Heat exchanger
In a heat exchanger ( 10 ) for transferring heat from a first fluid to a second fluid, which heat exchanger ( 10 ) comprises one or more flow passages ( 12 ) for a first fluid, the outer wall ( 26 ) of these passages is in heat-transferring contact with a flow body ( 20 ) made from metal foam for a second fluid. This metal foam has a gradient of the volume density of the metal, so that it is possible to achieve a favorable equilibrium between heat transfer and conduction, on the one hand, and flow resistance, on the other hand.
1. Heat exchanger for transferring heat from a first fluid to a second fluid, comprising one or more flow passages for a first fluid, which are arranged parallel to and at a distance from one another and the outer wall of which is in heat-transferring contact with a flow body for a second fluid, which is made from metal foam, wherein the metal foam has a constant number of pores (PPI) and has a gradient of volume density.
2. Heat exchanger according to claim 1 , wherein the flow body is composed of two layers of metal foam, of which layer surfaces with the same volume density face towards one another.
3. Heat exchanger according to claim 1 , wherein the volume density of the metal foam increases from an inflow side of the flow body for the second fluid towards the flow passages.
4. Heat exchanger according to claim 1 , wherein the flow passages have an elliptical cross section, the main axis of which extends in the direction of flow of the second fluid.
5. Heat exchanger according to claim 1 , wherein the flow passages comprise tubular bodies which are rectangular in cross section and are separated by sections of the flow body, the volume density of the sections of the flow body being highest in the vicinity of the outer walls of the flow passages.
6. Heat exchanger according to claim 2 , wherein the gradient alternately increases and decreases in the direction of flow of the first fluid.
7. Heat exchanger according to claim 1 , wherein the metal of the metal foam is copper.
8. Heat exchanger according to claim 1 , wherein the connection between the flow body and the outer wall of the at least one flow passage comprises a soldered joint.
9. Heat exchanger according to claim 8 , wherein the soldered joint comprises tin or a tin alloy.
10. Heat exchanger according to claim 1 , wherein the heat exchanger has a modular structure and is provided with coupling means for coupling modular heat exchangers to one another.
11. Heat pump for energy conversion, comprising a motor for compressing and displacing a gaseous second fluid, and a heat exchanger for transferring heat from a first fluid to the second fluid, and a heat exchanger for transferring heat from the second fluid to a third fluid, a regenerator being arranged between the beat exchangers, as seen in the direction of flow of the gas, wherein the heat exchangers comprise one or more flow passages for a first fluid, which are arranged parallel to and at a distance from one another and the outer wall of which is in heat-transferring contact with a flow body for a second fluid, which is made from metal foam, wherein the metal foam has a constant number of pores (PPI) has a gradient of volume density.
12. Heat pump according to claim 11 , wherein the regenerator comprises a layered structure of a plurality of layers of metal foam made from a metal with poor conductivity.
13. Heat pump according to claim 12 , wherein the metal of poor conductivity is nickel.