Wind Turbine Liquid Circuit Pressure Control Without Gas Bubbles

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Solution Overview

Problem

Existing cooling circuits in wind turbines face challenges with gas bubbles in expansion tanks, which escape over time, requiring frequent coolant topping and complex maintenance, especially since no suitable gases have been found to prevent this issue.

Innovation Solution

A cooling circuit design that uses an expansion tank with a compensating valve to regulate pressure through a static liquid column, eliminating the need for membrane or metal bellows expansion tanks, and includes a sight glass and level sensor for easy monitoring and maintenance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a gas bladder expansion tank is used to maintain pressure in the cooling circuit, then the desired pressure can be maintained through volume fluctuation compensation, but the gas gradually escapes from the bladder requiring frequent coolant topping and complex maintenance

Engineering Contradiction:
Improvepressure maintenance reliabilityVSAvoidmaintenance complexity
Core Design Contradiction:
ReliabilityVSEase of repair

Solution Approach 1:

The invention extracts and eliminates the gas bladder component from the expansion tank system. Instead of using a gas-filled bladder to compensate for volume fluctuations, the patent employs a simple liquid-filled expansion tank with a connection to the atmosphere through a dehumidifier, removing the source of the gas escape problem entirely while maintaining pressure stability through liquid volume compensation.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention replaces the complex, maintenance-intensive gas bladder system with a simple, robust liquid-filled expansion tank that has no moving parts or sealed compartments. The system uses inexpensive components that do not degrade over time like rubber bladders, eliminating the need for periodic replacement or complex maintenance interventions.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

2Reliability

If the expansion tank is sealed to prevent gas escape, then pressure can be maintained, but the system becomes complex and requires monitoring of gas volume and pressure equalization

Engineering Contradiction:
Improvepressure maintenance reliabilityVSAvoidsystem complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The expansion tank serves multiple functions simultaneously: it compensates for coolant volume fluctuations, maintains system pressure, provides a reference level for coolant filling, and allows for simple atmospheric pressure equalization through the dehumidifier connection. This multi-functionality is achieved with a simple open-top liquid-filled design rather than complex sealed systems with multiple components.

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

Solution Approach 2:

The system automatically maintains pressure and volume balance through the liquid-filled expansion tank connected to the atmosphere. The liquid column self-regulates pressure based on height, and the dehumidifier automatically manages atmospheric connection without requiring active control systems, sensors, or complex pressure equalization mechanisms.

Inventive Principle:
Principle #25Self-service

3Reliability

If coolant is frequently topped up to restore pressure after gas escape, then pressure can be maintained, but this process gradually replaces the gas volume with coolant until the bladder no longer serves its purpose

Engineering Contradiction:
Improvepressure maintenance reliabilityVSAvoidcoolant loss
Core Design Contradiction:
ReliabilityVSLoss of substance

Solution Approach 1:

The invention extracts and eliminates the gas bladder component that causes gas escape and subsequent coolant replacement issues. By using a liquid-filled expansion tank open to the atmosphere through a dehumidifier, the system prevents gas escape entirely, eliminating the cycle of coolant loss and replacement that occurs in gas bladder systems.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The expansion tank contains only liquid coolant, creating a homogeneous fluid system without gas-liquid interfaces. This eliminates the phase boundary problems that cause gas escape in bladder systems, ensuring that the entire volume remains as liquid coolant that can be easily monitored and refilled without gradual replacement issues.

Inventive Principle:
Principle #33Homogeneity

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 maintains optimal pressure without gas bubbles, simplifies maintenance, and reduces the risk of leakage and sealing issues, enhancing the reliability and availability of the cooling system.

Implementation Method 1

the expansion tank creates pressure in the liquid circuit by means of the static pressure of a liquid column

Methodology Applied
Scientific EffectStatic pressure of liquid column: Hydraulic Press

Implementation Method 2

Through such a pressure relief valve, pressure can escape to the outside when there is an overpressure in the expansion tank

Methodology Applied
Scientific EffectPressure relief: Pressure Drop

Implementation Method 3

a cooling section for cooling a component of the wind turbine by means of the coolant

Methodology Applied
Scientific EffectHeat transfer: Conduction (thermal)

Implementation Method 4

The heated liquid is then directed to a recooler, where it releases the stored heat

Methodology Applied
Scientific EffectConvection: Convection

Implementation Method 5

The heated liquid is then directed to a recooler, where it releases the stored heat

Methodology Applied
Scientific EffectHeat release: Heat Exchanger

Data Source

PatentEP3280912B1Wind turbine having a liquid circuit and components therefor
Publication Date: 2023.06.07 WOBBEN PROPERTIES GMBH
  • EP3280912B1 patent drawingFigure 1
  • EP3280912B1 patent drawingFigure 2
  • EP3280912B1 patent drawingFigure 3~4

AI summary

The invention relates to a wind turbine, which has a nacelle, having at least one liquid circuit (1). The liquid circuit has a cooling liquid, a cooling segment for cooling a component of the wind turbine by means of the cooling liquid, a recirculation cooler (4) for cooling the cooling liquid, a line system (2) for conducting the cooling liquid, and an equalization tank (8) for maintaining an operating pressure of the liquid circuit (1). The equalization tank (8) effects a pressure in the liquid circuit (1) by means of a static pressure of a liquid column.