Process for manufacture of a latent heat storage device

Abstract

A process for the preparation of latent heat storage composites is provided. The process comprises the steps of preparation of an expanded graphite material with a bulk density between 5 and 200 grams/liter which is readily wetted by a liquid phase change material, preparation of a pre-compressed matrix or a packed bed of the expanded graphite material, and manufacture of a latent heat storage composite by infiltration of the matrix or a packed bed with a phase change material in a liquid state.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a flow chart of an embodiment of a process for forming a composite of expanded graphite and a phase change material.

FIG. 2 shows a cross-sectional side view of an embodiment of a latent heat storage device.

Claims

1. A process comprising: configuring an expanded graphite material comprising a bulk density between 5 and 200 grams/liter (g/l) into a form; andinfiltrating the form with a phase change material in a liquid state.

2. The process of claim 1, wherein configuring an expanded graphite material into a form comprises: shaping the expanded graphite material into a matrix body.

3. The process of claim 2, wherein the expanded graphite material is shaped into a matrix body by compression.

4. The process of claim 3, wherein up to 70% by weight of non-expanded natural graphite is added to the expanded graphite material.

5. The process of claim 3, wherein the expanded graphite material is compressed to an apparent density between 30 and 1500 g/l.

6. The process of claim 3, wherein infiltrating the form comprises dip infiltrating the matrix body with the phase change material.

7. The process of claim 1, wherein prior to infiltrating, the method comprises transferring the phase change material into a liquid state.

8. The process of claim 1, wherein configuring an expanded graphite material into a form comprises: disposing the expanded graphite material in a vessel to form a bed.

9. The process of claim 8, wherein infiltrating comprises: covering the expanded graphite material with a layer of phase change material in the liquid state, andfollowing the method further comprises solidifying the phase change material.

10. The process of claim 9, wherein up to 70% by weight of non-expanded natural graphite is added to the expanded graphite material.

11. The process of claim 9, wherein prior to or after infiltrating, the packing density of the graphite material in the bed is increased by shaking or tamping.

12. The process of claim 1, wherein prior to configuring the expanded graphite material into a form, the method comprises: compressing the expanded graphite material into a web; andshredding the web into pieces comprising an average particle size between 5 microns and 20 millimeters.

13. The process of claim 12, wherein configuring an expanded graphite material into a form comprises: combining the web pieces with expanded graphite material that has not been compressed and shred into pieces.

14. The process of claim 12, wherein disposing the web pieces in a vessel to form a bed;covering the bed with a layer of phase change material; andthe liquid phase change material is infiltrated into the bed and solidified.

15. The method of claim 14, wherein after infiltrating, the method further comprises solidifying the phase change material.

16. The process of claim 12, wherein up to 70% by weight of non-expanded natural graphite is added to the web pieces.

17. The process of claim 14, wherein prior to or after infiltrating, the packing density of the graphite particles in the bed is increased by shaking or tamping.

18. The process of claim 17, wherein up to 70% by weight of non-expanded natural graphite is added to the cut pieces.

19. The process of claim 17, wherein prior to or after infiltrating, the packing density of the graphite particles in the bed is increased by shaking or tamping.

20. The process of claim 1, wherein configuring an expanded graphite material into a form comprises: combining expanded graphite material with non-expanded graphite and configuring the combination into the form.

21. The process of claim 1, wherein prior to configuring an expanded graphite material, the method further comprises: expanding a natural graphite to form an expanded graphite material.

22. The process of claim 21, wherein prior to expanding a natural graphite, the method comprises: grinding the natural graphite material into particles; andselecting graphite particles comprising a particle size below 50 mesh.

23. The process of claim 21, wherein expanding the natural graphite comprises: intercalating the graphite with an intercalating agent comprising an oxidizing agent; andthermally shocking the intercalated graphite at a temperature of up to 750° C.

24. The process of claim 1, wherein the phase change material has a phase change transition temperature between −100° C. and 500° C.

25. The process of claim 1, wherein the phase change material is selected from the group consisting of paraffins, sugar alcohols, thermoplastic polymers, water, aqueous solutions of salts, salt hydrates, salts and eutectic blends of salts and alkali metal hydroxides.

26. A process comprising: forming a bed comprising a latent heat storage composite comprising an expanded graphite material with a bulk density between 5 grams/liter and 200 grams/liter and a phase change material; andtransfer of the bed into a container provided with heat exchanger profiles.

27. The process of claim 26, wherein forming a bed further comprises shaking or tamping the bed.

28. A process for the manufacture of a latent heat storage device comprising: disposing a bed comprising an expanded graphite material into a heat storage container comprising a heat exchanger having heat exchanger tubes and space between the tubes, the bed being disposed in the space between the tubes, the expanded graphite material comprising a bulk density between 5 grams/liter (g/l) and 200 g/l; andinfiltrating the graphite bed with a phase change material.

29. The process of claim 26, wherein the bed comprises a mixture of expanded graphite and non-expanded graphite, the non-expanded graphite being present in an amount up to 70% by weight of the graphite in the bed up to 70% by weight of non-expanded natural graphite is added to the expanded graphite material.

30. The process of claim 26, wherein the phase change material has a phase transition temperature between −100° C. and +500° C.

31. The process of claim 26, wherein the phase change material is selected from the group comprising paraffins, sugar alcohols, thermoplastic polymers, water, aqueous solutions of salts, salt hydrates, mixtures of salt hydrates, salts and eutectic blends of salts and alkali metal hydroxides.

32. A process comprising: compressing an expanded graphite material having a bulk density between five g/l and 200 g/l into a planar foil-like web;shredding a web comprising compressed expanded graphite material into pieces having an average diameter between 5 μm and 20 mm;disposing a bed comprising the web pieces into a heat storage container;covering the bed with a layer of a phase change material in the liquid state; andinfiltrating the graphite bed with the phase change material.

33. The process of claim 31, wherein the bed comprises up to 70% by weight of non-expanded natural graphite.

34. The process of claim 31, wherein the phase change material has a phase transition temperature between −100° C. and +500° C.

35. The process of claim 31, wherein the phase change material is selected from the group consisting of paraffins, sugar alcohols, thermoplastic polymers, water, aqueous solutions of salts, salt hydrates, mixtures of salt hydrates, salts and eutectic blends of salts and alkali metal hydroxides.