METHODS AND SYSTEMS FOR TRANSPORTING TEMPERATURE-SENSITIVE PRODUCTS IN COLD ENVIRONMENTS

Abstract

The subject invention provides methods and packaging systems for controlling a thermal environment of a payload, such as a temperature-sensitive payload. Advantageously, the subject invention provides methods and systems that propagate heat, created by a thermal generator, throughout an enclosed environment, such as a packaging system for temperature-sensitive products. In specific preferred embodiments, the subject invention provides a warmer payload environment during cold weather that reduces hot or cold spots inside the packaging system.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application Ser. No. 63/744,936, filed Jan. 14, 2025, the disclosure of which is hereby incorporated by reference in its entirety, including all figures and tables.

BACKGROUND OF THE INVENTION

Temperature-sensitive products are items that must be maintained within specific temperature ranges to preserve their quality, efficacy, and/or safety. Examples of temperature-sensitive products include perishable food, pharmaceuticals (such as vaccines and insulin), biologics, chemicals, and certain electronics. Temperature-sensitive products require proper handling and storage to prevent spoilage, degradation, and/or loss of effectiveness.

Temperature-sensitive products can be affected by exposure to temperatures that are too high or too low during transportation. During transportation, such temperature-sensitive products are contained within a thermal shipping system as a payload, where the payload refers to at least one temperature-sensitive product that requires maintenance within a specified temperature range during transportation.

Many systems used for transporting temperature-sensitive products use an insulated container (such as Styrofoam) and a cold bank (such as frozen gel packs) to provide a chilled shipping environment for thermal maintenance of the products. The frozen gel packs are typically placed on the top of the product, on the bottom of the product, or on both the top and bottom of the product.

FIG. 1 shows a configuration that utilizes the cold bank at the top of the payload. Cold air is moved throughout the container via natural convection to maintain desired conditions (such as 2-8° C.). U.S. Pat. Nos. 9,689,602; 10,309,709; 11,248,831 and 11,898,795 disclose containers with a metalized bag that helps to distribute heat inside a container.

Maintaining the proper thermal environment for shipping temperature-sensitive products in very cold external conditions presents unique and difficult challenges. For example, during cold months, frozen gel packs can be replaced by liquid-form gel packs to protect payloads against low temperatures, including against freezing, during transit. The liquid gels provide protection against freezing by the energy released during the phase change from liquid into solid (latent heat of fusion). Unfortunately, the quantity of liquid gel packs required to prevent the freezing of a payload can be substantial, which increases the weight of the packaging system, decreases the volume available for a payload, increases the volume of the packaging system and, thus, increasing the cost of shipping.

If a heat source were to be placed in a shipping package near a product in order to raise the temperature, an uneven heat profile within the package could lead to inconsistent and deleterious payload temperatures. Due to the temperature sensitivity and required temperature maintenance ranges of products such as pharmaceuticals, diagnostics, and food products, the proximity of the heat source to a temperature-sensitive payload can destroy the payload and/or reduce its efficacy.

Thus, any generation of heat, and the propagation of heat in a shipping container, must be carefully controlled to avoid exposing payloads to excessively high temperatures while ensuring that sufficient heat reaches, and prevents freezing of, more distant payloads.

As a means to eliminate temperature gradients, phase change materials have been added to the walls of packaging systems. For example, U.S. Pat. Nos. 7,328,528 and 7,849,708 describe containers with walls filled with a phase change liquid (such as water) in an effort to provide a more uniform temperature inside the main container. Lining the walls with phase change material reduces the temperature stratification when, for example, the package is flipped during transit. Phase change packaging systems also contribute thermal protection as they provide additional insulation between the external environment and the internal environment.

Unfortunately, most phase change materials are water or vegetable oil based, which are heavy and can substantially increase the cost and carbon intensity of the shipping container system due to the additional weight.

BRIEF SUMMARY OF THE INVENTION

The subject invention provides methods and packaging systems for improving the thermal environment of a payload, such as a temperature-sensitive payload.

The methods and packaging systems of the subject invention maintain a desired temperature distribution for temperature-sensitive payloads that are shipped in an external environment that is colder than the desired interior temperature of the shipping package.

In preferred embodiments, the subject invention provides methods and systems that propagate heat, created by a thermal generator, throughout an enclosed environment, such as a packaging system for temperature-sensitive products. Advantageously, the temperature to which a temperature-sensitive product is shipped can be maintained in a range, such as 2-8° C., for a desired period of time, even when the exterior of the shipping package is exposed to extreme cold temperatures.

In a specific embodiment, the subject invention provides methods and shipping packages that utilize unique and advantageous combinations of a thermal generator together with a thermal propagator to create an optimized temperature distribution in a shipping package in order to protect temperature-sensitive payloads from temperatures outside of a desired temperature range.

The thermal generator may be, for example, an iron oxidation material, crystallization solution, or battery-operated heater. One or multiple types of thermal generators can be used.

The thermal generator, without the use of a thermal propagator, as described herein, could expose a temperature-sensitive payload located near the thermal generator to excessively high temperatures. The thermal propagator of the subject invention, which utilizes one or more thermally-conductive materials, with or without insulating materials, propagates heat evenly around a payload and mitigates exposure of the payload to excessive heat, thereby allowing the entire temperature-sensitive payload to be maintained and shipped within a desired temperature range, even when the shipping package is exposed to external environments colder than the desired temperature range for the payload.

Specific embodiments of the subject invention incorporate the thermal propagator's thermally-conductive material, such as aluminum foil and/or an insulating material, such as polypropylene foam, to house a thermal generator. The materials are specifically spatially-arranged, with respect to each other, in order to efficiently and precisely control thermal movement within a shipping package. When the system is placed inside a shipping package, the combination of conductive and insulating materials distribute the heat from the thermal generator throughout the interior of the shipping package in a pre-defined and controlled manner.

Accordingly, the shipping packages of the subject invention can be shipped in an environment that is colder than the desired temperature for the payload, thereby protecting the product from losing heat to the cold external environment outside the shipping package and facilitating the maintenance of a desired temperature range for a temperature-sensitive payload.

Advantageously, the methods and shipping packages of the subject invention can be used to increase the amount of time the payload and/or portions of the payload experience a desired temperature range and/or reduce the amount of time the payload and/or portions of the payload experience temperatures outside of the desired temperature range and/or experience an undesirable temperature range.

The methods and shipping packages of the subject invention can be used in shipping systems for a wide range of products including, but not limited to, pharmaceuticals, fresh produce, live seafood, meal kits, cosmetics, lotions, adhesives, paints, reactants, diagnostic samples, blood and blood products, infusion medications, nutritional supplements, electronics, wine and spirits, and plants.

Utilizing the described thermal generator and thermal propagator inside the shipping container maintains the temperature-sensitive payloads within the desired temperature range for a longer duration of time, while reducing the total weight of the shipping package, component costs, shipping costs, and carbon emissions, making it a more environmentally-friendly sustainable shipping packaging system.

BRIEF DESCRIPTION OF THE DRAWINGS

The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawings(s) will be provided by the Office upon request and payment of the necessary fee.

FIG. 1 shows a conventional insulated container system where (1) is an expanded polystyrene insulated container, (2) is 20° C. gel pack and (3) is a vial of a medical drug exposed to a colder outside environment.

FIG. 2 shows a conventional insulated container system where (1) is an expanded polystyrene insulated container with a thermal propagator (2) distributing heat from the bottom to the surrounding of vial of medical drug (3)

FIG. 3 shows a conventional insulated container system where (1) is an expanded polystyrene insulated container with a thermal propagator (2) distributing heat from the bottom to the surrounding of vial of medical drug (3) and having a −20° C. ice pack (4) to keep the payload in a temperature range of 2-8° C.

FIG. 4 shows a thermal propagator system using a high conductive material (1) at the top, a thermal generator (2) and a low conductive material (3) at the bottom.

FIG. 5 shows a sealed thermal propagator system using a high conductive material (1), a thermal generator (2), a low conductive material (3) at the bottom, and a very low conductive material (4) at the top.

FIG. 6 shows a sealed thermal propagator system using a high conductive material (1), a thermal generator (2), a low conductive material (3) at the bottom, and a very low conductive material (4) at the top and bottom.

FIG. 7 shows an embodiment in accordance with the subject invention where a thermal propagator was used without an insulation component on the top.

FIG. 8 shows an embodiment in accordance with the subject invention where a thermal propagator was used with an insulation component on the top.

FIG. 9 shows an embodiment in accordance with the subject invention where a non-insulated container is used to ship temperature sensitive products in a cold environment using a thermal propagator.

FIG. 10 shows a thermal propagator system using a high conductive material (1), a thermal generator (2), a low conductive material (3) at the bottom, and a very low conductive material (4) at the top, illustrating air movement created by openings of specific sizes and shapes that form channels acting as thermal paths.

FIG. 11 shows the effects of using a thermal propagator rather than a typical thermal generator on a vial of a medical drug and its proximity areas.

FIG. 12 shows an embodiment in accordance with the subject invention propagating heat from two thermal generators (2) for large shipping containers, wherein the thermal propagator system uses a high conductive material (1) at the top and a low conductive material (3) at the bottom.

FIG. 13 shows an embodiment in accordance with the subject invention using large, high thermal conductive wings (1) to propagate heat across larger surfaces, a thermal generator (2), and a low conductive material (3) at the bottom.

DETAILED DESCRIPTION OF THE INVENTION

The subject invention provides methods and systems for shipping payloads within a controlled temperature environment. Advantageously, the subject invention can be used to increase the amount of time a payload and/or portions of a payload experience a desired temperature range and/or reduce the amount of time a payload and/or portions of a payload experience temperatures outside of the desired temperature range.

In a specific embodiment, the subject invention provides methods and shipping packages that utilize unique and advantageous combinations of a thermal generator together with a thermal propagator to create an optimized temperature distribution in a shipping package in order to protect temperature-sensitive payloads from temperatures outside of a desired temperature range.

Specific embodiments of the subject invention incorporate thermally-conductive materials, such as aluminum and, optionally, insulating materials, such as polypropylene foam, positioned around a thermal generator, such as, for example, an iron oxidation material, a crystallization solution, or a battery-operated heater positioned inside a shipping package, such that heat is conducted in a controlled and directional manner from one or more locations in the interior of the shipping package to one or more other locations in the interior of the package, thereby preventing excessive heat being applied to temperature-sensitive products. The combinations of thermally conductive and insulated materials are referred to herein as a thermal propagator system.

The system of the subject invention can reduce the thermal gradient between the generated heat source and the most distal point of the shipping package by at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, or at least 70% or more.

Utilizing the methods and systems of the subject invention, temperature-sensitive payloads can be transported in a package having a temperature maintained at a desired temperature range such as, for example, frozen (−80° C. to −60° C. and −25° C. to −15° C.), refrigerated (2° C. to 8° C.), Controlled Room Temperature (2° C. to 30° C.), 2° C. to 15° C., −5° C. to 15° C., −2° C. to 12° C., 0° C. to 10° C., or 2° C. to 8° C.

Utilizing the thermal generator and thermal propagator of the subject invention inside the shipping package facilitates maintaining the desired temperature range for a long period of time, while reducing the weight of the shipping package. This results in reduced shipping costs and carbon intensity, thereby providing a more environmentally-friendly and sustainable shipping packaging system.

Selected Definitions

Ranges provided herein are understood to be shorthand for all of the values within the range. For example, a range of 1 to 20 is understood to include any number, combination of numbers, or sub-range from the group consisting of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, as well as all intervening decimal values between the aforementioned integers such as, for example, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, and 1.9. With respect to sub-ranges, “nested sub-ranges” that extend from either end point of the range are specifically contemplated. For example, a nested sub-range of an exemplary range of 1 to 50 may comprise 1 to 10, 1 to 20, 1 to 30, and 1 to 40 in one direction, or 50 to 40, 50 to 30, 50 to 20, and 50 to 10 in the other direction.

As used herein, “reduction” refers to a negative alteration, and the term “increase” refers to a positive alteration, wherein the negative or positive alteration is at least 0.25%, 0.5%, 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, or 100%.

As used herein, “reference” refers to a standard or control condition.

The transitional term “comprising,” which is synonymous with “including,” or “containing,” is inclusive or open-ended and does not exclude additional, unrecited elements or method steps. By contrast, the transitional phrase “consisting of” excludes any element, step, or ingredient not specified in the claim. The transitional phrase “consisting essentially of” limits the scope of a claim to the specified materials or steps “and those that do not materially affect the basic and novel characteristic(s)” of the claimed invention. Use of the term “comprising” contemplates other embodiments that “consist” or “consist essentially” of the recited component(s).

Unless specifically stated or obvious from context, as used herein, the term “or” is understood to be inclusive. Unless specifically stated or obvious from context, as used herein, the terms “a,” “and” and “the” are understood to be singular or plural. Unless specifically stated or obvious from context, as used herein, the term “about” is understood as within a range of normal tolerance in the art, for example within 2 standard deviations of the mean. About can be understood as within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the stated value.

Thermal Generator

Advantageously, the subject invention can be used for shipping payloads in an external environment that is colder than the interior of the shipping package, such as during cold weather. The thermal generator may be, for example, an iron oxidation material, crystallization solution, or battery-operated heater. One or multiple types of thermal generators can be used.

A thermal generator, such as a metal oxidation warmer, can generate, for example, 5161 kJ/kg whereas water gel or phase change material gel only have a latent heat of fusion of about 300 kJ/kg when freezing. In order to provide the desired temperature protection using water gel packs, a typical shipping container needs about 2.75 kg of gel compared to only 0.16 kg when using a metal oxidation warmer. In this specific case, using a thermal propagator with a thermal generator can reduce the total weight of a shipping package by, for example, about 3 kg by replacing the water gel packs to achieve a better thermal protection.

Thermal Propagator

While the thermal generator provides heat to help protect temperature-sensitive payloads from undesirable low temperatures when exposed to cold external shipping environments, the use of a thermal propagator is necessary to create a desirable, uniform temperature distribution inside the shipping package and prevent the temperature-sensitive payload from being exposed to unwanted high temperatures.

In some embodiments, the invention uses thermal conduction rather than, or in addition to, natural thermal convection, to evenly distribute the temperature from the thermal generator. The heat moves from the thermal generator toward a material, having a high thermal conductivity, and propagates throughout the shipping container, which reduces, or prevents, the payload from losing heat to the cold surroundings.

The thermal propagator provides a medium to move and direct heat that is generated by the thermal generator. Use of a thermal generator alone can generate as much as fifteen times more heat than a liquid gel pack. Therefore, a unique heat propagator is used according to the subject invention in order to avoid exposing temperature-sensitive payloads to temperatures in excess of a desired temperature range, and also to allow payloads located in a shipping package distally from the thermal generator to experience the desired temperature range.

Having a thermal generator with thermal propagator facilitates maintaining a desired heat distribution profile for extended periods of time, while reducing the weight of the shipping package, component costs, shipping costs, and carbon emissions, making it a more environmentally-friendly sustainable packaging system for shipments.

The thermal propagation component can utilize thermally conductive materials and/or one or more insulating materials to propagate heat within a shipping package without exposing payloads near the thermal generator to damagingly high temperatures, while contemporaneously transferring needed heat to payloads at distal locations inside the shipping package.

The thermal propagator can incorporate materials having high thermal conductivity and/or insulation materials that can be positioned to direct the heat propagation (by conduction, convection and/or radiation) without exposing proximal temperature-sensitive payloads to high temperatures.

The thermal propagator can have any of a variety of shapes and mechanical properties, such as wrapping (e.g., a conductive sheet), rigid, semi-rigid, and/or flexible. The thermal propagator transfers heat from the thermal generator to cooler portions of the interior of the shipping package through means of conduction, convection, and/or radiation. Embodiments of the thermal propagator can be permanent or temporary, and can incorporate materials made completely, or partially, of a conductive material having a high thermal conductivity. The selection and arrangement of the components can be used to control the time during which the temperature-sensitive payloads are within their desired temperature range.

In a specific embodiment, thermal contact is created between the thermal generator and a highly thermally-conductive material of a thermal propagator to propagate the heat away from the thermal generator. Such thermal contact can involve, for example, direct physical contact of the thermal generator with the thermal propagator(s). Other embodiments create indirect thermal contact between the thermal generator and the thermal propagator to facilitate sufficient heat transfer between the thermal generator and the thermal propagator to achieve the advantageous heat distribution profile of the system of the subject invention.

Specific embodiments have colors and finishes such as silver, blue, transparent, opaque, reflective, and/or matte.

The thermal generator can be enclosed permanently or temporarily. Any of a variety of methods can be used to secure the thermal generator including, for example, glue, heat-seal, Velcro, zipper, zip lock, tape, adhesive sticker, sewing, welding, stapling, screwing, and other means to assure the thermal generator remains in the desired physical association with the thermal propagator. The thermal propagator can be reclosable or reusable.

The shipping package in accordance with the subject invention can also utilize natural convection to distribute the heat inside the shipping package. A disadvantage of using natural convection to transfer heat inside the package is that natural convection is more effective when air gaps exist between the container and the payload in order to allow for the air movement to occur, as opposed to using a conductive equalizer such as described in U.S. Pat. Nos. 9,689,602; 10,309,709; 11,248,831 and 11,898,795.

The specific method(s) used to distribute the heat inside a container can affect the choice of the shape, size and material combinations used for the thermal propagator. In the case of a natural convection method, the thermal propagator needs to bring the heat from the thermal generator to areas where natural convection can occur.

Uniform temperature distribution provides better thermal protection by reducing temperature gradients. Inadequate temperature distribution reduces the effectiveness of a heat source, as the heat is not able to reach all areas, including locations distal to the heat source, inside a shipping package to protect each product from low temperatures. A thermal propagator can be placed inside of a shipping package at the top and/or bottom and/or sides and still provide enough heat protection for the products.

Effect and Exemplary Implementations of the Thermal Propagator

The temperature at the surface of a heat generator can easily exceed 45° C., where most of the temperature-sensitive products cannot be exposed to temperatures above 30° C.

As shown in the Table 1, a thermal propagator propagates heat from the thermal generator onto a larger surface area to keep the heat emission at a level safe for the temperature-sensitive payloads.

TABLE 1
Surface temperature (° C.) at 0 mm, 25
mm, 50 mm, and 75 mm from point heat emission
	Distance
	0	25	50	75
	(mm)	(mm)	(mm)	(mm)
No Thermal	38° C.	26.1° C.	25.2° C.	25.2° C.
Propagator
Thermal	28.2° C.	27.6° C.	27.2° C.	27.1° C.
Propagator

In a specific embodiment, a shipping package can have a surface area at the bottom of the package wherein the thermal propagator system is located and covering at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90% and/or at least 100% of the surface.

In some instances, the thermal propagator system can have additional coverage on the sidewalls of the container.

FIG. 2 shows an embodiment of the subject invention, incorporating a thermal propagator made of highly conductive material, designed for use with the container that is exposed to a cold external environment. FIG. 2 also shows heat transfer and heat movement with respect to this embodiment of the subject invention.

FIG. 3 shows an embodiment of the subject invention incorporating a thermal propagator made of highly conductive material and one cold bank at the top of the payload, designed for use with a container exposed to a cold external environment for temperature-sensitive products kept in a specific temperature range of 2-8° C. FIG. 3 shows heat transfer and heat movement with respect to the embodiment shown. FIGS. 2 and 3 show the heat moving on the thermal propagator for a shipping container using no cold bank and for a shipping container using one cold bank on the top, respectively. FIG. 2 also shows such heat transfer and heat movement of heat from the top, bottom, and two sides, and FIG. 3 shows the heat transfer and heat movement of heat around the top cold bank.

FIG. 4 shows an embodiment of a thermal propagator. In specific embodiments, the thermal conductance of the top material is sufficiently high to accomplish the heat transfer needed to maintain the product in a desired temperature profile, where the thermal conductance is the quantity of heat that passes in unit time through a plate of an area, A, and thickness, L, in units of W·K when there is a temperature difference of one degree Kelvin, in units of W·K⁻¹, where W is watts and K⁻¹ is inverse Kelvin.

Materials with a higher thermal conductivity can move the heat more rapidly, thus decreasing the chances for excessive heat to reach a temperature-sensitive product.

In preferred embodiments, the system of the subject invention uses highly-conductive materials having a thermal conductivity of at least 10 W/m−K, at least 50 W/m−K, at least 100 W/m−K, at least 150 W/m−K, and/or at least 200 W/m−K or more.

Examples of materials having thermal conductivities that can be utilized according to the subject invention include stainless steel (15 W/m−K), aluminum (205 W/m−K), aluminum foil (235 W/m-k), copper (400 W/m−K), and silver (429 W/m−K). Embodiments can use highly conductive materials with a thickness of at least 0.01 mm, at least 0.011 mm, at least 0.012 mm, at least 0.013 mm, at least 0.014 mm, at least 0.015 mm, less than 0.016 mm, less than 0.011 mm, and/or less than 0.2 mm. Specific embodiments utilize highly conductive materials with a thickness of 0.082 mm.

There are many variables that can be adjusted to achieve different rates of heat transfer, or thermal conductance, toward or away from the products, including, for example, the thermal conductivity of the material(s), the surface area of the conductive material(s), the thickness of the conductive material(s), and the use of conductive materials combined with insulation material(s).

In specific embodiments, the thermal conductance of the bottom material is low enough to prevent the heat transfer to undesired locations, thus further decreasing the chances for the heat to reach the temperature-sensitive product.

Certain embodiments use low conductive (insulating) materials to avoid direct contact on the products from the thermal generator, as it can reach 60° C. or more. Advantageously, materials with a low thermal conductivity can be used in some cases to prevent the heat from moving toward the payloads, thus decreasing the chances for excess heat to reach the temperature-sensitive payloads.

Specific embodiments use materials having a low thermal conductivity of less than 1 W/m−K, less than 0.5 W/m−K, less than 0.1 W/m−K, less than 0.05 W/m−K, and/or 0.03 W/m−K.

Examples of materials having low thermal conductivities that can be utilized in embodiments of the subject invention include expanded polystyrene (0.1 W/m−K), fiberglass (0.045 W/m−K), paper (0.05 W/m-k), polyethylene high-density (0.51 W/m−K), silica aerogel (0.003 W/m−K), and biotic materials such as wood wool (0.015 to 0.08 W/m−K). Embodiments can use low conductive materials with a thickness of at least 0.01 mm.

FIGS. 5 and 6 show examples of a thermal propagator using the combination of high and low conductive materials to achieve the desired thermal propagation.

FIGS. 7 and 8 show the propagation of the heat using the thermal propagator with or without an insulation component. The use of a combination of high and low thermal conductivity materials facilitates an improved distribution of the heat.

Reduced Carbon Intensity of Shipping Payloads

A “carbon footprint” may be defined as a measure of the total amount of carbon dioxide (CO₂) and other GHGs emitted directly or indirectly by a human activity or accumulated over the full life cycle of a product or service. As just one example, a product that requires a large volume to transport will likely have a larger carbon footprint than a product that can be shipped in a smaller volume.

Carbon footprints can be calculated using a Life Cycle Assessment (LCA) method, or can be restricted to the immediately attributable emissions from energy use of fossil fuels. A life cycle assessment (LCA, also known as life cycle analysis, ecobalance, and cradle-to-grave analysis) is the investigation and valuation of the environmental impacts of a given product or service caused or necessitated by its existence. The life cycle concept of the carbon footprint means that it is all-encompassing and includes all possible causes that give rise to carbon emissions. In other words, all direct (on-site, internal) and indirect emissions (off-site, external, embodied, upstream, downstream) need to be taken into account.

Normally, a carbon footprint is expressed as a CO₂ equivalent. Carbon dioxide equivalency is a quantity that describes, for a given mixture and amount of GHG, the amount of CO₂ that would have the same global warming potential (GWP), when measured over a specified timescale (generally, 100 years). Carbon dioxide equivalency thus reflects time-integrated radiative forcing. The carbon dioxide equivalency for a gas is obtained by multiplying the mass and the GWP of the gas. The following units are commonly used:

• • a) By the UN climate change panel IPCC: billion metric tonnes of CO₂ equivalent (GtCO₂ eq);
  • b) In industry: million metric tonnes of carbon dioxide equivalents (MMTCDE);
  • c) For vehicles: g of carbon dioxide equivalents/km (gCDE/km).

For example, the GWP for methane is 21 and for nitrous oxide 310. This means that emissions of 1 million metric tonnes of methane and nitrous oxide respectively is equivalent to emissions of 21 and 310 million metric tonnes of carbon dioxide.

Various methods exist in the art for calculating or estimating carbon footprints and may be employed in the subject invention.

Products and processes having a “low-carbon footprint” result in GHGs emitted per unit time that approach net-zero over the full life cycle of producing a system, component or product, through and until the system, component or product is ultimately used by human consumers. The net CO₂ and/or other GHG emissions can be, for example, less than about: 50%, 25%, 15%, 10%, 8%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.01%, 0.001% or 0% greater than net-zero emissions. In some embodiments, “low-carbon footprint” includes products or processes that result in negative GHG emissions due to, for example, their contribution to CO₂ capture.

The term “carbon footprint” is interchangeable herein with the terms “carbon intensity” and “emission intensity,” which are the measure of the emission rate of a given GHG relative to the “intensity” of a specific activity or industrial process. The emissions intensity can include amount of emissions relative to, for example, amount of fuel combusted, amount of an industrial product produced, total distance traveled, and/or number of economic units generated. Emissions intensity is measured across the entire life cycle of a product. For example, the emissions intensity of fuels is calculated by compiling all of the GHG emissions emitted along the supply chain for a fuel, including all the emissions emitted in exploration, mining, collecting, producing, transporting, distributing, dispensing and burning the fuel.

EXAMPLES

A greater understanding of the present invention and of its many advantages may be had from the following examples, given by way of illustration. The following examples are illustrative of some of the methods, applications, embodiments and variants of the present invention. They are not to be considered as limiting the invention. Numerous changes and modifications can be made with respect to the invention.

Example 1 Minimizing Temperature Gradients Inside the Packaging System

In this test, three corrugated boxes were used with each box containing an iron oxidation thermal generator. One corrugated box contained a thermal generator without the use of a thermal propagator. One corrugated box contained a thermal generator housed in a thermal propagator without an insulation component, and one corrugated box contained a thermal generator housed in a thermal propagator with an insulation component. Temperature data was collected in four different locations on the surface of the thermal propagator or heat source.

Corrugated box: 5.7 L (e-flute) with inside dimensions of 254 mm×178 mm×127 mm
Thermal generator: 0.054 kg of reactants for iron oxidation with dimensions 114 mm×83 mm×13 mm
Thermal propagator system (without insulation component): 203 mm×152 mm×13 mm

Materials:

• • A. Laminated polymer film 0.127 mm thickness (thermal conductivity: 0.33 W/(m−K))
  • B. Laminated aluminum film 0.068 mm thickness (thermal conductivity: 205 W/(m−K))
    Thermal propagator system (with insulation component): 203 mm×152 mm×19 mm

Materials:

• • A. Laminated polymer film 0.127 mm thickness (thermal conductivity: 0.33 W/(m−K))
  • B. Laminated aluminum film 0.068 mm thickness (thermal conductivity: 205 W/(m−K))
  • C. Insulation component: polypropylene foam with dimensions 114 mm×140 mm×6 mm

As it can be seen in Table 2 below, the temperature gradient on the surface of the thermal generator can be reduced by using a thermal propagator and even further reduced by implementing an insulation component with the thermal propagator.

TABLE 2
Surface temperature (° C.) of the
thermal generator at four different locations
	Location 1	Location 2	Location 3	Location 4
No Thermal	34° C.	32° C.	29° C.	28° C.
Propagator
Thermal Propagator	31° C.	30.5° C.	28° C.	27.5° C.
without Insulation
Component
Thermal Propagator	31.5° C.	30.5° C.	30° C.	28.5° C.
with Insulation
Component

The thermal propagator can be used with another technology called “TTx” where the whole payload is placed inside the TTx bag and the thermal propagator is placed outside on the top and/or bottom of the TTx bag, which will allow providing a heat source to keep the products inside the TTx bag at the right temperature range.

An example of this system is presented in FIG. 9 where the benefits of using a thermal propagator allow shipping temperature-sensitive products without using an insulated container.

Example 2 Eliminating the Need for Insulated Packaging Systems

Four corrugated boxes were tested against a 40-hour winter temperature profile that reached a minimum temperature of −5° C. Two boxes contained a refrigerated payload, and the other two boxes contained a room temperature payload. For the two refrigerated payloads, one box utilized a thermal generator housed in a thermal propagator, and one box used a thermal generator without a thermal propagator. For the two room temperature payloads, one box utilized a thermal generator housed in a thermal propagator, and one box used a thermal generator without a thermal propagator. Each box contained a TTx bag which held the payload surrounded by two gel packs (one on top of the payload and one on bottom of the payload). The refrigerated payloads used frozen gel packs, and the room temperature payloads used liquid gel packs. The thermal generator (with or without the thermal propagator) was placed inside the box, but outside of the TTx bag. A thermal generator (with or without the thermal propagator) was placed on the top and bottom of the closed TTx bag and its contents.

Corrugated box: 9.4 L (c-flute) with inside dimensions of 229 mm×203 mm×203 mm
Single payload: 127 mm×127 mm×89 mm containing 2 liquid-filled vials (10 mL each) conditioned at 20° C.
TTx bag: TTx™ 100 thermal insert having a thickness of 0.082 mm and standing dimensions of 203 mm×152 mm×305 mm
Frozen gel (for refrigerated payloads): 0.28 kg gel pack conditioned at −18° C., placed on top of payload; 0.74 kg gel pack conditioned at −18° C. placed on bottom of payload
Liquid gel (for room temperature payloads): 0.28 kg gel pack conditioned at 24° C. placed on top and bottom of payload
Thermal generator: 0.053 kg of reactants for iron oxidation with dimensions 114 mm×83 mm×13 mm
Thermal propagator system (without insulation component): 165 mm×127 mm×13 mm housing the thermal generator and placed on top and bottom of payload

Materials:

• • A. Laminated polymer film 0.127 mm thickness (thermal conductivity: 0.33 W/(m−K))
  • B. Laminated aluminum film 0.068 mm thickness (thermal conductivity: 205 W/(m−K))

Results:

TABLE 3
Time (h) payload is maintained in the desired temperature
range (2-8° C. for refrigerated payloads and 2-30°
C. for room temperature payloads) when using a thermal propagator
	Refrigerated Payloads		Room Temperature Payloads
	No		No
	Thermal	Thermal	Thermal	Thermal
	Propagator	Propagator	Propagator	Propagator
	6.2 hours	39 hours	2 hours	38 hours

As seen in Table 3 above, the use of a thermal propagator can extend the thermal duration of the packaging system by keeping the payload in the desired temperature range for a longer period. The results also exemplify the heat distribution capability of the thermal propagator.

TABLE 4
Minimum and maximum temperature (° C.) the payload
reached during the first 36-hours of testing; desired
temperature range for refrigerated payloads is 2-8°
C. and for room temperature payloads is 2-30° C.
	Refrigerated Payloads	Room Temperature Payloads
	No Thermal	Thermal	No Thermal	Thermal
	Propagator	Propagator	Propagator	Propagator
Minimum	−0.20°	C.	2.2° C.	8.0° C.	2.1° C.
Temperature
Maximum	22°	C.	7.6° C.	39° C.	27° C.
Temperature

Table 4 shows that without the use a thermal propagator, the payload is exposed to dangerously high and low temperatures that would destroy temperature-sensitive products. Implementing the thermal propagator with a thermal generator can eliminate the need for an insulated packaging system during the winter season for shipments less than 40 hours.

Embodiments of the invention can have openings or spacers to create channels for convection. As shown in FIG. 10, the openings provide a thermal path for the warm air to flow away from the thermal propagator and help to keeping the temperature-sensitive products in their temperature ranges when shipped in a colder environment.

The correct number of ventilation openings is important as too many openings can create a large heat flow that could expose the temperature-sensitive products to extreme high temperature that may damage them permanently.

In FIG. 11, the heat propagator with an appropriate number of openings creates the right amount of warm air reaching the temperature-sensitive products whereas too many openings expose the products to destructive temperatures. It is important to develop “thermal paths” so the warm air can circulate at specific locations to provide thermal protection. The total surface area of the openings is less than 3%, less than 2%, less than 1.5%, less than 1%, less than 0.5% or less than 0.1% of the total surface area of the thermal propagator.

Example 3 Promoting Convective Heat Transfer Inside the Packaging System

In this test, two 38 mm thick EPS containers were used. Each EPS container contained a thermal generator at the bottom and a payload on top. Each payload contained two temperature probes (at the top and bottom) for temperature monitoring of the payload. Each EPS container was fixed with two temperature probes to collect air temperature data at the top and bottom inside the container. One EPS container had a thermal generator housed in a thermal propagator with an insulation component and thermal paths, and the other EPS container had a thermal generator without a thermal propagator.

Insulated container: EPS 38 mm wall with inside dimensions 203 mm×152 mm×203 mm (6.3 L)
Load: 127 mm×127 mm×178 mm containing 4 liquid-filled vials (10 mL each)
Thermal generator: 0.054 kg of reactants for iron oxidation with dimensions 114 mm×83 mm×13 mm
Thermal Propagator System (with insulation component): 203 mm×152 mm×19 mm

Materials:

• • A. Laminated polymer film 0.127 mm thickness (thermal conductivity: 0.33 W/(m−K))
  • B. Laminated aluminum film 0.068 mm thickness (thermal conductivity: 205 W/(m−K))
  • C. Insulation component: polypropylene foam with dimensions 114 mm×140 mm×6 mm

The results presented in Table 5 below show that the addition of thermal paths to the thermal propagator promotes convective heat transfer by providing a path for the heat to move away from the thermal generator to other locations inside the container. The use of a thermal propagator with thermal paths allows heat to be distributed more uniformly across the payload and the packaging system. Temperature differences inside the container are reduced which helps to prevent hot spots and exposing nearby product to dangerously high temperatures.

TABLE 5
Air temperature (° C.) at two different locations
inside the EPS container (top and bottom) and payload
temperature (° C.) at two different locations (top and bottom)
	Air Temperature	Load Temperature
	Location 1	Location 2	Location 1	Location 2
	(Top)	(Bottom)	(Top)	(Bottom)
No Thermal	29° C.	30° C.	31° C.	37° C.
Propagator
Thermal	25° C.	26° C.	26° C.	28° C.
Propagator

Another embodiment utilizes more than one thermal generator in thermal contact with the thermal propagator to cover a larger area when using a large shipping container. When utilizing more than one thermal generator, the generators can be placed uniformly to provide the best thermal distribution profile as shown in FIG. 12.

Another way to cover a larger area is to extend the highly conductive materials used on the thermal propagator. Increasing the spans of the highly conductive materials (similar to wings) can cover not only one face of the shipping container but also multiple faces such as sidewalls. FIG. 13 shows an embodiment having extended highly-conductive materials.

Example 4 Detrimental Thermal Gradient Factor

The Detrimental Thermal Gradient (DTG) Factor reflects the ability of a system to propagate heat without exposing a product to destructive temperature.

A positive DTG Factor correspond to a protective effect with regard to protecting the product, and a higher positive number (>0) means better protection for the product. A negative DTG Factor indicate that the product is in a dangerous environment, and a lower negative number (<0) means the product will be destroyed faster. A number below −10 typically results in irreversible damages.

$\mathrm{DTG}{\mathrm{Factor}}_{\mathrm{air}}=\Delta T_a\times \left(T_{\mathrm{Da}}-T_{\mathrm{La}}\right)$ $\mathrm{DTG}{\mathrm{Factor}}_{\mathrm{product}}=\Delta T_p\times \left(T_{\mathrm{Dp}}-T_{\mathrm{Lp}}\right)$

• • ΔT_a=temperature gradient between the farthest locations in a system (air)
  • T_Da=maximum air temperature safe for product
  • T_La=temperature of the surrounding air at this location
  • ΔT_p=temperature gradient between the farthest locations in a system (product)
  • T_Da=maximum temperature for a product
  • T_La=temperature of the product at this location
    Using Table 5 the following calculations can be made:
  • Product maximum temperature=30° C.

Without a thermal propagator:

$\mathrm{DTG}{\mathrm{Factor}}_{\mathrm{air}}=\Delta T_{\mathrm{an}}\times {\left(T_{\mathrm{Da}}-T_{\mathrm{La}}\right)}_n=\left(\left(30-29\right)/0.23m\right)\times \left(\left(30-29\right)-\left(30-30\right)\right)=2.17°C{.}^2/m$ $\mathrm{DTG}{\mathrm{Factor}}_{\mathrm{product}}=\Delta T_p\times \left(T_{\mathrm{Dp}}-T_{\mathrm{Lp}}\right)=\left(\left(37-31\right)/0.089m\right)\times \left(\left(30-37\right)-\left(30-31\right)\right)=-269°C{.}^2/m$

With a thermal propagator:

$\mathrm{DTG}{\mathrm{Factor}}_{\mathrm{air}}=\Delta T_{\mathrm{an}}\times {\left(T_{\mathrm{Da}}-T_{\mathrm{La}}\right)}_n=\left(\left(26-25\right)/0.23m\right)\times \left(\left(30-26\right)-\left(30-25\right)\right)=19.6°C{.}^2/m$ $\mathrm{DTG}{\mathrm{Factor}}_{\mathrm{product}}=\Delta T_p\times \left(T_{\mathrm{Dp}}-T_{\mathrm{Lp}}\right)=\left(\left(28-26\right)/0.089m\right)\times \left(\left(30-28\right)-\left(30-26\right)\right)=67.4°C{.}^2/m$

Distance between top and bottom inside the cooler=0.23 m

Distance between top and bottom of the payload (vials)=0.089 m

Numerical Analysis of Conductive Heat Transfer on a Thermal Propagator

A thermal propagator with surface dimensions of 200 mm×160 mm has a thermal generator with surface dimensions of 80 mm×40 mm centered inside. The thermal generator generated heat measuring 32° C. at steady-state conditions. A numerical method of analysis is used to determine the temperature at different locations (nodes) on the surface of the thermal propagator and the heat transfer rate from the thermal generator to the boundary (edge) of the thermal propagator surface.

For this analysis, the surface of the thermal propagator is a two-dimensional body that is divided into equal increments (20 mm) in both the x and y directions. The nodal points are designated with the m locations indicating the x increment and n locations indicating the y increment. Temperatures at the nodal points within the body are determined using equation (1) below, the finite-difference approximation for conductive heat transfer in a two-dimensional body with square nodes. Once nodal temperatures are calculated, equation (2) below is used to determine the conductive heat transfer rate, Q, with the unit of Watts (W).

Finite-Difference Approximation for Conductive Heat Transfer in a Two-Dimensional Body with Square Nodes:

$\begin{array}{cc}{T}_{m,n}=\left(T_{m+1,n}+T_{m,n+1}+T_{m-1,n}+T_{m,n-1}\right)/4& \left(1\right)\end{array}$

• • T_m,n=temperature of node with coordinates (m,n)

Conductive Heat Transfer Rate:

$\begin{array}{cc}Q=\left(k\frac{\Delta x}{\Delta y}\Delta z\right)\mathrm{\Sigma \Delta }T& \left(2\right)\end{array}$

• • Q=heat transfer rate of the thermal propagator
  • k=thermal conductivity of thermal propagator surface (aluminum)
  • Δx=distance between nodes in the x direction
  • Δy=distance between nodes in the y direction
  • Δz=thickness of thermal propagator surface
  • ΔT=temperature difference between the boundary (edge) of the thermal propagator surface and the adjacent node
    Using Table 1 the following calculations can be made:
  • T₇ is the temperature at 40 mm from the thermal generator.

Using the equations outlined above:

$T_7=\left(32+26.8+23+27.4\right)/4=27.3°C.$

Now comparing the approximated value of T₇ to experimental data collected in table 1, a strong agreement is observed. Experimental data shows that at 50 mm from the thermal generator, the temperature was measured at 27.2° C., and the approximated value shows that at 40 mm from the heat source, the temperature should be 27.3° C. Now that theoretical calculations have been verified with experimental data, the conductive heat transfer rate for the thermal propagator can be calculated.

$Q=\left(202\right)*\left(20/20\right)*\left(0.000016\right)*\left(1.812\times {10}^4\right)=0.29W$

The thermal propagator allows for heat to be transferred via conduction at a rate of 0.29 W or 0.29 Joules per second (J/s). This demonstrates the efficiency of the conductive design of the thermal propagator in distributing heat beyond the immediate vicinity of the thermal generator. By facilitating heat transfer across the surface, the thermal propagator ensures that thermal energy is effectively spread, preventing localized overheating and enhancing the overall thermal management of the system.

Claims

1. A shipping package for providing and maintaining a desired thermal environment for a payload contained within the package, wherein the shipping package comprises:

a package defining an interior space into which a payload can be placed and enclosed;

a thermal generator within said interior space; and

a thermal propagator within said interior space;

wherein at least a portion of the thermal propagator is a high thermally-conductive material having a thermal conductance of at least 5 W/m−K; and wherein there is thermal connectivity between the thermal generator and the thermal propagator such that the thermal propagator propagates, through the interior space of the shipping package, heat from the thermal generator, thereby creating and maintaining the desired thermal environment inside the shipping package.

2. The shipping package according to claim 1, wherein said thermal propagator comprises a combination of said high thermally-conductive material and an insulating low thermally-conductive material, wherein the insulating material has a thermal conductivity of 1 W/m−K or less.

3. The shipping package according to claim 1, wherein said thermal propagator covers at least 20% of the surface in which the thermal propagator is located.

4. The shipping package according to claim 1, wherein said thermal propagator comprises a plurality of high thermally-conductive materials having a thermal conductance from 5 to 500 W/m−K.

5. The shipping package according to claim 1, wherein said thermal propagator is rigid.

6. The shipping package according to claim 1, wherein said thermal propagator is flexible.

7. The shipping package according to claim 1, wherein said thermal propagator comprises thermal paths through which heat can move from said thermal generator to distal portions of the interior space of said shipping package.

8. The shipping package according to claim 1, wherein said thermal propagator comprises thermal paths that have openings, wherein the total surface area of the openings is less than 3% of the total surface area of the thermal propagator.

9. The shipping package according to claim 1, wherein said thermal propagator is detachable from the shipping package.

10. The shipping package according to claim 1, having a contained therein a payload selected from pharmaceuticals, perishable food, fresh produce, live seafood, meal kits, cosmetics, lotions, adhesives, paints, reactants, diagnostic samples, blood and blood products, infusion medications, nutritional supplements, electronics, wine and spirits, and plants.

11. The shipping package according to claim 1, wherein the thermal generator produces thermal energy from oxidation material, crystallization solution, or battery-operated heater.

12. The shipping package of claim 1, wherein the volume of the internal space of the shipping package is from 1 liter to 2,300 liters.

13. The shipping package of claim 12, wherein the volume of the internal space of the shipping package is from 2 liters to 10 liters.

14. The method according to claim 1, wherein the conductive part of the thermal propagator has a thickness greater than or equal to 0.0005 mm.

15. The method according to claim 1, wherein the insulation part of the thermal propagator has a thickness greater than or equal to 0.0005 mm.

16. A method of providing and maintaining a desired thermal environment for a payload inside a shipping package, wherein the shipping package defines an interior space, and wherein the method comprises:

providing a thermal generator in the interior space of said shipping package;

positioning a thermal propagator proximate to the thermal generator such that there is thermal connectivity between said thermal generator and said thermal propagator;

wherein at least a portion of said thermal propagator has a thermal conductance of at least 5 W/m−K; and wherein the payload is positioned within the interior space of the shipping package and said thermal generator creates heat that is distributed by said thermal propagator inside the interior space, thereby creating and maintaining the desired thermal environment.

17. The method according to claim 16, wherein said thermal propagator comprises a combination of said high thermally-conductive material and an insulating low thermally-conductive material, wherein the insulating material has a thermal conductivity of less than 1 W/m−K.

18. The method according to claim 16, wherein said thermal propagator comprises a material having a thermal conductivity from 5 to 500 W/m−K.

19. The method according to claim 16, wherein said thermal propagator covers at least 20% of the surface in which the thermal propagator is located.

20. The method according to claim 16, wherein said thermal propagator extends the period of time the payload is maintained in a desired temperature range by distributing the heat from said thermal generator through the interior space of the shipping package by conduction, convection, radiation, or a combination of conduction, convection, and radiation.

21. The method according to claim 16, wherein said thermal propagator is flexible.

22. The method according to claim 16, wherein said thermal propagator is rigid.

23. The method according to claim 16, wherein said thermal propagator comprises a plurality of thermally-conductive materials.

24. The method according to claim 16, comprising positioning said thermal propagator on at least one side of the payload.

25. The method according to claim 16, wherein said thermal propagator has thermal paths through which heat from said thermal generator is moved to distal portions of the interior space of the shipping package.

26. The method according to claim 16, wherein said thermal propagator comprises thermal paths in which total surface area of the openings is less than 3% of the total surface area of the thermal propagator.

27. The method according to claim 16, used to transport a payload selected from pharmaceuticals, perishable food, fresh produce, live seafood, meal kits, cosmetics, lotions, adhesives, paints, reactants, diagnostic samples, blood and blood products, infusion medications, nutritional supplements, electronics, wine and spirits, and plants.

28. The method according to claim 16, wherein the temperature inside the shipping package is maintained in a temperature range required for a payload.

29. The method according to claim 16, used to ship a product through an outside environmental temperature lower than the minimum required temperature for the payload.

30. The method according to claim 16, wherein the thermal generator produces thermal energy from iron oxidation material, crystallization solution, or battery-operated heater.

31. The method of claim 16, wherein the volume of the internal space of the shipping package is from 1 liter to 2,300 liters.

32. The method of claim 31, wherein the volume of the internal space of the shipping package is from 2 liters to 10 liters.

33. The method according to claim 16, wherein the Detrimental Thermal Gradient Factor for the interior space of the shipping package is greater than zero.

34. The method according to claim 16, wherein the conductive part of the thermal propagator has a thickness greater than or equal to 0.0005 mm.

35. The method according to claim 16, wherein the insulation part of the thermal propagator has a thickness greater than or equal to 0.0005 mm.

36. The method of claim 16 which has a reduced carbon intensity for shipping an item compared to shipping the same item the same distance in a standard shipping package.