Use of a composite material for heat management

Abstract

The use of a composite material for heat management in the electrical and/or electronic area, in particular in a car. A grid-like structure filled with a phase change material (PCM), and to a composite material that includes a grid-like structure filled with PCM. The filled grid-like structure being present on a cover layer or between two cover layers.

Claims

1. A composite material for heat management in the electrical and/or electronic field, the composite material having a lattice structure which is filled with phase-change material (PCM), wherein the PCM is present in microencapsulated form with an encapsulation material selected from plastics forming a plastics shell for the PCM, the microencapsulated PCM has a size of 5 mm, and the lattice structure divides the composite material into plural regions, each region being filled with the PCM and encapsulated separately by walls of the lattice structure and the lattice structure comprises metal, ceramic or any mixtures thereof or the lattice structure comprises a lattice of expanded graphite in foil form.

2. The composite according to claim 1, wherein the lattice structure has a polygonal structure.

3. The composite according to claim 1, wherein the metal is selected from the group consisting of aluminium, copper and steel.

4. The composite according to claim 1, wherein the lattice structure has a wall thickness of from 0.01 to 2 mm.

5. The composite according to claim 1, wherein the phase change material (PCM) can be selected from the group consisting of sugar alcohols, paraffins, waxes, salt hydrates or fatty acids.

6. The composite according to claim 1, wherein the lattice structure is in addition filled with binder.

7. The composite according to claim 6, wherein the binder is selected from the group consisting of epoxy resins, silicone resins and acrylate resins.

8. The composite according to claim 6, wherein the binder proportion is from 2 to 40 wt. %.

9. A composite material having a lattice structure which is filled with PCM, wherein the filled lattice structure is located on a top layer or between two top layers, and wherein at least one top layer is selected from the group consisting of graphite foils, carbon fibre webs, carbon fibre laid scrim, copper foil and aluminium foil, wherein the PCM is present in microencapsulated form with an encapsulation material selected from plastics forming a plastics shell for the PCM, the microencapsulated PCM has a size of 5 mm, and the lattice structure divides the composite material into plural regions, each region being filled with the PCM and encapsulated separately by walls of the lattice structure.

10. The composite material according to claim 9, wherein the top layers have a thickness of from 10 m to 3 mm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the following, purely by way of example, the present invention is described by way of advantageous embodiments and with reference to the accompanying drawings, in which:

(2) FIG. 1 is a schematic plan view of the PCM/lattice structure composite material according to the second embodiment of the present invention, the surface having been opened in order to illustrate the internal filled lattice structure.

(3) FIG. 2 is a schematic side view according to the second embodiment of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

(4) FIG. 1 is a schematic plan view of the second embodiment. The sample size is 95140 mm (lb). The lattice structure (2), which consists here of aluminium and in which the PCM material (1) is filled, can be clearly seen. On the bottom and the top, a graphite foil is applied as a top layer (3) in each case.

(5) FIG. 2 is a schematic side view of the specimen from FIG. 1 according to the second embodiment of the present invention. The thickness (h) of the specimen is 11 mm. It can be clearly seen that the lattice structure (2) filled with PCM (1) is enclosed by the top layers (3) both on the top and on the bottom.

(6) The present invention is described in the following by way of embodiments, the embodiments not limiting the invention in any way.

Embodiment 1

(7) A specimen is produced that has the dimensions 1409511 mm. For this purpose, a honeycomb structure consisting of 50 layers of aluminium foils, each having a thickness of 50 m, is produced by offset point connection using a total of 2 g adhesive (Araldite 2000 (2014)) and subsequent separation. The desired honeycomb height is cut to length from the resulting block. This structure is then filled with 120 g PCM-binder material (100 g Micronal, melting point 28 C. and 20 g Araldite 2000 (2014).

Embodiment 2

(8) A specimen is produced that has the dimensions 1409511 mm. For this purpose, a honeycomb structure consisting of 50 layers of aluminium foils, each having a thickness of 50 m, is produced by offset point connection using a total of 2 g adhesive (Araldite 2000 (2014)) and subsequent separation. The desired honeycomb height is cut to length from the resulting block. This structure is then filled with 120 g PCM-binder material (100 g Micronal, melting point 28 C. and 20 g Araldite 2000 (2014) and clamped between two layers of graphite foil (500 m thick and 1.8 g/cm.sup.3 density).

(9) TABLE-US-00001 TABLE 1 Reference (without aluminium Embodiment Embodiment Measurement honeycomb) 1 2 method Density 0.9 0.9 0.9 Measuring [g/cm.sup.3] and weighing Thermal 0.3 1.5 1.5 DIN 51908 conductivity (2006-05); [W/(m .Math. K)] Bending 3.8 7 9 DIN 51902 strength (2009-05) [MPa] Modulus 220 900 1050 DIN 51902 of elasticity (2009-05) [MPa]

(10) It has surprisingly been found that, owing to the aluminium honeycomb structure, the thermal conductivity perpendicular to the sample plane, at 1.5 W/(m.Math.K), is significantly higher than for the pure PCM sample (reference sample: composition as per embodiment 1, but without an aluminium honeycomb structure), at 0.3 W/(m.Math.K) (see table 1). If conductive additives were added according to the prior art, at least 30 wt. % thereof would be required in order to achieve the same thermal conductivity, which would, however, reduce the heat capacity of the sample by at least 30%. However, by using the aluminium honeycomb structure, this is reduced only by 15%.

LIST OF REFERENCE SIGNS

(11) 1 phase change material 2 lattice structure 3 top layer b width of the specimen l length of the specimen h thickness of the specimen