Patent Publication Number: US-2006005827-A1

Title: Heater product, system and composition

Description:
This application claims the benefit of U.S. Provisional Application Ser. Nos. 60/567,878, 60/641,975, and 60/642,652, which were filed May 4, 2004, Jan. 7, 2005, and Jan. 10, 2005, respectively, and which are hereby incorporated by reference in their entirety in the present application. 
    
    
     TECHNICAL FIELD  
      The present disclosure is directed to a heater product, system and composition, and in particular to a flameless heater product, system and composition.  
     SUMMARY OF THE INVENTION  
      According to one aspect of the present disclosure, a heater product is provided. The heater product has a first cavity in which a first part of a heater composition is disposed, the first part comprising calcium oxide, a second cavity in which a second part of a heater composition is disposed, the second part including water, an reaction-initiation delayer and water-release limiter, and a barrier between the first cavity and the second cavity, such that when the barrier is removed, the first and second parts combine to provide an exothermic reaction.  
      According to another aspect of the present disclosure, another heater product is provided. The heater product includes an outer pouch, the outer pouch having a wall with an inner surface that defines an outer pouch cavity and an opening therethrough, an inner pouch disposed within the outer pouch cavity and attached to the outer pouch, the inner pouch having a wall with an inner surface that defines at least one inner pouch cavity and an outer surface, and a pull strip with a first portion secured to the outer surface of the inner pouch and a second portion disposed through the opening in the outer pouch. At least one reinforcing strip is secured to the outer surface of the inner pouch to guide a tear formed in the wall of the inner pouch when force is applied to the pull strip. A first part of a heater composition is disposed in the outer pouch cavity and a second part of a heater composition is disposed in the inner pouch cavity, the first and second parts capable of an exothermic reaction when combined.  
      Additional aspects of the disclosure are defined by the claims of this patent. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a perspective view of a heater product according to the present disclosure;  
       FIG. 2  is a perspective view, partially in section, of the heater product of  FIG. 1 ;  
       FIG. 3  is an enlarged, perspective view of a sealing mechanism for the releasing mechanism of the heater product of  FIG. 1 ;  
       FIG. 4  is a sectional view of a first embodiment of a heater system, including the heater product of  FIGS. 1-3 ;  
       FIG. 4A  is a perspective view of the embodiment of the heater system of  FIG. 4 , as assembled, ready to ship;  
       FIG. 5  is a perspective view of a second embodiment of a heater system, with the heater product removed;  
       FIG. 6  is a sectional view of the heater system of  FIG. 5 , with the heater product included;  
       FIG. 7  is a perspective view of a third embodiment of a heater system similar to that shown in  FIG. 5 ;  
       FIG. 8  is a frontal view of the heater system of  FIG. 7 ;  
       FIG. 9  is a side elevational view of the heater system of  FIG. 7 ;  
       FIG. 10  is a plan view of the heater system of  FIG. 7 ;  
       FIG. 11  is a perspective view of a fourth embodiment of a heater system, with the heater product removed;  
       FIG. 12  is a sectional view of the heater system of  FIG. 11 , with the heater product included;  
       FIG. 13  is an exploded, perspective view of a fifth embodiment of a heater system, with the heater product removed;  
       FIG. 14  is a sectional view of the heater system of  FIG. 13 , with the heater product included;  
       FIG. 15  is a sectional view of another embodiment of a heater product;  
       FIG. 16  is a plan view of another embodiment of an inner pouch, with the pull tab removed;  
       FIG. 17  is a plan view of the inner pouch of  FIG. 16 , with the pull tab shown;  
       FIG. 18  is a perspective view of another embodiment of a heater product;  
       FIG. 19  is a perspective view, partially in section, of the heater product of  FIG. 18 ;  
       FIG. 20A  is an exploded view of a sealing mechanism for use with the heater product of  FIG. 18 ;  
       FIG. 20B  is a perspective view of the sealing mechanism of  FIG. 20A , as assembled;  
       FIG. 20C  is a perspective view of the heater product, in fragmentary section, of the heater product of  FIG. 18  and the sealing mechanism of  FIG. 20A , as assembled;  
       FIG. 21  is a plan view, in section, of the inner pouch of the heater product of  FIG. 18 ;  
       FIG. 22  is a plan view of the inner pouch of the heater product of  FIG. 18 ; and  
       FIG. 23  is a bottom view of the inner pouch of the heater product of  FIG. 18 . 
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS  
      Although the following text sets forth a detailed description of numerous different embodiments of the invention, it should be understood that the legal scope of the invention is defined by the words of the claims set forth at the end of this patent. The detailed description is to be construed as exemplary only and does not describe every possible embodiment of the invention since describing every possible embodiment would be impractical, if not impossible. Numerous alternative embodiments could be implemented, using either current technology or technology developed after the filing date of this patent, which would still fall within the scope of the claims defining the invention.  
      It should also be understood that, unless a term is expressly defined in this patent using the sentence “As used herein, the term ‘______’ is hereby defined to mean . . . ” or a similar sentence, there is no intent to limit the meaning of that term, either expressly or by implication, beyond its plain or ordinary meaning, and such term should not be interpreted to be limited in scope based on any statement made in any section of this patent (other than the language of the claims). To the extent that any term recited in the claims at the end of this patent is referred to in this patent in a manner consistent with a single meaning, that is done for sake of clarity only so as to not confuse the reader, and it is not intended that such claim term be limited, by implication or otherwise, to that single meaning. Finally, unless a claim element is defined by reciting the word “means” and a function without the recital of any structure, it is not intended that the scope of any claim element be interpreted based on the application of 35 U.S.C. §112, sixth paragraph.  
       FIG. 1  illustrates a heater product  20  for use in a heater system  22 , five embodiments of which are shown in  FIGS. 4-14 .  
      As shown in  FIG. 1 , the heater product  20  may include an outer pouch  24  having a first end  26  and a second end  28 . The outer pouch  24  may include a pouch wall  30 , which may be flexible, semi-rigid, rigid, etc., having an outer surface  32  and an inner surface  34 , as shown in  FIGS. 3 and 4 . The inner surface  34  of the pouch wall  30  may define a cavity  36  in which is disposed an inner pouch  38 . The inner surface  34  of the pouch wall  30  may be described as having a first section  40  and a second section  42 , which with the pouch  24  disposed as illustrated in  FIGS. 2 and 4  may be described as an upper section  40  and a lower section  42 .  
      The inner pouch  38  also has a first end  44  and a second end  46 . As shown in  FIGS. 2 and 4 , the inner pouch  38  also includes a pouch wall  48  having an outer surface  50  and an inner surface  52 . Moreover, the inner surface  52  of the pouch wall  48  may be described as having a first (or upper) section  54  and a second (or lower) section  56 , with the inner pouch  38  disposed in the orientation illustrated in  FIGS. 2 and 4 .  
      It should be noted that designations such as “upper” and “lower” are for ease of discussion only, and are not meant to limit the disclosure in any fashion, for a similar designation may be used if the pouch was inverted with the section  42  being “upper” and the section  40  being “lower” and the section  56  being “upper” and the section  54  being “lower.” 
      As illustrated in  FIG. 2 , the wall  48  of the inner pouch  38  may be sealed at both the first and second ends  44 ,  46 . As seen in  FIG. 4 , the upper and lower sections  54 ,  56  of the inner surface  52  may also be joined to define at least two cavities, although a single cavity for the inner pouch  38  would also be within the scope of the present disclosure. As shown in  FIGS. 2 and 4 , the upper and lower sections  54 ,  56  of the inner surface  52  may be joined to form two partitions  58 ,  60  that in turn define three cavities, or chambers,  62 ,  64 ,  66  in which a liquid may be disposed, as will described in greater detail below. The cavities  62 ,  64 ,  66  may be of equal or unequal size; as shown, the cavity  64  is larger in volume than the cavities  62 ,  66 .  
      As further illustrated in  FIG. 4 , the inner surface  34  of the wall  30  of the outer pouch  24  may be joined to itself at the first and second ends  26 ,  28  of the outer pouch  24 . In particular, as shown in  FIG. 4 , as well as in  FIGS. 6, 8 , and  10 , the inner surface  34  of the outer pouch  24  may be joined at the second end  28  such that the second end  46  of the inner pouch  38  is disposed between the first and second sections  40 ,  42  of the inner surface  34  of the wall  30 . In this fashion, the second end  46  of the inner pouch  38  may be attached to the second end  28  of the outer pouch  24 . The first and second sections  40 ,  42  of the inner surface  34  of the wall  30  may also be joined at the first end  26  to close the first end  26  of the outer pouch  24 .  
      In operation, the contents of the cavities  62 ,  64 ,  66  are to be released into the cavity  36 . Consequently, the heater product  20  may include a release mechanism  70 , which includes a pull strip  72  (which may act as a barrier, as explained in greater detail below), holes  74 ,  76 , and partitions  58 ,  60  (which may act as barriers, as explained in greater detail below). As will be explained in greater detail below, the release mechanism  70  shown represents merely one possible release mechanism  70  that may be used in the heater product  20  of the present invention.  
      The release mechanism  70  may now be discussed in greater detail with reference to  FIGS. 2 and 4 . In particular, the pull strip  72  may have a first end  78  and a second end  80 . In between the first end  78  and the second end  80  may be a first section  82 , a second section  84 , and a third section  86 .  
      The first section  82  of the pull strip  72  overlies the holes  74 ,  76 , preventing the material in cavities  62 ,  66  from being released into the cavity  36 . The first section  82  may be releasably secured to the outer surface  50  of the inner pouch  38  through the use of, for example, a peelable seal, such as a thermally-induced peelable seal. It may not be necessary to secure the entirety of the first section  82  of the pull strip  72  to the outer surface  50  of the inner pouch  38 ; for example, the first section  82  may be releasably secured to the outer surface  50  only in the area adjacent to the holes  74 ,  76 .  
      The second section  84  may be connected to the first section  82 , and may lie back on top of the first section  82 , as best seen in  FIG. 4 , for example. The second section  84  may also be disposed through an opening  88  in the wall  30  of the outer pouch  24 . In fact, a sealing mechanism  90  may be disposed in the opening  88 , and the section  84  of the pull strip  72  may be disposed through the sealing mechanism  90 . As best seen in  FIG. 3 , the sealing mechanism  90  may include an inner piece  92  and an outer piece  94 , each of which may have a slit formed therethrough (only the slit  96  in the outer piece  94  being visible in  FIG. 3 ) and both of which may be made of, for example, a high-temperature flexible material, such as silicone rubber, polypropylene, low density polyethylene (LDPE), etc. The inner and outer pieces  92 ,  94  may be sealed to the wall  30  with a sealing mechanism appropriate for the materials which are used to make the inner and outer pieces  92 ,  94 . The section  84  of the pull strip  72  may be disposed through the slits in the pieces  92 ,  94 , which serve to keep the heater composition within the outer pouch  24  during shipment and to wipe the surfaces of the section  84  of the pull strip  72  as the section  84  is removed from the heater product  20 .  
      The third section  86  may terminate in the second end  80  of the pull strip  72 . The third section  86  of the pull strip  72  may be outside the outer pouch  24  of the heater product  20 , and may include an enlarged region  98 . The enlarged region  98  may be included to make it easier for the user of the product  20  to grip the end  80  of the pull strip  72  to apply force to the pull strip  72 .  
      As mentioned above, the release mechanism  70  may include not only the pull strip  72  and the holes  74 ,  76 , but also the partitions  58 ,  60 . In particular, the partitions  58 ,  60  may include at least a weakened section that will permit materials to pass between the cavity  64  and the cavities  62 ,  66  after the weakened section has given way. For example, the partition  58  may include a middle section  100  that is weakened relative to side sections  102 ,  104 , and the partition  60  may include a middle section  110  that is weakened relative to side sections  112 ,  114 .  
      The weakened sections  100 ,  110  may be defined in a variety of manners. As one example, seals at the weakened sections  100 ,  110  may not be as resistant to a pressure differential as the sections  102 ,  104  and  112 ,  114 . As a consequence, a significantly smaller pressure differential experienced across the weakened sections  100 ,  110  will cause those sections to fail and give way than would cause a similar behavior in sections  102 ,  104  and  112 ,  114 .  
      As noted above, the release mechanism  70  described herein is merely one embodiment of such a release mechanism. As one alternative embodiment, the release mechanism may include a pull strip, but rather than having the pull strip expose holes in the wall  48  of the inner pouch  38 , the pull strip may cause the wall  48  (which acts as a barrier in this embodiment) to separate along a section attached to the pull strip, and thereby release the contents of the inner pouch  38  into the outer pouch  24 . Alternatively, the release mechanism may not be an internal release mechanism. The release mechanism may include a separate tool that may be used to puncture through the outer pouch  24  and the inner pouch  38  and release the contents of the inner pouch  38  into contact with the contents of the outer pouch  24 . Moreover, the tool may be provided with the heater product  20  or heater system  22  (such as in the form of a specially-designed tool for such purpose), or the tool may be an implement that is generally available (such as a knife or a screwdriver, for example). As a further alternative, the release mechanism may include one or more seals or sealed apertures defined in the inner pouch  38  in communication with the cavities  62 ,  66 , which seals or sealed apertures (which may act as barriers) may burst under application of sufficient pressure to the outer surface  50  of the inner pouch  38 , thus removing the barrier and releasing the contents.  
      As further examples, there may be variation in the release mechanism  70  described above. For example, while only two holes  74 ,  76  are shown, the holes  74 ,  76  may each be replaced with a plurality of holes. Moreover, a plurality of holes may be defined in the wall  48  of the inner pouch  38 , in the upper section  54  of the wall  48 . These holes may be sealed until the time of release, and they may be of very small size. These holes may permit the contents of the cavity  64  to be released, preferably slowly, into the contents of the outer pouch  24 .  
      The heater product  20  and the heater system  22  may also include mechanisms that cooperate to limit the movement of the heater product  20  relative to the remainder of the heater system  22  when the heater product  20  is assembled with the heater system  22 , although such mechanisms are optional. Specifically, the heater product  20  may include holes  120 ,  122  at the first end  26  of the outer pouch  24  and holes  124 ,  126  at the second end  28 . As best seen in  FIG. 4 , the heater system  22  may include four anchors (two of which are shown)  130 ,  134  that may be attached to a base  138  and the holes  120 ,  122 ,  124 ,  126  to thereby limit the movement of the heater product  20  relative to the remainder of the heater system  22 . The heater product  20  may be stored separately from the remainder of the system  22 , and may only be assembled with the remainder of the system  22 , using the anchors  130 ,  134  for example, at the time of activation.  
      As shown in the system  22  illustrated in  FIG. 4 , the anchors  130 ,  134  may be shaped to be disposed about a tray  140  that may be disposed into the base  138 . In particular, the tray  140  may have an L-shaped edge  142  that runs about the periphery of the tray  140  (see  FIG. 3 ). The anchors  130 ,  134  may each have a first (or upper) section  144  that may be shaped to be disposed about the L-shaped edge  142 . The anchors  130 ,  134  may also each have a second (or lower) section  146  that may be shaped to be disposed through one of the holes  120 ,  122 ,  124 ,  126 . Although the lower sections  146  of, for example, the anchor  130  and the anchor  134  may have a different shape, the anchors may have the same shape as well.  
      Additionally, formed in the wall  30  of the outer pouch  24  is a plurality of holes  148  used for venting. The vent holes  148  are covered with a patch  149  that is releasably attached to the outer surface  32  of the wall  30  of the outer pouch  24 . The patch  149  prevents the materials disposed in the cavity  36  from being released through the vent holes  148 . As explained below, the patch  149  may be removed prior to activation; alternatively, the patch  149  may separate from the outer surface  32  under the influence of the thermal energy, pressure, steam, etc. generated in the outer pouch  24  after activation without the involvement of the user (self-opening or self-releasing).  
      Alternatively, a valve may be used in place of or in combination with the plurality of vent holes  148 . As one such example, a valve may be used that makes an audible noise (e.g., a “whistle”) with the build up of pressure, steam, etc. in the heater product  20 . The valve may thus serve as an indicator, for purposes of safety or to indicate that the product is “on” or “off”, for example.  
      Finally, as shown in  FIG. 4 , the heater system  22  may include a food tray  150  and a lid  152  disposed on the food tray  150 . The food tray  150  may be disposed (or nestled) within the tray  140 , and may have a lip  154  that cooperates with the edge  142  to keep the food tray  150  disposed over the heater product  20 . While there may exist a slight spacing or a gap between the food tray  150  and the heater pouch  20 , either initially or throughout the heating process, it is believed that heat transfer may be enhanced if the food tray  150  is in contact with the heater pouch  20 .  
      As for the contents of the outer and inner pouches  24 ,  38 , the structure of the heater product  20  is not limited to use with a particular type of chemical system, nor is the chemical system discussed herein limited to use in the heater product  20  described above. The heater product  20  and the chemical system enclosed therein as disclosed below may be useful separate and apart from the combination discussed in greater detail herein. For example, while the heater product  20  described above has outer and inner pouches  24 ,  38 , each of which contains one part of a two-part system, explained in greater detail below, inner pouch  38  may be removed entirely, and still the two-part system discussed below may be used, with the outer pouch  24  containing one part of the two-part system and the second part of the two-part system being introduced into the outer pouch  24  by puncturing the outer pouch and pouring the second part into the outer pouch  24  or by being absorbed through the outer pouch  24 .  
      Therefore, according to one embodiment of this disclosure, a two-part heater composition may be disposed in the outer and inner pouches  24 ,  38 , with the first part of the two-part heater composition initially disposed in the inner pouch  38  and the second part of the two-part heater composition initially disposed in the cavity  36  between the outer pouch  24  and the inner pouch  38 . When the first part is released from the inner pouch  38 , it comes in contact with the second part, and an exothermic reaction takes place.  
      The first part in the inner pouch  38  may include water (H 2 O), and the outer pouch  24  may include a basic anhydride, such as calcium oxide (CaO) or calcium chloride (CaCl 2 ). The outer pouch  24  may also include an acidic anhydride, such as phosphorous pentoxide (P 2 O 5 ), in addition to the basic anhydride. The first part in the inner pouch  38  may also include at least one chemical or composition that delays the initiation of the reaction when the water is released into contact with the calcium oxide. The first part in the inner pouch  38  may thus include sugar, such as sucrose, glucose, or fructose, for example. The first part in the inner pouch  38  may further include at least one chemical or composition that limits the rate at which water is released to the calcium oxide, although this may alternatively be provided by, for example, a semi-permeable membrane that may vary its permeability according to solubility, pressure and/or temperature. For example, this chemical or composition may be an absorbent, chemically-inert, thermally-resistant material, such as an absorbent, mineral-based, chemically-inert, thermally-resistant material. In this regard, the first part in the inner pouch  38  may include expanded perlite (“perlite”) and/or vermiculite, for example, which material may or may not be pre-moistened. Other absorbent materials, such as charcoal and wood flour, may also be used. The first part in the inner pouch  38  may also include other chemicals or compositions that may or may be not important to the reaction or the components of the reactive system. For example, the first part in the inner pouch  38  may include a preservative for the sugar used to delay the initiation of the exothermic reaction.  
      The ratio of the chemicals or compositions in the two-part system described herein may have a considerable degree of variation therein. For example, the ratio of water to calcium oxide, by weight, may vary between 0.15:1 and 1.25:1. Moreover, while a material such as perlite may be used, it need not be used; consequently, the ratio of perlite (in a moisture-free or bone-dry state) to water, by weight, may vary between 0:1 and 0.67:1. Likewise, while a material such as sugar may be used, it need not be used; hence, the ratio of sugar to water, by weight, may vary between 0:1 and 0.05:1. Factors that may influence the ratios used may include, among others, the heater product used, the heater system used, and the amount of material (food mass) to be warmed. It is believed that, relative to the amount of the material to be warmed, a direct relationship exists between the amount of material to be warmed and the amount of water and calcium oxide required; i.e., a greater amount of food mass requires more water and calcium oxide to be used.  
      According to one group of embodiments, useful with the heater product  20  discussed above and below, the ratio of water to calcium oxide, by weight, may vary between 0.2:1 and 0.6:1, and may particularly vary between 0.25:1 and 0.35:1. Moreover, the ratio of perlite (in a moisture-free or bone-dry state) to water, by weight, may vary between 0.06:1 and 0.14:1. Further, the ratio of sugar to water, by weight, may vary between 0.01:1 and 0.02:1. While the proportions of the chemicals and compositions used may vary within this group, one embodiment according to this disclosure uses 600 g of calcium oxide, 180 g of water, 15 g of perlite, and 2.7 g of sugar to produce a sufficient amount of thermal energy to maintain the temperature of 2 kg of food mass (e.g., chili) in an aluminum tray for upwards of one hour. It has also been found, according to another embodiment of this system, that use of 1200 g of calcium oxide, 360 g of water, 30 g of perlite and 5.4 g of sugar produces a sufficient amount of thermal energy to maintain the temperature of 2 kg of food mass in an aluminum tray for upwards of two hours. According to still another embodiment of this system, it has been further found that use of 750 g of calcium oxide, 225 g of water, 18.75 g of perlite and 3.375 g of sugar produces a sufficient amount of thermal energy to maintain the temperature of 2 kg of food mass in an aluminum tray for upwards of two hours. This further embodiment also included certain preservatives (0.4 g of citric acid (anhydrous) 99%, 0.2 g of sodium benzoate 99%, and 0.2 g of potassium sorbate 99%).  
      Other embodiments of the composition are possible.  
      For example, it has been found that suitable amounts of heat (for example, to maintain the temperature of 2 kg of food mass for approximately 45-50 minutes) may be produced when 200 g of calcium oxide is combined with a liquid component that includes 100 g of water and 1.5 g of sugar, the ratio of water to calcium oxide being 0.5:1 and the ratio of sugar to water being 0.015:1. Similar compositions using the same ratio of calcium oxide, water and sugar have also been tested and found useful, such as 400 g calcium oxide, 200 g water, and 3 g sugar; 420 g calcium oxide, 210 g water, and 3.15 g sugar; 450 g calcium oxide, 225 g water, and 3.38 g sugar; 500 g calcium oxide, 250 g water, and 3.75 g sugar; and 800 g calcium oxide, 400 g water, and 6 g sugar.  
      Additionally, it has been found that suitable amounts of heat (for example, to maintain the temperature of 2 kg of food mass for approximately one hour) may be produced when 500 g of calcium oxide is combined with a liquid component that includes 125 g of water and 1.56 g of sugar, the ratio of water to calcium oxide being 0.25:1 and the ratio of sugar to water being 0.012:1. It has also been found that suitable amounts of heat may be produced when 600 g of calcium oxide is combined with a liquid component that includes 150 g of water and 2.25 g of sugar, the ratio of water to calcium oxide being 0.25:1 and the ratio of sugar to water being 0.015:1.  
      It has further been found that suitable amounts of heat (for example, to maintain the temperature of 2 kg of food mass for approximately 90 minutes) may be produced when 600 g of calcium oxide is combined with a liquid component that includes 180 g of water, 2.7 g of sugar and 15 g of perlite, the ratio of water to calcium oxide being 0.3:1, the ratio of sugar to water being 0.015:1, and the ratio of perlite to water being 0.08. Similar success was found with similar amounts of calcium oxide, water and sugar and varying amounts of perlite, including 17.5 g (0.10:1), 20 g (0.11:1), 25 g (0.14:1) and 30 g (0.17:1). Suitable amounts of heat were also produced when 1200 g of calcium oxide is combined with a liquid component that includes 360 g of water, 5.4 g of sugar and 40 g of perlite, the ratio of water to calcium oxide being 0.3:1, the ratio of sugar to water being 0.015:1, and the ratio of perlite to water being 0.11:1.  
      It has also been found that suitable amounts of heat (for example, to maintain the temperature of 2 kg of food mass for approximately 90 minutes) may be produced when 600 g of calcium oxide is combined with a liquid component that includes 180 g of water, 9 g of sugar and 20 g of perlite, the ratio of water to calcium oxide being 0.3:1, the ratio of sugar to water being 0.050:1, and the ratio of perlite to water being 0.11:1.  
      To assemble the heater product  20 , the inner pouch  38  may be initially formed with ends  44 ,  46  closed and the pull strip  72  disposed over the holes  74 ,  76 , but with at least one side seam  158  open. A mixture of water, perlite and sugar may be disposed into each of the three cavities  62 ,  64 ,  66 . According to one embodiment, the cavities  62 ,  64 ,  66  are filled with unequal proportions of the mixture; for example, the proportions for the cavities  62 ,  64 ,  66  may be 20:60:20. The side seam  158  may then be sealed. The second and third sections  84 ,  86  of the pull strip  72  may then be disposed through the sealing mechanism  90 , which may already be fitted in the opening  88  of the wall  30  of the outer pouch  24 . The cavity  36  may then be filled with calcium oxide. The end  28  of the outer pouch  24  may then be sealed with the end  46  of the inner pouch  38  inside the seal, thereby attaching the inner pouch  38  to the outer pouch  24 .  
      It may be noted that, as shown, the orientation of the inner pouch  38  relative to the outer pouch  24  places the holes  74 ,  76  facing upwards. It is believed that this orientation of the holes  74 ,  76  may limit pooling of the material in the inner pouch  38  beneath the inner pouch  38  after release. Additionally, as shown, the inner pouch  38  is positioned such that it is proximate to the bottom of the outer pouch  24 . It is believed that this orientation of the inner pouch  38  relative to the outer pouch  24  prevents the inner pouch and/or the contents of the inner pouch  38  from acting as an insulator, limiting exchange of thermal energy with the food tray  150 . Moreover, the release mechanism  70  is disposed on top of the inner pouch  38  as shown. It is believe that this orientation of the release mechanism  70  may limit the resistance that the calcium oxide may present relative to removal of the release mechanism  70  from the heater product  20 .  
      To assemble the heater product  20  with the remainder of the heater system  22 , the anchors  130  may be disposed through the holes  120 ,  122  in the first end  26  of the outer pouch  24 , with the anchors  130  already attached to the tray  140  and the product  20  oriented as shown in  FIG. 4  with the opening  88  in the wall  30  of the outer pouch  24  disposed facing the bottom of the tray  140 . The anchors  134  may then be disposed through the holes  124 ,  126  in the second end  28  of the pouch  24 . The food tray  150  may then be disposed so that the lip  154  of the food tray  150  abuts and rests on the edge  142  of the tray  140 .  
      To activate the heater product  20 , the user may first remove the patch  149  from over the vent holes  148 . The user may then grasp the enlarged region  98  of the pull strip  72 , and may apply an outward force to the pull strip  72  until at least the holes  74 ,  76  have been exposed. According to one embodiment of the disclosure, force may be applied to the pull strip  72  until the entire pull strip  72  has been removed from the heater product  20 .  
      As the water/perlite/sugar mixture is released into the calcium oxide, the exothermic reaction may be initially delayed by the presence of the sugar, to permit, for example, the user to assemble the heater product  20  with the remainder of the heater system  22  (e.g., by disposing the heater product  20  into the tray  140  and disposing the tray  150  on top of the tray  140  and the heater product  20 ). After the initial release of water into contact with the calcium oxide, further release of water to the calcium oxide may occur in a controlled fashion by virtue of, for example, the presence of the perlite and the multiple cavities or chambers  62 ,  64 ,  66  of the inner pouch  38 . That is, it is believed that, as the perlite material is heated, the perlite material may release moisture in the form of steam into contact with the calcium oxide in the outer pouch  24 . Additionally, the thermal energy generated by the release of moisture in contact with the calcium oxide, may cause the water/perlite/sugar mixture in the second cavity  64 , which has remained sealed thus far, to increase in temperature. It is presently believed that, as the temperature of the mixture increases, given that the amount of mixture present is constant and the volume of the cavity  64  is relatively constant, the pressure in the cavity  64  increases and causes a pressure differential across the weakened sections  100 ,  110 . It is also believed that an increase in pressure in the cavity  64  may also be caused by the interaction between the trays  140 ,  150  and the heater product  20 . Further, it is believed that the seals that form the partitions  58 ,  60  may begin to weaken because of the increase in temperature. Eventually, the weakened section  100 ,  110  of at least one of the partitions  58 ,  60  may fail and give way, causing the material in the second cavity  64  to be released, preferably slowly, into contact with the calcium oxide in the cavity  36  via at least one of the cavities  62 ,  66 . As an alternate path, the material in the second cavity  64  may also be released via the plurality of small holes defined in the upper section  54  of the wall  48 , as discussed above.  
      It is believed that by using a system in which water and water vapor are released in a controlled fashion into contact with the calcium oxide, undesirable spiking of the temperature of the food may be avoided. That is, it is believed that the gradual release of the water to the calcium oxide, through the use of moisture-absorbent material, for example perlite, and the sequential release of the first part of the two-part system from the cavities  62 ,  64 ,  66  may cause undesirable spiking of the temperature of the food to be avoided, which may have the additional consequence of avoiding charring of the food. It is also believed that the gradual release of thermal energy may improve the efficiency of the exchange of thermal energy between the heater product  20  and the food tray  150 . Further, it may improve the overall efficiency of the system  22  by minimizing the energy losses to the production of vented steam.  
      The reaction between the water and the calcium oxide continues for some amount of time, during which time thermal energy may be supplied to the food in the food tray  150 . The thermal energy may be supplied to the food in the tray  150  along a first path defined by contact between the heater pouch  20  and the food tray  150 . However, thermal energy may also be supplied to the food in the food tray  150  as a consequence of the release of, for example, steam from the heater product  20 , even if the heater product  20  is not in direct contact with the food tray  150 . Because the indirect exchange of thermal energy through steam may not be as efficient as the direct exchange of thermal energy through contact, it may be preferred to partially close the vent holes  148  through contact with the underside of the food tray  150  to prevent steam losses.  
      Having thus discussed the structure, assembly and operation of an embodiment of the heater product  20  and heater system  22 , the further embodiments of the present disclosure are discussed.  
       FIGS. 4-15  show various alternative embodiments of the heater system  22  using a heater product  20 , as previously described. In discussing these additional embodiments, similar elements will be designated using similar reference numerals with the use of a single prime for the embodiment shown in  FIGS. 5 and 6 , a double prime for the embodiment shown in  FIGS. 11 and 12 , and a triple prime for the embodiment shown in  FIGS. 13 and 14 . While the heater product  20  is common to all four embodiments of the heater system  22 , this need not necessarily be the case, and the structure of the heater product  20  and the composition of the materials disposed in the heater product  20  may vary between and among the various embodiments.  
      While the embodiment shown in  FIG. 4  has a base  138  into which a plurality of trays  140 ,  150  are nested, with the heater product  20  disposed between the trays  140 ,  150 , the embodiment of the heater system  22 ′ shown in  FIGS. 5 and 6  includes a different mechanism for disposing the heater product  20 ′ proximate to the food tray  150 ′. As shown, the base  138 ′ has an opening  170  formed in the side, as well as an opening in the top through which the food tray  150 ′ is disposed. Into the opening  170  is disposed a drawer  172 , which can be moved relative to the base  138 ′ between an open state, as shown in  FIG. 5 , and a closed state, as shown in  FIG. 6 . The drawer  170  has side walls  174  and a bottom  176 , which define a receptacle  178  into which a heater product  20 ′ may be placed. Rather than using the clip-like anchors  130 ,  134  shown in  FIG. 4 , anchors  180  (two of which are shown in  FIG. 6 ) are used that are attached to the side walls  174 . The anchors  180  cooperate with the holes  120 ,  122 ,  124 ,  126  as the anchors  130 ,  134  did in the previous embodiment.  
      The embodiment of  FIGS. 7-10  is similar to that shown in  FIGS. 5 and 6  in that a drawer is included in the base, and is moveable between an open state and a closed state. The embodiment of  FIGS. 7-10  differs from that shown in  FIGS. 5 and 6  in that a lid is included above the base, covering the food tray to prevent loss of heat.  
      The embodiment of  FIGS. 11 and 12  shows a heater system  22 ″ wherein the heater product  20 ″ is used with a conventional chafer dish arrangement. In this embodiment, anchors  130 ″,  134 ″ (two of which are shown) similar to those used in  FIG. 4  are included to limit the movement of the heater product  20 ″ relative to the remainder of the system  22 ″. Further, a thin platform, or spacer,  190  may be disposed under the heater product  20 ″ to ensure the proximity between the heater product  20 ″ and the food tray  150 ″.  
      The embodiment of  FIGS. 13 and 14  shows a heater system  22 ′″, in the form of a take-out container, wherein the heater product  20 ′″ is used with a nested arrangement of trays, as is shown in  FIG. 4 . However, unlike the nested arrangement of trays shown in  FIG. 4 , anchors  200  are attached, as in the embodiment shown in  FIGS. 5 and 6 , to the side walls  202  of the tray  140 ′″ that is disposed into the base  138 ′″. For that matter, the trays need not be nested, but instead stacked one on top of the other to form a space in between into which a heater product  20 ′″ may be disposed.  
      Also illustrated, in  FIG. 15 , is an alternative embodiment of the heater product  20 , which will be designated with the reference numeral  20 A. Unlike the heater product  20 , the heater product  20 A may include an outer tray  210  and an inner pouch  212 . The outer tray  210  may have an opening  214  over which a lid  216  may be disposed. The outer tray  210  may have a lip  218  that extends about the periphery of the tray  210  and about which an edge  220  of the lid  216  may be secured, by crimping, for example. In particular, the inner pouch  212  may have a tail section  222  that is secured to the outer tray  210 , by securing the tail section  222  between the tray  210  and the lid  216 . The heater product  20 A may also include a release mechanism  224 , which may be of the pull-strip variety that causes a wall of the inner pouch  212  to separate to permit materials within the inner pouch  212  to be released into the outer tray  210 .  
      In assembly, the inner pouch  212  may be filled with the first part (e.g., water/sugar/perlite) of the two-part exothermic composition referenced above, although other compositions and system may be used. The inner pouch  212  may then be disposed in the outer tray  210 , with the tail section  222  disposed on the lip  218  of the tray  210 . The outer tray  210  may then be filled with other part (e.g., calcium oxide and/or phosphorous pentoxide) of the two-part system. The lid  216  may then be disposed onto the outer tray  210 , with the release mechanism (pull strip)  224  fed through an opening  226  in the lid  216 . The edge  220  of the lid  216  may then be crimped about the lip  218  of the tray  210 , thereby closing the tray  210  and securing the pouch  212  to the tray  210 .  
      In operation, an end of the release mechanism  224  may be grasped by the user, and a force applied to separate or tear the wall of the inner pouch  212  along a line of attachment of the release mechanism  224  with an outer surface  228  of the inner pouch  212 . The tearing or separation of the inner pouch  212  may cause the contents of the inner pouch  212  to be released into the material in the outer tray  210 .  
      It may be noted that because the outer tray  210  may be made of a more rigid material than the outer pouch  24  of the heater product  20 , it may not be necessarily to utilize a system of anchors, as shown in the embodiments of the system  22 ,  22 ′,  22 ″,  22 ′″. Moreover, the rigidity of the product  20 A may also assist in maintaining a consistent area of contact between the product  20 A and a food tray disposed on top of the product  20 A, for example.  
      Additionally illustrated, in  FIGS. 16 and 17 , is an alternative embodiment of the inner pouch  38  of the heater product  20 , the alternative embodiment being designated with the reference numeral  38 A. The inner pouch  38 A may be assembled with the other components of the heater product as shown in  FIGS. 1 and 2  relative to inner pouch  38 , and as explained in greater detail below.  
      Unlike the inner pouch  38 , the inner pouch  38 A may have a single cavity  250  that may be formed by sealing (e.g., heat sealing) the inner pouch  38 A along ends  252 ,  254  and  256 ,  258 . Also unlike the inner pouch  38 , the inner pouch  38 A has no holes  74 ,  76 , but instead relies upon rupture of the inner pouch wall  260  to release the contents therefrom.  
      In particular, a pull tab, or strip,  262  may be fixedly secured (e.g., with one or more heat seals) to an outer surface  264  of the inner pouch wall  260 , which pull tab  262  may depend from the heater product in the same or similar fashion to the pull tab  72  illustrated in  FIGS. 1 and 2 . Strips  266 ,  268  of reinforcing material (such as, for example, SCOTCH-brand Reinforced Filament Tape #8981, available from 3M of St. Paul, Minn.) may also be fixedly secured to the outer surface  264  of the inner pouch wall  262 . The first strip of reinforcing material  266  may be disposed such that it is axially aligned with the pull tab  262 , while the strips  268  may be disposed at an angle to a line that passes through the pull tab  262  and the first strip  266 .  
      In use, force may be applied to the pull tab  262  causing it to move from the left to the right, across the inner pouch  38 A as shown in  FIGS. 16 and 17 . This, in turn, may cause the inner pouch wall  260  to rupture. The first strip  266  of reinforcing material, which may be partially overlapped by the pull tab  262 , may guide the tear in the inner pouch wall  260  initiated by the force applied to the pull tab  262  so as to limit the likelihood that the tear will be too small to release the contents of the inner pouch  38 A. On the other hand, the strips  268  may guide the tear in the inner pouch wall  260  to limit the likelihood that the tear will be too large such that the user will be unable to remove the pull tab  262  and associated portion of the ruptured inner pouch wall  260  from the heater product.  
       FIGS. 18-23  illustrates an alternative heater product  20 B, with an outer pouch  300  similar to that shown in  FIGS. 1 and 2  and an inner pouch  314  similar to that shown in  FIGS. 16 and 17 .  
      As shown in  FIG. 18 , the heater product  20 B may include an outer pouch  300  (made of, for example, foil on a linear low density polyethylene sealant) having a first end  302  and a second end  304 . As shown in  FIG. 19 , the outer pouch  300  may include a pouch wall  306 , which may be flexible, semi-rigid, rigid, etc., having an outer surface  308  and an inner surface  310  (see  FIG. 20C ). The inner surface  310  of the pouch wall  306  may define a cavity  312  in which is disposed an inner pouch  314 . The inner surface  310  of the pouch wall  306  may be described as having a first section and a second section, which with the pouch  300  disposed as illustrated in  FIGS. 18 and 19  may be described as an upper section and a lower section.  
      The inner pouch  314  (made of, for example, polyester on foil on a polyethylene sealant) also has a first end  320  and a second end  322 . As shown in the Figures, the inner pouch  314  also includes a pouch wall  324  having an outer surface  326  ( FIG. 18 ) and an inner surface  328  ( FIG. 21 ). Moreover, the inner surface  328  of the pouch wall  324  may be described as having a first (or upper) section and a second (or lower) section.  
      It should be noted that designations such as “upper” and “lower” are for ease of discussion only, and are not meant to limit the disclosure in any fashion, for a similar designation may be used if the pouch was inverted with the second section of the outer pouch being “upper” and the first section being “lower” and the second section of the inner pouch being “upper” and the first section being “lower.” 
      As illustrated in  FIG. 21 , the wall  324  of the inner pouch  314  may be sealed at both the first and second ends  320 ,  322 . Thus, similar to the embodiment of the inner pouch  38 A shown in  FIGS. 16 and 17 , the inner pouch  314  has a single cavity  334 . Unlike the embodiment of inner pouch  38 A, the seals at the first and second ends  320 ,  322  may have a chevron-shaped section, which chevron-shaped section may assist in lowering the pull force required to tear the wall  324  of the inner pouch  314 .  
      As further illustrated in  FIG. 19 , the inner surface  310  of the wall  306  of the outer pouch  300  may be joined to itself at the first and second ends  302 ,  304  of the outer pouch  300 . In particular, as shown in  FIG. 19 , the inner surface  310  of the outer pouch  300  may be joined at the second end  304  such that the second end  322  of the inner pouch  314  is disposed between the first and second sections of the inner surface  310  of the wall  306 . In this fashion, the second end  322  of the inner pouch  314  may be attached to the second end  304  of the outer pouch  300 . The first and second sections of the inner surface  310  of the wall  306  may also be joined at the first end  302  to close the first end  302  of the outer pouch  300 .  
      The outer and inner pouches  300 ,  314  may also be attached together in other ways. For example, the outer surface  326  of the inner pouch  314  may have adhesive strips  339  attached thereto, as shown in  FIG. 23 . The adhesive strips may be used to attach the outer an inner pouches  300 ,  314  together to limit the space beneath the inner pouch  314  between the outer pouch  300  and the inner pouch  314 .  
      In operation, the contents of the cavity  334  are to be released into the cavity  312 . Consequently, the heater product  20 B may include a release mechanism  340 , which includes a pull strip  342  and strips of reinforcing material  344 ,  346 . In this regard, the inner pouch  314  is similar to the inner pouch  38 A shown in  FIGS. 16 and 17 .  
      The release mechanism may now be discussed in greater detail with reference to  FIGS. 19 and 22 . In particular, the pull strip  342  (made of, for example, nylon laminated to a low density polyethylene sealant) may have a first end  348  and a second end  350 . In between the first end  348  and the second end  350  may be a first section  352 , a second section  354 , and a third section  356 .  
      The first section  352  of the pull strip  342  may be fixedly secured (e.g., with one or more heat seals) to the outer surface  326  of the inner pouch wall  324 . The strips  344 ,  346  of reinforcing material (such as, for example, SCOTCH-brand Reinforced Filament Tape #8981, available from 3M of St. Paul, Minn.) may also be fixedly secured to the outer surface  326  of the inner pouch wall  324 . The first strip of reinforcing material  344  may be disposed such that it is axially aligned with the pull strip  342 , while the strips  346  may be disposed parallel to and slightly offset from a line that passes through the pull strip  342  and the first strip  344 . There also exists a gap between the first strip  344  and the second strips  346 .  
      In use, force may be applied to the pull strip  342 . This, in turn, may cause the inner pouch wall  324  to rupture. The first strip  344  of reinforcing material, which may be totally overlapped by the pull strip  342  (see  FIG. 19 , only a portion of the pull strip  342  is shown in  FIG. 22  to improve clarity), may guide the tear in the inner pouch wall  324  initiated by the force applied to the pull tab  342  so as to limit the likelihood that the tear will be too small to release the contents of the inner pouch  314 . On the other hand, the strips  346  may guide the tear in the inner pouch wall  324  to limit the likelihood that the tear will be too large such that the user will be unable to remove the pull strip  342  and associated portion of the ruptured inner pouch wall  324  from the heater product.  
      The second section  354  may be connected to the first section  352 , and may lie back on top of the first section  352 , as best seen in  FIG. 19 , for example. The second section  354  may also be disposed through an opening  360  in the wall  306  of the outer pouch  300 . In fact, a sealing mechanism  362  (see  FIGS. 20A-20C ) may be disposed beneath the opening  360 , and the section  354  of the pull strip  342  may be disposed through the sealing mechanism  362  and then the opening  360 .  
      As best seen in  FIG. 20A , the sealing mechanism  362  may include a first piece  364 , a second piece  366  and a third piece  368 , although the mechanism may be formed as a one or two-piece mechanism as well. The first piece  364  and the second piece  368  may have slits  370 ,  372  formed therethrough, while the middle piece  364  may have a larger slot  374  formed therethrough. All three pieces  364 ,  366 ,  368  may be made of, for example, low density polyethylene (LDPE). The three pieces  362 ,  364 ,  368  may be joined together, for example through the use of fasteners, such as staples, as shown in  FIG. 20B . As shown in  FIG. 20C , the assembly of pieces  362 ,  364 ,  366  may then be attached to the inner surface  310  of the wall  306  through the use of an attachment patch  376 , as shown, the attachment patch  376  also having a slit (not shown) formed therethrough. In operation, the cavity defined by the slot  374  may act as a “catch” to receive any material that is not removed from the strip  342  by the third piece  368 , but that is removed by the first piece  362 .  
      The third section  356  may terminate in the second end  350  of the pull strip  342 . The third section  356  of the pull strip  342  may be outside the outer pouch  300  of the heater product  20 B, and may include an enlarged region  380 . The enlarged region  380  may be included to make it easier for the user of the product  20 B to grip the end  350  of the pull strip  342  to apply force to the pull strip  342 .  
      The embodiment of heater product  20 B may also differ from that shown in  FIGS. 1 and 2  in that the vent holes  148  have been replaced with a number of pinholes  390  (see  FIG. 18 ). In fact, the several hundred pinholes may be made in the wall  306  of the outer pouch  300 . These pinholes  390  may permit steam to escape from the outer pouch  300  during operation. While the holes  390  should be small enough to prevent the escape of materials from the outer pouch  300 , the holes  390  (and the opening  360 ) may be covered by a removable adhesive label that prevents loss of material in shipment and may be removed prior to activation.