US20080017348A1 - Apparatus for thawing frozen food items - Google Patents
Apparatus for thawing frozen food items Download PDFInfo
- Publication number
- US20080017348A1 US20080017348A1 US11/865,785 US86578507A US2008017348A1 US 20080017348 A1 US20080017348 A1 US 20080017348A1 US 86578507 A US86578507 A US 86578507A US 2008017348 A1 US2008017348 A1 US 2008017348A1
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- United States
- Prior art keywords
- thawing
- food item
- air
- chamber
- flow
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24C—DOMESTIC STOVES OR RANGES ; DETAILS OF DOMESTIC STOVES OR RANGES, OF GENERAL APPLICATION
- F24C15/00—Details
- F24C15/16—Shelves, racks or trays inside ovens; Supports therefor
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24C—DOMESTIC STOVES OR RANGES ; DETAILS OF DOMESTIC STOVES OR RANGES, OF GENERAL APPLICATION
- F24C15/00—Details
- F24C15/32—Arrangements of ducts for hot gases, e.g. in or around baking ovens
- F24C15/322—Arrangements of ducts for hot gases, e.g. in or around baking ovens with forced circulation
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
- F25D23/00—General constructional features
- F25D23/12—Arrangements of compartments additional to cooling compartments; Combinations of refrigerators with other equipment, e.g. stove
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
- F25D25/00—Charging, supporting, and discharging the articles to be cooled
- F25D25/02—Charging, supporting, and discharging the articles to be cooled by shelves
- F25D25/028—Cooled supporting means
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
- F25D31/00—Other cooling or freezing apparatus
- F25D31/005—Combined cooling and heating devices
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
- F25D2317/00—Details or arrangements for circulating cooling fluids; Details or arrangements for circulating gas, e.g. air, within refrigerated spaces, not provided for in other groups of this subclass
- F25D2317/06—Details or arrangements for circulating cooling fluids; Details or arrangements for circulating gas, e.g. air, within refrigerated spaces, not provided for in other groups of this subclass with forced air circulation
- F25D2317/066—Details or arrangements for circulating cooling fluids; Details or arrangements for circulating gas, e.g. air, within refrigerated spaces, not provided for in other groups of this subclass with forced air circulation characterised by the air supply
- F25D2317/0661—Details or arrangements for circulating cooling fluids; Details or arrangements for circulating gas, e.g. air, within refrigerated spaces, not provided for in other groups of this subclass with forced air circulation characterised by the air supply from the bottom
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
- F25D2700/00—Means for sensing or measuring; Sensors therefor
- F25D2700/16—Sensors measuring the temperature of products
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S165/00—Heat exchange
- Y10S165/918—Heated and cooled food cabinets and/or trays
Definitions
- This invention relates generally to thawing or defrosting apparatus and, more particularly, to apparatus for thawing or defrosting frozen foods.
- thawing large frozen food items such as whole turkeys or chickens and large cuts of meat
- thawing in a refrigerator a general rule of thumb is to allow 24 hours of thawing time for every 5 pounds of weight.
- thawing a large frozen food item in a refrigerator can take several days.
- An apparatus for thawing a frozen food item, including a chamber dimensioned to receive the frozen food item, a heat exchanger operable to either heat air in the chamber or to cool the air in the chamber, a fan for creating a flow of the air within the chamber; and a tray disposed in the chamber and having an upper surface adapted to receive and support a lower surface of the frozen food item.
- the tray is adapted to receive a portion of the flow of air and to provide the portion of the flow of air to the lower surface of the food item such that the portion of the flow of air is distributed across the lower surface of the food item and directed upwardly about the food item.
- FIG. 1 is a front view of one embodiment of an apparatus for thawing a frozen food item positioned in a chamber of the apparatus, wherein the apparatus includes a tray positioned within the chamber to receive the frozen food item;
- FIG. 2 is a side cross sectional view of the thawing apparatus of FIG. 1 , wherein the tray has an upper wall having an upper surface to receive the frozen food item;
- FIG. 3 is a side cross sectional view of the thawing apparatus 10 of FIG. 2 wherein the tray includes a cover;
- FIGS. 4A-4D show several different embodiments of the tray of FIG. 2 ;
- FIG. 5 is a diagram of one embodiment of a control system of the thawing apparatus of FIG. 1 ;
- FIGS. 6-9 are graphs illustrating how experimental data can be used to empirically determine values of parameters of information used by the control system of FIG. 5 to effect several predefined thawing cycles.
- FIG. 1 is a front view of one embodiment of an apparatus 10 for thawing a frozen food item 12 positioned in a chamber 14 of the apparatus 10 .
- the food item 12 may be, for example, a whole turkey or chicken, or a large cut of meat such as a brisket or a pot roast.
- the chamber 14 is dimensioned to receive the food item 12 .
- the thawing apparatus 10 can thaw the frozen food item 12 automatically, relatively quickly, and in a way that reduces health risks.
- the food item 12 is thawed within the thawing apparatus 10 by forced convection heating. Once thawed to the extent desired, the food item 12 is maintained at a desired relatively cool temperature, or within a desired cool temperature range, by forced convection cooling.
- the thawing apparatus 10 allows the food item 12 to be thawed in a shorter period of time then if the food item 12 is left standing at room temperature. Additionally, the thawing apparatus 10 avoids spoilage of the food item 12 , once thawed, by maintaining the food item 12 at a relatively cool temperature at which bacteria do not multiply quickly.
- the thawing apparatus 10 is advantageously sized to fit on a typical kitchen countertop in a typical American home. As indicated in FIG. 1 , the thawing apparatus 10 has a width dimension “W.” In one embodiment, the width dimension W of the thawing apparatus 10 is about 12 inches.
- the thawing apparatus 10 has four resilient bumpers or “feet” extending downwardly from corresponding corners of a rectangular underside surface to protect a countertop onto which the thawing apparatus 10 is placed. Two of the resilient bumpers are visible in FIG. 1 , and are labeled 16 A and 16 B.
- the thawing apparatus 10 includes a thermally insulated housing 18 . As shown in FIG. 1 , the chamber 14 is located within the insulated housing 18 , and the insulated housing 18 includes a door in a front wall that provides access to the chamber 14 .
- the thawing apparatus 10 also includes a tray 20 positioned in the chamber 14 .
- the tray 20 has an upper surface 22 adapted to receive and support a lower surface 24 of the food item 12 .
- the lower surface 24 of the food item 12 is in contact with, and supported by, the upper surface 22 of the tray 20 .
- the thawing apparatus 10 includes a fan that creates a flow of air within the chamber 14 .
- the tray 20 receives a portion 26 of the flow of air created by the fan, and provides the portion 26 of the flow of air to the lower surface 24 of the food item 12 such that the portion 26 is distributed across the lower surface 24 of the food item 12 and directed upwardly about the food item 12 as indicated in FIG. 1 .
- the tray 20 includes multiple spaced support posts 28 , wherein upper surfaces of the posts 28 form the upper surface 22 of the tray 20 . Side surfaces of the posts 28 distribute the portion 26 of the flow of air across the lower surface 24 of the food item 12 , and also direct the portion 26 upwardly about the food item 12 . In general, the portion 26 of the flow of air circulates between the posts 28 and across a portion of the lower surface 24 of the food item 12 not resting on the posts 28 .
- the tray 20 may be, for example, removable for cleaning.
- tray 20 Other embodiments of the tray 20 are possible, and several alternate embodiments of the tray 20 are described in detail below. Further, other means of enhancing circulation of the portion 26 of the flow of air across the lower surface 24 of the food item 12 are also possible and contemplated.
- the thawing apparatus 10 includes a heat exchanger operable to either heat air in the chamber 14 or to cool the air in the chamber 14 .
- a heat exchanger operable to either heat air in the chamber 14 or to cool the air in the chamber 14 .
- FIG. 1 Visible in FIG. 1 are an air inlet grate 30 and an air outlet grate 32 in a partition 34 that forms a rear wall of the chamber 14 .
- the flow of air created by the fan passes through the heat exchanger, enters the chamber 14 via the air inlet grate 30 and the tray 20 , and exits the chamber 14 via the air outlet grate 32 .
- the thawing apparatus 10 includes an optional temperature detector 35 for detecting a temperature of an outer surface of the food item 12 .
- the temperature detector 35 may be coupled to a control unit that controls the heat exchanger dependent upon the temperature of the outer surface of the food item 12 .
- the temperature detector 35 may be, for example, a thermocouple probe or an infrared temperature detector. Suitable temperature detectors are commercially available.
- the thawing apparatus 10 operates in a thawing or defrost mode and a cooling mode.
- the food item 12 is thawed or defrosted during the defrost mode.
- the thawing apparatus 10 enters the cooling mode.
- the temperature of the outer surface of the food item 12 is advantageously kept at a relatively low temperature at which bacteria do not multiply quickly. In one embodiment, the outer surface of the food item 12 is kept below about 40 degrees Fahrenheit (deg. F.).
- the thawing apparatus 10 includes a control panel 36 having a defrost mode indicator light 38 , a refrigeration mode indicator light 40 , an optional temperature display 42 , and a keypad 44 .
- the defrost mode indicator light 38 is lighted during the thawing or defrost mode
- the refrigeration mode indicator light 40 is lighted during the cooling mode.
- the temperature display 42 is typically included in the thawing apparatus 10 when the optional temperature detector 35 is present, and may be used to display the temperature of the outer surface of the food item 12 as measured by the temperature detector 35 .
- the keypad 44 is provided to receive user input.
- the user input is used by the thawing apparatus 10 circuitry to determine certain parameters of the defrost mode. For example, in one embodiment described in detail below, the user enters a type of the food item and a weight of the food item via the keypad 44 .
- This user input is used by the thawing apparatus 10 to find a corresponding one of several predefined thawing cycles stored in a memory, and the corresponding thawing cycle is implemented.
- Other information could be input alternatively or additionally to potentially alter the thawing cycle implemented, such as the temperature of the outer surface of the food item 12 during the defrost mode and/or a length of time of the defrost mode, if desired.
- the thawing apparatus 10 could implement a thawing cycle that holds the surface of the food item 12 at or within a certain range of the input temperature and/or completes the thawing cycle in relation to the time input.
- FIG. 2 is a side cross sectional view of the thawing apparatus 10 of FIG. 1 .
- the thawing apparatus 10 is advantageously sized to fit on a typical kitchen countertop in a typical American home.
- the thawing apparatus 10 has a height dimension “H” and a depth dimension “D.”
- the height dimension H of the thawing apparatus 10 is about 10 inches
- the depth dimension D of the thawing apparatus 10 is about 14 inches.
- the fan described above is labeled 50 in FIG. 2
- the heat exchanger described above is labeled 52 in FIG. 2 .
- the flow of air created by the fan 50 passes through the heat exchanger 52 , enters the chamber 14 via the air inlet grate 30 (see FIG. 1 ) and the tray 20 , and exits the chamber 14 via the air outlet grate 32 (see FIG. 1 ).
- the heat exchanger 52 is mounted in a rear wall 55 of the insulated housing 18 .
- the thawing apparatus 10 operates in a thawing or defrost mode and a cooling mode.
- the heat exchanger 52 heats the flow of air produced by the fan 50 during the defrost mode, and cools the flow of air produced by the fan 50 during the cooling mode.
- the heat exchanger 52 is a thermoelectric heat exchanger.
- a suitable thermoelectric heat exchanger is available from Marlow Industries, Inc., 10451 Vista Park Road, Dallas, Tex. 75238.
- the heat exchanger 52 has a portion 56 positioned external the insulated housing 18 .
- the thawing apparatus 10 includes another fan 58 for circulating air about the portion 56 of the heat exchanger 52 external the insulated housing 18 .
- An electric motor 60 drives both the fan 50 for creating the flow of air within the chamber 14 and the fan 58 for circulating the air about the portion 56 of the heat exchanger 52 positioned external the insulated housing 18 .
- the fans 50 and 58 are driven by a single drive shaft 62 extending from the electric motor 60 .
- the fan 50 creates a flow of air within the chamber 14 .
- the tray 20 receives the portion 26 of the flow of air created by the fan 50 , and provides the portion 26 of the flow of air to the lower surface 24 of the food item 12 such that the portion 26 is distributed across the lower surface 24 of the food item 12 and directed upwardly about the food item 12 .
- Another portion 53 of the flow of air created by the fan 50 advantageously flows across an upper surface 54 of the food item 12 .
- the tray 20 has an upper wall 64 having the upper surface 22 and an opposed lower surface 66 .
- the upper wall 64 has multiple holes 68 extending between the upper surface 22 and the lower surface 66 .
- the tray 20 has a plenum 70 extending between two opposed ends. The tray 20 receives the portion 26 of the flow of air created by the fan 50 via the plenum 70 at one of the ends.
- the plenum 70 and the holes 68 in the upper wall 64 distribute the portion 26 of the flow of air across the lower surface 24 of the food item 12 .
- the holes 68 in the upper wall 64 also direct the portion 26 of the flow of air upwardly about the food item 12 as indicated in FIG. 2 .
- the insulated housing 18 includes a door that provides access to the chamber 14 .
- a drain pan 74 positioned at an end of the tray 20 near the door for catching any moisture that condenses on the frozen food item 12 and drips into the tray 20 during the defrost mode.
- FIG. 3 is a side cross sectional view of the thawing apparatus 10 of FIG. 2 wherein the tray 20 includes a cover 80 .
- the cover 80 is adapted to extend over the upper surface 22 of the tray 20 , and to receive the portion 53 of the flow of air created by the fan 50 .
- the cover 80 channels the portion 53 across the upper surface 54 of the food item 12 , helping to maximize contact between the portion 53 of the flow of air and the upper surface 54 .
- the cover 80 has multiple holes 82 extending therethrough to allow flowing air to escape the cover 80 .
- the cover 80 also has a handle 84 positioned in a central portion of an upper surface to facilitate removal of the cover 80 from, and placement of the cover 80 over, the upper surface 22 of the tray 20 .
- FIGS. 4A-4D will now be used to describe several different various embodiments of the tray 20 of FIG. 2 .
- the tray 20 of FIG. 2 includes the upper wall 64 with the upper surface 22 and the opposed lower surface 66 .
- the upper wall 64 has multiple holes 68 extending between the upper surface 22 and the lower surface 66 .
- the upper surface 22 of the tray 20 generally has parallel and alternating ridges 90 and grooves 92 .
- the ridges 90 are substantially triangular in cross section, and are formed by angled surfaces that come together to form linear peaks.
- the grooves 92 between the ridges 90 have substantially flat lowermost (i.e., “bottom”) surfaces.
- the ridges 90 and the grooves 92 both have rounded surfaces, and the ridges 90 and the grooves 92 form a wavy structure.
- the ridges 90 have substantially flat uppermost (i.e., “top”) surfaces, and the grooves 92 have substantially flat lowermost surfaces.
- the ridges 90 have substantially flat uppermost surfaces, and the grooves 92 are formed by angled surfaces that meet to form linear valleys or troughs.
- FIG. 5 is a diagram of one embodiment of a control system 100 of the thawing apparatus 10 of FIG. 1 .
- the control system 100 includes a control unit 102 coupled to a memory 104 and to the keypad 44 (see FIG. 1 ).
- the control unit 102 is also coupled to the heat exchanger 52 (see FIG. 2 ), and to the optional temperature detector 35 (see FIGS. 1-3 ).
- the memory 104 is used to store information of each of multiple predefined thawing cycles 106 .
- the keypad 44 is used to receive user input.
- control unit 102 receives user input via the keypad 44 , and uses the user input to search the memory 104 to find a corresponding one of the predefined thawing cycles 106 .
- the control unit 102 finds the corresponding one of the predefined thawing cycles 106
- the control unit retrieves the information of the corresponding thawing cycle 106 from the memory 104 .
- the control unit 102 generates a control signal dependent upon the information of the corresponding thawing cycle 106 , and provides the control signal to the heat exchanger 52 to effect the corresponding one of the thawing cycles 106 .
- the thawing apparatus 10 When effecting one of the thawing cycles 106 , the thawing apparatus 10 operates in the defrost mode.
- the user input includes a type of the food item and a weight of the food item
- the information of each of the multiple predefined thawing cycles 106 includes a food item type, a food item weight or range of weights, a thawing cycle temperature, and a thawing cycle duration.
- the thawing cycle temperature specifies a temperature of an outer surface of the food item 12 (see FIG. 1 ) to be achieved during the defrost mode
- the thawing cycle duration specifies a duration of the defrost mode.
- control unit 102 searches the memory 104 using the type and weight of the food item to determine the corresponding one of the predefined thawing cycles 106 .
- the corresponding one of the predefined thawing cycles 106 has food item type information that matches, or includes, the food item type of the user input, and food item weight information that matches, or includes, the food item weight of the user input.
- control unit 102 finds the corresponding one of the predefined thawing cycles 106 , the control unit 102 retrieves the thawing cycle temperature and the thawing cycle duration of the corresponding thawing cycle 106 from the memory 104 , and controls the heat exchanger 52 dependent upon the thawing cycle temperature and the thawing cycle duration of the corresponding thawing cycle.
- Values of parameters of the information of the thawing cycles 106 used to effect the thawing cycles 106 may be determined empirically via experimentation, or analytically by applying heat transfer equations.
- the control unit 102 controls the heat exchanger 52 such that the food item 12 is heated until the temperature of the outer surface of the food item 12 is expected to be, based on empirical or analytical methods, or is measured to be, based on input from the optional temperature detector 35 , the thawing cycle temperature retrieved from the corresponding thawing cycle 106 in the memory 104 .
- the thawing cycle temperature is generally about 45 deg. F.
- control unit 102 controls the heat exchanger 52 to keep the outer surface of the food item 12 at approximately the thawing cycle temperature, or within a temperature range about the thawing cycle temperature.
- the thawing apparatus 10 includes the optional temperature detector 35 (see FIGS. 1-3 ), and the control unit 102 is configured to control the heat exchanger 52 dependent upon both the information of the corresponding thawing cycle 106 and the temperature of the outer surface of the food item 12 as detected by the temperature detector 35 .
- the control unit 102 may be configured to control the heat exchanger 52 such that the food item 12 is heated until the temperature of the outer surface of the food item 12 , as measured by the temperature detector 35 , reaches the thawing cycle temperature retrieved from the corresponding thawing cycle 106 in the memory 104 .
- control unit 102 may control the heat exchanger 52 such that the temperature of the outer surface of the food item 12 , as measured by the temperature detector 35 , is substantially maintained at the thawing cycle temperature, or within a temperature range about the thawing cycle temperature.
- the thawing apparatus 10 enters the cooling mode following completion of the defrost mode.
- the temperature of the outer surface of the food item 12 is advantageously kept at a relatively cool temperature (e.g., below about 40 deg. F.) such that bacterial growth is sufficiently slowed.
- the control unit 102 is configured to control the heat exchanger 52 such that following the thawing cycle duration (i.e., following the defrost mode), the control unit 102 controls the heat exchanger 52 such that the outer surface of the food item 12 is expected to be, based on empirical or analytical methods, or is measured to be, based on input from the optional temperature detector 35 , a predefined cooling mode temperature, or within a temperature range about the cooling mode temperature.
- the cooling mode temperature is typically below 40 deg. F.
- Information that specifies the cooling mode temperature may be stored in the memory 104 like, or as part of, the information of the thawing cycles 106 .
- the predefined cooling mode temperature is 38 deg. F. It is noted that 38 deg. F. is approximately the temperature within most American home refrigerators.
- the outer surface of the food item 12 may be maintained at about the cooling mode temperature for a desired period of time, or indefinitely. For example, a user may select a duration of the cooling mode via the keypad 44 .
- the thawing apparatus 10 includes the optional temperature detector 35 (see FIGS. 1-3 ), and during the cooling mode the control unit 102 is configured to control the heat exchanger 52 dependent upon both the predefined cooling mode temperature and the temperature of the outer surface of the food item 12 as detected by the temperature detector 35 .
- the control unit 102 may retrieve the information that specifies the cooling mode temperature from the memory 104 , and control the heat exchanger 52 such that the food item 12 is cooled until the temperature of the outer surface of the food item 12 , as measured by the temperature detector 35 , reaches the cooling mode temperature.
- control unit 102 may control the heat exchanger 52 such that the temperature of the outer surface of the food item 12 , as measured by the temperature detector 35 , is substantially maintained at the cooling mode temperature, or within a temperature range about the cooling mode temperature.
- values of parameters of the information of the thawing cycles 106 used to effect the thawing cycles 106 may be determined empirically via experimentation, or analytically by applying heat transfer equations.
- FIGS. 6-9 are graphs illustrating how experimental data can be used to empirically determine values of parameters of the information of the multiple predefined thawing cycles 106 of FIG. 5 .
- the data of FIGS. 6-9 may be used to generate the predefined thawing cycles 106 of FIG. 5 .
- FIG. 6 is a graph of temperature versus time obtained during a thawing operation, wherein 1 pound of beef was thawed in a prototype of the thawing apparatus 10 of FIG. 1 .
- the graph of FIG. 6 includes a first curve of a temperature at an exterior location of the meat during the thawing, and a second curve of a temperature in a middle portion of the meat during the thawing.
- FIG. 7 is a graph of temperature versus time obtained during a thawing operation wherein 1 pound of beef was thawed at 22 degrees Celsius (71.6 deg. F.) on a flat surface using natural convection.
- the graph of FIG. 7 includes a first curve of a temperature at an exterior location of the meat during the thawing, a second curve of a temperature in a middle portion of the meat during the thawing, and a third curve of a temperature at a bottom portion of the meat during the thawing.
- the data of FIG. 7 may be used to determine how long it takes 1 pound of beef to thaw on a kitchen countertop at room temperature. This thawing time may be used as a thawing time baseline.
- FIG. 8 is a graph of temperature versus time obtained during a thawing operation wherein 1 pound of beef was thawed in a prototype of the thawing apparatus 10 of FIG. 1 , without the tray 20 .
- a bottom portion of the meat was positioned on a flat bottom surface the chamber 14 (see FIG. 1 ), the air within the chamber 14 was maintained at 16 degrees Celsius (60.8 deg. F.), and forced air convection was employed.
- FIG. 8 includes a first curve of a temperature at an exterior location of the meat during the thawing, a second curve of a temperature in a middle portion of the meat during the thawing, and a third curve of a temperature at the bottom portion of the meat during the thawing.
- FIG. 8 may be used to show that inclusion of the tray 20 , and the resulting exposure of more surfaces of the meat to forced air convection, significantly reduces thawing time over simply placing the meat on the flat bottom surface.
- FIG. 9 is a graph of temperature versus time obtained during a thawing operation wherein 1 pound of beef was thawed in a prototype of the thawing apparatus 10 of FIG. 1 , without the tray 20 , and wherein the meat was elevated 1 inch above a flat bottom surface of the chamber 14 .
- the air within the chamber 14 was maintained at 24 degrees Celsius (75.2 deg. F), and forced air convection was employed.
- FIG. 9 includes a first curve of a temperature of air entering the chamber 14 (i.e., air outlet temperature), a second curve of a temperature of the air in the chamber 14 , a third curve of a temperature at a location on the exterior of the meat during the thawing, and a fourth curve of a temperature in a middle portion of the meat during the thawing.
- FIG. 9 may be used to show that inclusion of the tray 20 , and the resulting exposure of more surfaces of the meat to the forced convection, reduces thawing time over simply elevating the meat above the flat bottom surface.
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- Combustion & Propulsion (AREA)
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- Thermal Sciences (AREA)
- Freezing, Cooling And Drying Of Foods (AREA)
Abstract
An apparatus is disclosed for thawing a frozen food item, including a chamber dimensioned to receive the frozen food item, a heat exchanger operable to either heat air in the chamber or to cool the air in the chamber, a fan for creating a flow of the air within the chamber; and a tray disposed in the chamber and having an upper surface adapted to receive and support a lower surface of the frozen food item. The tray is adapted to receive a portion of the flow of air and to provide the portion of the flow of air to the lower surface of the food item such that the portion of the flow of air is distributed across the lower surface of the food item and directed upwardly about the food item.
Description
- This application is a continuation of U.S. patent application Ser. No. 11/174,912 entitled APPARATUS FOR THAWING FROZEN FOOD ITEMS filed Jul. 5, 2005, which claims priority to U.S. Provisional Application entitled THERMO-ELECTRIC DEFROSTER AND THAWING SYSTEM, Ser. No. 60/646,899, filed Jan. 25, 2005.
- 1. Field of the Invention
- This invention relates generally to thawing or defrosting apparatus and, more particularly, to apparatus for thawing or defrosting frozen foods.
- 2. Description of the Related Art
- Recommended methods for thawing large frozen food items, such as whole turkeys or chickens and large cuts of meat, include thawing in a refrigerator and thawing in cold water. When thawing a large frozen food item in a refrigerator, a general rule of thumb is to allow 24 hours of thawing time for every 5 pounds of weight. As a result, thawing a large frozen food item in a refrigerator can take several days.
- While thawing a large frozen food item in cold water is significantly faster (about 2.5 hours for every 5 pounds), the water must be changed about every half hour. Thus the cold water thawing method requires frequent attention over several hours.
- If a large frozen food item is left on a kitchen counter to thaw at room temperature, about 70 degrees Fahrenheit (deg. F.), part of the frozen food item often warms to over 40 deg. F. over time, allowing bacteria to multiply quickly and creating a health hazard.
- It would be beneficial to have an apparatus for thawing frozen food items that works automatically, relatively quickly, and in a way that reduces health risks.
- An apparatus is disclosed for thawing a frozen food item, including a chamber dimensioned to receive the frozen food item, a heat exchanger operable to either heat air in the chamber or to cool the air in the chamber, a fan for creating a flow of the air within the chamber; and a tray disposed in the chamber and having an upper surface adapted to receive and support a lower surface of the frozen food item. The tray is adapted to receive a portion of the flow of air and to provide the portion of the flow of air to the lower surface of the food item such that the portion of the flow of air is distributed across the lower surface of the food item and directed upwardly about the food item.
- For a more complete understanding of the present invention and the advantages thereof, reference is now made to the following Detailed Description taken in conjunction with the accompanying drawings, in which:
-
FIG. 1 is a front view of one embodiment of an apparatus for thawing a frozen food item positioned in a chamber of the apparatus, wherein the apparatus includes a tray positioned within the chamber to receive the frozen food item; -
FIG. 2 is a side cross sectional view of the thawing apparatus ofFIG. 1 , wherein the tray has an upper wall having an upper surface to receive the frozen food item; -
FIG. 3 is a side cross sectional view of thethawing apparatus 10 ofFIG. 2 wherein the tray includes a cover; -
FIGS. 4A-4D show several different embodiments of the tray ofFIG. 2 ; -
FIG. 5 is a diagram of one embodiment of a control system of the thawing apparatus ofFIG. 1 ; and -
FIGS. 6-9 are graphs illustrating how experimental data can be used to empirically determine values of parameters of information used by the control system ofFIG. 5 to effect several predefined thawing cycles. - In the following discussion, numerous specific details are set forth to provide a thorough understanding of the present invention. However, those skilled in the art will appreciate that the present invention may be practiced without such specific details. In other instances, well-known elements have been illustrated in schematic or block diagram form in order not to obscure the present invention in unnecessary detail. Additionally, for the most part, details concerning network communications, electromagnetic signaling techniques, and the like, have been omitted inasmuch as such details are not considered necessary to obtain a complete understanding of the present invention, and are considered to be within the understanding of persons of ordinary skill in the relevant art.
- It noted that, unless indicated otherwise, all functions described herein may be performed in either hardware or software, or some combination thereof. In a preferred embodiment, however, the functions are performed by a processor, such as a computer or an electronic data processor, in accordance with code, such as computer program code, software, and/or integrated circuits that are coded to perform such functions, unless indicated otherwise.
-
FIG. 1 is a front view of one embodiment of anapparatus 10 for thawing a frozenfood item 12 positioned in achamber 14 of theapparatus 10. Thefood item 12 may be, for example, a whole turkey or chicken, or a large cut of meat such as a brisket or a pot roast. In general, thechamber 14 is dimensioned to receive thefood item 12. - The
thawing apparatus 10 can thaw the frozenfood item 12 automatically, relatively quickly, and in a way that reduces health risks. In general, thefood item 12 is thawed within thethawing apparatus 10 by forced convection heating. Once thawed to the extent desired, thefood item 12 is maintained at a desired relatively cool temperature, or within a desired cool temperature range, by forced convection cooling. Thethawing apparatus 10 allows thefood item 12 to be thawed in a shorter period of time then if thefood item 12 is left standing at room temperature. Additionally, thethawing apparatus 10 avoids spoilage of thefood item 12, once thawed, by maintaining thefood item 12 at a relatively cool temperature at which bacteria do not multiply quickly. - In the embodiment of
FIG. 1 , thethawing apparatus 10 is advantageously sized to fit on a typical kitchen countertop in a typical American home. As indicated inFIG. 1 , thethawing apparatus 10 has a width dimension “W.” In one embodiment, the width dimension W of thethawing apparatus 10 is about 12 inches. Thethawing apparatus 10 has four resilient bumpers or “feet” extending downwardly from corresponding corners of a rectangular underside surface to protect a countertop onto which thethawing apparatus 10 is placed. Two of the resilient bumpers are visible inFIG. 1 , and are labeled 16A and 16B. - In the embodiment of
FIG. 1 , thethawing apparatus 10 includes a thermally insulatedhousing 18. As shown inFIG. 1 , thechamber 14 is located within theinsulated housing 18, and theinsulated housing 18 includes a door in a front wall that provides access to thechamber 14. Thethawing apparatus 10 also includes atray 20 positioned in thechamber 14. In general, thetray 20 has anupper surface 22 adapted to receive and support alower surface 24 of thefood item 12. InFIG. 1 , thelower surface 24 of thefood item 12 is in contact with, and supported by, theupper surface 22 of thetray 20. - As described in more detail below, the
thawing apparatus 10 includes a fan that creates a flow of air within thechamber 14. In general, thetray 20 receives aportion 26 of the flow of air created by the fan, and provides theportion 26 of the flow of air to thelower surface 24 of thefood item 12 such that theportion 26 is distributed across thelower surface 24 of thefood item 12 and directed upwardly about thefood item 12 as indicated inFIG. 1 . - In the embodiment of
FIG. 1 , thetray 20 includes multiple spacedsupport posts 28, wherein upper surfaces of theposts 28 form theupper surface 22 of thetray 20. Side surfaces of theposts 28 distribute theportion 26 of the flow of air across thelower surface 24 of thefood item 12, and also direct theportion 26 upwardly about thefood item 12. In general, theportion 26 of the flow of air circulates between theposts 28 and across a portion of thelower surface 24 of thefood item 12 not resting on theposts 28. Thetray 20 may be, for example, removable for cleaning. - Other embodiments of the
tray 20 are possible, and several alternate embodiments of thetray 20 are described in detail below. Further, other means of enhancing circulation of theportion 26 of the flow of air across thelower surface 24 of thefood item 12 are also possible and contemplated. - As described in more detail below, the
thawing apparatus 10 includes a heat exchanger operable to either heat air in thechamber 14 or to cool the air in thechamber 14. Visible inFIG. 1 are anair inlet grate 30 and anair outlet grate 32 in apartition 34 that forms a rear wall of thechamber 14. The flow of air created by the fan passes through the heat exchanger, enters thechamber 14 via theair inlet grate 30 and thetray 20, and exits thechamber 14 via theair outlet grate 32. - In the embodiment of
FIG. 1 , thethawing apparatus 10 includes anoptional temperature detector 35 for detecting a temperature of an outer surface of thefood item 12. When included in thethawing apparatus 10, thetemperature detector 35 may be coupled to a control unit that controls the heat exchanger dependent upon the temperature of the outer surface of thefood item 12. Thetemperature detector 35 may be, for example, a thermocouple probe or an infrared temperature detector. Suitable temperature detectors are commercially available. - In the embodiment of
FIG. 1 , thethawing apparatus 10 operates in a thawing or defrost mode and a cooling mode. In general, thefood item 12 is thawed or defrosted during the defrost mode. Following completion of the defrost mode, thethawing apparatus 10 enters the cooling mode. During the cooling mode, the temperature of the outer surface of thefood item 12 is advantageously kept at a relatively low temperature at which bacteria do not multiply quickly. In one embodiment, the outer surface of thefood item 12 is kept below about 40 degrees Fahrenheit (deg. F.). - In the embodiment of
FIG. 1 , thethawing apparatus 10 includes acontrol panel 36 having a defrostmode indicator light 38, a refrigerationmode indicator light 40, anoptional temperature display 42, and akeypad 44. In general, the defrostmode indicator light 38 is lighted during the thawing or defrost mode, and the refrigerationmode indicator light 40 is lighted during the cooling mode. Thetemperature display 42 is typically included in thethawing apparatus 10 when theoptional temperature detector 35 is present, and may be used to display the temperature of the outer surface of thefood item 12 as measured by thetemperature detector 35. - The
keypad 44 is provided to receive user input. Generally speaking, the user input is used by thethawing apparatus 10 circuitry to determine certain parameters of the defrost mode. For example, in one embodiment described in detail below, the user enters a type of the food item and a weight of the food item via thekeypad 44. This user input is used by thethawing apparatus 10 to find a corresponding one of several predefined thawing cycles stored in a memory, and the corresponding thawing cycle is implemented. Other information could be input alternatively or additionally to potentially alter the thawing cycle implemented, such as the temperature of the outer surface of thefood item 12 during the defrost mode and/or a length of time of the defrost mode, if desired. In such cases, thethawing apparatus 10 could implement a thawing cycle that holds the surface of thefood item 12 at or within a certain range of the input temperature and/or completes the thawing cycle in relation to the time input. -
FIG. 2 is a side cross sectional view of thethawing apparatus 10 ofFIG. 1 . As described above, thethawing apparatus 10 is advantageously sized to fit on a typical kitchen countertop in a typical American home. As indicated inFIG. 2 , thethawing apparatus 10 has a height dimension “H” and a depth dimension “D.” In one embodiment, the height dimension H of thethawing apparatus 10 is about 10 inches, and the depth dimension D of thethawing apparatus 10 is about 14 inches. - The fan described above is labeled 50 in
FIG. 2 , and the heat exchanger described above is labeled 52 inFIG. 2 . As described above, the flow of air created by thefan 50 passes through theheat exchanger 52, enters thechamber 14 via the air inlet grate 30 (seeFIG. 1 ) and thetray 20, and exits thechamber 14 via the air outlet grate 32 (seeFIG. 1 ). - In the embodiment of
FIGS. 1 and 2 , theheat exchanger 52 is mounted in arear wall 55 of theinsulated housing 18. As described above, thethawing apparatus 10 operates in a thawing or defrost mode and a cooling mode. In general, theheat exchanger 52 heats the flow of air produced by thefan 50 during the defrost mode, and cools the flow of air produced by thefan 50 during the cooling mode. In one embodiment, theheat exchanger 52 is a thermoelectric heat exchanger. A suitable thermoelectric heat exchanger is available from Marlow Industries, Inc., 10451 Vista Park Road, Dallas, Tex. 75238. - In the embodiment of
FIGS. 1 and 2 , theheat exchanger 52 has aportion 56 positioned external theinsulated housing 18. Thethawing apparatus 10 includes anotherfan 58 for circulating air about theportion 56 of theheat exchanger 52 external theinsulated housing 18. Anelectric motor 60 drives both thefan 50 for creating the flow of air within thechamber 14 and thefan 58 for circulating the air about theportion 56 of theheat exchanger 52 positioned external theinsulated housing 18. Thefans single drive shaft 62 extending from theelectric motor 60. - As described above, the
fan 50 creates a flow of air within thechamber 14. Thetray 20 receives theportion 26 of the flow of air created by thefan 50, and provides theportion 26 of the flow of air to thelower surface 24 of thefood item 12 such that theportion 26 is distributed across thelower surface 24 of thefood item 12 and directed upwardly about thefood item 12. Anotherportion 53 of the flow of air created by thefan 50 advantageously flows across anupper surface 54 of thefood item 12. By splitting the flow of air created by thefan 50 into portions, and causing or directing the portions to flow across different surfaces of thefood item 12, thefrozen food item 12 can be thawed in significantly less time. - In the embodiment of
FIG. 2 , thetray 20 has anupper wall 64 having theupper surface 22 and an opposedlower surface 66. Theupper wall 64 hasmultiple holes 68 extending between theupper surface 22 and thelower surface 66. Thetray 20 has aplenum 70 extending between two opposed ends. Thetray 20 receives theportion 26 of the flow of air created by thefan 50 via theplenum 70 at one of the ends. Theplenum 70 and theholes 68 in theupper wall 64 distribute theportion 26 of the flow of air across thelower surface 24 of thefood item 12. Theholes 68 in theupper wall 64 also direct theportion 26 of the flow of air upwardly about thefood item 12 as indicated inFIG. 2 . - As described above, the
insulated housing 18 includes a door that provides access to thechamber 14. Ahandle 72 attached to the door, and used to open and close the door, is shown inFIG. 2 . Also shown inFIG. 2 is adrain pan 74 positioned at an end of thetray 20 near the door for catching any moisture that condenses on thefrozen food item 12 and drips into thetray 20 during the defrost mode. -
FIG. 3 is a side cross sectional view of thethawing apparatus 10 ofFIG. 2 wherein thetray 20 includes acover 80. In general, thecover 80 is adapted to extend over theupper surface 22 of thetray 20, and to receive theportion 53 of the flow of air created by thefan 50. Thecover 80 channels theportion 53 across theupper surface 54 of thefood item 12, helping to maximize contact between theportion 53 of the flow of air and theupper surface 54. In the embodiment ofFIG. 3 , thecover 80 hasmultiple holes 82 extending therethrough to allow flowing air to escape thecover 80. Thecover 80 also has ahandle 84 positioned in a central portion of an upper surface to facilitate removal of thecover 80 from, and placement of thecover 80 over, theupper surface 22 of thetray 20. -
FIGS. 4A-4D will now be used to describe several different various embodiments of thetray 20 ofFIG. 2 . As described above, thetray 20 ofFIG. 2 includes theupper wall 64 with theupper surface 22 and the opposedlower surface 66. Theupper wall 64 hasmultiple holes 68 extending between theupper surface 22 and thelower surface 66. InFIGS. 4A-4D , theupper surface 22 of thetray 20 generally has parallel and alternatingridges 90 andgrooves 92. - In the embodiment of
FIG. 4A , theridges 90 are substantially triangular in cross section, and are formed by angled surfaces that come together to form linear peaks. Thegrooves 92 between theridges 90 have substantially flat lowermost (i.e., “bottom”) surfaces. In the embodiment ofFIG. 4B , theridges 90 and thegrooves 92 both have rounded surfaces, and theridges 90 and thegrooves 92 form a wavy structure. In the embodiment ofFIG. 4C , theridges 90 have substantially flat uppermost (i.e., “top”) surfaces, and thegrooves 92 have substantially flat lowermost surfaces. In the embodiment ofFIG. 4D , theridges 90 have substantially flat uppermost surfaces, and thegrooves 92 are formed by angled surfaces that meet to form linear valleys or troughs. -
FIG. 5 is a diagram of one embodiment of acontrol system 100 of thethawing apparatus 10 ofFIG. 1 . In the embodiment ofFIG. 5 , thecontrol system 100 includes acontrol unit 102 coupled to amemory 104 and to the keypad 44 (seeFIG. 1 ). Thecontrol unit 102 is also coupled to the heat exchanger 52 (seeFIG. 2 ), and to the optional temperature detector 35 (seeFIGS. 1-3 ). In the embodiment ofFIG. 5 , thememory 104 is used to store information of each of multiple predefined thawing cycles 106. As described above, thekeypad 44 is used to receive user input. - In general, the
control unit 102 receives user input via thekeypad 44, and uses the user input to search thememory 104 to find a corresponding one of the predefined thawing cycles 106. When thecontrol unit 102 finds the corresponding one of the predefined thawing cycles 106, the control unit retrieves the information of thecorresponding thawing cycle 106 from thememory 104. In general, thecontrol unit 102 generates a control signal dependent upon the information of thecorresponding thawing cycle 106, and provides the control signal to theheat exchanger 52 to effect the corresponding one of the thawing cycles 106. - When effecting one of the thawing cycles 106, the
thawing apparatus 10 operates in the defrost mode. In one embodiment, the user input includes a type of the food item and a weight of the food item, and the information of each of the multiple predefined thawing cycles 106 includes a food item type, a food item weight or range of weights, a thawing cycle temperature, and a thawing cycle duration. In one embodiment, the thawing cycle temperature specifies a temperature of an outer surface of the food item 12 (seeFIG. 1 ) to be achieved during the defrost mode, and the thawing cycle duration specifies a duration of the defrost mode. - In one embodiment, the
control unit 102 searches thememory 104 using the type and weight of the food item to determine the corresponding one of the predefined thawing cycles 106. In general, the corresponding one of the predefined thawing cycles 106 has food item type information that matches, or includes, the food item type of the user input, and food item weight information that matches, or includes, the food item weight of the user input. When thecontrol unit 102 finds the corresponding one of the predefined thawing cycles 106, thecontrol unit 102 retrieves the thawing cycle temperature and the thawing cycle duration of thecorresponding thawing cycle 106 from thememory 104, and controls theheat exchanger 52 dependent upon the thawing cycle temperature and the thawing cycle duration of the corresponding thawing cycle. - Values of parameters of the information of the thawing cycles 106 used to effect the thawing cycles 106, such as thawing cycle temperature and thawing cycle duration, may be determined empirically via experimentation, or analytically by applying heat transfer equations. In general, to effect the corresponding one of the thawing cycles 106, the
control unit 102 controls theheat exchanger 52 such that thefood item 12 is heated until the temperature of the outer surface of thefood item 12 is expected to be, based on empirical or analytical methods, or is measured to be, based on input from theoptional temperature detector 35, the thawing cycle temperature retrieved from thecorresponding thawing cycle 106 in thememory 104. The thawing cycle temperature is generally about 45 deg. F. Once the outer surface of thefood item 12 reaches the thawing cycle temperature, thecontrol unit 102 controls theheat exchanger 52 to keep the outer surface of thefood item 12 at approximately the thawing cycle temperature, or within a temperature range about the thawing cycle temperature. - In one embodiment, the
thawing apparatus 10 includes the optional temperature detector 35 (seeFIGS. 1-3 ), and thecontrol unit 102 is configured to control theheat exchanger 52 dependent upon both the information of thecorresponding thawing cycle 106 and the temperature of the outer surface of thefood item 12 as detected by thetemperature detector 35. For example, during the defrost mode, thecontrol unit 102 may be configured to control theheat exchanger 52 such that thefood item 12 is heated until the temperature of the outer surface of thefood item 12, as measured by thetemperature detector 35, reaches the thawing cycle temperature retrieved from thecorresponding thawing cycle 106 in thememory 104. Further, once the temperature of the outer surface of thefood item 12 reaches the thawing cycle temperature during the defrost mode, thecontrol unit 102 may control theheat exchanger 52 such that the temperature of the outer surface of thefood item 12, as measured by thetemperature detector 35, is substantially maintained at the thawing cycle temperature, or within a temperature range about the thawing cycle temperature. - As described above, the
thawing apparatus 10 enters the cooling mode following completion of the defrost mode. During the cooling mode, the temperature of the outer surface of thefood item 12 is advantageously kept at a relatively cool temperature (e.g., below about 40 deg. F.) such that bacterial growth is sufficiently slowed. In general, thecontrol unit 102 is configured to control theheat exchanger 52 such that following the thawing cycle duration (i.e., following the defrost mode), thecontrol unit 102 controls theheat exchanger 52 such that the outer surface of thefood item 12 is expected to be, based on empirical or analytical methods, or is measured to be, based on input from theoptional temperature detector 35, a predefined cooling mode temperature, or within a temperature range about the cooling mode temperature. As described above, the cooling mode temperature is typically below 40 deg. F. Information that specifies the cooling mode temperature may be stored in thememory 104 like, or as part of, the information of the thawing cycles 106. - In one embodiment, the predefined cooling mode temperature is 38 deg. F. It is noted that 38 deg. F. is approximately the temperature within most American home refrigerators. The outer surface of the
food item 12 may be maintained at about the cooling mode temperature for a desired period of time, or indefinitely. For example, a user may select a duration of the cooling mode via thekeypad 44. - In one embodiment, the
thawing apparatus 10 includes the optional temperature detector 35 (seeFIGS. 1-3 ), and during the cooling mode thecontrol unit 102 is configured to control theheat exchanger 52 dependent upon both the predefined cooling mode temperature and the temperature of the outer surface of thefood item 12 as detected by thetemperature detector 35. For example, after the completion of the defrost mode, thecontrol unit 102 may retrieve the information that specifies the cooling mode temperature from thememory 104, and control theheat exchanger 52 such that thefood item 12 is cooled until the temperature of the outer surface of thefood item 12, as measured by thetemperature detector 35, reaches the cooling mode temperature. Further, once the temperature of the outer surface of thefood item 12 reaches the cooling mode temperature during the cooling mode, thecontrol unit 102 may control theheat exchanger 52 such that the temperature of the outer surface of thefood item 12, as measured by thetemperature detector 35, is substantially maintained at the cooling mode temperature, or within a temperature range about the cooling mode temperature. - As described above, values of parameters of the information of the thawing cycles 106 used to effect the thawing cycles 106 may be determined empirically via experimentation, or analytically by applying heat transfer equations.
FIGS. 6-9 are graphs illustrating how experimental data can be used to empirically determine values of parameters of the information of the multiple predefined thawing cycles 106 ofFIG. 5 . In general, the data ofFIGS. 6-9 may be used to generate the predefined thawing cycles 106 ofFIG. 5 . -
FIG. 6 is a graph of temperature versus time obtained during a thawing operation, wherein 1 pound of beef was thawed in a prototype of thethawing apparatus 10 ofFIG. 1 . During the thawing operation, the air within the chamber 14 (seeFIG. 1 ) was maintained at 24 degrees Celsius (75.2 deg. F.). The graph ofFIG. 6 includes a first curve of a temperature at an exterior location of the meat during the thawing, and a second curve of a temperature in a middle portion of the meat during the thawing. -
FIG. 7 is a graph of temperature versus time obtained during a thawing operation wherein 1 pound of beef was thawed at 22 degrees Celsius (71.6 deg. F.) on a flat surface using natural convection. The graph ofFIG. 7 includes a first curve of a temperature at an exterior location of the meat during the thawing, a second curve of a temperature in a middle portion of the meat during the thawing, and a third curve of a temperature at a bottom portion of the meat during the thawing. The data ofFIG. 7 may be used to determine how long it takes 1 pound of beef to thaw on a kitchen countertop at room temperature. This thawing time may be used as a thawing time baseline. -
FIG. 8 is a graph of temperature versus time obtained during a thawing operation wherein 1 pound of beef was thawed in a prototype of thethawing apparatus 10 ofFIG. 1 , without thetray 20. During the thawing operation, a bottom portion of the meat was positioned on a flat bottom surface the chamber 14 (seeFIG. 1 ), the air within thechamber 14 was maintained at 16 degrees Celsius (60.8 deg. F.), and forced air convection was employed. The graph ofFIG. 8 includes a first curve of a temperature at an exterior location of the meat during the thawing, a second curve of a temperature in a middle portion of the meat during the thawing, and a third curve of a temperature at the bottom portion of the meat during the thawing.FIG. 8 may be used to show that inclusion of thetray 20, and the resulting exposure of more surfaces of the meat to forced air convection, significantly reduces thawing time over simply placing the meat on the flat bottom surface. -
FIG. 9 is a graph of temperature versus time obtained during a thawing operation wherein 1 pound of beef was thawed in a prototype of thethawing apparatus 10 ofFIG. 1 , without thetray 20, and wherein the meat was elevated 1 inch above a flat bottom surface of thechamber 14. During the thawing operation, the air within thechamber 14 was maintained at 24 degrees Celsius (75.2 deg. F), and forced air convection was employed. The graph ofFIG. 9 includes a first curve of a temperature of air entering the chamber 14 (i.e., air outlet temperature), a second curve of a temperature of the air in thechamber 14, a third curve of a temperature at a location on the exterior of the meat during the thawing, and a fourth curve of a temperature in a middle portion of the meat during the thawing.FIG. 9 may be used to show that inclusion of thetray 20, and the resulting exposure of more surfaces of the meat to the forced convection, reduces thawing time over simply elevating the meat above the flat bottom surface. - Having thus described the present invention by reference to certain of its preferred embodiments, it is noted that the embodiments disclosed are illustrative rather than limiting in nature and that a wide range of variations, modifications, changes, and substitutions are contemplated in the foregoing disclosure and, in some instances, some features of the present invention may be employed without a corresponding use of the other features. Many such variations and modifications may be considered desirable by those skilled in the art based upon a review of the foregoing description of preferred embodiments. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention.
Claims (6)
1. An apparatus for thawing a frozen food item, comprising:
a chamber dimensioned to receive the food item;
a heat exchanger operable to selectively heat or cool the chamber;
a fan configured to create a flow of air in the chamber; and
a support structure comprising one or more surfaces configured to support a lower surface of the food item in the chamber, and to restrict and to direct at least a portion of the flow of air to the lower surface of the food item.
2. The apparatus of clam 1 wherein the support structure comprises a plurality of ridges selected from the group consisting of substantially flat top ridges, rounded top ridges, and substantially triangular top ridges.
3. The apparatus of clam 1 wherein at least one of the surfaces comprises one or more openings, through which at least a portion of the flow of air is directed.
4. The apparatus of clam 1 further comprising a drain pan configured to catch moisture dripping from the support structure.
5. An apparatus for thawing a frozen food item, comprising:
a chamber dimensioned to receive the food item;
a fan for creating a flow of air in the chamber; and
a heat exchanger operable to selectively heat or cool at least a portion of the flow of air, wherein the heat exchanger is disposed in at least a portion of the flow of air, upstream of the fan.
6. An apparatus for thawing a frozen food item, comprising:
a chamber dimensioned to receive the food item;
a fan for creating a flow of air in the chamber;
a partition configured to separate the flow of air from the chamber and direct the flow of air through at least a portion of the heat exchanger prior to reaching the fan; and
a heat exchanger operable to selectively heat or cool at least a portion of the flow of air.
Priority Applications (1)
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US11/865,785 US20080017348A1 (en) | 2005-01-25 | 2007-10-02 | Apparatus for thawing frozen food items |
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US64689905P | 2005-01-25 | 2005-01-25 | |
US11/174,912 US7348522B1 (en) | 2005-01-25 | 2005-07-05 | Apparatus for thawing frozen food items |
US11/865,785 US20080017348A1 (en) | 2005-01-25 | 2007-10-02 | Apparatus for thawing frozen food items |
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US11/174,912 Continuation US7348522B1 (en) | 2005-01-25 | 2005-07-05 | Apparatus for thawing frozen food items |
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US11/865,785 Abandoned US20080017348A1 (en) | 2005-01-25 | 2007-10-02 | Apparatus for thawing frozen food items |
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US11/174,912 Expired - Fee Related US7348522B1 (en) | 2005-01-25 | 2005-07-05 | Apparatus for thawing frozen food items |
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Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20150285552A1 (en) * | 2014-04-07 | 2015-10-08 | General Electric Company | Refrigerator appliance and a method for defrosting a food item |
EP3364113A1 (en) * | 2017-02-21 | 2018-08-22 | BSH Hausgeräte GmbH | Cooking device with a blow opening |
DE102017218977A1 (en) | 2017-10-24 | 2019-04-25 | BSH Hausgeräte GmbH | Domestic refrigerating appliance with a thawing compartment and method for operating such a household refrigerating appliance |
DE102018201813A1 (en) | 2018-02-06 | 2019-08-08 | BSH Hausgeräte GmbH | Domestic refrigerating appliance with a thawing compartment and method for operating such a household refrigerating appliance |
WO2019154692A1 (en) | 2018-02-06 | 2019-08-15 | BSH Hausgeräte GmbH | Domestic refrigeration appliance having a defrosting compartment and method for operating a domestic refrigeration appliance of this type |
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