AU2020103697A4

AU2020103697A4 - Reversible Liquid/Solid Phase Change Composition

Info

Publication number: AU2020103697A4
Application number: AU2020103697A
Authority: AU
Inventors: Kester Solomon
Original assignee: Individual
Current assignee: Individual
Priority date: 2020-11-26
Filing date: 2020-11-26
Publication date: 2021-02-04
Anticipated expiration: 2028-11-26

Abstract

The present invention relates broadly to a reversible liquid/solid phase change composition or phase change material (PCM). The PCM in each of the examples 5 includes a hydrated mixture of Sodium Chloride and water at respective weight percentage amount of between 20% to 30% and 70% to 80%, and an effective amount of a nucleating agent. .0 cc c-4

Description

cc

c-4

Editorial Note 2020103697 There is 8 pages of Description only.

DESCRIPTION Reversible Liquid/Solid Phase Change Composition

FIELD OF THE INVENTION

The present invention relates broadly to a reversible liquid/solid phase change composition and relates particularly, though not exclusively, to a phase change material (PCM) comprising sodium chloride. The invention further relates to a Temperature Controlled Packaging (TCP) or other energy storage device adapted to contain a PCM.

.0

BACKGROUND OF THE INVENTION

US patent nos. 4,412,931 and 4,637,888 describe reversible phase change compositions for strong energy and include mixtures of calcium chloride/potassium salt and calcium chloride/calcium bromide, respectively. Each of these phase change .5 compositions also includes a nucleating agent which is effective in reducing supercooling. The selection of nucleating agents disclosed includes Ba(OH) 2, BAO, Bal 2 , BaS 2 O3 , BaCO 3 , BaCI 2 , BaF 2 , BaF 2 .HF, Sr(OH) 2 , SrO, SrCO 3 , SrF 2 , Sr 2 , SrC 2

, and SrBr 2. The nucleating agents of US 4,412,931 were added in an amount from 0.005 to 2.0 weight% whereas the agents of US 4,673,888 were added at 0.5 weight o0 %.

The advent of the Covid-19 Pandemic in 2020, has resulted in vaccines being developed. The vaccines often use Adjuvants to improve the immune response of the vaccine. Some adjuvants need to be kept at temperatures below -150 C.

The phase diagram of salt water is well known. As is the ice/NaCI.2H20 eutectic point of -- 21.1°C, with -22-27 wt% of NaCI. Published latent energy is -220J/g. The maximum amount of NaCI you can dissolve in water is -30%, slightly increasing with temperature.

Unlike CaCl2 phase change compositions which can be modified to yield a range of phase change temperatures. If the NaCI concentration is lower than the eutectic concentration, I.E. below 23.3-27%, the system will decompose into salt-free ice and liquid water.

Definitive work altering the -21.1C phase change temperature is very hard to find. And rarer still is technical data focusing on improving the latent energy J/g of a NaCI Phase Change Composition.

Sodium Chloride (NaCI) is mentioned in research papers as a -21°C Phase Change Composition, with limited technical data. Patent literature focusing on Sodium .0 Chloride as a -21°C Phase Change Material is sparse. Whereas, PCM patents and research papers focusing on Hydrated Calcium Chloride PCM are abundant.

Not only is Sodium Chloride as a -21°C Phase Change Material research papers and patents limited. Definitive work that alters the -21°C phase change temperature is hard .5 to find.

Rarer still, is research papers and patents describing nucleating agents effective in reducing supercooling of hydrated Sodium Chloride.

Equally rare, if not more so is to find research papers and patents describing nucleating agents effective in increasing the latent energy (J/g) of the Phase Change Material greater than 220J/g.

This invention specifically focuses on hydrated Sodium Chloride and an effective amount of nucleating agent(s) to produce a -150 C to -250 C Phase Change Material with little to no supercooling. The ability to modify the phase change temperature. And improve the PCMs latent energy.

SUMMARY OF THE INVENTION

According to one aspect of the present invention there is provided a reversible liquid/solid phase change composition comprising a hydrated mixture of NaCI and H2 0 or derivatives thereof, at respective weight percent amounts of between 20% to 30% and 80% to 70%, and an effective amount of nucleating agent.

According to another aspect of the invention there is provided a reversible liquid/solid phase change composition having a melting temperature of between -150 C to -25C. More preferably the phase change temperature is between -19 0 C to -230 C, said .o composition comprising a mixture of NaCI H20 and MgCl 2 , NH4CI, NH4Br, KNO3, NaNO3 or derivatives thereof, and an effective amount of nucleating agent.

Preferably the composition further comprises from between about 70 to 80 weight

% water.

.5

Preferably the nucleating agent is present in the effective amount wherein crystallisation of the composition for retrieval of stored energy is affected at -15 0 C or colder. More preferably the nucleating agent is present at less than about 8 weight %. Even more preferably the nucleating agent is at between greater than zero weight % and 6%.

Preferably the nucleating agent is one of a singularity or plurality of nucleating agents. More preferably the nucleating agent(s) is selected from the group consisting of NH4CI, KNO3, NaNO3, CaCl2, MgCl 2 .6H2 0, MgCl 2 , and derivatives or mixtures thereof. Even more preferably the nucleating agent is present in the effective amount wherein during crystallisation supercooling of the composition is reduced to less than about2 0 C.

According to a further aspect of the invention there is provided an energy storage device comprising encapsulation means being adapted to contain a reversible liquid/solid phase change composition comprising a hydrated mixture Sodium Chloride and water or derivatives thereof, at respective weight percent amounts of between about 20% to 30% NaCI and an effective amount of a nucleating agent. This energy storage device has implications in the Temperature Controlled Packing industry to aid the transport of temperature sensitive products such as Adjuvants for Covid-19 and other vaccines.

Preferably the encapsulation means is in the form of macro and/or micro encapsulation means and includes sealing means to prevent evaporation, or leakage .0 of the composition. More preferably the encapsulation means includes a coating, powder or resin, a plastic, such as HDPE or any Temperature Controlled Packaging (TCP) device or plastic, or metal container, or hermetically sealed films, foils or plastic and/or metal laminates.

.5 BRIEF DESCRIPTION OF THE FIGURE

The figure is a part sectional view of a storage device of an embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In order to achieve a better understanding of the nature of the present invention, o preferred examples of a reversible liquid/solid phase change composition or phase change material (PCM) will now be described. The PCM in each of the following examples includes a hydrated mixture of Sodium Chloride and water at respective weight percentage (wt %) amounts of between 20% to 30% and 70% to 80% and an effective amount of a nucleating agent.

Example 1

NaCI From about 20 to about 30 wt %

CaCl2 In an amount greater than zero and less 5 wt %

H 20 Balance of up to 100 wt %

Example 2

NaCI From about 20 to about 30 wt

% NH4Br In an amount greater than zero and less than 5 wt

% KNO 3 In an amount greater than zero and less than 2.5 wt

% H 20 Balance of up to 100 wt

% Example 3

NaCI From about 20 to about 30 wt

% MgCl 2 .6H2 0 In an amount greater than zero and less than 5 wt

% .o NH4CI In an amount greater than zero and less than 3 wt

% H 20 Balance of up to 100 wt %

Example 4

NaCI From about 20 to about 30 wt %

.5 MgCl 2 .6H2 0 In an amount greater than zero and less than 8 wt %

CaCl2 In an amount greater than zero and less than 5 wt%

H 20 Balance of up to 100 wt %

The PCM of these examples has a melting temperature of between -150 C to -25C but more particularly in the -19 0C to -23 0C range. The PCM has application as a buffer or passive or non-passive cool sink in thermal energy storage Biopharma Temperature Controlled Packaging (TCP) to modulate swings in temperatures and to assist in stabilisation of temperatures to enhance the effect of Temperature Controlled Packaging (TCP) to increase the duration of Thermo Control within the temperature range to -150 C to -250 C.

The nucleating agents of the preceding examples are understood to be effective in ensuring the congruent melting behaviour of the NaCI mixture. It is also recognised that the nucleating agents are effective in reducing supercooling of the PCM to less than about 2°C during crystallisation. The nucleating agents are understood to provide crystallisation or freezing temperatures of the PCM at colder (less than) than -150 C during retrieval of the stored PCM energy. The nucleating agent is preferably present at less than about 10 wt % and as reflected in the preceding examples and more preferably present at between greater than zero to 5 wt %. It is possible that the nucleating agent may exist in amounts greater than 5 weight percent without detriment to the function of the PCM, although at these high amounts the nucleating agent does not exhibit any further benefits in reducing supercooling.

.0

The PCM may also include minor impurities which do not detrimentally affect the function of the hydrated NaCI mixture. The enthalpy of the preferred PCM of the invention is from about 180 to 280 Joules per gram (J/g). It is to be understood that enthalpy is equivalent to the internal energy plus the produce of the pressure and .5 volume and is measured by the heat content per unit mass, for example J/g. It has been found that the PCM mixture based on hydrated NaC is particularly well suited in that it displays congruent melting. That is, at the melting point of the PCM, solid and liquid phases are in stable equilibrium. In the preferred example the solid phase contains no hydrated NaCI other than the correct hydrate or solid solutions thereof o whereas the liquid phase contains, for every mole of NaCI correct moles of water plus sufficient water to form the stable hydrate of any additive materials in solution.

In another aspect of the invention the PCM is contained in an energy storage device. The energy storage device may have application in b cooling where for example it is used as a cool sink placed in chiller tanks. The energy storage device includes a macro and/or micro encapsulation means.

The figure shows a spherical or ball shaped energy storage device 100. The encapsulation means of this embodiment includes a spherical shell 102 formed of a polyethylene plastic material having a flanged opening 104. The device 100 also includes a polyethylene plug 106 designed to be inserted and ultrasonically welded to the flanged opening 104 for hermetically sealing the shell 102. The shell 102 or encapsulation means contains a select volume of the PCM 108 with an air pocket 110 disposed above the PCM 108.

Now that several preferred embodiments of the invention have been described in some detail it will be apparent to those skilled in the art that the reversible liquid/solid phase change composition and energy storage device have the following advantages:

1. The selection of NaCI in conjunction with the nucleating agent provides freezing temperatures, preferably at less than (colder) -15 0 C of the PCM during .0 crystallisation;

2. The selection of NaCI in conjunction with the nucleating agent reduces supercooling of the PCM during crystallisation;

.s 3. The selection of NaCI in conjunction with the nucleating agent increases the latent energy (J/g) of the PCM

4. The selection of NaCI in conjunction with the nucleating agent provides congruent melting during phase changes; and '0 5. The PCM tolerates impurities without its function being detrimentally affected.

Those skilled in the art will appreciate that the invention described herein is susceptible to variations and modifications other than those specifically described. For example, the particular compositions exemplified may be varied provided they remain within the broad scope of the invention. All such variations and modifications are to be considered within the scope of the present invention the nature of which is to be determined from the foregoing description.

All publications mentioned in this specification are herein incorporated by reference. Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is solely for the purpose of providing a context for the present invention. It is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present invention as it existed anywhere before the priority date of each claim on this application.

Editorial Note 2020103697 There is 2 pages of Claims only.

Claims

• A reversible liquid/solid phase change composition comprising a hydrated mixture of NaCI or derivatives thereof, at respective weight percent amounts of between 20% to 30% (Anhydrous Sodium Chloride) and an effective amount of a nucleating agent.

• A reversible liquid/solid phase change composition having a melting temperature of between -15 0C to -25 0C, and more particularly in the -18 0C to - 23 0C range .0 said composition comprising a mixture of NaCl or derivatives thereof, and an effective amount of a nucleating agent.

• A reversible composition as defined in either of claims 8 or 2 further comprising from between about 70 to 80 weight % water. .5 • A composition as defined in any one of the preceding claims wherein the nucleating agent is present in the effective amount wherein crystallisation of the composition for retrieval of stored energy is effected at -18 0 C or greater.

'0 • A composition as defined in claim 4 wherein the nucleating agent is present at less than about 8.0 weight percent.

• A composition as defined in any one of the preceding claims wherein the nucleating agent is selected from the group consisting NH4CI, KNO3, NaNO3, CaCl2 MgCl 2 .6H2 0, MgCl2 and derivatives or mixtures thereof.

• A composition as defined in claim 6 wherein the nucleating agent is present in the effective amount wherein during crystallisation supercooling of the composition is reduced to less than about 20 C.

• An energy storage device comprising encapsulation means being adapted to contain a reversible liquid/solid phase change composition comprising a hydrated mixture of NaCI or derivative thereof, at respective weight percent amount of between about 20% to 30% and an effective amount of a nucleating agent.

SA device as defined in claim 8 wherein the encapsulation means is in the form of macro and/or micro encapsulation means and includes sealing means to prevent evaporation of the composition.

SA device as defined in either of claims 8 or 9 wherein the encapsulation means includes a coating, power or resin, a plastic or metal container Gel Packs or HDPE or any other Cool Pack or any other Temperature Sensitive Packaging (TCP), or hermetically sealed films, foils or plastic and/or metal laminates.