REFRIGERATED DISPLAY CASE SYSTEMS

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 U.S.C. § 119 to U.S. Provisional Patent Application Ser. No. 63/697,710, filed on Sep. 23, 2024, the entire contents of which are incorporated by reference herein.

TECHNICAL FIELD

The present disclosure is directed to refrigerated display case systems and, more particularly, refrigerated display case systems that include a refrigerated display case and a closed-circuit vapor compression cycle refrigeration system coupled to the refrigerated display case.

BACKGROUND

Some refrigerated display cases utilize a flammable refrigerant, such as a hydrocarbon refrigerant. In some cases, a refrigerant charge capacity of such refrigerants can be subject to enhanced safety testing or regulations. For example, a potential leak of such a charge must not exceed a specific level or concentration within the boundaries of the display case. This can ensure that a potential leak will not be ignited by a source external to the display case. This requirement can be particularly challenging to meet in a closed reach-in door case, where a leak that is generated within the enclosed space that encloses merchandise can lead to excessive levels at the boundaries of the case when the doors are opened.

SUMMARY

In a first example implementation, a refrigerated display case system includes a display case that defines an inner volume configured to store one or more perishable items; a closed-circuit refrigeration system; and a control system. The closed-circuit refrigeration system includes a condensing unit including at least one compressor and at least one condenser assembly; and a cooling assembly that includes at least one cooling coil and at least one evaporator fan configured to circulate an airflow from the inner volume through the at least one cooling coil to cool the airflow with a liquid phase of a hydrocarbon refrigerant supplied from the condensing unit. The at least one evaporator fan is configured to circulate the cooled airflow to the inner volume to adjust or maintain a temperature of the inner volume. The control system is communicably coupled to the cooling assembly and the condensing unit and configured to perform operations including operating the condensing unit and the cooling assembly in a refrigeration cycle to cool the inner volume and a defrost cycle to defrost the cooling assembly; and operating the evaporator fan independent of the refrigeration cycle and the defrost cycle.

In an aspect combinable with the first example implementation, the condensing unit includes at least one condenser fan, and the control system is configured to perform operations including operating the condenser fan independent of the refrigeration cycle and the defrost cycle.

In another aspect combinable with one, some, or all of the previous aspects, the hydrocarbon refrigerant includes propane.

In a second example implementation, a refrigerated display case system includes a display case that defines an inner volume configured to store one or more perishable items; a closed-circuit refrigeration system; and a control system. The closed-circuit refrigeration system includes a condensing unit including at least one compressor and at least one condenser assembly that includes a condenser fan; and a cooling assembly that includes at least one cooling coil and at least one evaporator fan configured to circulate an airflow from the inner volume through the at least one cooling coil to cool the airflow with a liquid phase of a hydrocarbon refrigerant supplied from the condensing unit. The at least one evaporator fan is configured to circulate the cooled airflow to the inner volume to adjust or maintain a temperature of the inner volume. The control system is communicably coupled to the cooling assembly and the condensing unit and configured to perform operations including operating the condensing unit and the cooling assembly in a refrigeration cycle to cool the inner volume and a defrost cycle to defrost the cooling assembly; and operating the condenser fan independent of the refrigeration cycle and the defrost cycle.

In an aspect combinable with the second example implementation, the control system is configured to perform operations including operating the evaporator fan independent of the refrigeration cycle and the defrost cycle.

In another aspect combinable with one, some, or all of the previous aspects, the hydrocarbon refrigerant includes propane.

In a third example implementation, a refrigerated display case system includes a display case that defines an inner volume configured to store one or more perishable items; a closed-circuit refrigeration system; at least one exhaust fan; and a control system. The closed-circuit refrigeration system includes a condensing unit including at least one compressor and at least one condenser assembly that includes at least one condenser fan; and a cooling assembly that includes at least one cooling coil and at least one evaporator fan configured to circulate an airflow from the inner volume through the at least one cooling coil to cool the airflow with a liquid phase of a hydrocarbon refrigerant supplied from the condensing unit. The at least one evaporator fan is configured to circulate the cooled airflow to the inner volume to adjust or maintain a temperature of the inner volume. The at least one exhaust fan is positioned adjacent or near the display case. The control system is communicably coupled to the cooling assembly, the condensing unit, and the at least one exhaust fan, the control system configured to perform operations including operating the condensing unit and the cooling assembly in a refrigeration cycle to cool the inner volume and a defrost cycle to defrost the cooling assembly; and operating the at least one exhaust fan independent of the refrigeration cycle and the defrost cycle.

In an aspect combinable with the third example implementation, the control system is configured to perform operations including operating the at least one condenser fan independent of the refrigeration cycle and the defrost cycle.

In another aspect combinable with one, some, or all of the previous aspects, the control system is configured to perform operations including operating the at least one evaporator fan independent of the refrigeration cycle and the defrost cycle.

Another aspect combinable with one, some, or all of the previous aspects includes a conduit coupled to the at least one exhaust fan.

In another aspect combinable with one, some, or all of the previous aspects, the conduit includes an inlet at or near a low point of the inner volume and an outlet external to the display case.

In another aspect combinable with one, some, or all of the previous aspects, the low point is at or near a condensate drain of the display case.

In another aspect combinable with one, some, or all of the previous aspects, the at least one exhaust fan is mounted at or on a top portion of the display case.

In another aspect combinable with one, some, or all of the previous aspects, the hydrocarbon refrigerant includes propane.

In a fourth example implementation, a refrigerated display case system includes a display case that defines an inner volume configured to store one or more perishable items; a closed-circuit refrigeration system; a refrigerant leak detection sensor; and a control system. The closed-circuit refrigeration system includes a condensing unit including at least one compressor and at least one condenser assembly that includes at least one condenser fan; and a cooling assembly that includes at least one cooling coil and at least one evaporator fan configured to circulate an airflow from the inner volume through the at least one cooling coil to cool the airflow with a liquid phase of a hydrocarbon refrigerant supplied from the condensing unit. The at least one evaporator fan is configured to circulate the cooled airflow to the inner volume to adjust or maintain a temperature of the inner volume. The control system is communicably coupled to the cooling assembly, the condensing unit, and the refrigerant leak detection sensor, the control system configured to perform operations including operating the condensing unit and the cooling assembly in a refrigeration cycle to cool the inner volume; and operating at least one of the condensing unit or the cooling assembly in a defrost cycle to defrost the cooling assembly.

In an aspect combinable with the fourth example implementation, the refrigerant leak detection sensor includes a refrigerant gas sensor, and the operations include determining that the refrigerant gas sensor detects a refrigerant leak greater than a specified leak threshold; and based on the determination, operating at least one of the evaporator fan, the condenser fan, or an exhaust fan independent of the refrigeration cycle and the defrost cycle.

In another aspect combinable with one, some, or all of the previous aspects, the refrigerant leak detection sensor includes a door open sensor or case proximity sensor or motion sensor.

In another aspect combinable with one, some, or all of the previous aspects, the operations include determining that the door open sensor or case proximity sensor or motion sensor is tripped; and based on the determination, operating at least one of the evaporator fan, the condenser fan, or an exhaust fan independent of the refrigeration cycle and the defrost cycle.

In another aspect combinable with one, some, or all of the previous aspects, the refrigerant leak detection sensor includes a refrigerant suction pressure sensor.

In another aspect combinable with one, some, or all of the previous aspects, the operations include determining that a value of a refrigerant suction pressure determined by the refrigerant suction pressure sensor is less than a specified value; and based on the determination, operating at least one of the evaporator fan, the condenser fan, or an exhaust fan independent of the refrigeration cycle and the defrost cycle.

In another aspect combinable with one, some, or all of the previous aspects, the hydrocarbon refrigerant includes propane.

In a fifth example implementation, a refrigerated display case system includes a display case that defines an inner volume configured to store one or more perishable items and a closed-circuit refrigeration system that includes a condensing unit including at least one compressor and at least one condenser assembly that includes at least one condenser fan; and a cooling assembly that includes at least one cooling coil and at least one evaporator fan configured to circulate an airflow from the inner volume through the at least one cooling coil to cool the airflow with a liquid phase of a hydrocarbon refrigerant supplied from the condensing unit. The at least one evaporator fan is configured to circulate the cooled airflow to the inner volume to adjust or maintain a temperature of the inner volume. The system includes a condensing unit housing that at least partially encloses the condensing unit on a top portion of the display case; and a refrigerant piping chase that extends at or adjacent the condensing unit housing to at or adjacent the cooling assembly. The refrigerant piping chase is configured to at least partially enclose one or more refrigerant piping conduits between the condensing unit and the cooling assembly.

In an aspect combinable with the fifth example implementation, the condensing unit includes an airflow opening.

In another aspect combinable with one, some, or all of the previous aspects, the refrigerant piping chase includes a first chase portion mounted on the top portion of the display case and a second case portion mounted to a back panel of the display case.

In another aspect combinable with one, some, or all of the previous aspects, the hydrocarbon refrigerant includes propane.

In a sixth example implementation, a refrigerated display case system includes a display case that defines an inner volume configured to store one or more perishable items and a closed-circuit refrigeration system that includes a condensing unit including at least one compressor and at least one condenser assembly that includes at least one condenser fan; and a cooling assembly that includes at least one cooling coil and at least one evaporator fan configured to circulate an airflow from the inner volume through the at least one cooling coil to cool the airflow with a liquid phase of a hydrocarbon refrigerant supplied from the condensing unit. The at least one evaporator fan is configured to circulate the cooled airflow to the inner volume to adjust or maintain a temperature of the inner volume. The system includes a grease and condensate trap assembly fluidly coupled to at least one drain of the display case. The grease and condensate trap assembly is configured to receive liquid and particulates from the at least one drain and separate the liquid from the particulates. The system includes a condensate pump positioned in a liquid reservoir of the grease and condensate trap assembly and configured to circulate the separated liquid from the liquid reservoir to an evaporator pan of the condensing unit.

In an aspect combinable with the sixth example implementation, the grease and condensate trap assembly includes a particulate reservoir separate from the liquid reservoir; and a strainer positioned in the particulate reservoir.

In another aspect combinable with one, some, or all of the previous aspects, the at least one drain is positioned at a low point location of the display case.

In another aspect combinable with one, some, or all of the previous aspects, the hydrocarbon refrigerant includes propane.

The details of one or more implementations of the subject matter described in this disclosure are set forth in the accompanying drawings and the description. Other features, aspects, and advantages of the subject matter will become apparent from the description, the drawings, and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic drawing of an example implementation of a refrigerated display case system according to the present disclosure.

FIG. 1B is a schematic drawing of a condensing unit of a refrigerated display case system according to the present disclosure.

FIGS. 2A-2D are schematic drawings of an example implementation of a portion of a refrigerated display case system that includes one or more refrigerant charge leak mitigation assemblies according to the present disclosure.

FIG. 3 is a control logic diagram for an example implementation of a refrigerated display case system that includes one or more refrigerant charge leak mitigation assemblies according to the present disclosure.

FIG. 4 is a flowchart of an example method of operating a refrigerant charge leak mitigation assembly of a refrigerated display case system according to the present disclosure.

FIG. 5 is a control logic diagram for another example implementation of a refrigerated display case system that includes one or more refrigerant charge leak mitigation assemblies according to the present disclosure.

FIG. 6 is a flowchart of another example method of operating a refrigerant charge leak mitigation assembly of a refrigerated display case system according to the present disclosure.

FIG. 7 is a flowchart of another example method of operating a refrigerant charge leak mitigation assembly of a refrigerated display case system according to the present disclosure.

FIG. 8 is a control logic diagram for another example implementation of a refrigerated display case system that includes one or more refrigerant charge leak mitigation assemblies according to the present disclosure.

FIG. 9 is a flowchart of another example method of operating a refrigerant charge leak mitigation assembly of a refrigerated display case system according to the present disclosure.

FIGS. 10A-10H are schematic drawings of another example implementation of a refrigerated display case system that includes one or more refrigerant charge leak mitigation assemblies according to the present disclosure.

FIGS. 11A-11C are schematic drawings of another example implementation of a refrigerated display case system that includes one or more refrigerant charge leak mitigation assemblies according to the present disclosure.

FIGS. 12A-12E are schematic drawings of another example implementation of a condensing unit of a refrigerated display case system according to the present disclosure.

DETAILED DESCRIPTION

The present disclosure describes systems and methods for refrigerated display cases, including refrigerated display case systems that include a refrigerated display case and a closed-circuit refrigeration system that operates to maintain a temperature of the display case to store perishable items therein. In some aspects, example implementations of refrigerated display case systems according to the present disclosure utilize propane (i.e., R290) as the refrigerant in the closed-circuit refrigeration system. In some aspects, such as due to the flammability of propane, a total amount (e.g., in grams) of propane within the closed-circuit refrigeration system cannot exceed a particular amount. For example, depending on the size of the display case, the total amount can be limited to 150 grams of propane refrigerant charge. Other examples of refrigerated display case system 100 can include a charge of less than 300 grams of R290 (e.g., for some closed display cases) or less than 500 grams or R290 (e.g., for some open display cases). However, should the closed-circuit refrigeration system have less than the maximum charge, such as due to leaks in the suction and/or liquid lines, then the cooling efficiency and performance of the system can degrade. Other refrigerants, such as carbon dioxide, HFCs, blends such as A2L refrigerants, can also be used in the closed-circuit refrigeration system of the refrigerated display case system 100.

Thus, in some aspects, the system may perform best with a critical charge of propane (or other type of) refrigerant, with the critical charge being an amount of refrigerant that does not exceed a maximum amount, but which is sufficient to allow the closed-circuit refrigerant system to meet its published or nominal cooling performance standards.

However, a refrigerated display case with a propane refrigerant charge capacity greater than 150 grams is subject to enhanced UL safety testing per UL 60335-2-89. Under Annex CC of this standard, a potential leak must not exceed specific lower flammability limit (LFL) levels within the boundaries of the case. This requirement ensures that a potential leak (e.g., from a brazed joint in refrigerant hard piping or otherwise, within the display case or within the display case system) will not be ignited by a source external to the case. This requirement has proven to be particularly challenging to meet in a closed reach-in door case, where a leak that is generated within the enclosed merchandising space will lead to excessive LFL levels at the boundaries of the case when the doors are opened.

FIGS. 1A and 1B are schematic drawings of a refrigerated display case system 100 that includes a case mounted condensing unit 300 according to the present disclosure. In this example, the refrigerated display case system 100 includes a display case 102 that encloses an inner volume 104 into which perishable items (such as food or drinks) can be stored and maintained at a particular refrigerated (or freezing) temperature. In this example, the display case 102 includes at least one (and often two) access door 106, and even up to six access doors 106 (with handle 108), that allows access into the inner volume 104. Other implementations of the display case 102 may not include the door 106 but may instead have an opening that allows access to the inner volume 104 from an external environment (such as a human-occupiable building of a convenience or grocery store).

In this example, optional wheels 110 are coupled to the display case 102 and are part of the display case 102 to allow movement of the refrigerated display case system 100 along a support surface 101, such as a floor. In other examples, however, the wheels 110 may be removed or optional and the display case 102 can rest on the support surface 101.

In the example implementation of FIGS. 1A and 1B, the refrigerated display case system 100 includes a closed-circuit refrigeration system that is comprised of a condensing unit 300 (shown in these figures as positioned on a top surface 107 of the display case 102) and a cooling assembly 200. Cooling assembly 200, in this example, is positioned in a plenum 112 that is separated from inner volume 104 by panel 114 (such as a perforated panel). Cooling assembly 200 includes, generally, at least one cooling coil 202 and at least one fan 204. During operation of the closed-circuit refrigeration system, relatively warm return airflow 208 is circulated by fan 204 from the inner volume 104 to (and through) cooling coil 202, where it is cooled by liquid refrigerant supplied to the cooling coil 202 through liquid line 210. In some aspects, the liquid line 210 is a capillary tube or other semi-flexible conduit. Relatively cold supply airflow 206 is supplied to inner volume 104 to maintain a particular temperature within inner volume 104.

Condensing unit 300, in this example, includes a housing 301 that encloses at least one compressor 302 with a suction 304 and a discharge 305. Suction 304 is connected (e.g., brazed or otherwise) to a suction line 306. Compressor 302 is fluidly coupled through discharge 305 to supply a compressed refrigerant vapor to at least one condenser coil 316. At least one fan (or pump) 314 supplies a cooling fluid (air or liquid) 320 to the condenser coil 316 to condense the compressed refrigerant vapor to refrigerant liquid.

An expansion valve 318 (which can be positioned in the cooling assembly 200) is fluidly coupled to the condenser coil 316 to receive the liquid refrigerant (at a high pressure) and expand the refrigerant liquid to a low pressure (colder) refrigerant liquid that is supplied to the cooling assembly 200 through liquid line 210. Expansion valve 318 can be, for example, a thermal expansion valve. In some aspects when the liquid line 210 is a capillary tube, the capillary tube can act as the metering/expansion device in the closed-circuit refrigeration system, thereby removing the expansion valve 218. In some aspects, another portion of the rigid suction line 306 extends toward the condensing unit 300 from an aperture external to the display case 102 (e.g., along a back panel).

In an example implementation of a refrigerant charge leak mitigation assembly (“mitigation assembly”) and/or operation implemented by the refrigerated display case system 100, the at least one fan 204 (also referred to as evaporator fan 204) can be operated to ensure that leaked refrigerated (e.g., propane) from the closed-circuit refrigeration system of the refrigerated display case system 100 does not exceed a specified LFL or concentration within or adjacent (e.g., within a certain, specified envelope that surrounds) the display case 102.

In this example mitigation assembly and/or operation implemented by the refrigerated display case system 100, the evaporator fan 204 can be operated during time periods in which the closed-circuit refrigeration system is operating (i.e., during active cooling of the inner volume 104 that includes compressor operation) as well as during time periods in which the closed-circuit refrigeration system is not operating (i.e., in time periods when compressor 302 is not operating) to disperse any possible refrigerant leaks to an ambient or external environment around the display case 102, thus ensuring that an LFL limit is met. Thus, in this example mitigation assembly and/or operation implemented by the refrigerated display case system 100, the evaporator fan 204 can be operated at all times (e.g., at all times in which power is supplied to the refrigerated display case system 100 and, more specifically, the evaporator fan 204).

However, conventional refrigerated display case design requires the evaporator fans to be automatically turned off at various times during the performance cycle. Most notably, in low-temperature cases, evaporator fan(s) 204 is typically shut off during the defrost cycle to allow sufficient defrosting of the evaporator and to avoid undesirable heating of the merchandised products. Thus, in some aspects of this example mitigation assembly and/or operation implemented by the refrigerated display case system 100, the evaporator fan 204 can be operated 100% of the time but, during, for example, a defrost cycle, the evaporator fan 204 can run at a reduced speed and volumetric airflow (e.g., compared to speed and airflow output during active cooling of the inner volume 104 that includes compressor operation) or at a pulsed operation (with short periods of fan non-operation) to ensure that the defrost cycle is properly completed and merchandise does not heat to unacceptable levels.

In another example implementation of a refrigerant charge leak mitigation assembly (“mitigation assembly”) and/or operation implemented by the refrigerated display case system 100, the at least one fan 314 (also referred to as condenser fan 314) can be operated to ensure that leaked refrigerated (e.g., propane) from the closed-circuit refrigeration system of the refrigerated display case system 100 does not exceed a specified LFL or concentration within or adjacent (e.g., within a certain, specified envelope that surrounds) the display case 102.

In this example mitigation assembly and/or operation implemented by the refrigerated display case system 100, the condenser fan 314 can be operated during time periods in which the closed-circuit refrigeration system is operating (i.e., during active cooling of the inner volume 104 that includes compressor operation) as well as during time periods in which the closed-circuit refrigeration system is not operating (i.e., in time periods when compressor 302 is not operating) to disperse any possible refrigerant leaks above the display case 102 to an ambient or external environment around the display case 102, thus ensuring that an LFL limit is met. Thus, in this example mitigation assembly and/or operation implemented by the refrigerated display case system 100, the condenser fan 314 can be operated at all times (e.g., at all times in which power is supplied to the refrigerated display case system 100 and, more specifically, the condenser fan 314). Additionally, full time operation of the condenser fan 314 can allow for “traditional” electronic components to be used in place of ignition-proof components in the condensing unit 300, thereby reducing the material cost of the condensing unit 300.

In some aspects, the aforementioned refrigerant charge leak mitigation assemblies and/or operations implemented by the refrigerated display case system 100 can be used in combination. For example, the evaporator fan 204 and the condensing fan 314 can be operated 100% of the time (e.g., when power is available to these components) as described to ensure any refrigerant leak does not exceed LFL levels.

FIGS. 2A-2D are schematic drawings of an example implementation of a portion of a refrigerated display case system that includes one or more additional refrigerant charge leak mitigation assemblies (combinable with those previously described or implemented independently thereof). In this example, the one or more refrigerant charge leak mitigation assemblies can be implemented in the refrigerated display case system 100 shown in FIGS. 1A and 1B. FIG. 2A shows a sectional view of the display case 102 (and inner volume 104) with the condensing unit 300 sitting on a top surface of the display case 102 (and typically, in a commercial setting, hidden by a false wall or other barrier to visibility from customers). FIG. 2B shows a detailed view of the top surface of the display case 102 including a portion of the condensing unit 300. FIG. 2C shows a rear view of the display case 102 and condensing unit 300. FIG. 2D shows a bottom view of the display case 102.

In this example mitigation assembly and/or operation implemented by the refrigerated display case system 100, an exhaust fan, such as an inline exhaust fan 260 can be positioned at or near the condensing unit 300 (such as on a top panel of the display case 102 as shown in FIG. 2B). The inline exhaust fan 260 can be operated (e.g., 100% of the time, during operation of the refrigerated display case system 100 such as during active cooling, or upon determination of a refrigerant leak as described more fully herein) to circulate an airflow from external to the display case 102, through the inline exhaust fan 260, and through an outlet 261 to provide an airflow to disperse leaked refrigerant around the display case 102 (such as near the condensing unit 300) to an environment surrounding the refrigerated display case system 100 (thus ensuring that the specified LFL level is not exceeded).

As shown in this example of FIGS. 2A-2D, a T-fitting 264 is installed into a condensate water drain line 268 of the display case 102. The T-fitting 264 can be installed in the drain line 268 opposite an outlet 266 of the drain line 268. From this T-fitting 264, a tubing 262 (e.g., flexible tube) is run, e.g., along a back panel of the display case 102 (shown in FIG. 2C) and to the top panel of the display case 102 (shown in FIG. 2B). The tubing 262 is connected to the inline exhaust fan 260.

This example mitigation assembly and operation can exhaust leaked refrigerant within the display case 102 to an external environment around the condensing unit 300. For example, a potential leak that develops within the inner volume 104 of the case 102 during, e.g., a defrost cycle will settle to the bottom of the display case 102 due to a density ratio of refrigerant (e.g., propane) to air. This leaked refrigerant can, during operation of the inline exhaust fan 260, be circulated from the drain line 268, through the T-fitting 264 (as water passes through the outlet 266), through the tubing 262, and from the fan 260 to the outlet 261. The inline exhaust fan 260, in this example, is positioned so that its discharge air is directed on top of the display case 102 where any potential leak will be adequately distributed by the condenser fan 314 (running, as described previously, at 100% operation).

In some examples, the inline exhaust fan 260 (and accompanying components as described) can be installed and utilized in place of operating the evaporator fan 204 at 100% operation. For example, as described, 100% operation of the evaporator fan 204 (to mitigate refrigerant leaks) may interfere with or be detrimental to a defrost cycle of the refrigerated display case system 100. For instance, 100% operation of the evaporator fan 204 can cause excessive heat to be transferred to merchandise (e.g., perishable food) during a defrost cycle (to defrost, for example, the evaporator coil 202). Thus, in some aspects, the evaporator fan 204 can be operated normally (e.g., only during a refrigeration cycle or more simply, not during a defrost cycle) and the inline exhaust fan 260 can be operated 100% of the time during a refrigeration cycle and a defrost cycle (in combination with 100% operation of the condenser fan 314 or otherwise).

FIG. 3 is a control logic diagram (also referred to as a “control system”) 350 for an example implementation of a refrigerated display case system that includes one or more refrigerant charge leak mitigation assemblies according to the present disclosure. In this example, the control logic diagram 350 shows a display case controller 999 (that controls operations, such as refrigeration and defrost operations) of the refrigerated display case system 100. The display case controller 999 is electrically coupled to the inline exhaust fan 260 and the evaporator fan 204 through a fan relay 990. In this example, and to implement the operation of the inline exhaust fan 260 previously described, the fan relay 990 is a normally closed relay that, when energized, opens during a refrigeration cycle and closes during a defrost cycle. The inline exhaust fan 260 is turned on and the evaporator fan 204 is turned off when the fan relay 990 is closed, and the inline exhaust fan 260 is turned off and the evaporator fan 204 is turned on when the fan relay 990 is open.

FIG. 4 is a flowchart of an example method 400 of operating a refrigerant charge leak mitigation assembly of a refrigerated display case system according to the present disclosure. In this example, method 400 describes a control algorithm for operating the inline exhaust fan 260 (or “blower”) (and more specifically, operation of the motor of the fan 26) during a defrost cycle. The case controller 999 determines mode of operation of 1 (normal, or refrigeration) or 2 (defrost) [step 402]. In mode 1, the evaporator fan 204 is on, and in mode 2 the evaporator fan 204 is off [step 404]. A mode check is performed by the controller 999 to determine if the current mode is 1 (normal) [step 406]. If yes, then the exhaust fan 260 is off and the fan relay 990 is open [step 408]. If no, then the exhaust fan 260 is on and the fan relay 990 is closed [step 410]. A signal is sent from the controller 999 to the fan relay 990 [step 412]. The exhaust fan 260 continues to operate [step 414].

Although the inline exhaust fan 260 is shown on top of the display case 102, other (or alternative) fans or blowers can be provided and operated to disperse leaked refrigerant and controlled in a similar manner as the inline exhaust fan 260 or the evaporator fan 204 (as described herein). For example, additional fans can be located on top of, behind, or underneath the display case 102 to move air away from an envelope that surrounds the display case 102, which may collect excessive concentrations of leaked refrigerant leading to the LFL level being excessive. In addition, air baffles can also be added to the display case 102 that utilize an airflow from, e.g., the condenser fan 314 to disperse concentrations of a leaked refrigerant at such locations.

FIG. 5 is a control logic diagram 500 for another example implementation of a refrigerated display case system that includes one or more refrigerant charge leak mitigation assemblies according to the present disclosure. For example, with reference also to FIG. 1A, a refrigerant leak sensor 502 can be installed in the refrigerated display case system 100, such as within the display case 102. In some aspects, the refrigerant leak sensor 502 can be positioned at a location in which leaked refrigerant may settle (due to a density difference between it and air). For instance, the sensor 502 can be placed within the inner volume 104 (or otherwise) of the display case 102 at a lowest point where it would encounter the leaked refrigerant (e.g., propane) which is less dense than the air in the volume 104.

The refrigerant leak sensor 502 may be used in combination with a relay or controller to force operation of the evaporator fan 204 in the event of a refrigerant leak. A leak occurring during a defrost cycle (e.g., when the evaporator fan(s) 204) is typically off) will trip the sensor 502, which will force the evaporator fan(s) 204 to run to adequately distribute the leaked refrigerant in an environment external to the display case 102. In some aspects, this example mitigation assembly and/or operation can be designed for a safety application according to UL 60730 or similar industry standards. The refrigerant leak sensor 502 can be or include an infrared, catalytic diffusion, electrochemical, semiconductor, photoionization, or photoacoustic sensor.

In some aspects, the refrigerant leak sensor 502 can meet or have the following characteristics. The sensor 502 can detect a gas of R290. The sensor 502 can have one or more agency listings of UL 60335-2-89, UL 60079-29, or UL 2075. The sensor 502 can be a stand-alone sensor with on-board relays to allow the design to bypass the requirements of section 22.116 of 60335-2-89, however, the sensor 502 could also be wired to a controller that is designed to this or similar standard. The sensor 502 can use communication of a local relay, with normally open preferred. The sensor 502 can be a relay to trip on rise to ˜15% LFL and an automatic reset on fall to ˜5% LFL (values being approximate). The sensor 502 can use a supply voltage of 120 V (preferred, with others as acceptable). The sensor 502 can use a shielded cable to avoid interference from high voltage lines. The sensor 502 can have a product lifespan>10 years. The sensor 502 can work within ambient conditions represent application within the display case 102; however, less severe conditions can be considered if the sensor 502 is mounted outside of the case 102 (e.g., outside of the inner volume 104). These conditions can include a working temperature range: −20° F.-100° F.; a working humidity range: 0-100% RH; freeze/thaw cycles: 1 per day; ingress protection (e.g., IP 68 preferred); and readings not impacted by condensation.

Turning now to FIG. 5, in this example, the control logic diagram 500 shows the display case controller 999 (that controls operations, such as refrigeration and defrost operations) of the refrigerated display case system 100. The display case controller 999 is electrically coupled to the evaporator fan 204 through the fan relay 990, which in turn is electrically coupled with electrical power through the refrigerant leak sensor 502. In this example, and to implement the operations associated with the refrigerant leak sensor 502 previously described, the fan relay 990 (as normally open) closes upon detection (by the sensor 502) of, e.g., 15% LFL. The evaporator fan 204 is turned on when the fan relay 990 closes and the evaporator fan 204 is turned off when the fan relay 990 is open. The controller 999 can also include a fan relay that is used to turn off the evaporator fan 204 during a defrost operation.

FIG. 6 is a flowchart of another example method 600 of operating a refrigerant charge leak mitigation assembly of a refrigerated display case system according to the present disclosure. In this example, method 600 describes a control algorithm for operating the evaporator fan 204 in combination with the refrigerant leak sensor 502. The case controller 999 determines mode of operation of 1 (normal, or refrigeration) or 2 (defrost) [step 602]. In mode 1, the evaporator fan 204 is on, and in mode 2 the evaporator fan 204 is off [step 604]. A mode check is performed by the controller 999 to determine if the current mode is 1 (normal) [step 606]. If yes, then the evaporator fan 204 is on (and the fan relay 990 is closed) [step 608]. If no, then the refrigerant leak sensor 502 is checked to determine if a refrigerant leak (sufficient to trip the sensor 502) is detected [step 610]. If yes, then the evaporator fan 204 is on (and the fan relay 990 is closed) [step 612]. If no, then the evaporator fan 204 is turned off or remains off if in mode 2 (and the fan relay 990 is open) [step 614].

FIG. 7 is a flowchart of another example method 700 of operating a refrigerant charge leak mitigation assembly of a refrigerated display case system according to the present disclosure. For example, with reference also to FIG. 1A, a door open switch 701 can be installed in the refrigerated display case system 100, such as at or on the door 106, the door handle 108, or any appropriate location in which the switch 701 triggers upon opening of the door 108 to allow access to the inner volume 104. In some aspects, the door open switch 701 (or a motion or proximity sensor 701) detects when the door 106 is opened. If a switch is used, the switch can be wired to a relay that would operate the evaporator fan(s) 204 to run when the door 106 is opened. This wiring approach could be similar to the control diagram 500, with the door open switch 701 replacing the refrigerant leak sensor 502 in the circuit (although both mitigation assemblies could be used in combination). Alternative to a door switch, a non-contact magnetic proximity switch listed to UL 508, or a contact-style switch can be used.

With reference to FIG. 7, method 700 describes a control algorithm for operating the evaporator fan 204 in combination with the door open switch 701. The case controller 999 determines mode of operation of 1 (normal, or refrigeration) or 2 (defrost) [step 702]. In mode 1, the evaporator fan 204 is on, and in mode 2 the evaporator fan 204 is off [step 704]. A mode check is performed by the controller 999 to determine if the current mode is 1 (normal) [step 706]. If yes, then the evaporator fan 204 is on (and the fan relay 990 is closed) [step 708]. If no, then the door open switch 701 is checked to determine if the door 106 is open (or there is a person in proximity to the door 106 if a proximity switch is used) [step 710]. If yes, then the evaporator fan 204 is on (and the fan relay 990 is closed) [step 712]. If no, then the evaporator fan 204 is turned off or remains off if in mode 2 (and the fan relay 990 is open) [step 714].

FIG. 8 is a control logic diagram 800 for another example implementation of a refrigerated display case system that includes one or more refrigerant charge leak mitigation assemblies according to the present disclosure. For example, with reference also to FIG. 1B, a suction pressure sensor 801 can be installed on a suction (inlet) side of the compressor 302, such as within the suction line 306 as shown in this example. In some aspects, the suction pressure sensor 801 can measure a pressure value of the vapor or gas refrigerant (e.g., propane) returned to the compressor 302 from the evaporator coil 202.

In some aspects, the suction pressure sensor 801 can act as (or be) a low-pressure switch that detects a presence of a refrigerant leak when the sensed pressure value is less than a specified value. Generally, in response to the leak detection, the evaporator fan 204 can be turned on (if not already running). For example, in some aspects, a leak introduced into the display case 102 can result in a reduction in suction pressure of the refrigerant (e.g., propane). When a critical quantity of refrigerant is lost, the system suction pressure can fall below a cut-out set point of the suction pressure sensor 801 as a low-pressure switch. An open electrical contact in the suction pressure sensor 801 can then engage a relay to shut off the compressor 302 and force the evaporator fan(s) 204 to run. However, this functionality can still allow the evaporator fan(s) 204 to be turned off during a defrost cycle that prevents the formation of hoar frost accumulation on merchandised products and interior surfaces of the display case 102.

Turning to the control logic diagram 800, the display case controller 999 (that controls operations, such as refrigeration and defrost operations) of the refrigerated display case system 100 is electrically coupled to the evaporator fan 204 through the fan relay 990, which in turn is electrically coupled with electrical power through the suction pressure sensor 801. In this example, the suction pressure sensor 801 is a low pressure switch (e.g., listed to EN60730-2-6) that opens when compressor suction pressure falls below, e.g., ˜5 psi. A compressor relay 803 is electrically coupled between the compressor 302 and fan relay 990 and represents, e.g., a 208 V relay that drives compressor relay operation. A compressor relay on the controller 999 also can open when amperage requirements exceed limits (as well as controls temperature regulation). In this example, the fan relay 990 is a double pole relay that provides power to the evaporator fan 204 to turn it on when the suction pressure sensor 801 opens (which also shuts off the compressor 302). A fan relay on the controller 999 turns the evaporator fan 204 off during defrost operations.

FIG. 9 is a flowchart of another example method 900 of operating a refrigerant charge leak mitigation assembly of a refrigerated display case system according to the present disclosure. Method 900 describes a control algorithm for operating the evaporator fan 204 in combination with the suction pressure sensor 801. The case controller 999 determines that the display case 102 is running in normal (refrigeration cycle) operation [step 902]. A check is performed by the controller 999 to determine if the compressor suction pressure is normal pressure (e.g., above a specified threshold) [step 904]. If yes, then the compressor 302 continues to run [step 906]. If no, then compressor suction pressure is checked to determine if the pressure value is below, e.g., 5 psi [step 908]. If yes, then the evaporator fan 204 is turned on and the compressor 302 is turned off [step 910]. If no, then the compressor 302 remains on [step 912].

FIGS. 10A-10H are schematic drawings of another example implementation of a refrigerated display case system that includes one or more refrigerant charge leak mitigation assemblies according to the present disclosure. Generally, FIGS. 10A-10H show portions of the refrigerated display case system 100, including the condensing unit 300 and display case 102, in which a condensing unit housing 1002 at least partially encloses the condensing unit 300 and a piping chase 1006 at least partially covers refrigerant lines 1012 (i.e., the suction line 306 and the liquid line 210) between the condensing unit 300 and the cooling assembly 200. In some aspects, the condensing unit housing 1002 and the piping chase 1006 can also be implemented with one or more of the refrigerant charge leak mitigation assemblies previously described.

Conventional refrigerated display cases do not include or require a protective housing on external refrigerant charge-carrying components such as a condensing unit or refrigerant piping (such as copper or other rigid piping). Facia panels are typically used to conceal the condensing unit atop the display case and, along with other features, can act as sound abatement as well. Facia panels and sound abatement features, however, do not mitigate or enclose a refrigerant leak from the refrigerant piping or protect external refrigeration features from physical damage or impact in a refrigerated display case system that uses propane with greater than a 150 g refrigerant charge.

As shown in these figures, the condensing unit housing 1002 encloses the condensing unit 300 on top of the display case 102 and includes an opening 1004 that facilitates an airflow to a condenser coil (such as coil 316 shown in FIG. 1B). In example aspects, the condensing unit housing 1002 can be formed of a rigid material, such as metal. One or more panels of the condensing unit housing 1002, including a panel affixed over the opening 1004, can be perforated to allow a condenser airflow into the housing 1002 during operation of the condensing unit 300. Through the condensing unit housing 1002, refrigerant leaks can be prevented or mitigated, for example, to meet or help meet certain regulatory requirements while meeting other functional requirements of the refrigerated display case system 100.

In some aspects, the condensing unit housing 1002 is comprised of a modular construction formed of multiple formed sheet metal panels that, when fastened together, provide certain advantages. For example, the condensing unit housing 1002 protects the condensing unit 300 and piping extensions from the unit 300 from physical damage/impact (per UL 60335-2-89). The condensing unit housing 1002 provides a path for the free flow of air driven by the condenser fan. The condensing unit housing 1002 assists in safely dispersing any leaked refrigerant charge away from potentially sensitive components in combination with the condenser fan to enhance an ignition protection zone. The condensing unit housing 1002 provides ease of manufacturing individual components, ease of handling, and ease of assembly. The condensing unit housing 1002 provides serviceability to change out individual parts including access to components with tools even in locations with ceiling height limitations by unfastening individual panels of the housing 1002 (while providing protection). The condensing unit housing 1002 provides flexibility for installation and can be easily removed and refit or reassembled even in locations with ceiling or doorway height limitations. The condensing unit housing 1002 can act as an integrated balloon-guard and sound abatement device. The condensing unit housing 1002 consists of outlets for self-contained operations of refrigeration, electrical, and condensate management features

As further shown in FIGS. 10A-10H, the refrigerated display case system of this example implementation includes the piping chase 1006. Piping chase 1006, in this example, is made up of a horizontal chase 1008 that sits atop the display case 102 and adjacent the housing 1002, as well as a vertical chase 1010 that extends vertically from the horizontal chase 1008 and along a rear panel of the display case 102. In some aspects, each chase 1008 and 1010 is individually removable (as shown in the figures) to allow access to the refrigerant piping 1012.

In this example implementation, the piping chase 1006 can function as external riser piping protection. The piping chase 1006 can be used both individually or in combination with the condensing unit housing 1002 (such as to meet or help meet the UL 60335-2-89 requirements). The piping chase 1006 also protects the external risers (refrigerant piping 1012) and the joint of the threaded couplings in the refrigerant piping.

In some aspects, the vertical chase 1010 is a fixed panel that protects the refrigerant piping egress in addition to an existing foamed egress box on the rear of the display case 102. The vertical chase 1010 can also protect and provides rigidity to the horizontal chase 1008 when assembled over it. The horizontal chase 1008 can have multiple portions with at least one acting as a resting step for the threaded couplings during installation and doorway transition, thereby preventing the deformation of the refrigerant lines 1012.

FIGS. 11A-11C are schematic drawings of another example implementation of a refrigerated display case system that includes one or more refrigerant charge leak mitigation assemblies according to the present disclosure. FIG. 11A shows a schematic diagram of a refrigerated display case system 1100 that includes a display case 1102, a condensing unit 1130, a grease trap assembly 1140 that includes a condensate pump 1120, and a condensate line 1110 that extends from the pump 1120 up to the condensing unit 1130. As shown in this example, the grease trap assembly 1140 is fluidly coupled to one or more drains 1150 that collect liquid, debris, and other particulate matter from a bottom (e.g., low point) of the display case 1102.

Generally, self-contained refrigerated display cases have challenges with the management of condensate mixed with decomposing food particles of all sizes. Typically, this mixture is separated within a display case tank with a raised strainer. However, this may not help with smaller and finer particles or semi-solids that get pumped from the drain line and accumulate in the evaporator pan of, for example, a cooling assembly of the refrigerated display case system. During case servicing, these are typically cleaned or replaced with a new heater pan. In display cases that utilize a hydrocarbon refrigerant, such as propane, this pan is combined with a condensing unit, which makes servicing both riskier and cost-prohibitive. Additionally, propane refrigerant sensors and controllers that meet required UL requirements for devices dedicated to protective control do not currently exist.

The example implementation of the refrigerated display case system 1100 includes a low-profile condensate and grease trap assembly 1140 with an integrated pump 1120 that can be used to ensure both grease/particulate removal while maintaining regulatory compliance with UL 60335-2-89, Annex CC for propane refrigerant. In this example, the condensate pump 1120 can be a UL-approved epoxy-encapsulated pump to qualify for ignition-proof operation with propane refrigerant (but can also be used in non-propane display cases as well).

Conventional self-contained refrigerated display cases (non-propane cases) typically consist of separate components of a condensate evaporator pan, a condensing unit, and a drain pump. In the example refrigerated display case system 1100 that utilizes propane refrigerant, a condensate evaporator pan 1131 is integrated with the condensing unit 1130. Thus, condensate from the condensate and grease trap assembly 1140 can be circulated by the pump 1120 through the condensate piping 1110 to the pan 1131 (and then evaporated, typically, through operation of the condensing unit 1130 that circulates airflow over the pan 1131 by the condenser fan). This change has increased the risk of condensate management issues related to grease accumulation, and the accumulation of fine food particles, which decompose over time, can lead to contamination.

FIGS. 11B and 11C show an example implementation of the condensate and grease trap assembly 1140. As shown in these figures, the condensate and grease trap assembly 1140 includes a dual compartment tray 1141 that includes a deposition tray 1142 into which a strainer 1144 can be placed. A collection basin 1143 is separate from the deposition tray 1142 to catch liquid (substantially particulate-free) that overflows the deposition tray 1142 through the strainer 1144. A grease removal flange and containment cover 1147 acts to skim floating particles and oil.

As shown in this example, the pump 1120 is positioned within the collection basin 1143 as an encapsulated submersible condensate pump. From the collection basin 1143, liquid therein is pumped to the evaporator pan 1131 of the condensing unit 1130 (to be evaporated).

FIGS. 12A-12E are schematic drawings of another example implementation of a condensing unit 1200 of a refrigerated display case system according to the present disclosure. FIG. 12A is an isometric view of the condensing unit 1200; FIG. 12B is a front view through a section of the condensing unit 1200; FIG. 12C is a top view of the condensing unit 1200 with a top shroud of the condensing unit 1200 removed to expose an interior volume; FIG. 12D is a front isometric view of the condensing unit 1200 with the top shroud of the condensing unit 1200 removed to expose the interior volume; and FIG. 12E is a rear isometric view of the condensing unit 1200 with the top shroud of the condensing unit 1200 removed to expose the interior volume.

In this example implementation, the condensing unit 1200 includes one or more internal panels that fluidly separate an interior volume of a housing of the condensing unit 1200 into two or more chambers. In some aspects, one of the two or more chambers can enclose components that hold, circulate, and/or compress a working fluid, such as a flammable refrigeration (e.g., R290 or otherwise). Another of the two or more chambers can enclose components that can produce a spark, such as electrical components (e.g., a junction box). In some aspects, the one or more panels can also provide structural protection to refrigerant piping, e.g., during transportation of the unit 1200 or otherwise.

As shown in the example implementation of FIGS. 12A-12F, the condensing unit 1200 includes a top shroud 1202, a side housing 1233, and a bottom frame 1204 that, collectively, combine to form at least part of, and in example aspects, all of a structural housing and support structure for the condensing unit 1200 (e.g., for lifting purposes and when mounted semi-permanently to, for instance, a refrigerated display case). The structural housing of the top shroud 1202, the side housing 1233, and the bottom frame 1204 define an interior volume 1208 of the condensing unit 1200 into which all or most of the components of a closed circuit mechanical refrigeration cycle are enclosed. Ventilation panels 1206, in this example, are installed in one or both of the top shroud 1202 and side housing 1233 (e.g., to facilitate an airflow between the interior volume 1208 and an ambient environment, whether indoors or outdoors).

As shown, interior volume 1208 encloses a compression assembly 1210 that includes at least one compressor 1212 and at least one condenser 1214 (e.g., that includes at least one fan and at least one heat exchanger). Refrigerant piping 1222 (shown in FIGS. 12C and 12E but also running into and out of the condensing unit 1200) carries the flammable refrigerant (such as propane) within the interior volume 1208 and, e.g., to one or more evaporator coils (for example, in a refrigerated display case).

As further shown in this example of FIGS. 12A-12F, at least one panel 1216 is positioned in the interior volume 1208 and fluidly separates the volume 1208 into at least two plenums: plenum 1203 and plenum 1205. In this example, the compression assembly 1210, as well as a drain pan 1228, are located in the plenum 1205, as is most or all of the refrigerant piping 1222. Thus, in this example, the components in which the flammable refrigerant circulates, is compressed, and is condensed, are entirely or substantially within the plenum 1205.

In this example, an electric junction box 1220 is located in the plenum 1203. Electric junction box 1220 can receive or be electrically coupled with electric power conductors that supply electric power for operation of the condensing unit 1200 (e.g., operation of the compressor 1212, a fan of the condenser 1214, as well as, e.g., valves, sensors, pumps, other fans, and any electrically powered components of the condensing unit 1200. Electric junction box 1220, in this example, can be a spark source of the condensing unit 1200 and, if a spark occurs, can potentially ignite any flammable refrigerant fluid within the interior volume 1208 or adjacent the condensing unit 1200.

As shown in this example, panel 1216 fluidly separates the interior volume 1208 into plenum 1203 (e.g., a non-refrigerant plenum) and plenum 1205 (e.g., a refrigerant plenum). By separating the interior volume 1208 into one chamber that encloses flammable refrigerant and another, fluidly separated chamber that encloses no or a negligent amount of flammable refrigerant, an unwanted or dangerous ignition of such flammable refrigerant by an electric spark can be avoided or reduced. In this example, the panel 1216 includes a flange 1232 that can be coupled to, sealed against, or otherwise engage the top shroud 1202 to create a fluid seal between plenums 1203 and 1205. Vertical sides 1235 of the panel 1216 can be coupled to, sealed against, or otherwise engage the side housing 1233 to also create the fluid seal between plenums 1203 and 1205.

In some aspects, one or more gaps 1207 can be formed in the panel 1216, such as to allow electrical conduit to connect the electrical junction box 1220 with the compression assembly 1210, or for other purposes. For example, in some aspects, gap 1207 can be used for an electrical conduit from a compressor section of the condensing unit 1200 (e.g., interior volume 1208) to the electrical junction box 1220. In some aspects, the electrical conduit can be steel or a flame retardant material.

While this specification contains many specific implementation details, these should not be construed as limitations on the scope of what may be claimed, but rather as descriptions of features specific to particular implementations. Certain features that are described in this specification in the context of separate implementations can also be implemented in combination in a single implementation. Conversely, various features that are described in the context of a single implementation can also be implemented in multiple implementations separately or in any suitable subcombination. Moreover, although features may be described as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination.

A number of implementations have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the disclosure. For example, example operations, methods, or processes described may include more steps or fewer steps than those described. Further, the steps in such example operations, methods, or processes may be performed in different successions than that described or illustrated in the figures. As another example, various components of a refrigerated display case system according to the present disclosure, such as thermostats or other controls, check valves, shut off valves, or other piping appurtenances are not shown for simplicity. Accordingly, other implementations are within the scope of the following claims.