Heat exchanger

Abstract

A heat exchanger may be manufactured using a number of different methods, each having their own benefits and deficiencies. A method of making a monolithic heat exchanger having a plurality of conduits passing through it is provided and comprises the steps of: providing a plurality of successive layers of a material to be remelted and energy beam remelting predetermined regions of each layer in accordance with a predetermined design. The energy beam remelting of each layer is performed prior to the addition of a successive layer. The regions of each layer which are subjected to energy beam remelting form solid structures within the layer, and the energy beam remelting of each layer fuses the remelted regions of each layer to the remelted regions of the preceding layer. This results in the manufacture of a three-dimensional monolithic unit. The heat exchanger is manufactured to have a surface area density of at least 5000 m2 / m3 and a mean average porosity of at least 0.6. The energy beam could, for example, be a laser beam or an electron beam.

Description

technical field [0001] The present invention relates to a heat exchanger and a method of manufacturing the heat exchanger. Preferred embodiments of the invention relate to heat exchangers and methods of making heat exchangers suitable for use in Stirling engines. Background technique [0002] Stirling engine heater (the heat exchanger, thermal fluid and waste heat, heat from solar energy and other heat sources transfer part of their heat to the pressurized raw gas (charge gas) in the engine through the heat exchanger, the heat The fluid (usually hot gas from a fuel combustion process) can be assembled from a cylindrical array of usually U-shaped tubes, with combustion gases passing down and radially outward, usually from above the center of the array, or inside the array Pass radially outward, first between the inner arms of the U-tubes and then between their outer arms. The tube consists, for example, of stainless steel or a heat-resistant alloy. Additionally, the burner...

AI Technical Summary

Problems solved by technology

[0017] 1. Manufacturing of each board is relatively expensive, which includes precision machining, photochemical etching and / or other similar processes, and the diffusion bonding process itself

[0018] 2. The use of flat plates limits the ability to design heat exchangers in three dimensions

This means that despite achieving the bond strength of a diffusion bonded structure made of parent materials, the heat exchanger is not capable of operating at the combined high temperature and pressure required in a Stirling engine

[0020] 4. The extremely high pressure used to bond the plates can cause deformation of the area between each pair of adjacent grooves in the same plate, so allowance must be made by providing a wider area than necessary

[0022] 6. As a result of the last two disadvantages above, compared to plate-fin compact heat exchangers of brazed stainless steel with a porosity of 0.6-0.7, and with high-performance aluminum or copper plate-fin heat exchangers with a porosity of more than 0.8 Compared with compact heat exchangers, the porosity of this heat exchanger is relatively low - about 0.5-0.6

[0024] 8. Diffusion bonding methods for making compact heat exchangers cannot easily add fins or other surface enhancements

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