Sewer-Integrated Pipe System for Ground Heat Extraction in Urban Areas

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Solution Overview

Problem

Existing methods for installing underground pipe systems to harness terrestrial heat are complex and difficult to implement in heavily built-up environments, such as cities, due to the need for extensive excavation and potential damage to existing infrastructure.

Innovation Solution

A sewer-based system where a pipe system is embedded within a concrete second wall that covers at least 75% of the internal height of the sewer, allowing for efficient heat extraction from the surrounding ground while also serving as a renovation layer for existing sewers, with flexible pipes to minimize damage from ground movements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If a pipe system is placed at a slight depth of one to two metres to heat fluid using terrestrial heat, then heat extraction efficiency is improved, but the complexity of construction increases due to extensive excavation requirements

Engineering Contradiction:
Improveheat extraction efficiencyVSAvoidconstruction complexity
Core Design Contradiction:
Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The patent combines the heat extraction function with the sewer structure itself. The pipe system is integrated into the sewer wall (second wall), allowing the sewer to serve dual purposes: wastewater conveyance and heat extraction. This eliminates the need for separate shallow burial installation and reduces construction complexity in urban areas.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The sewer structure is given multiple functions: it continues to serve as a wastewater conduit while simultaneously acting as a heat exchange system. The second wall of the sewer contains the pipe system, making the sewer itself a multi-functional element that addresses both sanitation and heating needs.

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

2Quantity of substance

If extensive excavation is performed to install a pipe system for heat extraction, then heat extraction capability is improved, but damage to existing underground infrastructure increases

Engineering Contradiction:
Improveheat extraction capabilityVSAvoiddamage to existing infrastructure
Core Design Contradiction:
Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The pipe system is nested within the existing sewer structure. Instead of installing pipes separately in excavated ground, the patent places the heat extraction pipes inside the wall of the existing sewer, utilizing the already-dug space and avoiding additional excavation that could harm other infrastructure.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The sewer infrastructure is already in place from previous construction activities. The patent takes advantage of this pre-existing structure by integrating the heat extraction system into it, thereby avoiding the need for new excavation and the associated risks to other underground utilities.

Inventive Principle:
Principle #10Preliminary action

3Use of energy by moving object

If the pipe system extends over a large part of the sewer height to obtain heat from ground on all sides, then heat extraction efficiency is improved, but the complexity of the pipe system installation increases

Engineering Contradiction:
Improveheat extraction efficiencyVSAvoidpipe system installation complexity
Core Design Contradiction:
Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The pipe system is merged with the sewer wall structure. By embedding pipes within the second wall that extends over 75% of the sewer height, the installation leverages the existing structural framework, reducing the complexity of supporting and positioning the pipes compared to free-standing installations.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The second wall is specifically designed to contain the pipe system and is made of concrete to provide thermal mass and structural support. This localized enhancement of the sewer structure at the regions where heat extraction is needed optimizes thermal performance without requiring complex modifications throughout the entire system.

Inventive Principle:
Principle #3Local quality

4Stability of the object's composition

If a rigid pipe system is used for heat extraction, then structural stability is improved, but vulnerability to damage from ground movements increases

Engineering Contradiction:
Improvestructural stabilityVSAvoidresistance to ground movements
Core Design Contradiction:
Stability of the object's compositionVSReliability

Solution Approach 1:

The patent specifies using flexible pipes for the heat extraction system. These flexible pipes can accommodate ground movements, settlements, and deformations without breaking, maintaining system reliability while the concrete second wall provides the necessary structural stability and thermal mass.

Inventive Principle:
Principle #30Flexible shells and thin films

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 approach enables easier installation and renovation of heat extraction systems in urban areas, allowing for increased heat capture from the ground and simultaneous sewer renovation, with flexible pipes reducing vulnerability to ground movements.

Implementation Method 1

a pipe system for conducting a fluid to be heated being disposed in said second wall, whereby heat can be obtained from the ground surrounding the sewer on all sides

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP3450877B1Underground device for obtaining heat from the ground and method for the underground placement of a pipe system for obtaining heat from the ground
Publication Date: 2020.06.17 RENOTEC NV
  • EP3450877B1 patent drawingFigure 1
  • EP3450877B1 patent drawingFigure 2
  • EP3450877B1 patent drawingFigure 3

AI summary

Method for the underground placement of a pipe system (7) for obtaining heat from the ground (14), in which a second wall (5) is installed on the inner side of a first wall (4) of a sewer (3), in which a pipe system (7) is installed in said second wall (5), the sewer having a height (H), in which the pipe system (7) is installed over at least 33% of said height (H), preferably over at least 50% of said height (H) and with greater preference over at least 75% of said height (H). With this method terrestrial heat can be obtained from the ground surrounding the sewer (3). Preferably said second wall (5) has an inner surface (13) and an outer surface (6), in which said pipe system (7) is installed in said second wall (5) in a position lying closer to the outer surface (6) than to the inner surface (5).