A drain system and a shower or shower cabin

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Solution Overview

Problem

Existing drain systems for recovering thermal energy from shower greywater face a trade-off between flowrate capacity and heat recovery performance due to size constraints, leading to reduced efficiency and increased fouling.

Innovation Solution

A drain system incorporating a water level control pipe portion and a downcomer with a contraction downstream of the heat exchanger to stabilize flow and maintain wetting, enhancing flowrate while preventing fouling and optimizing thermal energy recovery.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the size of the heat exchanger and associated equipment is reduced, then the device complexity and installation space requirements are minimized, but the flowrate capacity and heat recovery performance are reduced

Engineering Contradiction:

Improvesize of heat exchangerVSAvoidflowrate capacity

Core Design Contradiction:

Volume of moving objectVSProductivity

Solution Approach 1:

The patent employs hydraulic principles by introducing a downcomer with a contraction that creates a venturi effect, accelerating greywater flow through the heat exchanger. This hydraulic design enables increased flowrate capacity without proportionally increasing heat exchanger size, resolving the contradiction between compact dimensions and flow handling capability

Inventive Principle:

Principle #29Pneumatics and hydraulics

Solution Approach 2:

The patent changes the flow parameters by introducing a contraction in the downcomer that accelerates the greywater velocity. This parameter change (increasing flow velocity) allows the system to maintain high flowrate capacity through a smaller heat exchanger volume, as the accelerated flow compensates for the reduced contact time and surface area

Inventive Principle:

Principle #35Parameter changes

2Productivity

If the flowrate of greywater through the heat exchanger is increased, then the productivity and heat recovery capacity are improved, but the wetting of the heat exchanger may become insufficient leading to increased fouling

Engineering Contradiction:

Improveflowrate of greywaterVSAvoidwetting of heat exchanger

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The water level control pipe portion functions as a feedback mechanism that monitors and maintains the water level in the downcomer. This feedback control ensures that sufficient water is available to maintain continuous wetting of the heat exchanger surfaces, preventing fouling even at increased flowrates

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The downcomer with contraction acts as an intermediary element that mediates between the high flowrate requirement and the wetting requirement. The contraction accelerates flow while the water level control ensures sufficient water supply maintains wetting, resolving the contradiction between speed and coverage

Inventive Principle:

Principle #24Intermediary (Mediator)

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 achieves increased flowrate and maintained wetting of the heat exchanger, improving thermal energy recovery efficiency and reducing fouling, while being cost-effective and user-friendly.

Implementation Method 1

a heat exchanger arranged downstream of the drain inlet and comprising a grey water inlet and grey water outlet, the heat exchanger being configured to heat a flow of incoming cold water with the greywater flowing from the grey water inlet to the grey water outlet

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

a downcomer arranged downstream of the water level control pipe portion and comprising a contraction for increasing the flowrate of greywater from the grey water inlet to the grey water outlet

Methodology Applied

Scientific EffectPressure differential: Pressure Gradient

Data Source

PatentUS20250369703A1A drain system and a shower or shower cabin

Publication Date: 2025.12.04 ENDUCE AB

AI summary

A drain system for recovering thermal energy from a flow of shower or faucet greywater. The drain system comprises: a drain inlet for receiving greywater; a heat exchanger configured to heat a flow of incoming cold water with the greywater flowing from a grey water inlet to a grey water outlet; and a water level control pipe portion arranged downstream of the grey water outlet. The drain system further comprises a downcomer arranged downstream of the water level control pipe portion. The downcomer comprises a contraction for increasing the flowrate of greywater from the grey water inlet to the grey water outlet.