Abstract:
An apparatus and method for thawing a product. The apparatus includes a heating chamber, and an electrical control unit. The heating chamber includes a product chamber that holds a product, at least one heating element, each heating element emitting infrared energy in a direction of the product, and at least one temperature sensor, each temperature sensor measuring a surface temperature of the product. The electrical control unit includes a processor that controls and monitors said at least one heating element, and said at least one temperature sensor to raise a temperature of the product from an initial temperature to a set-point temperature, a connection to each heating element, and a connection to each temperature sensor.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates, in general, to the field of radiant heating devices. In particular, the present invention relates to an apparatus that thaws a product with infrared energy. 
     2. Description of the Related Art 
     Health care facilities use medical products, such as plasma, Fresh Frozen Plasma, blood, and the like, at surgery centers and urgent care facilities. It is a common practice to freeze the product in its sealed prepackaged plastic pouches for storage, and thaw it when necessary. The prior art describes a wet-bath heating system for thawing the frozen product. A health care professional places the frozen product into a temperature-controlled water bath to thaw it to a liquid state. After thawing the product, a health care professional removes it from the water bath, and places it in a temperature-controlled area for use anytime during the next twenty-four hour period. 
     The prior art wet-bath heating system has certain flaws. Since these prior art systems submerge the medical product in the water bath, there is contact between the heating system and the product. This contact provides the potential for system contamination. If the water bath is contaminated with bacteria, even though the plastic pouch provides a barrier against direct contamination of the contents of the pouch, water from the bath may seep into contact with an inlet end of a connector tube for the pouch. Bacteria in or near a connector tube creates the possibility that when the connector tube seal is punctured, the contents may contact the bacteria, thereby contaminating the contents. A prior art method avoids this class of contamination by placing the pouch to be thawed inside another pouch. Unfortunately, this solution may increase the time required to thaw the contents due to the increased thickness of the plastic in the double-walled pouch, and the double-walled pouch configuration may cause the inner pouch to float. Another drawback of the prior art wet-bath heating system is that if pouch ruptures, the water bath is contaminated and must be sanitized before it can be used again. 
     Infrared radiators (emitters) use electromagnetic radiation to transfer heat from an energy source to an object. The transfer of the heat occurs without the need for any contact between the emitter and the object, or any transfer medium between the emitter and the object. The wavelength of the infrared radiation ranges from 780 nm to 1 mm, with mid-infrared in the range from 780 nm to 1400 nm, medium infrared in the range between 1400 nm and 3000 nm, and far infrared or dark emitters for everything above 3000 nm. 
     Thus, there is a need for a heating device that utilizes infrared energy to thaw a product, reduces the time to thaw the product, and maintains separation between the heating system and the pouch to reduce the potential for contamination. The present invention addresses this need. 
     SUMMARY OF THE INVENTION 
     Aspects of the present invention provide an apparatus and method for thawing a product. The apparatus includes a heating chamber, and an electrical control unit. The heating chamber includes a product chamber that holds a product, at least one heating element, each heating element emitting infrared energy in a direction of the product, and at least one temperature sensor, each temperature sensor measuring a surface temperature of the product. The electrical control unit includes a processor that controls and monitors said at least one heating element, and said at least one temperature sensor to raise a temperature of the product from an initial temperature to a set-point temperature, a connection to each heating element, and a connection to each temperature sensor. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of one exemplary embodiment of an apparatus in accordance with the present invention. 
         FIG. 2  is another perspective view of the apparatus shown in  FIG. 1 . 
         FIG. 3  is a top elevation view, in cross section of the apparatus shown in  FIG. 1 . 
         FIG. 4  is a block diagram that illustrates, in detail, one embodiment of the control circuits for the apparatus shown in  FIG. 3 . 
         FIG. 5  is a flow diagram that illustrates methods according to various embodiments of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  is a perspective view of one exemplary embodiment of an apparatus in accordance with the present invention. The thawing unit  100  shown in  FIG. 1  is a self-contained apparatus that is capable of thawing a product, such as plasma, Fresh Frozen Plasma, blood, and other biological products, or the like. The thawing unit  100  comprises an enclosure  110 , a front cover  120 , a chamber door support  130 , and a chamber door  140  that enclose a heating chamber and an electrical control unit. 
     The enclosure  110  is an outer cover that encloses the bottom, three sides, and the top of the thawing unit  100  with a cutout for attaching the chamber door support  130 . The enclosure  110  includes leveling feet  111  attached to each of the four corners of the bottom surface of the enclosure  110 . The leveling feet  111  function to level the thawing unit  100  before operation. The enclosure  110  also includes a power supply  112 , and a data communications port  113 . In various embodiments, the power supply  112  receives standard electrical power (120 V AC or 230 V AC), and the data port  113  is an Ethernet data communications port. 
     The front cover  120  includes fasteners  121  that secure the front cover  120  to the enclosure  110 . In one embodiment, the fasteners  121  are thumb screws located at each corner of the front cover  120 . The front cover  120  also includes a cutout that receives an operator interface  122  to take input from an operator and allow the operator to control the performance of the necessary functions to thaw the product by allowing the software to hardware communications that will control the thawing unit  100 . In one embodiment, the operator interface  122  includes a display  123 , and function buttons  124 . The display  123  communicates current data and processing messages to an operator, and the function buttons  124  allow the operator to control the processing performed by the thawing unit  100 . In one embodiment, the display  123  is a touch screen display that may be programmed to include the function buttons  124 . 
     The chamber door support  130  attaches through a cutout in the top surface of the enclosure  110 . The chamber door  140  attaches to the top surface of the chamber door support  130 . In one embodiment, two shoulder bolt hinges  141  are the means for attaching the chamber door  140  to the chamber door support  130 , thereby allowing the chamber door  140  to rotate 90 degrees from the horizontal top surface of the enclosure  110  and an operator to access to the product chamber  210 . The chamber door  140  also includes a handle  142  that allows to the operator of the thawing unit  100  to lift the chamber door  140  and access the heating chamber. 
       FIG. 2  is another perspective view of the apparatus shown in  FIG. 1 . As shown in  FIG. 2 , with reference to  FIG. 1 , the top surface of the enclosure  110  with the chamber door  140  in a partially open position. The chamber door support  130  includes an opening that receives a product chamber  210 . The product chamber  210  includes a locating pin  211  to ensure proper alignment of the product chamber  210  in the heating chamber. A clamp mechanism  212  holds the product  220  in the product chamber  210 . In various embodiments, the product  220  is a medical product, such as plasma, Fresh Frozen Plasma, blood, and the like, a biomedical industry product, and a pharmaceutical industry product. The chamber door support  130  also includes an opening  230  that engages a latch  231  in the chamber door  140 , and a closed door sensor  240  to detect that the chamber door  140  is properly closed before beginning operation of the thawing unit  100 . 
       FIG. 3  is a top elevation view, in cross section of the apparatus shown in  FIG. 1 . As shown in  FIG. 3 , with reference to  FIG. 1  and  FIG. 2 , the enclosure  110  houses a heating chamber  310  and an electrical control unit  360 . In one embodiment, a structural member  301  separates the heating chamber  310  from the electrical control unit  360 . 
     The heating chamber  310  shown in  FIG. 3  has an outer wall, an inner wall  312 , and a layer of insulation  311 . The heating chamber  310  is constructed to enclose an area for the purpose of containing radiated heat and insulating the product  220  held inside the product chamber  210  from the ambient temperature. The heating chamber  310  also includes heating elements  320 , thermocouple  330 , temperature sensors  340 , and a product chamber detection sensor  350 . 
     The heating elements  320  are located inside the heating chamber  310  in the space between the inner wall  312  and the product chamber  210 . The heating elements  320  produce a dry, radiant heat that is directed toward the product chamber  210  and the product  220 . In one embodiment, the heating elements  320  are ceramic infrared heaters (emitters) that are flat and produce a uniform pattern for even heating at a close proximity between the emitter and the target being heated. In another embodiment, the heating elements  320  are ceramic infrared heaters (emitters) that are concave and produce a concentrated radiant pattern that is highly effective at heating the target. In yet another embodiment, the heating elements  320  are ceramic infrared heaters (emitters) that are convex and produce a distributed radiant pattern that is highly effective at distributing the heat to the target. In one embodiment, the dry, radiant heat that the heating elements  320  emit is mid-infrared energy with a wavelength in the range of 3-50 μm controlled to provide a wavelength of 9.35031 micron or a temperature of 310.15 K. In addition to providing radiant heat, this mid-infrared energy range has also been shown in the prior art to have a therapeutic affect on blood and other medical products. As shown in the embodiment depicted in  FIG. 3 , the thawing unit  100  positions four heating elements  320  at 90 degree angles around the product chamber  210  to maximize the coverage of the radiated heat exposure on the product  220 . 
     The thermocouple  330  is located inside the heating chamber  310  in the space between the inner wall  312  and the product chamber  210 . The thermocouple  330  monitors the actual temperature of one of the heating elements  320  that generates the correct surface temperature of the product  220 . In one embodiment, the thermocouple  330  is a type J thermocouple. In another embodiment, the thermocouple  330  is integrated with the heating elements  320  by mounting it in one of the heating elements  320 . 
     The temperature sensors  340  are located inside the heating chamber  310  in the space between the inner wall  312  and the product chamber  210 . The temperature sensors  340  are able to measure the surface temperature of the product  220  through the product chamber  210 . In one embodiment, the temperature sensors  340  are infrared temperature sensors that can measure the surface temperature of the product  220  through a product chamber  210  that has an acrylic sidewall. The temperature sensors  340  are capable of detecting temperatures in the range of 273.15 K to 388.15 K or wavelengths between 10.61688 and 7.471338 micrometer (μm) with a accuracy of ±276.15 K. A stainless steel housing that encloses the temperature sensors  340  provides an International Protection (IP) Code (i.e., International Protection Rating, or Ingress Protection Rating) of IP67. As shown in the embodiment depicted in  FIG. 3 , the thawing unit  100  includes two temperature sensors  340  with each positioned around the product chamber  210  and between two adjacent heating elements  320 , and separated from each other by 90 degrees to maximize the accuracy of the measurement of the surface temperature of the product  220 . In another embodiment, the thawing unit  100  includes two temperature sensors  340  with each positioned around the product chamber  210  and between two adjacent heating elements  320 , and separated from each other by 180 degrees to maximize the accuracy of the measurement of the surface temperature of the product  220 . 
     The product chamber detection sensor  350  is located inside the heating chamber  310  in the space between the inner wall  312  and the product chamber  210 . The product chamber detection sensor  350  is an inductive proximity sensor that detects metal when it is within 1 mm of the front surface of the product chamber detection sensor  350 . A stainless steel housing that encloses the product chamber detection sensor  350  provides a rating of IP67. In one embodiment, the stainless steel housing is a 5 mm threaded stainless steel outer shell. In one embodiment, the product chamber detection sensor  350  is positioned to detect a metal pin that is inserted in the bottom surface of the product chamber  210  when the product chamber  210  is properly oriented in the heating chamber  310 . 
     In one embodiment, the product chamber  210  is located substantially in the center of the heating chamber  310 , and is a vessel having a substantially flat bottom surface, and cylindrical side wall that is open at the top. The product chamber  210  functions as a containment system to isolate the product  220  from the heating chamber  310  and the remainder of the enclosure  110 . In one embodiment, the product chamber  210  is constructed from an acrylic material having substantial strength, substantial durability, and substantial transparency. The substantial strength of the product chamber  210  prevents a rupture of the product  220  from contaminating the heating chamber  310  and the remainder of the enclosure  110 . The substantial durability of the product chamber  210  allows it to withstand irradiation to sanitize it before its initial use, and after a contamination incident. The substantial transparency of the product chamber  210  allows it to filter the passage of the energy from the heating elements  320  thereby allowing a desired range of wavelengths, and preventing an undesired range of wavelengths. In one embodiment, the desired range of wavelengths is mid-infrared energy, and the undesired range of wavelengths above and below mid-infrared energy. 
     The electrical control unit  360  shown in  FIG. 3  includes a power entry module  370 , and an electrical control panel  380 . The power entry module  370  receives electrical power from the power supply  112  and converts the power for use by the various components of the thawing unit  100 . The power entry module  370  and the data communications port  113  connect to the electrical control panel  380 . 
     The electrical control panel  380  controls the operation of the hardware components and monitors the performance of the methods of the present invention. In one embodiment, the electrical control panel  380  is a printed circuit board that includes fuses  381  to provide circuit protection for the heating elements  320 , relays  382  to control the on-off state of the heating elements  320 , a processor  383 , a temperature sensor panel connector  384 , a safety switch panel connector  385 , a heat element feedback panel connector  386 , a heat element power panel connector  387 , and a terminal block  388 . The processor  383  is a special-purpose computing device that performs the methods of the present invention. In one embodiment the processor  383  is a central processing unit (CPU) or application-specific integrated circuit (ASIC) that includes a memory device, and a processor disposed in communication with the memory device, where the processor is configured to execute program instructions to control the hardware components and monitor methods performed by the thawing unit  100 . In another embodiment, the processor  383  is an electrically erasable programmable read-only memory (EEPROM) configured to execute program instructions to control the hardware components and monitor methods performed by the thawing unit  100 . The processor  383  communicates via the temperature sensor panel connector  384  with the temperature sensors  340  in the heating chamber  310  to monitor the temperature of the product  220  during operation of the thawing unit  100 . The processor  383  communicates via the safety switch panel connector  385  with the locating pin  211  and the product chamber detection sensor  350  in the heating chamber  310 , and the closed door sensor  240  in the chamber door support  130  to maintain safe operation of the thawing unit  100 . The processor  383  communicates via the heat element feedback panel connector  386  and the heat element power panel connector  387  with the heating elements  320  in the heating chamber  310  to monitor the integrity and safety of the heating elements  320 . The processor  383  communicates via the terminal block  388  with the operator interface  122  to communicate with the operator of the thawing unit  100 .  FIG. 4  is a block diagram that illustrates, in detail, one embodiment of the control circuits for the apparatus shown in  FIG. 3 . 
     The pre-operation setup of the thawing unit  100  begins with leveling the thawing unit  100  on an operating surface. The operator places a level on the chamber door support  130  and adjusts the leveling feet  111  to level the thawing unit  100  from front-to-back and left-to-right. Once the thawing unit  100  is level, the operator connects a power cord (not shown) to the power supply  112  to provide electrical power to the thawing unit  100 , and moves the power switch (not shown) into the “on” position. The operator interface  122  provides step-by-step instructions to the operator of the thawing unit  100 . 
       FIG. 5  is a flow diagram that illustrates methods according to one embodiment of the present invention. The process  500  shown in  FIG. 5  begins with a series of safety checks. The process  500  determines whether the product chamber  210  is in place (step  505 ). If the product chamber  210  is not in place (step  505 , N branch), the operator interface  122  prompts the operator to install the product chamber  210  (step  510 ) until the product chamber  210  is properly installed. If the product chamber  210  is in place (step  505 , Y branch), the process  500  determines whether the product  220  is in the product chamber  210  (step  515 ). If the product  220  is not in the product chamber  210  (step  515 , N branch), the operator interface  122  prompts the operator to install the product  220  (step  520 ) until it detects the product  220  in the product chamber  210 . If the product  220  is in the product chamber  210  (step  515 , Y branch), the process  500  determines whether the chamber door  140  is closed (step  525 ). If the chamber door is not closed (step  525 , N branch), the operator interface  122  prompts the operator to close the chamber door  140  until it detects that the chamber door  140  is closed. If the chamber door  140  is closed (step  525 , Y branch), the process  500  completes the safety checks and prepares to begin the thawing process. 
     In one embodiment, the thawing unit  100  will successfully pass the safety checks by the operator opening the chamber door  140 , removing the clamp mechanism  212 , attaching the product  220  to the clamp mechanism  212 , and inserting the clamp mechanism  212  and product  220  into a set of notches in the top of the product chamber  210  until it is fully seated. The operator closes the chamber door  140  until the latch  231  engages the opening  230  in the chamber door support  130 . When the closed door sensor  240  detects that the chamber door  140  is closed, and the product chamber detection sensor  350  detects the product  220  and the proper installation of the product chamber  210  in the heating chamber  310 , the thawing cycle will begin. 
     After completing the safety checks, the process  500  begins the thawing process by starting the cycle timer (step  535 ), and recording the current time and temperature detected by the temperature sensors  340  in the heating chamber  310  (step  550 ) and displaying the current time and temperature data (step  555 ) on the operator interface  122 . In one embodiment, starting the cycle timer (step  535 ) and the recording of the current time and temperature (step  550 ) are started as parallel processes. The process  500  begins heating the product  210  by increasing the temperature output by the heating elements  320  (step  560 ) and reading the temperature of the product  210  detected by the temperature sensors  340  (step  565 ). The process  500  determines whether the detected temperature has reached a pre-determined set-point temperature (step  570 ). If the set-point temperature has not been reached (step  570 , N branch), the process records the current time and temperature (step  550 ), and continues as described above. When the set-point temperature has been reached (step  570 , Y branch), the process  500  turns off the power to the heating elements  320  (step  575 ), reads the temperature of the product  210  detected by the temperature sensors  340  (step  560 ), and continues as described above. The process  500  continues to read the cycle time (step  545 ), until it determines that the cycle is complete (step  540 , Y branch), and the operator interface  122  displays a “Cycle Complete” message (step  580 ). 
     Although the disclosed embodiments describe a fully functioning heating device that utilizes infrared energy to thaw a product, the reader should understand that other equivalent embodiments exist. Since numerous modifications and variations will occur to those reviewing this disclosure, the heating device that utilizes infrared energy to thaw a product is not limited to the exact construction and operation illustrated and disclosed. Accordingly, this disclosure intends all suitable modifications and equivalents to fall within the scope of the claims.