High-density latent heat storage device

Patent metadata

Field	Value
Publication number	US-11041680-B2
Application number	US-201716306693-A
Country	US
Kind code	B2
Filing date	Jun 2, 2017
Priority date	Jun 3, 2016
Publication date	Jun 22, 2021
Grant date	Jun 22, 2021

Abstract

Latent heat storage devices are disclosed, such as latent heat storage devices comprising a phase change material encapsulated in sufficiently conductive tubes, wherein the tubes are arrayed in a hexagonal-packed pattern. The devices herein can be used, for example, in residential and/or commercial HVAC systems.

First claim

What is claimed is:

1. A latent heat storage device comprising:
a containment tank;
a plurality of cylindrical encapsulation tubes having a hollow interior, wherein the cylindrical encapsulation tubes are arrayed in a hexagonal-packed pattern, are comprised of a sufficiently conductive material, and are contained within the containment tank;
a phase change material, contained within the hollow interior of the cylindrical encapsulation tubes; and
a means for connecting the containment tank in fluid communication with a first source of heat transfer fluid to allow a heat transfer fluid to flow through a heat transfer fluid space to exchange heat with the phase change material;
wherein the latent heat storage device has a first resistance ratio of less than about 0.1, wherein the first resistance ratio is defined by the equation:

R
t

R
c

=

π
3

72
⁢

(

2
⁢

3

-
π

)

⁢

(

r
o

+

r
i

)

⁢

/

⁢
2

(

r
o

-

r
i

)

⁢

Nu
⁢

⁢

k
f

k
t

wherein:
R t is the resistance of conduction around the encapsulation tube [° K/W];
R c is the resistance of convection between the heat transfer fluid (HTF) and the encapsulation tube [° K/W];
r o is the outside radius of the encapsulation tube [m];
r i is the inside radius of the encapsulation tubing [m];
k f is the conductivity of the heat transfer fluid [W/(m·° K)];
k t is the conductivity of the encapsulation tube material [W/(m·° K)]; and
Nu is the Nusselt number.

2. The device of claim 1 , wherein the sufficiently conductive tubes are comprised of a metal.

3. The device of claim 2 , wherein the sufficiently conductive tubes are comprised of copper.

4. The device of claim 2 , wherein the sufficiently conductive tubes are comprised of aluminum.

5. The device of claim 1 , wherein the phase change material is selected from water (ice), a salt hydrate, a fatty acids, or a paraffin hydrocarbon.

6. The device of claim 5 , wherein the phase change material is a paraffin hydrocarbon.

7. The device of claim 6 , wherein the phase change material comprises tetradecane.

8. The device of claim 7 , wherein the phase change material comprises at least 99% tetradecane.

9. The device of claim 1 , wherein the phase change material has a phase change temperature in a range between 5° C. and 12° C.

10. The device of claim 1 , wherein the heat transfer fluid comprises an aqueous solution of ethylene glycol, propylene glycol, glycerol, or combinations thereof.

11. The device of claim 10 , wherein the heat transfer fluid comprises an aqueous solution containing about 35% by volume propylene glycol.

12. The device of claim 1 , wherein the latent heat storage device has a resistance ratio of less than about 0.05.

13. A latent heat storage device comprising:
a containment tank;
a plurality of cylindrical encapsulation tubes having a hollow interior, wherein the cylindrical encapsulation tubes are arrayed in a hexagonal-packed pattern, are comprised of a sufficiently conductive material, and are contained within the containment tank;
a phase change material, contained within the hollow interior of the cylindrical encapsulation tubes; and
a means for connecting the containment tank in fluid communication with a first source of heat transfer fluid to allow a heat transfer fluid to flow through a heat transfer fluid space to exchange heat with the phase change material;
wherein the latent heat storage device has a resistance ratio of less than about 0.1, wherein the resistance ratio is defined by the equation:

R
t

R
p

=

π
2

18

⁢

(

r
o

+

r
i

)

⁢

/

⁢
2

(

r
0

-

r
i

)

⁢

k
p

k
t

wherein:
R t is the resistance of conduction around the encapsulation tube [° K/W];
R p is the resistance of conduction between the PCM and the encapsulation

Assignees

• Univ Texas

Inventors

• Novoselac Atila
• Bourne Stephen

Classifications

• F28F1/045

  with assemblies of stacked elements · CPC title

• F28D2020/0021

  the heat storage material being enclosed in loose or stacked elements · CPC title

• Y02E60/14

  Thermal energy storage · CPC title

• F28D20/02 Primary

  using latent heat · CPC title