Fuel Cell Cooling Loop Using Pump Losses for Cold-Start Heating

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Solution Overview

Problem

Conventional fuel cell systems require additional heat sources to maintain optimal operating temperatures, especially in low-temperature environments, which increases complexity, weight, and cost.

Innovation Solution

A cooling system with a thermal fluid circulation and a pump whose thermal power loss performance can be varied to increase the temperature of the thermal fluid, eliminating the need for additional heat sources by utilizing existing components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If additional heat sources are added to heat the fuel cell and hydrogen evaporator, then the temperature control requirement is met, but the number of components increases resulting in greater production effort, costs, installation space, and weight

Engineering Contradiction:
Improvefuel cell temperatureVSAvoidnumber of components
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The pump is designed to perform dual functions: conveying the thermal fluid through the system and generating heat through its power losses. By controlling the pump's operating parameters, it can switch between circulation mode and heating mode, eliminating the need for separate heating devices.

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

Solution Approach 2:

The pump utilizes its own power losses, which would otherwise be wasted energy, to heat the thermal fluid. This self-service approach converts a harmful factor (power loss) into a useful function (heating), removing the dependency on additional heat sources.

Inventive Principle:
Principle #25Self-service

2Temperature

If additional heat sources are added to heat the fuel cell and hydrogen evaporator, then the temperature control requirement is met, but the system weight increases

Engineering Contradiction:
Improvefuel cell temperatureVSAvoidfuel cell system weight
Core Design Contradiction:
TemperatureVSWeight of moving object

Solution Approach 1:

The pump is designed to perform dual functions: conveying the thermal fluid through the system and generating heat through its power losses. By controlling the pump's operating parameters, it can switch between circulation mode and heating mode, eliminating the need for separate heating devices.

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

Solution Approach 2:

The pump utilizes its own power losses, which would otherwise be wasted energy, to heat the thermal fluid. This self-service approach converts a harmful factor (power loss) into a useful function (heating), removing the dependency on additional heat sources.

Inventive Principle:
Principle #25Self-service

3Temperature

If additional heat sources are added to heat the fuel cell and hydrogen evaporator, then the temperature control requirement is met, but the installation space requirements increase

Engineering Contradiction:
Improvefuel cell temperatureVSAvoidinstallation space
Core Design Contradiction:
TemperatureVSArea of stationary object

Solution Approach 1:

The pump is designed to perform dual functions: conveying the thermal fluid through the system and generating heat through its power losses. By controlling the pump's operating parameters, it can switch between circulation mode and heating mode, eliminating the need for separate heating devices.

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

4Temperature

If the pump's thermal power loss is increased to heat the thermal fluid, then the heating function is achieved, but the energy efficiency of the pump for fluid conveyance decreases

Engineering Contradiction:
Improvethermal fluid temperatureVSAvoidpump energy efficiency
Core Design Contradiction:
TemperatureVSLoss of energy

Solution Approach 1:

The pump's operating parameters are dynamically adjusted based on system requirements. The controller can vary the pump speed and operating point to optimize the balance between fluid conveyance efficiency and heat generation, allowing the system to adapt between circulation-dominated and heating-dominated modes.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The operating parameters of the pump (such as speed, flow rate, and head) are changed to control the thermal power loss. By adjusting these parameters, the system can optimize the trade-off between the pump's conveying function and its heating function based on real-time temperature requirements.

Inventive Principle:
Principle #35Parameter changes

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

This solution allows for efficient heating of fuel cell systems without additional components, reducing weight, space requirements, and system complexity while maintaining optimal reactivity and safety.

Implementation Method 1

The thermal power loss of the pump does not support the conveyance of the thermal fluid, but only heats the thermal fluid flowing through the pump. The pump control is configured, for example, to increase the thermal power loss of the pump by injecting a direct current component (in addition to the alternating current for actuating the pump) into the stator of the pump motor.

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Implementation Method 2

Fuel cells are typically fed with a fuel and an oxidant, which then generates electricity. Since this electricity generation in the fuel cell usually also generates heat, the fuel cell is usually equipped with a heat exchanger that is coupled to a cooling system.

Methodology Applied
Scientific EffectHeat exchanger: Heat Exchanger

Data Source

PatentEP4325608B1Cooling system and method for operating a cooling system for at least one component of a fuel cell system
Publication Date: 2025.04.02 DIEHL AVIATION GILCHING GMBH
  • EP4325608B1 patent drawingFigure 1~2
  • EP4325608B1 patent drawingFigure 3
  • EP4325608B1 patent drawingFigure 4

AI summary

A cooling system (30) for at least one component (12) of a fuel cell system (10) equipped with a heat exchanger (34) has a refrigeration system (38) and a thermofluid circuit (32) which is connected on the one hand to a thermofluid inlet (35) and a thermofluid outlet (36) of the heat exchanger (34) of the respective component (12) of the fuel cell system (10) and on the other hand to a heat exchanger (39) of the refrigeration system (38).The thermofluid is conveyed through the heat exchanger (34) of the respective component (12) of the fuel cell system (10) and through the heat exchanger (39) of the refrigeration system (38) by means of a pump (40) in the thermofluid circuit (32), whereby a thermal power loss of the pump (40) is varied in order to increase the temperature of the thermofluid by increasing the thermal power loss of the pump (40) when an increased temperature level of the respective component (12) of the fuel cell system (10) is required, instead of using additional heat sources.