power source 40.
The system 10 may be positioned in an indoors space or at an outdoor location. During a refrigerant leak from the system 10, the refrigerant may collect near or around the base of the system 10 inside or outside of the system 10 due to the refrigerant being heavier than the surrounding air. Such collection or concentration may cause a flammability hazard. The sensor 42 of one or more embodiments will be located at or near the base or lowest point of the system 10. With the system 10 and/or method 100 of the present disclosure, the operation of the blower 26 functions to dilute, disperse, or otherwise disrupt the collected refrigerant, such as refrigerant leaking from the system 10, to reduce the concentration of refrigerant in the air of an indoor or outdoor space in which the system 10 is located, thereby reducing the refrigerant level to a level below the lower flammability limit and reducing the likelihood of ignition.
Further, the opening 15 in the return conduit 14 operates to create a vacuum effect whereby the air atmosphere 17 surrounding the HVAC/R system is pulled into the opening 15 in the room in which HVAC/R system 10 is located by increasing the speed and volume of air 17 entering therein. The air 17 entrainment in the vicinity, in effect, pulls additional air into the at least one HVAC/R component 22 and the room in which the HVAC/R system 10 is located, thereby, diluting the leaked refrigerant to reduce the likelihood of ignition. It will be appreciated that, upon a main power source outage, the mitigation or dilution operations described above may not be available. It will be further appreciated that the auxiliary power source 40, control logic of the controller 25 and/or sensor 42 upon sensing of a refrigerant level above a predetermined refrigerant level, and the powering of the blower 26, the controller 25, the sensor 42, and/or the damper 12 provide a mitigation system and operation to reduce the likelihood of refrigerant ignition in the event of a main power source outage.
While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only certain embodiments have been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected.

Claims

What is claimed is:

1. An HVAC/R system configured to receive power from a main power source, the HVAC/R system comprising:

an HVAC/R component configured to contain a refrigerant and allow a refrigerant to flow therethrough;

a detecting mechanism configured to detect a concentration of the refrigerant within a gas volume outside of the HVAC/R component; and

a blower configured to operate under power from an auxiliary power source upon detection of the refrigerant above a predetermined refrigerant level during a main power source outage, wherein the blower is in fluid communication with the gas volume.

2. The system of claim 1, wherein the detecting mechanism operates under power from the auxiliary power source at least during the main power source outage.

3. The system of claim 1, further comprising a return conduit operably coupled to the at least one HVAC/R component, the return conduit including an opening to allow airflow therethrough.

4. The system of claim 3, further comprising a mitigation damper operably coupled to the return conduit and positioned adjacent to the opening to selectively allow airflow through the opening upon detection of the refrigerant by the detecting mechanism.

5. The system of claim 1, further comprising a controller in electrical communication with the detecting mechanism and the blower.

6. The system of claim 5, wherein the controller operates under power from the auxiliary power source at least during the main power source outage.

7. The system of claim 1, wherein the blower is further configured to operate for a predetermined time period following detection of the refrigerant below the predetermined refrigerant level by the detecting mechanism.

8. The system of claim 1, wherein the predetermined refrigerant level is a lower flammability limit of the refrigerant.

9. The system of claim 1, wherein the HVAC/R system is disposed in an outdoor space.

10. The system of claim 1, wherein the HVAC/R system is disposed in an indoor space.

11. The system of claim 1, wherein the auxiliary power source includes at least one battery.

12. The system of claim 1, wherein the auxiliary power source includes a distributed energy source.

13. The system of claim 1, wherein the auxiliary power source includes a renewable energy source.

14. The system of claim 1, wherein the detecting mechanism is a sensor.

15. The system of claim 1, wherein the detecting mechanism is a system control algorithm.

16. The system of claim 1, further comprising an enclosure which at least partially surrounds the gas volume and the HVAC/R component.

17. A method of operating an HVAC/R system configured to receive power from a main power source, the method comprising:

circulating a refrigerant through an HVAC/R component;

detecting a concentration of the refrigerant outside of the HVAC/R component; and

powering a blower with an auxiliary power source during a main power source outage if the concentration of refrigerant detected is above a predetermined refrigerant level.

18. The method of claim 16, further comprising opening a mitigation damper if the concentration of refrigerant detected is above the predetermined refrigerant level.

19. The method of claim 17, wherein the mitigation damper is operably coupled to a return conduit.

20. The method of claim 16, further comprising powering a detecting mechanism configured to detect a concentration of the refrigerant outside of the HVAC/R component with the auxiliary power source during the main power source outage.

21. The method of claims 16, further comprising:

controlling the blower with a controller electrically connected to a detecting mechanism; and

powering the controller with the auxiliary power source during the main power source outage.

22. The method of claim 16, further comprising operating the blower for a predetermined time period following detection of a concentration of the refrigerant above the predetermined refrigerant level.

23. The method of claim 16, wherein the auxiliary power source includes at least one battery.

24. The method of claim 16, wherein the auxiliary power source includes a distributed energy source.