The present invention relates to a refrigeration system for a merchandiser and, more specifically, to a dilution system for a hydrocarbon refrigeration system.
Refrigerated merchandisers are used by grocers to store and display food items in a product display area that must be kept within a predetermined temperature range. These merchandisers generally include a case that is conditioned by a refrigeration system that has a compressor, a condenser, and at least one evaporator connected in series with each other. Typically, existing merchandisers use refrigerants such as R404a, R134a, or carbon dioxide.
Some refrigeration systems utilize hydrocarbon-based refrigerant (e.g., propane) that has a higher tendency to be flammable relative to conventional refrigerants. There are ways to reduce the risk of the ignition of a hydrocarbon-based refrigerant such as using intrinsically safe electrical components, and quality control to minimize any potential for leaks. However, a flammable mixture of refrigerant and air may exist inside the merchandiser and an ignition source such as a static electrical discharge may occur, causing the air and refrigerant mixture to ignite. When there is no path for the energy released by the ignition to escape, which is especially common in sealed cases, the excessive internal pressure may cause the case to explode.
In one aspect, the invention provides a refrigerated merchandiser including a case that defines a product display area configured to support product and a refrigeration circuit at least partially disposed within the case. The refrigeration circuit includes a compressor configured to circulate a refrigerant through the refrigeration circuit and a dilution device coupled to the refrigeration circuit. The dilution device includes a valve assembly and a container supporting a pressurized fluid. The valve assembly is in fluid communication with the refrigeration circuit and selectively variable to an open state to fluidly couple the container to the refrigeration circuit such that the fluid is discharged into the refrigeration circuit in response to a condition of the refrigeration circuit exceeding a threshold value.
In another aspect, the invention provides a method of evacuating a refrigeration circuit of a merchandiser. The method includes charging the refrigeration circuit with a hydrocarbon refrigerant and conditioning a product display area of the merchandiser via heat exchange between refrigerant in the refrigeration circuit and a fluid in communication with the product display area. The method also includes detecting a pressure condition within the refrigeration circuit and discharging a pressurized fluid into the refrigeration circuit in response to the pressure condition exceeding a predetermined threshold value.
In another aspect, the invention provides a refrigerated merchandiser including a case defining a product display area and a refrigeration circuit at least partially disposed within the case. The refrigeration circuit includes a compressor configured to circulate a hydrocarbon refrigerant through the refrigeration circuit and a dilution device including a container supporting a fluid. The container is only fluidly coupled to the refrigeration circuit in response to a pressure differential between hydrocarbon refrigerant in the refrigeration circuit and the fluid supported in the container exceeding a predetermined threshold.
Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings.
Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways.
Although the illustrated merchandiser 10 includes doors 45 that enclose the access opening 40, the merchandiser 10 can be an open-front merchandiser without doors. The doors 45 are mounted to a frame 50 that includes mullions 55 separating each of the doors 45. The doors 45 may be hinged or sliding doors. Also, the merchandiser 10 can be a vertical merchandiser, as illustrated in
The condenser 85 is connected to the expansion valve 90 via a first fluid line 105, and the expansion valve 90 is connected to the evaporator 95 via a second fluid line 110. The evaporator 125 is connected to the compressor 110 via a suction line 115. While the system 70 of
With continued reference to
The valve assembly 125 can include a single valve or a plurality of valves and is fluidly coupled to the refrigeration circuit 75 through a first dilution line 135. The container 130 is fluidly connected to the valve assembly 125 opposite the fluid line 135 via a second dilution line 140. In one construction, the first dilution line 135 is coupled to the refrigeration circuit 75 between the compressor 80 and the condenser 85. As illustrated by dashed lines in
Also, the dilution device 120 may be directly connected to the valve assembly 125, eliminating the second dilution line 140. In another construction, the valve assembly 125 can be part of the refrigeration circuit 75 (i.e. located within the refrigeration circuit 75) such that the refrigerant constantly flows through the valve assembly 125 during normal operation.
The illustrated valve assembly 125 includes at least one valve that is variable between an open state and a closed state based on a condition of the refrigeration system 70. The valve 125 is variable to the open state in response to the condition reaching or exceeding a predetermined threshold value, which may be brought upon by a refrigerant leak. The valve is maintained in the closed state during normal operation of the refrigeration system 70 (i.e. when the condition has not reached the threshold value). The condition may also be a result of any incident that would render it desirable to dilute the circuit 75 with the pressurized fluid.
For example,
The pressures sensed by the sensors 145, 150 can be used separately or cooperatively to determine whether the valve assembly 125 should be adjusted to the open state. Also, while two pressure sensors 145, 150 are illustrated, the system 75 may include more or fewer than two pressure sensors. The pressures sensors 145, 150 may be used to determine whether there is a leak in the circuit 75 by comparing the sensed pressure value to normal or expected leak pressure values (or a range of values). The sensors 145, 150 can be used to solely control the state of the valve assembly 125, although the valve assembly 125 can be configured to open in response to 1) the condition of the circuit 75 reaching/exceeding the threshold value, or 2) data sensed by the sensors 145, 150 (e.g., to provide system redundancy). Although not shown, the sensors 145, 150 can be connected to a controller that selectively opens the valve assembly 125.
With reference to
The ratios defined during normal operation are exemplary predetermined pressure differential threshold values that can be used to define when the valve to the open state. For example, the refrigerant pressure may drop to or below 40 psig in response to a leak in the circuit 75, or undesired pooling of refrigerant in a section of the circuit 75. At this lower pressure, the ratio defined by the fluid pressure relative to the refrigerant pressure increases to 12.5 (the pressure differential rises to 460 psig).
The dilution system is activated when the refrigerant pressure drops below a threshold value due to a refrigerant leak or pooling of refrigerant in a section of the circuit 75. That is, whenever the refrigerant pressure in the circuit 75 drops below 40 psig in this example, or the ratio or pressure differential increases beyond their respective values defined by the drop in pressure to or below 40 psig, the valve 125 responds by moving to the open state so that the pressurized fluid in the container 130 can evacuate and dilute the circuit 75. The pressure gradient between the pressurized fluid and the refrigerant pressure in the system 70 force the pressurized fluid into the circuit 70 when the valve 125 is opened. Also, the fluid released into the refrigeration circuit 75 can flow through the leak, if one exists, to dilute the refrigerant-air mixture so that the mixture of refrigerant and air is below a predetermined value (e.g., 25%) relative to the lower flammability limit of the mixture.
In general, and as described above, the open state of the valve 125 can be triggered based solely upon the refrigerant pressure drop, or based on the pressure differential between the pressurized fluid and the refrigerant in the circuit 75 reaching or increasing beyond the predetermined threshold. Other factors may also be used to determine when the valve 125 is opened.
In the event of a refrigerant leak, the valve assembly 125 opens to permit the pressurized fluid contained in the container 130 to be released into the circuit 75. The pressurized fluid floods the refrigeration circuit 75 and dilutes the refrigerant. When the system 70 has a leak, the pressurized fluid also evacuates the circuit 75 to minimize the likelihood that a flammable condition can arise. In addition, the system 70 may automatically alert a user that a leak or refrigerant pooling has occurred so that further action may be taken. After the system 70 has been repaired or otherwise returned to a normal operational state, the refrigeration system can be recharged and the dilution system can be recharged for subsequent use.
The dilution system passively dilutes the refrigeration circuit 75 in response to an abnormal condition of the circuit 75 without the need for power. That is, the valve mechanically opens in response to a drop in refrigerant pressure (indicated by the drop in pressure or a significant change in the pressure differential, for example) to dilute the refrigerant in the circuit 75 using the built-in pressure gradient. In the event of a leak or pooling, the passive dilution system automatically releases a volume of pressurized gas into the refrigeration circuit 75 to minimize the risk that refrigerant could ignite.
Various features of the invention are set forth in the following claims.
Number | Name | Date | Kind |
---|---|---|---|
2507380 | Morrison | May 1950 | A |
3386261 | Cornelius | Jun 1968 | A |
5650563 | Cooper | Jul 1997 | A |
5718119 | Wakita | Feb 1998 | A |
5802860 | Barrows | Sep 1998 | A |
6056162 | Leighley | May 2000 | A |
6128911 | Mathews | Oct 2000 | A |
6196008 | Fujitaka | Mar 2001 | B1 |
6425252 | Kobayashi | Jul 2002 | B1 |
7127902 | Levy | Oct 2006 | B1 |
20050086952 | Nonaka et al. | Apr 2005 | A1 |
20050132728 | Lifson | Jun 2005 | A1 |
20050268642 | Appler | Dec 2005 | A1 |
20060049329 | Duerr | Mar 2006 | A1 |
20080209920 | Mikheev | Sep 2008 | A1 |
20090056353 | Sunderland | Mar 2009 | A1 |
20090133416 | Swofford et al. | May 2009 | A1 |
20090145143 | McMasters | Jun 2009 | A1 |
20090183519 | Nishikawa et al. | Jul 2009 | A1 |
20090272131 | McMasters | Nov 2009 | A1 |
20100107660 | Kawano | May 2010 | A1 |
20100300129 | Bean, Jr. et al. | Dec 2010 | A1 |
20110041523 | Taras | Feb 2011 | A1 |
20110167841 | Appler | Jul 2011 | A1 |
20120023983 | Giaros | Feb 2012 | A1 |
20130025717 | Leif | Jan 2013 | A1 |
20130255294 | Crawford | Oct 2013 | A1 |
20140123691 | Shapiro | May 2014 | A1 |
20140182684 | McMasters | Jul 2014 | A1 |
Number | Date | Country |
---|---|---|
1475588 | Nov 2004 | EP |
2001174108 | Jun 2001 | JP |
Number | Date | Country | |
---|---|---|---|
20150282643 A1 | Oct 2015 | US |