In-Line Dialysate Heating Through Turbulent Cassette Flow

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Solution Overview

Problem

Dialysis machines, particularly PD machines, face challenges in accurately and efficiently heating dialysate to body temperature due to susceptibility to temperature variation and the need for rapid heating, while also minimizing cassette size.

Innovation Solution

The implementation of a disposable cassette with a fluid flow channel designed for turbulent flow, featuring specific dimensions and projections, and optionally incorporating thermal gel pouches, to enhance heat transfer efficiency and temperature control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If in-line heating is used to heat dialysate continuously, then heating efficiency and temperature control are improved, but the system complexity and cassette size increase

Engineering Contradiction:
Improveheating efficiencyVSAvoidcassette size
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The fluid flow channel is divided into multiple segments with different cross-sectional areas along the flow path. The channel includes a first section with a larger cross-sectional area and a second section with a smaller cross-sectional area, creating flow regime transitions that enhance heat transfer efficiency while maintaining a compact cassette design.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention changes the geometric parameters of the fluid flow channel, specifically the cross-sectional area variations and the inclusion of projections that alter flow characteristics. These parameter changes create turbulent flow patterns that significantly improve heat transfer from the heating element to the dialysate, resolving the contradiction between heating efficiency and cassette size.

Inventive Principle:
Principle #35Parameter changes

2Loss of time

If heating time is reduced to speed up treatment, then productivity is improved, but temperature stability and heating accuracy deteriorate

Engineering Contradiction:
Improveheating timeVSAvoidtemperature stability
Core Design Contradiction:
Loss of timeVSReliability

Solution Approach 1:

The invention creates flow turbulence through geometric features (projections and cross-sectional area changes) that act as flow disruptors. This turbulence creates chaotic fluid motion that enhances heat transfer coefficients, allowing rapid heating while maintaining temperature stability through improved thermal contact between the heating element and dialysate.

Inventive Principle:
Principle #18Mechanical vibration

Solution Approach 2:

By optimizing the geometric parameters of the flow channel including the placement and dimensions of projections, the invention creates optimal flow conditions for rapid yet stable heating. The cross-sectional area variations and projection configurations are specifically designed to maximize heat transfer efficiency within a compact space, enabling quick heating without sacrificing temperature accuracy.

Inventive Principle:
Principle #35Parameter changes

3Quantity of substance

If cassette size is minimized to reduce material usage and cost, then manufacturing efficiency is improved, but heat transfer capability and heating accuracy deteriorate

Engineering Contradiction:
Improvecassette sizeVSAvoidtemperature control accuracy
Core Design Contradiction:
Quantity of substanceVSMeasurement precision

Solution Approach 1:

The invention utilizes three-dimensional flow patterns created by cross-sectional area variations and projections within the flow channel. By creating turbulence through geometric features rather than increasing the overall channel volume, the design achieves enhanced heat transfer in a compact cassette, maintaining temperature control accuracy while minimizing material usage.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The invention optimizes geometric parameters including the dimensions, positions, and configurations of flow channel features such as projections and cross-sectional area changes. These parameter optimizations create high-efficiency heat transfer pathways within a compact design, achieving accurate temperature control without requiring excessive cassette size or material consumption.

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 design achieves faster and more precise heating of dialysate to body temperature, reducing treatment time and cassette size, while maintaining temperature stability.

Implementation Method 1

a heating chamber to heat the dialysate to a predetermined temperature

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

the fluid flow channel is arranged and configured to provide turbulent flow of dialysate through the fluid flow channel to provide increased heat transfer from the heating chamber to the dialysate

Methodology Applied
Scientific EffectTurbulent flow: Turbulence

Data Source

PatentEP4028072B1In-line heating of dialysis fluids
Publication Date: 2025.10.01 FRESENIUS MEDICAL CARE HOLDINGS INC
  • EP4028072B1 patent drawingFigure 1
  • EP4028072B1 patent drawingFigure 2
  • EP4028072B1 patent drawingFigure 3

AI summary

Dialysis systems and methods for operating dialysis machines (e.g., peritoneal dialysis machines) for conducting dialysis treatments are disclosed. The dialysis system may include a dialysis machine for transferring dialysate to a patient from a dialysate source. The dialysate may flow from the dialysate source through a cartridge or cassette (e.g., a disposable cartridge or cassette) positionable within the dialysis machine. The cassette includes a fluid flow channel. The dialysis machine includes a heating chamber for in-line heating of the dialysate in the fluid flow channel. The fluid flow channel is arranged and configured to provide turbulent flow of the dialysate through the fluid flow channel to provide increased heat transfer from the heating chamber to the dialysate.