U.S. patent application number 13/734594 was filed with the patent office on 2013-07-11 for porous oxygen activated heater.
This patent application is currently assigned to RECHARGEABLE BATTERY CORPORATION. The applicant listed for this patent is RECHARGEABLE BATTERY CORPORATION. Invention is credited to Christopher Pedicini, Lawrence A. Tinker.
Application Number | 20130174835 13/734594 |
Document ID | / |
Family ID | 48743050 |
Filed Date | 2013-07-11 |
United States Patent
Application |
20130174835 |
Kind Code |
A1 |
Tinker; Lawrence A. ; et
al. |
July 11, 2013 |
POROUS OXYGEN ACTIVATED HEATER
Abstract
An substrate heater includes at least a wet porosity of between
15-35% to allow for sufficient electrolyte solution and porosity
for access of a reducing agent within the substrate and oxygen.
Inventors: |
Tinker; Lawrence A.;
(College Station, TX) ; Pedicini; Christopher;
(Nashville, TN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
RECHARGEABLE BATTERY CORPORATION; |
College Station |
TX |
US |
|
|
Assignee: |
RECHARGEABLE BATTERY
CORPORATION
College Station
TX
|
Family ID: |
48743050 |
Appl. No.: |
13/734594 |
Filed: |
January 4, 2013 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
61583410 |
Jan 5, 2012 |
|
|
|
61583418 |
Jan 5, 2012 |
|
|
|
Current U.S.
Class: |
126/263.02 |
Current CPC
Class: |
F24V 30/00 20180501 |
Class at
Publication: |
126/263.02 |
International
Class: |
F24J 1/00 20060101
F24J001/00 |
Claims
1. A heater comprising: a composite heater substrate that
exothermically reacts with oxygen, wherein the composite heater
substrate has a wet porosity of between 15-35%.
2. The heater of claim 1 wherein the composite heater substrate has
a dry porosity of approximately 60%.
3. The heater of claim 1 wherein the composite heater substrate has
a dry porosity of approximately between 60-65%.
4. The heater of claim 1 wherein the heater comprises: a reducing
agent, a binder, a promoter and an electrolyte.
5. A heater comprising: a porous flexible substrate including a
reducing agent, a binder, and a promoter, the porous flexible
substrate being activated with an electrolyte solution; and, a
package surrounding the porous flexible substrate to selectively
prevent oxygen access to the porous flexible substrate to control
an exothermic reaction between the porous flexible substrate and
atmospheric oxygen, wherein the porous flexible substrate has a wet
porosity of between approximately 15-35%.
6. The heater of claim 5 wherein the porous flexible substrate has
a dry porosity of approximately 60%.
7. The heater of claim 5 wherein the porous flexible substrate has
a dry porosity of approximately between 60-65%.
8. The heater of claim 5, wherein the heater includes approximately
82% by weight of the reducing agent, approximately 6.5% by weight
of promoter, and approximately 12% of binder.
9. The heater of claim 8, wherein the heater has a dry porosity of
approximately 60%.
10. The heater of claim 9, wherein the heater includes between
approximately 5-8 g of electrolyte solution.
11. The heater of claim 10, wherein the electrolyte solution is a
20% by weight solution of potassium chloride.
12. A heater comprising: a flexible substrate that includes a
binder and a reducing agent that will produce heat in the present
of oxygen; the flexible substrate being porous; the flexible
substrate being activated by an electrolyte solution such that the
flexible substrate includes a wet porosity sufficient to achieve a
desired temperature in an acceptable amount of time.
13. The heater of claim 12, wherein the desired temperature is
140.degree. F.
14. The heater of claim 13, wherein the acceptable amount of time
is less than 15 minutes.
15. The heater of claim 12, wherein the wet porosity is between
approximately 15-35%.
16. The heater of claim 12, wherein the desired temperature is
approximately 100.degree. F. than an initial temperature of the
heater.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional
Application No. 61/583,410 filed on Jan. 5, 2012, and to U.S.
Provisional Application No. 61/583,418 filed on Jan. 5, 2012, both
of which are incorporated herein by reference in their
entirety.
FIELD OF THE INVENTION
[0002] The invention relates to a porous heater that uses oxygen
(generally atmospheric oxygen) as a source of a chemical reactant
for an exothermic reaction.
BACKGROUND OF THE INVENTION
[0003] Portable flameless heaters are currently used in a variety
of applications, such as heating comestible, medical, and consumer
items.
[0004] Some heaters utilize the reaction of magnesium and water to
produce heat. While such a heater produces a sufficient amount of
heat, hydrogen gas is product of the exothermic reaction. This can
generate safety, transportation, storage, and disposal concerns. In
addition, the exothermic reaction requires water, which can be
tiresome to constantly carry around.
[0005] Other heaters utilize the heat from the reaction of
"quicklime" (calcium oxide) and water. While this reaction does not
generate hydrogen as a byproduct, it still is based upon using
water as a reactant. Accordingly, this type of heater also requires
a user to constantly have a sufficient amount of water.
Furthermore, the specific energy of the system is low
(approximately 1.2 kJ per gram of calcium oxide), making it a
suitable, but ineffective, alternative to the magnesium and water
heaters.
[0006] In addition to the water-based heaters described above, it
is known to utilize oxygen-based heaters. Oxygen-based heaters,
such as those described in U.S. Pat. Nos. 5,984,995, 5,918,590 and
4,205,957, have certain benefits over water-based heaters.
[0007] First, oxygen-based heaters do not require the addition of
water to generate heat. Second, because oxygen-based heaters
generate heat only in the presence of oxygen, the exothermic
reaction can be stopped by simply preventing oxygen access. In
addition, some such heaters allow for the exothermic reaction to be
restarted at a later time by re-introducing oxygen. Furthermore,
since oxygen is abundant in the atmosphere, these heaters do not
require mixing of components or additional reactants (as oxygen
from the atmosphere is the only missing reactant).
[0008] The assignee of the present invention has provided
oxygen-base heaters and various packages for same. See, e.g., U.S.
Pat. No. 7,722,782, issued on May 25, 2010; U.S. application Ser.
No. 12/376,927, filed on Feb. 9, 2009; U.S. application Ser. No.
12/874,338, filed on Sep. 2, 2010; U.S. application Ser. No.
61/583,418, filed on Jan. 5, 2012; U.S. application Ser. No.
61/714,526, filed on Oct. 16, 2012; U.S. application Ser. No.
61/716, 226, filed on Oct. 19, 2012; U.S. application Ser. No.
61/716,279, filed on Oct. 19, 2012; and, U.S. application Ser. No.
61/716,906, filed on Oct. 22, 2012, all of which are incorporated
herein by reference.
[0009] These disclosed heaters and packages are successful at
providing an oxygen based heater and/or package for same.
[0010] Since these heaters typically are a porous composite
structure and rely on the reaction of atmospheric oxygen with a
chemical constituent of the heater composite, the porosity of the
composite heater is an important feature for providing an efficient
and effective heater.
[0011] The present invention is directed to providing a heater that
has sufficient porosity so as to be efficient and effective without
compromising performance, as well as other benefits.
SUMMARY OF THE INVENTION
[0012] In one aspect of the present invention, the present
invention is directed towards an oxygen based heater with a wet
porosity of approximately 15-35%. The heater may also include a dry
porosity of approximately 60%.
[0013] In another aspect of the present invention, the present
invention is directed towards a heater with the wet porosity of
approximately 15-35% in a package.
[0014] The dry porosity refers to the porosity of the heater sheet
before the electrolyte is introduced, and the wet porosity refers
to the porosity of the sheet after electrolyte has been added. The
organization of the components within the heater sheet to achieve
these porosity ranges is an important attribute to ensure that the
heater includes the right micro-environment for the oxygen
initiated reaction to occur and these porosity ranges are an
indication of establishing the right microstructure.
[0015] If the dry or wet porosity is too small, oxygen diffusion to
the reaction sites is reduced and, therefore, the heater
performance is reduced.
[0016] On the other hand, if the dry porosity is too high, the
integrity of the heater sheet is compromised and this can impact
the ability to manufacture and handle the sheet.
[0017] Similarly, if the wet porosity is too high, the performance
of the heater sheet will be reduced due to a lack of electrolyte to
support the reaction.
[0018] Accordingly, the present invention is also directed at
providing a heater with a wet porosity sufficient to reach a
desired temperature in an acceptable amount of time.
[0019] These and other benefits should be apparent to those of
ordinary skill in the art in view of the present disclosure.
[0020] It is to be understood that the aspects and objects of the
present invention described above may be combinable and that other
advantages and aspects of the present invention will become
apparent to those having ordinary skill in the art upon reading the
following description of the drawing and the detailed description
thereof.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] The present invention will become more fully apparent from
the following description and appended claims, taken in conjunction
with the accompanying drawings. Understanding that the accompanying
drawings depict only typical embodiments, and are, therefore, not
to be considered to be limiting of the scope of the present
disclosure, the embodiments will be described and explained with
specificity and detail in reference to the accompanying drawings as
provided below.
[0022] FIG. 1 is a graph showing the temperature after 5 minutes
for various heaters according to the present invention.
[0023] FIG. 2 is a graph showing the time it takes various heaters
according to the present invention to achieve a 100.degree. F.
temperature rise (starting from a 40.degree. F. temperature).
[0024] FIG. 3 is a graph showing the time it takes heaters
according to the present invention to reach their respective
maximum temperatures.
[0025] FIG. 4 is a side cutaway view of an embodiment of a heater
according to the present invention in a package.
DETAILED DESCRIPTION OF THE DRAWINGS
[0026] While this invention is susceptible of embodiment in many
different forms, there is shown in the drawings and will herein be
described in detail one or more embodiments with the understanding
that the present disclosure is to be considered as an
exemplification of the principles of the invention and is not
intended to limit the invention to the embodiments illustrated.
[0027] Reference throughout this description to features,
advantages, objects or similar language does not imply that all of
the features and advantages that may be realized with the present
invention should be or are in any single embodiment of the
invention. Rather, language referring to the features and
advantages is understood to mean that a specific feature,
advantage, or characteristic described in connection with an
embodiment is included in at least one embodiment of the present
invention. Thus, any discussion of the features and advantages, and
similar language, throughout this specification may, but does not
necessarily, refer to the same embodiment.
[0028] Various composite heaters were prepared by forming sheets of
material using a standard mixing and rolling process developed by
the and with the formulation shown in Table 1. The heater includes
Zn as a reducing agent. The heater also includes carbon treated
with KMnO.sub.4 as a promoter and a polytetrafluoroethylene as a
binding agent that holds the chemical constituents together and
allows for a flexible composite heater to be made. A preferred
carbon is Ketjenblack KB300J produced by AkzoNobel Polymer
Chemicals, and a preferred polytetrafluoroethylene is a powdered
polytetrafluoroethylene such as Laurel Product's Marzon-10. Other
chemical constituents could be included and still fall within the
scope of the present invention. For example, the heater may also
include additives to improve stability such as indium, bismuth,
stannates, or silicates.
TABLE-US-00001 TABLE 1 Sheet Formulation g w/w % Zn 3375 81.70%
KMnO.sub.4 1.9 0.04% Carbon 268.1 6.49% polytetrafluoroethylene 486
11.76% Total 4131.0 100.0%
[0029] The properties of the produced composite heaters are shown
in table 2. The dry porosity is determined by calculating the
theoretical density of the components in the dry heater sheet and
then subtracting the apparent density from the theoretical density.
The difference is then divided by the theoretical density to
determine the dry porosity.
TABLE-US-00002 TABLE 2 Apparent Sheet Weight, Thickness Thickness
Vol- Density Dry % Properties g (inches) (cm) ume g/cm3 Porosity
Max 30.34 0.050 0.127 15.77 2.00 64.3% Min 28.20 0.048 0.122 15.14
1.79 60.0% Average 29.13 0.049 0.124 15.43 1.89 62.3%
[0030] The composite heaters were activated with various amounts of
a 20% (by weight) potassium chloride solution and assembled into
pouches. The different amounts of the electrolyte solution are
shown in Table 3. The use of the various amounts also resulted in
different wet porosities, also shown in Table 3. The wet porosity
is determined by calculating the free volume in the dry heater
sheet, subtracting the volume of activator solution added to the
sheet to determine the final free volume and then dividing by the
sheet volume.
TABLE-US-00003 TABLE 3 Free Total Vol- Activator Liquid Final Free
Final % ume, Solution Volume, Volume, Wet Porosity cm.sup.3 Weight,
g cm.sup.3 cm.sup.3 Porosity Group A 61.9% 9.37 4.9 4.3 5.09 33.6%
Group B 61.9% 9.37 6.4 5.5 3.83 25.3% Group 60.9% 9.23 8.0 7.0 2.27
15.0% C(a) Group 63.6% 10.03 7.8 6.7 3.29 20.8% C(b) Group D 63.6%
10.03 9.2 8.0 2.02 12.8% Group E 62.8% 9.90 10.88 9.46 0.44
2.8%
[0031] The performance of each of the composite heaters was
evaluated in a standard eight ounce water bag test in which the
temperature of water is monitored during the heating process.
[0032] The parameters of the test that were measured are as
follows: the temperature rise in five minutes; the time to raise
the water temperature by 100.degree. F. from an initial temperature
of 40.degree. F.; the time to reach the maximum temperature; and,
the maximum temperature achieved. In these tests, the 140.degree.
F. desired temperature was chosen as a desired temperature because
a temperature of 140.degree. F. is a desired temperature for a
comestible when heated from a cold temperature. As used herein
"desired temperature" means a temperature that is chosen and which
represents a temperature sufficient to achieve the purposes of the
heater (i.e., heat a comestible, boil water, melt ice, etc.).
[0033] FIGS. 1-3 illustrate the effect of wet porosity on the
performance of heater pouches.
[0034] More specifically, FIG. 1 shows the temperature rise in five
minutes for various composite heaters. As shown and demonstrated by
FIG. 1, the lower the porosity, the slower the temperature rise (in
the initial five minutes). This indicates a lack of oxygen access
to reaction sites within the composite heater. By increasing the
wet porosity, it is believed there is more access to the reaction
sites within the heater structure leading to a faster rate of
reaction and higher temperature at five minutes.
[0035] The effect of wet porosity on the time that it takes for a
heater pouch to achieve a 100.degree. F. temperature rise in an
eight ounce water bag test is shown in FIG. 2. As shown, in the
range of 15-35% wet porosity there is only a small impact on the
time to 100.degree. F. rise. However, lowering the wet porosity to
less than 10% greatly increases the time needed to achieve the same
temperature rise. This effect is believed to also indicate a
reduced oxygen access to reaction sites leading to a slower
reaction rate and thus, a longer time for the temperature rise. As
a result, it is believed that more than approximately 12 minutes to
reach the desired temperature was unacceptable. An "acceptable
time" would be a time in which the heater reaches the desired
temperature (and thus can sufficiently perform its desired
function).
[0036] Finally, the effect of wet porosity on the time it takes to
reach the maximum water temperature in the test is shown in FIG. 3.
As is demonstrated in FIG. 3, the time to maximum increases as the
wet porosity decreases. This trend is believed to reflect the lower
access to reaction sites due to a decrease in available porosity in
the heater sheet.
[0037] As shown in FIG. 4, heater 6 may be disposed inside of
package 5. Such package 5 may be a pouch comprising first sheet 9
and second sheet 12. Second sheet 12 includes a plurality of
openings 14 forming oxygen access portion 11. Disposed over at
least oxygen access portion 11 may be flap 8 (or other similar
structure capable of selectively opening and preferably
re-closing). Flap 8 may include adhesive 10 to secure flap 8 over
oxygen access portion 11 when the production of heat is not desired
or no longer desired. As shown, package 5 may include side 7
without any openings 14; however, the depicted package is merely a
representative package which selectively prevents oxygen access to
heater 6 to control an exothermic reaction between heater 6 and
atmospheric oxygen.
[0038] Heater 6 is made according to the present invention, and as
disclosed above, is a porous flexible substrate which includes a
reducing agent, a binder, and a promoter. Heater 6 is also
activated with an electrolyte solution. Furthermore, heater 6 has a
wet porosity of between approximately 15-35%.
[0039] Such a heater will provide a sufficient amount of heat and
reach the desired temperature within an acceptable amount of time,
based in part, upon the porosity of the heater itself.
[0040] It is to be understood that additional embodiments of the
present invention described herein may be contemplated by one of
ordinary skill in the art and that the scope of the present
invention is not limited to the embodiments disclosed. While
specific embodiments of the present invention have been illustrated
and described, numerous modifications come to mind without
significantly departing from the spirit of the invention, and the
scope of protection is only limited by the scope of the
accompanying claims.
* * * * *