Patent Application
20220299242
With 40-60 kWh/sf-year electric usage intensity (EUI), supermarkets (i.e., grocery stores) have one of the highest EUIs of any commercial buildings. Refrigeration accounts for approximately 50% of the electric energy used by supermarkets. Medium temperature refrigerated open vertical display cases (OVDCs) comprise nearly 50% of total OVDC line-ups in a typical supermarket, with more than 80% of their energy usage attributed to infiltration of air from the surrounding space (i.e., air at ambient conditions within the supermarket). OVDCs primarily use air to extract heat via convective heat transfer.
Typical OVDCs use a constant-volume fan to discharge refrigerated air from a grille at the top front of the case. This refrigerated jet of air removes heat from the case and entrains warm, moist air from the supermarket ambient before returning to the evaporator via a grille at the bottom of the case. At the same time, a large portion of the case's cold air mixes with the adjacent sales area's air and spills out in front of the case. As the return air travels across the cold evaporator (maintained at approximately 19° F.), it deposits its moisture as frost. The heat of refrigeration is typically rejected to the supermarket ambient and not recovered. The entrainment of warm and moist air into the case dominates the case's heat gain and results in a total cooling load of approximately 1,300 Btu/hr-ft2. The high energy use due to air at supermarket ambient temperatures accounts for approximately 80% of the cooling load in this design. The front formation on the evaporator restricts air flow and hampers heat transfer combined with efforts to remove the frost further degrade the energy efficiency of the OVDC. There is highly variable and non-uniform product temperature between the shelves (up to 10° F. in temperature variation between shelves). The “spilled” air into the supermarket ambient makes the supermarket (particularly near the OVDCs) uncomfortable for shoppers. This “spilled” air cannot be reclaimed by space or water heating systems and ends up as a space cooling load. Thus, there remains a need for an energy efficient and effective OVDC.
An aspect of the present disclosure is a system for cooling a food product using radiant cooling, the system including an open vertical display case including a wall, a plurality of piping positioned in the wall and including a first refrigerant stream, and a refrigeration circuit including a second refrigerant stream, in which the plurality of piping is positioned within the wall and configured to cool the food product using radiant cooling. In some embodiments, the system also includes a coil and a fan, in which the first refrigerant stream is routed through the coil, the coil is configured to cool an air stream resulting in a cooled air stream, and the fan is configured to direct the cooled air stream to the food product to cool the food product using convective cooling. In some embodiments, the system also includes a phase change material, in which the first refrigerant stream and the second refrigerant stream are routed through the phase change material, the first refrigerant stream is in thermal contact with the phase change material and the second refrigerant stream, the second refrigerant stream is in thermal contact with the phase change material and the first refrigerant stream, and the phase change material acts as a thermal energy storage system. In some embodiments, the phase change material has a transition temperature below 0° C. In some embodiments, the phase change material is ammonium chloride (NH4Cl) and/or potassium chloride (KCl). In some embodiments, the phase change material is potassium fluoride tetrahydrate (KF.4H2O), manganese nitrate hexahydrate (Mn(NO3)2.6H2O), calcium chloride hexahydrate (CaCl2.6H2O), calcium bromide hexahydrate (CaBr2.6H2O), lithium nitrate hexahydrate (LiNO3.6H2O), sodium sulfate decahydrate (Na2SO4.10H2O), sodium carbonate decahydrate (NaCo3.10H2O), sodium orthophosphate dodecahydrate (Na2HPO4.12H2O), and/or zinc nitrate hexahydrate (Zn(NO3)2.6H2O). In some embodiments, the refrigeration circuit includes a condenser, a compressor, and an expansion valve. In some embodiments, the condenser is configured to transfer heat from the first refrigerant stream to the building's heating system. In some embodiments, the condenser is configured to transfer heat from the first refrigerant stream to the water supply. In some embodiments, the wall is a vertical side of the open vertical display case. In some embodiments, the wall is a horizontal canopy of the open vertical display case.
An aspect of the present disclosure, a method for cooling a food product using radiant cooling in an open vertical display case, the method including positioning a plurality of piping comprising a first refrigerant stream through a wall of an open vertical display case and operating a refrigeration circuit comprising a second refrigerant stream, in which the positioning includes cooling the food product using radiant cooling. In some embodiments, routing the first refrigerant stream through a coil, cooling an air stream using the coil, resulting in a cooled airstream, and directing the cooled air stream to the food product using a fan, in which the directing includes cooling the food product using convective cooling. In some embodiments, the refrigeration circuit includes a condenser, a compressor, and an expansion valve. In some embodiments, the method includes connecting the condenser to a water supply, in which the connecting includes transferring heat from the second refrigerant stream to the water supply through the condenser. In some embodiments, connecting the condenser to a building heating system, in which the connecting includes transferring heat from the second refrigerant stream to the building heating system through the condenser. In some embodiments, the method includes utilizing a phase change material as a heat exchanger between the first refrigerant stream and the second refrigerant stream, in which the utilizing includes storing thermal energy in the phase change material. In some embodiments, the phase change material includes a transition temperature below 0° C. In some embodiments, the wall is a vertical side of the open vertical display case. In some embodiments, the wall is a horizontal canopy of the open vertical display case.
Some embodiments of the present disclosure are illustrated in the referenced figures of the drawings. It is intended that the embodiments and figures disclosed herein are to be considered illustrative rather than limiting.
The embodiments described herein should not necessarily be construed as limited to addressing any of the particular problems or deficiencies discussed herein. References in the specification to “one embodiment”, “an embodiment”, “an example embodiment”, “some embodiments”, etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.
As used herein the term “substantially” is used to indicate that exact values are not necessarily attainable. By way of example, one of ordinary skill in the art will understand that in some chemical reactions 100% conversion of a reactant is possible, yet unlikely. Most of a reactant may be converted to a product and conversion of the reactant may asymptotically approach 100% conversion. So, although from a practical perspective 100% of the reactant is converted, from a technical perspective, a small and sometimes difficult to define amount remains. For this example of a chemical reactant, that amount may be relatively easily defined by the detection limits of the instrument used to test for it. However, in many cases, this amount may not be easily defined, hence the use of the term “substantially”. In some embodiments of the present invention, the term “substantially” is defined as approaching a specific numeric value or target to within 20%, 15%, 10%, 5%, or within 1% of the value or target. In further embodiments of the present invention, the term “substantially” is defined as approaching a specific numeric value or target to within 1%, 0.9%, 0.8%, 0.7%, 0.6%, 0.5%, 0.4%, 0.3%, 0.2%, or 0.1% of the value or target.
As used herein, the term “about” is used to indicate that exact values are not necessarily, attainable. Therefore, the term “about” is used to indicate this uncertainty limit. In some embodiments of the present invention, the term “about” is used to indicate an uncertainty limit of less than or equal to ±20%, ±15%, ±10%, ±5%, or ±1% of a specific numeric value or target. In some embodiments of the present invention, the term “about” is used to indicate an uncertainty limit of less than or equal to ±1%, ±0.9%, ±0.8%, ±0.7%, ±0.6%, ±0.5%, ±0.4%, ±0.3%, ±0.2%, or ±0.1% of a specific numeric value or target.
The present disclosure relates to an improved open vertical display case (OVDC) which utilizes radiant cooling to cool and/or maintain food products at a target temperature. The radiant cooling is performed using a plurality of piping routed through the walls and containing a first refrigerant stream, which may be very cold. In some embodiments, convective cooling may also be performed using a fan directing air cooled by the first refrigerant stream flowing through a coil to the OVDC. The plurality of piping may be cooled using a refrigeration circuit. In some embodiments, a phase change material may be used for thermal energy storage and positioned between the plurality of piping and the refrigeration circuit. In some embodiments, the refrigeration circuit may be connected to heating ventilation and air conditioning (HVAC) systems and water heating systems within the building. The improved OVDC as described herein may be more energy efficient, may be able to serve as a flexible grid resource, and may be able to contribute heat to other building applications.
In some embodiments, the improved OVDC which makes the display portion (i.e., the food product shelves) the central components of a refrigeration system and integrates with HVAC systems and water heating systems within the building. The systems described herein may allow the improved OVDC to serve as a flexible grid resource and respond to demand response events and/or participate in load shaving/shifting strategies for the building. For example, the phase change material may act as both a heat exchanger and a thermal energy storage system and may be used to supply cooling without needing electrical power to run the refrigeration circuit. The improved OVDC may also utilize an improved cooling mechanism using radiant and (in some embodiments) low-airflow convective cooling.
The improved OVDC 105 may be operated at a thermostatic set point, based on the food products it is designed to contain on the shelf 115. Food products may be placed on the shelf 115, which through the radiant cooling emitted by the first refrigerant stream in the plurality of piping 125 may be maintained at a desired temperature (e.g., 34° F.). The lower portion of the improved OVDC 105 may include a refrigeration circuit 130 to extract heat from the first refrigerant stream to maintain the thermostatic set point of the improved OVDC 105. This refrigeration circuit 130 may reclaim this heat for space and water heating of the entire building (i.e., supermarket), improving overall building energy efficiency (via connection 160). During demand response events and/or as a part of a load shaving/shifting strategy the phase change material 120 may keep food products at the desired cooled temperature without the use of electrical energy.
The improved. OVDC 105 lacks the “air curtain” typical in most OVDCs, which is a major source of wasted energy and infiltration of warm air into the cooled food product area. Additionally, the improved OVDC 105 also lacks the evaporator coil typical in most OVDCs, which is a source of frost and its significant adverse repercussions on thermal performance. In some embodiments, the improved OVDC 105 uses radiant cooling coupled with low air-flow convective cooling n some embodiments, the low air-flow convective cooling may be introduced by a fan 155 through small perforations on the back interior wall 110 of the improved OVDC 105. The cooled air may “wrap around” food products on the shelf 115. The low-airflow cooled air may travel horizontally across the shelf 115 and/or vertically between the shelves 115. The shelves 115 may be made of a perforated/porous (i.e., “breathable”) material such as mesh, wire, or chain-link material to allow cooled air to easily circulate through the improved OVDC 105. Simultaneously, radiant cooling may supplement the low air flow mechanism to further ensure the improved OVDC 105 is maintained at the thermostatic set point. Depending on the safety requirements of the food products to be stored in the improved OVDC 105, the thermostatic set point may be set to just above freezing. A small pump (not shown in
In some embodiments, the wall 120 may be made of a substantially conductive material on the interior side (i.e., on the side oriented towards the food product or shelf 115). Examples of substantially conductive materials include aluminum, copper, steel, and/or plastic. The wall 120 may have an exterior side (i.e., the exterior of the improved OVDC 105) made of a substantially, insulative material. Examples of a substantially insulative material include plastic, fiberglass, mineral wool, polyurethane foam, and/or concrete. A wall 120 may refer to a vertical side a vertical wall) and/or a horizontal side (i.e., a canopy, shelf 115, or floor of the display area).
In some embodiments, the plurality of piping 125 may be made of a substantially conductive material, such as aluminum, copper, steel, and/or plastic. In some embodiments, the plurality of piping 125 may be in physical contact with the wall 120. The plurality of piping 125 may “zig-zag” or curve back and forth through the wall 120, to provide multiple sources of radiant cooling.
The first refrigerant stream 165 and/or the second refrigerant stream 150 may be any liquid material capable of transferring heat, such as water, glycol, hydrocarbons, hydrofluorocarbons, carbon dioxide, ammonia, haloalkanes, propane, and/or isobutane. In some embodiments, the first refrigerant stream 165 may be a “safer” material (meaning it is less toxic or non-toxic) than the second refrigerant stream 150, given the proximity of the first refrigerant stream 165 to food products. In some embodiments, the first refrigerant stream 165 may be cooled by the phase change material 120 and/or the second refrigerant stream 150 to a temperature in the range of about −5° C. to about 5° C. For optimal performance of the improved OVDC 105 and maintaining product temperatures to within limits set by the U.S. Food and Drug Administration, the first refrigerant stream 165 may be cooled to a temperature in the range of about −0.5° C. to about 0.5° C.
As shown in
The core food product 200 temperatures are shown in
The improved OVDC 105 shown in
In some embodiments, the method 300 also includes routing 315 the first refrigerant stream 165 through a coil 175, cooling 320 an air stream 180 using the coil 175 (resulting in a cooled airstream 195), and directing 325 the cooled air stream 195 to the food product 200 using a fan 155. The directing 325 includes cooling the food product 200 using convective cooling. The convective cooling and radiant cooling may be combined to defectively cool the food products or maintain the temperature of the food products at acceptable temperatures (i.e., temperatures regulated by the U.S. Food and Drug Administration), In some embodiments, at least one fan 155 may be present for each shelf 115 in the improved OVDC 105, In other embodiments, the number of fans may be less than or greater than the number of shelves 115 in the improved OVDC. The fans may be operated using electrical energy.
In some embodiments, the method 300 also includes connecting 330 the condenser 135 to the building water supply and/or the building heating system. Waste heat from the condenser may be used by the building's water supply or heating system (i.e., heating ventilation and air conditioning (HVAC) system). The connecting 330 may be done by directing a third refrigerant stream through the condenser, which can transfer the waste heat to the water supply or heating system. Alternatively, the connecting 330 may be done by routing the water supply or building air through the condenser to recover the waste heat directly.
In some embodiments, the method 300 also includes utilizing 335 a phase change material 120 as a heat exchanger between the first refrigerant stream 195 and the second refrigerant stream 150. The utilizing 335 may also including storing thermal energy in the form of cold energy in the phase change material 120. In some embodiments, for example, during off-peak hours, the refrigeration circuit 130 may “charge” freeze) the phase change material 120, then, during on-peak hours, the refrigeration circuit 130 may be turned off or turned down and the phase change material 120 may cool the first refrigerant stream 165. This allows the improved OVDC 105 to operate with significantly lower (if not no) energy from the electrical grid.
In some embodiments, the phase change material 120 may have a transition temperature (i.e., a temperature at which the phase change material 120 changes phase between solid and liquid) below 32° F. (0° C.) to achieve desired refrigeration requirements for food products. In some embodiments, the phase change material 120 may have high thermal conductivity (i.e., greater than about 10 W/m-K) to enable rapid charge/discharge times. In some embodiments, the phase change material 120 may have sufficient energy density (i.e., a heat of fusion greater than about 55 kWh/m3) to enable advanced refrigeration load flexibility capabilities. In some embodiments, the phase change material 120 may have stability over multiple cycles. Examples of phase change material 120 may include inorganic phase change materials such as salt-water eutectic solutions or salt hydrates. Some examples of phase change material 120 include ammonium chloride (NH4Cl) and/or potassium chloride (KCl). In some embodiments, the phase change material 120 may be a salt hydrate. Examples of salt hydrates include potassium fluoride tetrahydrate (KF.4H2O), manganese nitrate hexahydrate (Mn(NO3)2.6H2O), calcium chloride hexahydrate (CaCl2.6H2O), calcium bromide hexahydrate (CaBr2.6H2O), lithium nitrate hexahydrate (LiNO3.6H2O), sodium sulfate decahydrate (Na2SO4.10H2O), sodium carbonate decahydrate (NaCo3.10H2O), sodium orthophosphate dodecahydrate (Na2HPO4.12H2O), or zinc nitrate hexahydrate (Zn(NO3)2.6H2O). In some embodiments, inorganic phase change materials may require surface modification of the expanded graphite prior to compression to successfully impregnant the inorganic phase change material into treated graphite structures, such as graphite matrices.
A system for cooling a food product using radiant cooling, the system comprising
The system of Example 1, further comprising:
The system of Examples 1 or 2, further comprising:
The system of Example 3, wherein:
The system of any of Examples 1-4, wherein:
The system of any of Examples 1-5, wherein:
The system of Example 6, wherein:
The system of Example 7, wherein:
The system of any of Examples 1-8, wherein:
The system of Example 9, wherein:
The system of any of Examples 1-10, wherein:
The system of Example 9, wherein:
The system of any of Examples 1-12, wherein:
The system of Example 12, wherein:
The system of any of Examples 1-14, wherein:
The system of any of Examples 1-15, wherein:
The system of any of Examples 1-16, wherein:
The system of any of Example 1-17, wherein:
The system of any of Examples 1-18, wherein:
The system of any of Examples 1-19, wherein:
The system of any of Examples 1-20, wherein:
The system of any of Examples 1-21, wherein:
The system of any of Examples 1-22, wherein:
A method for cooling a food product using radiant cooling in an open vertical display case, the method comprising:
The method of Example 24, further comprising:
The method of Examples 24 or 25, wherein:
The method of Example 26, further comprising:
The method of Example 27, wherein:
The method of Example 27, wherein:
The method of Example 26, further comprising:
The method of Example 30, wherein:
The method of any of Examples 24-31, further comprising:
The method of any of Examples 24-32, wherein:
The method of any of Examples 24-33, wherein:
The method of Example 34, wherein:
The method of Example 35, wherein:
The method of any of Examples 24-35, wherein:
The method of any of Examples 24-37, wherein:
The method of any of Examples 24-38, wherein:
The method of any of Examples 24-39, wherein:
The method of any of Examples 24-40, wherein:
The method of any of Examples 24-41, wherein:
The method of any of Examples 24-42, wherein:
The method of any of Examples 24-43, wherein:
The method of any of Examples 24-44, wherein:
The method of any of Examples 24-45, wherein:
The foregoing discussion and examples have been presented for purposes of illustration and description. The foregoing is not intended to limit the aspects, embodiments, or configurations to the form or forms disclosed herein. In the foregoing Detailed Description for example, various features of the aspects, embodiments, or configurations are grouped together in one or more embodiments, configurations, or aspects for the purpose of streamlining the disclosure. The features of the aspects, embodiments, or configurations may be combined in alternate aspects, embodiments, or configurations other than those discussed above. This method of disclosure is not to be interpreted as reflecting an intention that the aspects, embodiments, or configurations require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment, configuration, or aspect. While certain aspects of conventional technology have been discussed to facilitate disclosure of some embodiments of the present invention, the Applicants in no way disclaim these technical aspects, and it is contemplated that the claimed invention may encompass one or more of the conventional technical aspects discussed herein. Thus, the following claims are hereby incorporated into this Detailed Description, with each claim standing on its own as a separate aspect, embodiment, or configuration.
This application claims priority to U.S. Provisional Patent Application No. 63/162,074 filed on Mar. 17, 2021, the contents of which are incorporated herein by reference in their entirety.
This invention was made with United States government support under Contract No. DE-AC36-08GO28308 awarded by the U.S. Department of Energy. The United States government has certain rights in this invention.
| Number | Date | Country | |
|---|---|---|---|
| 63162074 | Mar 2021 | US |
