Subsea Unit Cooling via Conduction and Convection

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Solution Overview

Problem

Existing subsea installations face challenges in efficiently cooling heat generating components due to the need for thick enclosures to withstand pressure differences, which increases weight, cost, and hinders efficient cooling, while pressurized systems lack efficient cooling mechanisms.

Innovation Solution

A subsea unit with heat generating components in thermal conductive connection with the housing, utilizing a dielectric liquid to create a convective flow for cooling, where the first component dissipates heat to the sea water via conduction and the dielectric liquid, and the second component is cooled via convection, with optional heat sinks and flow directing structures to enhance heat transfer and convective flow.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the enclosure uses thick walls to withstand pressure difference, then the structural strength is improved, but the cooling efficiency deteriorates and weight increases

Engineering Contradiction:
Improvestructural strengthVSAvoidcooling efficiency
Core Design Contradiction:
StrengthVSTemperature

Solution Approach 1:

The enclosure is segmented into two functional zones: a thin-walled pressure-equalized chamber for electronics and a separate thick-walled pressure-resistant shell. This segmentation allows each zone to be optimized independently - the thin chamber enables efficient cooling while the outer shell provides structural strength.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The thin-walled pressure-equalized enclosure is nested within the thick-walled pressure-resistant shell. The inner enclosure contains the electronics and dielectric liquid, while the outer shell withstood hydrostatic pressure, creating a nested structure that resolves the contradiction between strength and cooling efficiency.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Strength

If the enclosure uses thick walls to withstand pressure difference, then the structural strength is improved, but the device weight increases

Engineering Contradiction:
Improvestructural strengthVSAvoidequipment weight
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

The structural function is segmented from the cooling function. Only the outer shell needs to be thick-walled for pressure resistance, while the inner enclosure can be thin-walled. This segmentation reduces overall weight compared to a completely thick-walled enclosure.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Thick walls are applied locally only where pressure resistance is needed (outer shell), while the inner enclosure walls are thin. This localized application of thickness optimizes the weight-strength tradeoff by providing strength only where necessary.

Inventive Principle:
Principle #3Local quality

3Strength

If the enclosure uses thick walls to withstand pressure difference, then the structural strength is improved, but the manufacturing cost increases

Engineering Contradiction:
Improvestructural strengthVSAvoidmanufacturing cost
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The enclosure is divided into two separable components: a thin-walled inner enclosure and a thick-walled outer shell. This segmentation allows each component to be manufactured independently using appropriate processes, reducing overall manufacturing complexity and cost.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The inner enclosure and outer shell are combined through assembly (e.g., flanges, bolts, or welding) to form the complete pressure-equalized enclosure. This merging of components allows cost optimization through specialized manufacturing of each part.

Inventive Principle:
Principle #5Merging (Combining)

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 provides efficient cooling of heat generating components by combining conduction and convection, reducing the need for thick enclosures and enhancing heat transfer, thereby optimizing cooling performance while maintaining pressure compensation.

Implementation Method 1

the first component is in thermal conductive connection with the housing... the heat generated in the first component can be conducted through the housing to the surrounding sea water

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

A portion of said heat heats the dielectric liquid within the housing and thereby creates a convective flow, which cools the second component

Methodology Applied
Scientific EffectConvection: Convection

Implementation Method 3

the first component is cooled by both conduction and convection... cooled by heat dissipation to the dielectric liquid via convection

Methodology Applied
Scientific EffectConvection heat transfer: Convection

Implementation Method 4

the heat generated in the first component can be conducted through the housing to the surrounding sea water

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP2803813B1A subsea unit with conduction and convection cooling
Publication Date: 2019.02.27 ABB (SCHWEIZ) AG
  • EP2803813B1 patent drawingFigure 1~2
  • EP2803813B1 patent drawingFigure 3~4
  • EP2803813B1 patent drawingFigure 5~6

AI summary

The present disclosure relates to a subsea unit (10; 12; 14; 16; 18) comprising a housing (20) containing a dielectric liquid (30), a first heat generating component (40) and a second heat generating component (50). The first heat generating component (40) is arranged in thermal connection with the housing (20) and the second heat generating component (50) is arranged at a distance from the housing (20). A method of cooling heat generating components contained in a housing of a subsea unit is also presented.