# US 11,994,346 B2 · Heat exchanger and cooling method

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- Number: US 11,994,346 B2
- Document ID: US11994346B2
- Status: Granted
- Kind: B2
- Application number: 17/595,215
- Filed: 2020-05-20
- Published: 2022-07-14
- Granted: 2024-05-28
- Earliest claimed: 2019-05-20
- Assignees: Technische UniversitäT Dresden
- Applicants: Technische Universitat Dresden
- Inventors: Andreas Wagner; Yixia Xu; Ullrich Hesse
- Web page: https://patentgrep.com/patent/US11994346B2

## CPC

- F28D 1/05341: {with multiple rows of conduits or with multi-channel conduits combined with a particular flow pattern, e.g. multi-row multi-stage radiators}
- F25B 9/008: {the refrigerant being carbon dioxide}
- F25B 39/02: Evaporators
- F28D 1/05316: {Assemblies of conduits connected to common headers, e.g. core type radiators (F28D1/05366 takes precedence)}
- F28F 1/006: {with variable shape, e.g. with modified tube ends, with different geometrical features (F28F1/025, F28F1/06, F28F1/08, F28F9/16, F28F9/18 take precedence)}
- F28F 1/32: the means having portions engaging further tubular elements
- F28F 9/0282: {by varying the geometry of conduit ends, e.g. by using inserts or attachments for modifying the pattern of flow at the conduit inlet or outlet}
- F28F 13/08: by varying the cross-section of the flow channels
- F25B 1/10: with multi-stage compression (with cascade operation F25B7/00)
- F25B 2309/061: with cycle highest pressure above the supercritical pressure
- F25B 2400/02: Centrifugal separation of gas, liquid or oil
- F25B 2400/13: Economisers
- F25B 2400/23: Separators
- F25B 2500/18: Optimization, e.g. high integration of refrigeration components
- F28D 2021/0068: {for refrigerant cycles}
- F28D 2021/0071: {Evaporators}
- F28D: HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT (fluid heaters having heat generating means and heat transferring means F24H; furnaces F27; details of heat-exchange apparatus of general)
- F25B: REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F28F: DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION (water and air traps, air venting F16)

## Abstract

According to various embodiments of the invention, a heat exchanger can have at least one duct for conveying a coolant, wherein the at least one duct has a first section and a second section, the first section being arranged in the at least one duct upstream relative to the second section, in relation to a flow direction of the coolant, the second section having a cross section area that is larger than a cross section area of the first section, such that a sublimation of the coolant in the second section is made possible.

## Claims

### Claim 1

A heat exchanger comprising at least one duct for carrying refrigerant, the at least one duct comprising a first section and a second section;
wherein the first section is disposed upstream relative to the second section with respect to a direction of flow of the refrigerant in the at least one duct;
wherein the second section has a cross-sectional area that is larger than a cross-sectional area of the first section so as to allow sublimation of the refrigerant in the second section; wherein the at least one duct comprises a narrowing member disposed in the first section such that the cross-sectional area of the first section is reduced.

### Claim 2 (depends on 1)

The heat exchanger according to claim 1,
wherein the cross-sectional area of the first section is dimensioned to prevent sublimation of the refrigerant in the first section.

### Claim 3 (depends on 1)

The heat exchanger according to claim 1,
wherein the cross-sectional area of the first section is dimensioned such that the refrigerant is at a pressure level in the first section that is greater than a pressure level of a triple point of the refrigerant.

### Claim 4 (depends on 1)

The heat exchanger according to claim 1,
wherein the cross-sectional area of the first section and the cross-sectional area of the second section are dimensioned such that the refrigerant is expanded into an at least partially solid aggregate state in the second section.

### Claim 5 (depends on 1)

The heat exchanger according to claim 1,
wherein the refrigerant comprises carbon dioxide.

### Claim 6 (depends on 1)

The heat exchanger according to claim 1,
wherein the first section has a cross-sectional area in a range from about 0.0001 mm2 to about 0.8 mm2.

### Claim 7 (depends on 1)

The heat exchanger according to claim 1,
wherein the second section has a cross-sectional area in a range from about 0.01 mm2 to about 400 mm2.

### Claim 8 (depends on 1)

The heat exchanger according to claim 1,
wherein the cross-sectional area of the first section and the cross-sectional area of the second section are dimensioned such that sublimation of the refrigerant flowing into the at least one duct is prevented in the first section and that sublimation of the refrigerant is enabled as a result of a pressure drop of the refrigerant during the transition from the first section to the second section.

### Claim 9 (depends on 1)

A refrigeration system comprising the heat exchanger according to claim 1.

### Claim 10

A cooling method for cooling a fluid by sublimation of a refrigerant comprising the following:
Providing a refrigerant to a heat exchanger, the heat exchanger comprising at least one duct for carrying refrigerant;
Guiding the refrigerant into the at least one duct, wherein the at least one duct comprises a first section and a second section;
wherein the first section is disposed upstream relative to the second section with respect to a direction of flow of the refrigerant in the at least one duct;
wherein the second section has a cross-sectional area that is larger than a cross-sectional area of the first section o as to allow sublimation of the refrigerant in the second section; and wherein the at least one duct comprises a narrowing member disposed in the first section such that the cross-sectional area of the first section is reduced; and
providing heat transfer between the refrigerant flowing into the second section and the fluid to be cooled, such that the refrigerant flowing in the second section is sublimated and the fluid to be cooled is cooled.

### Claim 11

A heat exchanger comprising at least one duct for carrying refrigerant, wherein the at least one duct comprises a first section, a second section, and a narrowing member disposed in the first section such that the cross-sectional area of the first section is reduced;
wherein the first section is disposed upstream relative to the second section with respect to a direction of flow of a refrigerant in the at least one duct,
wherein the first section is configured such that the refrigerant flowing into the first section is at a pressure level which is above a pressure level of a triple point of the refrigerant, and
wherein the second section is configured such that a refrigerant flowing into the second section is at a pressure level which is below the pressure level of the triple point of the refrigerant.

### Claim 12 (depends on 1)

The heat exchanger of claim 1,
wherein a cross-sectional area of the first section is dimensioned to prevent sublimation of the refrigerant in the first section,
wherein the cross-sectional area of the first section is dimensioned such that the refrigerant is at a pressure level in the first section that is greater than a pressure level of a triple point of the refrigerant, and
wherein the cross-sectional area of the first section and the cross-sectional area of the second section are dimensioned such that the refrigerant is expanded into an at least partially solid aggregate state in the second section.