# US 11,994,068 B2 · Buffer heat exchangers for hydrogen engines

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- Number: US 11,994,068 B2
- Document ID: US11994068B2
- Status: Granted
- Kind: B2
- Application number: 17/397,889
- Filed: 2021-08-09
- Published: 2023-02-09
- Granted: 2024-05-28
- Earliest claimed: 2021-08-09
- Assignees: Pratt & Whitney Canada Corp.
- Applicants: Pratt & Whitney Canada Corp.
- Inventors: Scott Smith; Eric Durocher
- Web page: https://patentgrep.com/patent/US11994068B2

## CPC

- F02C 7/14: of fluids in the plant {, e.g. lubricant or fuel (F02C7/185 takes precedence)}
- F02C 3/22: the fuel or oxidant being gaseous at standard temperature and pressure (F02C3/28 takes precedence)
- F02C 3/28: using a separate gas producer for gasifying the fuel before combustion
- F02C 7/16: characterised by cooling medium
- F02C 7/185: {Cooling means for reducing the temperature of the cooling air or gas}
- F02C 7/224: Heating fuel before feeding to the burner
- F02C 3/24: the fuel or oxidant being liquid at standard temperature and pressure
- F05D 2220/323: for aircraft propulsion, e.g. jet engines
- F05D 2260/213: by the provision of a heat exchanger within the cooling circuit
- F02C: GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS (construction of turbines F01D; jet-propulsion plants F02K; construction of compressors or fans F04; generating combustion products of high pressure or high velocity F23R; using gas turbines in compression refrigeration plants F25B11/00)
- F05D: INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS

## Abstract

In accordance with at least one aspect of this disclosure, there is provided a heat exchange system. The heat exchange system includes a first heat exchanger and a second heat exchanger. The first heat exchanger includes an engine fluid conduit fluidly connecting an engine fluid inlet to an engine fluid outlet. A first internal buffer fluid conduit fluidly connects a first buffer fluid inlet to a first buffer fluid outlet where the engine fluid conduit is in fluid isolation from the first internal buffer fluid conduit but is in thermal communication with the first internal buffer fluid conduit for heat exchange between the engine fluid and the buffer fluid.

## Claims

### Claim 1

A method for heating hydrogen in a hydrogen powered aircraft engine; comprising
flowing engine oil through a first engine fluid conduit of a first heat exchanger;
flowing engine compressor bleed air through a second engine fluid conduit of the first heat exchanger;
flowing the hydrogen through a hydrogen conduit of a second heat exchanger;
flowing a buffer fluid through a first buffer fluid conduit of the first heat exchanger and a second buffer fluid conduit of the second heat exchanger, wherein the first engine fluid conduit, the second engine fluid conduit and the first buffer fluid conduit are fluidly isolated, wherein the hydrogen conduit and the second buffer fluid conduit are fluidly isolated;
transferring heat from the engine oil and the engine compressor bleed air flowing through the first and the second engine fluid conduits to the buffer fluid flowing through the first buffer fluid conduit of the first heat exchanger;
transferring heat from the buffer fluid flowing through the second buffer fluid conduit to the hydrogen flowing through the hydrogen conduit of the second heat exchanger;
flowing engine turbine exhaust through a third engine fluid conduit of a third heat exchanger;
flowing the buffer fluid exiting from the second heat exchanger through a third buffer fluid conduit of the third heat exchanger, the third buffer fluid conduit fluidly connected to a fourth buffer fluid conduit of the second heat exchanger, whereby the buffer fluid enters a first buffer inlet of the second heat exchanger to pass through the second buffer fluid conduit and exits the second heat exchanger through a first buffer outlet, the buffer fluid flows from the first buffer outlet to the third heat exchanger to flow through the third buffer fluid conduit, and the buffer fluid flows from the third buffer fluid conduit to a second buffer inlet of the second heat exchanger to pass through the fourth buffer fluid conduit to a second buffer outlet of the second heat exchanger;
transferring heat from the engine turbine exhaust flowing through the third engine fluid conduit to the buffer fluid flowing through the third buffer fluid conduit of the third heat exchanger; and
transferring heat from the buffer fluid flowing through the fourth buffer fluid conduit to the hydrogen flowing through the hydrogen conduit of the second heat exchanger.

### Claim 2 (depends on 1)

The method as recited in claim 1, wherein the buffer fluid is a non-flammable fluid.

### Claim 3 (depends on 2)

The method as recited in claim 2, wherein the buffer fluid has zero water content.

### Claim 4 (depends on 1)

The method as recited in claim 1, comprising using heat from the engine oil, the engine compressor bleed air and the engine turbine exhaust for vaporizing the hydrogen upstream of a combustor of the hydrogen powered aircraft engine.

### Claim 5 (depends on 1)

The method as recited in claim 1, comprising providing the second heat exchanger in a main external hydrogen fluid conduit of the hydrogen powered aircraft engine.