U.S. patent application number 11/610192 was filed with the patent office on 2007-12-20 for self-heating chemical system for sustained modulation of temperature.
This patent application is currently assigned to UNIVERSITY OF SOUTH FLORIDA. Invention is credited to Raquel Carvallo, Brandon Smeltzer, Aydin K. Sunol, Sermin G. Sunol.
Application Number | 20070289720 11/610192 |
Document ID | / |
Family ID | 38309701 |
Filed Date | 2007-12-20 |
United States Patent
Application |
20070289720 |
Kind Code |
A1 |
Sunol; Aydin K. ; et
al. |
December 20, 2007 |
Self-Heating Chemical System for Sustained Modulation of
Temperature
Abstract
A self-heating chemical system using one or more primary
components for exothermic reactions (such as calcium oxide), one or
more porous components that can serve as a heat sink and conductor
of heat as well as under going chemical transformations that
release heat (zeolite), a weak acid (citric acid) for sustained
modulation of temperature and pH. Exothermic reactions, mixing of
some chemicals, sorption of certain chemicals, phase changes in
chemicals, and dissolution of some chemicals in solvents release
heat during these operations. The rate of heat generation coupled
with mass and energy transfer rates to or from system(s) allows
modulation of the temperature of systems. The modulation can be
further enhanced by controlled release and availability of some of
the components. This method provides with a class of self-heating
product applications and focuses on the modulation of temperature
through sequestering of reactions with different rates, heat
release through dissolution, heat release through mixing, heat
release through sorption, heat release through phase change as well
as controlling mass and heat transfer rates.
Inventors: |
Sunol; Aydin K.; (Lutz,
FL) ; Smeltzer; Brandon; (Lutz, FL) ; Sunol;
Sermin G.; (Lutz, FL) ; Carvallo; Raquel;
(Tampa, FL) |
Correspondence
Address: |
SMITH HOPEN, PA
180 PINE AVENUE NORTH
OLDSMAR
FL
34677
US
|
Assignee: |
UNIVERSITY OF SOUTH FLORIDA
3802 Spectrum Blvd. Suite 100
Tampa
FL
33612
|
Family ID: |
38309701 |
Appl. No.: |
11/610192 |
Filed: |
December 13, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60597605 |
Dec 13, 2005 |
|
|
|
Current U.S.
Class: |
165/80.5 ;
165/132; 252/67 |
Current CPC
Class: |
Y02E 50/30 20130101;
C09K 5/18 20130101; Y02E 50/10 20130101 |
Class at
Publication: |
165/080.5 ;
165/132; 252/067 |
International
Class: |
F28F 7/00 20060101
F28F007/00; F28D 21/00 20060101 F28D021/00 |
Claims
1. A heat-producing composition comprising calcium oxide, zeolite
and one or more weak acids.
2. The composition according to claim 1 wherein the one or more
weak acids is citric acid.
3. The composition according to claim 2 wherein the weight ratio of
the calcium oxide:zeolite:citric acid is about 8:1:1.
4. The composition according to claim 1 wherein the composition is
encapsulated in a coating.
5. The composition according to claim 4 wherein the coating is
water-soluble.
6. The composition according to claim 4 wherein the coating is
selected from the group consisting of water-soluble polymers and
sugars.
7. A heating element to provide extended heat transmission
comprising: a containment member comprising water; and a reaction
mixture comprising calcium oxide and zeolite, wherein release of
the water in the containment member allows contact with the
reaction mixture thereby producing an exothermic reaction.
8. The heating element according to claim 7 wherein the reaction
mixture further comprises one or more one or more weak acids to
neutralize the calcium hydroxide produced by the reaction of the
water with the calcium oxide and further regulate temperature.
9. The heating element according to claim 8 wherein the one or more
weak acids is citric acid.
10. The heating element according to claim 9 wherein the weight
ratio of the reaction mixture of calcium oxide:zeolite:citric acid
is about 8:1:1.
11. The heating element according to claim 7 wherein the reaction
mixture is encapsulated in a coating.
12. The heating element according to claim 11 wherein the coating
is water-soluble.
13. The heating element according to claim 11 wherein the coating
is selected from the group consisting of water-soluble polymers and
sugars.
14. A heating element to provide extended heat transmission
comprising: an inner containment member comprising water; and an
outer containment member comprising a reaction mixture comprising
calcium oxide, zeolite and a weak acid, wherein release of the
water in the inner containment member allows contact with the
reaction mixture thereby producing an exothermic reaction.
15. The heating element according to claim 14 wherein the one or
more weak acids is citric acid.
16. The heating element according to claim 14 wherein the contents
of the outer containment member are under vacuum.
17. The heating element according to claim 14 wherein the inner
containment member is at a pressure higher that the outer
containment member.
18. The heating element according to claim 16 wherein the outer
containment member is vacuum-sealed to the inner containment
member.
19. The heating element according to claim 14 wherein the reaction
mixture is encapsulated in a coating.
20. The heating element according to claim 19 wherein the coating
is water-soluble.
21. The heating element according to claim 19 wherein the coating
is selected from the group consisting of water-soluble polymers and
sugars.
22. The heating element according to claim 15 wherein the reaction
mixture is encapsulated in a coating.
23. A self-heating chemical system for the production of warm
towels comprising a pouch system containing one or more towels and
a heating element, the heating element comprising an inner
containment member comprising water and an outer containment member
comprising a reaction mixture comprising calcium oxide, zeolite and
a weak acid, wherein release of the water in the inner containment
member allows contact with the reaction mixture thereby producing
an exothermic reaction.
24. The self-heating chemical system according to claim 23 wherein
the one or more weak acids is citric acid.
25. The self-heating chemical system according to claim 23 wherein
the contents of the outer containment member are under vacuum.
26. The self-heating chemical system according to claim 23 wherein
the reaction mixture is encapsulated in a coating.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to currently pending U.S.
Provisional Patent Application 60/597,605, entitled, "Self Heating
Chemical Systems for Sustained Modulation of Temperature", filed
Dec. 13, 2005, the contents of which are herein incorporated by
reference.
FIELD OF INVENTION
[0002] This invention relates to a self-heating system where the
heat is provided by chemical reactions, mixing, sorption, phase
change, and dissolution.
BACKGROUND OF THE INVENTION
[0003] Many self-heating products are emerging in the marketplace.
The applications include products for food, beverages, and hand
warmers. There are many areas such as disposable wipes where an
unmet need exists is in the application of the technology. These
applications, as well as others, require self-heating through the
reaction of chemicals. The initiation and control of these
reactions, retention and distribution of heat, and handling of
materials are key issues. These issues are only partially handled
for various products in the market. One key area not addressed in
the market is a sustained modulation of heat.
SUMMARY OF INVENTION
[0004] A self-heating chemical system using one or more primary
components for exothermic reactions (such as calcium oxide), one or
more porous components that can serve as a heat sink and conductor
of heat as well as under going chemical transformations that
release heat (zeolite), a weak acid (citric acid) for sustained
modulation of temperature and pH. Exothermic reactions, mixing of
some chemicals, sorption of certain chemicals, phase changes in
chemicals, and dissolution of some chemicals in solvents release
heat during these operations. The rate of heat generation coupled
with mass and energy transfer rates to or from system(s) allows
modulation of the temperature of systems. The modulation can be
further enhanced by controlled release and availability of some of
the components. This method provides with a class of self-heating
product applications and focuses on the modulation of temperature
through sequestering of reactions with different rates, heat
release through dissolution, heat release through mixing, heat
release through sorption, heat release through phase change as well
as controlling mass and heat transfer rates.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] For a fuller understanding of the invention, reference
should be made to the following detailed description, taken in
connection with the accompanying drawings, in which:
[0006] FIG. 1 is an illustration depicting a procedure for a
chemical mixture for a self-heating chemical system for sustained
heat modulation. The mix includes 17 g. of CaO (uncalcined), 8.5 g.
HZeo, 1 g. citric acid, 4 g. PE and 36 ml. water.
[0007] FIG. 2 is a graph illustrating the temperature profile of
the activated system depicted in FIG. 1. T1 through T4 refer to the
temperature at various distances from the chemical pouch containing
the reactants with distance increasing from T1 to T4.
[0008] FIG. 3 is an illustration depicting a procedure for a
calcined CaO chemical mixture of a self-heating chemical system for
sustained heat modulation. The mix included 17 g. of CaO
(calcined), 8.5 g. HZeo, 1 g. citric acid, 4 g. PE and 36 ml.
water.
[0009] FIG. 4 is a graph illustrating the temperature profile of
the activated system depicted in FIG. 3. T1 through T4 refer to the
temperature at various distances from the chemical pouch containing
the reactants.
[0010] FIG. 5 is a graph depicting the moisture absorbed by the CaO
as a function of time.
[0011] FIG. 6 is a graph illustrating the center temperature
profile using the chemical mix composed of a primary heater (CaO),
a porous component that also generates heat (Zeolite), and a weak
acid (citric acid).
[0012] FIG. 7 is a graph illustrating the use of a slight vacuum to
mix the chemicals with the water.
[0013] FIG. 8 is graph illustrating temperature profiles for a
system using 5 towels and having a composition including 17.5 g. of
CaO, 4.5 g. Chabazite, 3 g. citric acid, and 35 ml. water. The
graph illustrates the temperature at various points within the
pouch system.
[0014] FIG. 9 is a pair of illustration. (A) is a graph depicting a
desirable time-temperature band, and modulation thereof, for the
heating system. (B) is an illustration depicting a coated chemical
component/substrate for the system.
[0015] FIG. 10 is an illustration depicting a five towel
application of the chemical pouch system utilizing a self-heating
chemical system for sustained heat modulation.
[0016] FIG. 11 is an illustration depicting the chemical pouch
system of the five towel application depicted in FIG. 10.
[0017] FIG. 12 is an illustration depicting a generalized scheme
for a chemical pouch.
[0018] FIG. 13 is a series of illustrations depicting the
activation of the generalized scheme of the chemical pouch depicted
in FIG. 12. (A) depicts the pouch in an unactivated state with
water filling the inner pouch exerting pressure on the pouch walls
as indicated by the "p". (B) depicts the activation of the chemical
pouch by applying pressure/force, denoted "F" externally to the
pouch resulting in rupture of the inner pouch and release of water
contained therein. (C) depicts the activated chemical pouch
releasing heat denoted "Q".
[0019] FIG. 14 is a series of illustrations depicting a chemical
pouch, based upon the generalized scheme of FIG. 12, surrounded by
a towel. (A) depicts the pouch in the unactivated state where the
pouch is completely surrounded by a towel. (B) depicts the pouch
and towel system upon activation with the release of heat (Q).
[0020] FIG. 15 is a series of illustrations depicting a
self-heating chemical system with the system seal in a in a pouch.
(A) depicts the system in the unactivated state. (B) depicts the
activated system in the pouch.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0021] The disclosed invention is a self-heating chemical system
for sustained modulation of temperature. A self-heating chemical
system using one or more primary components for exothermic
reactions (such as calcium oxide), one or more porous components
that can serve as a heat sink and conductor of heat as well as
under going chemical transformations that release heat (zeolite), a
weak acid (citric acid) for sustained modulation of temperature and
pH. Exothermic reactions, mixing of some chemicals, sorption of
certain chemicals, phase changes in chemicals, and dissolution of
some chemicals in solvents release heat during these operations.
The rate of heat generation coupled with mass and energy transfer
rates to or from system(s) allows modulation of the temperature of
systems. This invention relates to a mixture that allows
sequencing. The key reactions/transformation are as follows:
CaO+H.sub.2O.fwdarw.Ca(OH).sub.2 calcium oxide+water.fwdarw.calcium
hydroxide Zeolite+Water.fwdarw.Hydrated zeolite+Water
CaO.MgO+H.sub.2O.fwdarw.Ca(OH).sub.2+MgO
MgO+H.sub.2O.fwdarw.Mg(OH).sub.2
2Ca(OH).sub.2+3C.sub.6H.sub.8O.sub.7(aq.).fwdarw.Ca.sub.2(C.sub.6H.sub.5O-
.sub.7).sub.3.4H.sub.2O+2H.sub.2O calcium hydroxide+citric
acid.fwdarw.calcium citrate
[0022] Referring to FIG. 6 there is a graph illustrating the heat
generated as a function of time of a chemical mix composed of a
primary heater (CaO), a porous component that also generates heat
(Zeolite), and a weak acid (citric acid). The amount of chemical
used is this illustration is about 42 gr. The mix is 77% CaO, 14%
Zeolite and 9% Citric Acid by weight for full recipe; and 84% CaO
and 16% Zeolite for the recipe without citric acid. The total
amount of chemicals and water used is the same in all three cases.
As shown, the system can heat fast and maintain a uniform and high
temperature.
[0023] Referring to FIG. 7 there is shown a graph illustrating the
temperature profile comparing a vacuum to non-vacuum. The results
illustrate the advantages of using slight vacuum. As depicted, the
vacuum provides an avenue for rapid and thorough mixing of water
(solvent) with the chemicals. The resulting reaction avoids hot
spots due to improper mixing that happens during the initial
period. Furthermore, vacuumed containment results in more uniform
and higher temperatures, at latter periods, upon mixing. The porous
component allows intra-particle void space. The inter-particle void
space is not pertinent and is reduced during vacuuming.
[0024] Referring to FIG. 8 there is shown the time-temperature
profile of a 5 towel system employing 7.5 g. of CaO, 4.5 g.
Chabazite, 3 g. citric acid, and 35 ml. water. The figure
illustrates temperature profiles of five disposable wash clothes
heated using the aforementioned chemical system composed of
chemicals containment (chemical pouch) and containment comprised of
water (water pouch). All but water is in one pouch while water is
in another pouch. When the chemicals are mixed the reaction is
initiated to heat the adjacent wash clothes. The time-temperature
profiles of five wash clothes are given in FIG. 8 along with the
chemical recipe.
[0025] FIG. 9(A) illustrates a desirable time-temperature band the
heating system should be modulated within as well as one of the
ways it can be achieved. The coated material, as shown in FIG.
9(B), can be any of the chemical (zeolite, calcium oxide and citric
acid) components. All or fraction of the compounds can be
encapsulated. The particle size of the chemicals, chemicals coated,
coating thickness, coating material, porosity of the porous
compounds, the amount of chemicals used, the composition of the
chemical mix, and the amount of water used all enable modulating
and sustained performance within the desirable time-temperature
band.
[0026] FIG. 10 illustrates a self-heating system for sustained
modulation providing a contained packet system (16) with five
towels (60). A vacuum is used to create a gradient for the water to
move into the chemical pouch (10). Referring to FIG. 11, the vacuum
allows the chemical mix (20) to wet faster and therefore heat
faster and more evenly when the water pouch (42) containing the
water (40) is broken. As the water pouch (42) is broken, the water
is contained within the sealant film (22) of the chemical pouch
(10). The porous material allows more reaction area and enables
pulling vacuum better. The pull vacuum helps to empty void space.
Since the pouch material is flexible and takes the shape of
material (i.e. the chemical particles) you are vacuuming, the
available space for the water to go through is very limited if you
do not have porous particles. In the absence of porous particles,
the volume you would have is limited to void space between
neighboring particles. Instead, in the present instance, the porous
matrix in the particles allows space for water without the chemical
pouch expanding significantly.
[0027] Referring to FIG. 12, there is shown a generalized schema of
the chemical pouch (10) of the self-heating chemical system for
sustained modulation of heat. The pouch is a dual layer system with
water (40) contained in the inner water pouch (42) and the chemical
mix (20) contained in the outer pouch, the limit of which is
defined by the outer sealant film (22). By sequestering the water
in the inner pouch, the system can be stored and transported in an
unactivated/unreacted state. Heat generation begins upon rupture of
the water pouch (40).
[0028] Referring to FIG. 13 there is shown the procedure for
activation of an exemplary system. In the unactivated state the
water (40) is maintained in the water pouch (42), filling the pouch
and applying a pressure (p) on the inner walls of the water pouch
(42). Referring to FIG. 13 (B), a user exerts a force (F) on the
external walls of the sealant film (22) chemical pouch (10),
causing the water pouch (22) to rupture. The rupture of the water
pouch (42) allows the water (40) contained therein the escape the
water pouch (42) and mix with the chemical mix (20) contained
within the sealant film (22). Referring to FIG. 13(C), it is
illustrated that the mixture of the water (40) with the chemical
mix (20) within the chemical pouch system (10) produces an
exothermic reaction that liberates heat (Q).
[0029] Referring to FIG. 14(A) there is shown a generalized schema
of a towel system (12) employing the self-heating chemical system
for sustained modulation of heat. The towel system utilizes one or
more towels (60) chemical surrounding a chemical pouch system (10).
FIG. 14(B) illustrates the towel system upon rupture of the water
pouch (42), thus allowing the mixture of the water (40) with the
chemical mixture (20) resulting in the liberation of heat (Q) from
the system.
[0030] Referring to FIG. 15 there is shown a generalized schema of
a towel-pouch system (16) wherein a towel system (12) employing the
self-heating chemical system (10) for sustained modulation of heat
is contained. The towel-pouch system (16) includes an outer film
(82) to store and contain the towel system (12) employing the
chemical pouch (10) of the self-heating chemical system for
sustained modulation of heat. Where applicable, an insulator can be
localized to the area (80) immediately adjacent to the outer film
(82) to insulate the chemical system and the heat (Q) produced by
the reaction of the system. The outer film (82) further includes a
seal (84) to facilitate entry into the towel-pouch system (16) and
removal of the towels system (12) contained therein.
[0031] The present invention facilitates the time-temperature
modulation of heating. Furthermore, components, principally the
water which initiates the reaction is sequestered, while upon the
rupture of the water pouch the chemical component system enables
the effective missing of the water with the chemicals. In certain
aspect, the two pouch system utilizes heating components such as
CaO/Zeolite/Citric acid in an outer pouch that is vacuumed. The
inner pouch contains the water. When you break the inner pouch by
squeezing pouches, the inner pouch breaks and water rapidly
permeates and diffuses into the chemicals.
[0032] Citric acid is used in the reaction to neutralize the
reaction mix. The citric acid goes through an exothermic reaction
producing calcium citrate to further generate heat. It also has an
endothermic dissolution step in water that cools the system in a
regulated fashion to keep the temperatures within acceptable
limits. Also, Calcium citrate is environmentally friendly compound.
MgO as shown in the previous formulas above is quick lime raw
material mix. The mixture enables the following: [0033] The CaO
reactions are fast and generate more heat while Zeolite generates
less heat and more slowly. A mix avoids hot spots and enables
sustained heating. [0034] The zeolite is highly porous and enable
pulling vacuum. Thus, we can mix both zeolite and CaO rapidly and
uniformly. [0035] The zeolite stores heat and conducts uniformly.
[0036] Zeolites are environmentally friendly.
[0037] The system can be further tailored by encapsulating the
chemical mixture in a coating. The coating chemicals can then
dissolve and disintegrate with temperature, pH change and mixing
with water. It is further envisioned that the thickness of the
coating can be tailored to achieve desired rates of reaction, such
as delaying the initiation of reaction by the contact with the
water. It is further envisioned that particles of various depths of
coating may be used in an individual application to further tailor
the modulation of response by having particles with thinner
coatings initiate reaction more quickly, while thicker coatings
producing a delayed response. The coating chemicals can be water
soluble polymers or sugars or any other chemical that disintegrates
with heating
[0038] The system provides economy, sustainment and modulation of
heat release, storage of energy. The towels used in such a system
can be wet towels or dry towels, The towel system is meant to be
exemplary of the types of uses that can be provided in a chemical
system for sustained modulation of heat, but should not be
interpreted as limiting to that particular application.
[0039] The disclosures of all publications cited above are
expressly incorporated herein by reference, each in its entirety,
to the same extent as if each were incorporated by reference
individually.
[0040] It will be seen that the advantages set forth above, and
those made apparent from the foregoing description, are efficiently
attained and since certain changes may be made in the above
construction without departing from the scope of the invention, it
is intended that all matters contained in the foregoing description
or shown in the accompanying drawings shall be interpreted as
illustrative and not in a limiting sense.
[0041] It is also to be understood that the following claims are
intended to cover all of the generic and specific features of the
invention herein described, and all statements of the scope of the
invention which, as a matter of language, might be said to fall
there between. Now that the invention has been described,
* * * * *