Process for manufacture of a latent heat storage body

Abstract

The invention relates to a process for the preparation of latent heat storage bodies by cold isostatic pressing of a mixture of expanded graphite material and a phase change material, and to latent heat storage bodies obtained by cold isostatic pressing of a mixture of expanded graphite material and a phase change material.

Description

BRIEF DESCRIPTION OF THE FIGS.

FIG. 1 schematically illustrates an embodiment of a method of forming a latent heat storage body in accordance with the present invention.

FIG. 2 illustrates in-plane and through-plane thermal conductivity of a shaped latent heated body in accordance with an embodiment of the present invention.

Claims

1. A process comprising: isostatic pressing of a mixture of a phase change material and an expanded graphite material into a shaped body at a temperature below the melting point of the phase change material.

2. The process of claim 1, wherein the expanded graphite material comprises expanded graphite particles with a bulk density between 2 and 200 grams per liter.

3. The process of claim 1, wherein the expanded graphite material comprises particles prepared by cutting a planar foil-like web obtained by compression of expanded graphite particles into fragments having an average diameter between 5 microns and 20 millimeters.

4. The process of claim 1, wherein the expanded graphite material comprises expanded graphite particles with a bulk density between 2 and 200 grams per liter and particles prepared by cutting a planar foil-like web obtained by compression of expanded graphite particles into fragments having an average diameter between 5 microns and 20 millimeters.

5. The process of claim 1, wherein a non-expanded graphite material is added to the expanded graphite material so that the weight fraction of the non-expanded graphite in the graphite material is less than or equal to 70 percent.

6. The process of claim 1, wherein the phase change material is one of the group comprising paraffins, sugar alcohols, polymers, water, organic acids, mixtures of organic acids, aqueous solutions of salts, salt hydrates, mixtures of salt hydrates, inorganic salts, organic salts, eutectic blends of salts, clathrate hydrates and alkali metal hydroxides.

7. The process of claim 1, wherein a volume fraction of the expanded graphite material in the mixture of the phase change material and the expanded graphite material is at least 2 percent.

8. The process of claim 5, wherein a volume fraction of expanded graphite material in the mixture comprising the expanded graphite material, the non-expanded graphite material and the phase change material is at least 2 percent.

9. The process of claim 1, wherein the temperature at which isostatic pressing is performed is between approximately 20 to 25 degrees Celsius.

10. The process of claim 1, wherein isostatic pressing is performed with a pressurizing medium cooled to a temperature below a melting point of the phase change material.

11. The process of claim 1, wherein isostatic pressing comprises (a) building up of a target pressure between 140 and 200 Megapascals within 10 minutes and (b) decompression within 30 minutes

12. The process of claim 1, further comprising finishing the shaped body by a technique selected from the group consisting of sawing, milling and drilling.

13. A latent heat storage body comprising: a mixture of a phase change material and an expanded graphite material wherein the anisotropy factor obtained from the ratio between in-plane and through-plane thermal conductivity is less than or equal to 3.5.

14. The latent heat storage body of claim 13, wherein the expanded graphite material comprises expanded graphite particles with a bulk density between 2 and 200 grams per liter.

15. The latent heat storage body of claim 13, wherein the expanded graphite material comprises particles prepared by cutting a planar foil-like web obtained by compression of expanded graphite particles into fragments having an average diameter between 5 microns and 20 millimeters.

16. The latent heat storage body of claim 13, wherein the expanded graphite material comprises expanded graphite particles with a bulk density between 2 and 200 grams per liter and particles prepared by cutting a planar foil-like web obtained by compression of expanded graphite particles into fragments having an average diameter between 5 microns and 20 millimeters.

17. The latent heat storage body of claim 13, wherein a non-expanded graphite material is added to the expanded graphite material so that the weight fraction of the non-expanded graphite in the graphite material is less than or equal to 70 percent.

18. The latent heat storage body of claim 13, wherein the phase change material is one of the group comprising paraffins, sugar alcohols, polymers, water, organic acids and their mixtures, aqueous solutions of salts, salt hydrates, mixtures of salt hydrates, inorganic and organic salts and eutectic blends of salts, clathrate hydrates and alkali metal hydroxides.

19. The latent heat storage body of claim 13, wherein a volume fraction of the expanded graphite material in the latent heat storage body is at least 2 percent.

20. The latent heat storage body of claim 17, wherein a volume fraction of the expanded graphite material in the latent heat storage body comprising a mixture the expanded graphite material, the non-expanded graphite particles and the phase change material is at least 2 percent.