Exhaust Water Condensation for Hydrogen Engine Combustion Control

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Solution Overview

Problem

Hydrogen combustion in internal combustion engines is prone to abnormal combustion, knock, and high NOx emissions, particularly when operated under rich conditions, and existing solutions like exhaust gas recirculation and water dilution face efficiency and cost issues.

Innovation Solution

A system that recycles water from exhaust gases by condensation using an exhaust gas collector and condenser, integrated with a heat exchanger, to provide cooled air and water for injection into the combustion chamber, reducing the need for frequent water refills and enhancing combustion control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-generated harmful factors

If water is used to dilute hydrogen combustion, then combustion temperature is reduced and NOx emissions decrease, but water tank requires frequent refilling

Engineering Contradiction:
ImproveNOx emissionsVSAvoidwater tank refilling frequency
Core Design Contradiction:
Object-generated harmful factorsVSLoss of time

Solution Approach 1:

The patent recovers water from exhaust gases by condensing water vapor produced during hydrogen combustion. The exhaust gas stream is cooled below dew point temperature to condense water vapor, which is then collected and returned to the water tank for reuse in combustion dilution, eliminating the need for frequent refilling while maintaining low NOx emissions

Inventive Principle:
Principle #34Discarding and recovering

Solution Approach 2:

The system makes the combustion system self-sufficient by internally recycling water from its own exhaust products. The water needed for combustion dilution is generated by the combustion process itself and is recovered through condensation, creating a closed-loop system that does not require external water supplementation during operation

Inventive Principle:
Principle #25Self-service

2Temperature

If exhaust gas recirculation (EGR) is used to dilute hydrogen, then combustion temperature is reduced, but additional pumping systems are required reducing overall efficiency

Engineering Contradiction:
Improvecombustion temperatureVSAvoidpumping system complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The patent extracts water vapor from the exhaust gas stream through condensation and separates it for reuse. Instead of recirculating the entire exhaust gas mixture as in EGR systems, only the water component is extracted and recovered, eliminating the need for complex exhaust gas pumping systems while still achieving combustion temperature control through water dilution

Inventive Principle:
Principle #2Taking out (Extraction)

3Loss of substance

If water condensation from exhaust is implemented, then water consumption is reduced, but additional heat exchanger components are needed

Engineering Contradiction:
Improvewater consumptionVSAvoidheat exchanger components
Core Design Contradiction:
Loss of substanceVSDevice complexity

Solution Approach 1:

The patent designs the heat exchanger to perform multiple functions simultaneously: it cools the exhaust gas stream to enable water condensation, and the cooled exhaust gas can be utilized for other purposes such as cabin heating or preheating intake air. This multi-functionality reduces the need for separate heat exchanger components while achieving water recovery

Inventive Principle:
Principle #6Universality (Multi-functionality)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The system effectively manages hydrogen combustion by reusing condensed exhaust water for injection, minimizing abnormal combustion and NOx emissions, while improving engine efficiency and reducing the need for external water supply.

Implementation Method 1

an exhaust water condenser configured to condense at least a part of water contained in the exhaust gases

Methodology Applied
Scientific EffectCondensation: Condensation

Implementation Method 2

the exhaust water condenser is a heat exchanger comprising a cooling source comprising outside air and/or engine coolant

Methodology Applied
Scientific EffectHeat exchange: Heat Exchanger

Data Source

PatentEP4116568B1A system for controlling hydrogen combustion in a hydrogen internal combustion engine
Publication Date: 2026.05.20 VOLVO TRUCK CORP
  • EP4116568B1 patent drawingFigure 1~2
  • EP4116568B1 patent drawingFigure 3

AI summary

The invention relates to a hydrogen internal combustion engine system (10) comprising a combustion chamber (12) connected to a hydrogen intake system (14), an air intake system (16) and a water intake system (18) for controlling hydrogen combustion, characterized in that the water injection system (18) comprises an exhaust gas collector (30) connected to an exhaust water condenser (32) configured to condense at least a part of water contained in the exhaust gases.