Humidifier Chamber with Segmented Heaters for Gas Saturation
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Solution Overview
Problem
Existing respiratory humidification systems for CPAP therapy often fail to deliver gases at 100% saturation due to varying flow rates and temperature differences, leading to inefficient humidification and potential discomfort for patients.
Innovation Solution
A humidification chamber design with a finned heater in the upstream half and a separate heater base in the downstream half, creating a tortuous path for gases to ensure maximum heating and saturation, while maintaining separate control over each heater unit for optimal performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single heater base is used to heat water in the humidification chamber, then the structure is simple, but the gases cannot achieve 100% saturation due to varying flow rates and temperature differences
Solution Approach 1:
The single heater base is divided into two separate heater bases: a first heater base positioned upstream to heat gases before they enter the water volume, and a second heater base positioned downstream to heat gases after they pass over the water. This segmentation allows independent control of heating stages, ensuring gases achieve 100% saturation regardless of flow rate variations while maintaining structural manageability through modular design.
Solution Approach 2:
Different regions of the humidification chamber are assigned different heating functions with distinct heater bases. The upstream region receives preheating to prepare gases for efficient water vapor absorption, while the downstream region provides final heating to maintain temperature through the water volume. This local differentiation of heating quality ensures optimal saturation conditions at each stage of gas passage.
2Weight of moving object
If the humidifier chamber is located remotely from the patient, then the weight burden on the patient is reduced, but the gases may cool and condense in the delivery conduit
Solution Approach 1:
The first heater base performs preliminary heating of gases in the humidification chamber before they enter the delivery conduit. By preheating the gases to body temperature or higher, the system prevents temperature drops that would cause condensation during transport through the conduit, eliminating the harmful effect of condensation while maintaining remote chamber placement.
Solution Approach 2:
The second heater base continues the heating action throughout the gas passage through the water volume and into the delivery conduit. This continuous heating ensures gases maintain elevated temperature from the humidification chamber through the entire delivery path, preventing condensation formation and maintaining humidity without requiring the chamber to be close to the patient.
3Use of energy by moving object
If heater elements are placed close to the water volume to maximize heating efficiency, then energy usage is reduced, but the risk of water boiling and chamber pressure increase is higher
Solution Approach 1:
The heating function is segmented into two stages with separate heater bases positioned at different locations relative to the water volume. The first heater base is positioned upstream where it can efficiently heat gases without direct water contact, while the second heater base is positioned downstream where it maintains temperature through the water volume. This segmentation allows high heating efficiency while preventing localized overheating and water boiling that would cause pressure increases.
Solution Approach 2:
Gases serve as an intermediary medium between the heater bases and the water volume. Instead of heaters directly contacting water (which would cause boiling and pressure rise), the heaters warm the gases that then pass over the water, transferring heat indirectly. This intermediary approach maintains high heating efficiency while preventing direct water heating to boiling points, thus controlling chamber pressure.
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 higher absolute humidity and consistent temperature delivery, reducing the risk of condensation and enhancing patient comfort by ensuring gases are fully saturated and heated to body temperature.
Implementation Method 1
Gases are passed to the patient by way of a patient interface 2... The cannula 2 is connected to a gases transportation pathway or inspiratory conduit 3 that in turn is connected to a humidifier chamber 5. A flow of gases is provided through the chamber 5 by an integrated blower unit contained within the housing 10.
Implementation Method 2
The finned heater 12a is positioned in the upstream half 20 of the humidification chamber 5a... The finned heater 12a is configured and shaped so that gases entering the chamber must pass over, between, and around the fins 24.
Implementation Method 3
The downstream half 21 contains a volume of water 6a that is heated by the heater base 13a... Water vapour fills the volume of the chamber above the surface of the water 6, rising from the surface of the water 6.
Implementation Method 4
Water vapour fills the volume of the chamber above the surface of the water 6, rising from the surface of the water 6. Gases from the blower or fan pass into the chamber 5 through inlet 11 and become humidified as they pass across the top half of the chamber 5.
Implementation Method 5
The finned heater 12a is configured and shaped so that gases entering the chamber must pass over, between, and around the fins 24. This ensures that substantially the entire volume of gases passing into the chamber 5a becomes heated.
Implementation Method 6
Atmospheric air enters the housing 10 through an inlet 9 on the back of the casing 10, and is pressurised by a blower or fan assembly. The air is then passed into the humidification chamber 5 through an inlet 11.
Data Source
Figure 1
Figure 2a
Figure 2b
AI summary
A respiratory humidifier chamber for use with a breathing assistance apparatus is described. The chamber comprises a watertight vessel having an inlet for receiving gases from the breathing assistance apparatus, and an outlet through which heated humidified gases exit the vessel for delivery to a patient. The chamber has a partition which divides the chamber into upstream and downstream sub-chambers. The sub-chambers are separated by the partition except for an aperture which passes through the partition and allows gaseous communication between the sub-chambers. The downstream sub-chamber includes a heater base which heats a volume of water contained within it. The aperture is located above the volume of water. The upstream sub-chamber contains an internal heater which heats gases passing through it from the inlet to the aperture. At least part of the internal heater is located immediately adjacent the aperture.