Flow Distribution Mixer for Viscosity-Independent HPLC Mixing
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Solution Overview
Problem
In high performance liquid chromatography (HPLC), fluctuations in the mixing ratio of eluent flows can lead to baseline noise and poor reproducibility of analysis, especially when using UV-absorbing additives, and existing mixers struggle to maintain a constant eluent composition over time, particularly during gradient mode where viscosity varies.
Innovation Solution
A flow distribution mixer that distributes an inlet flow into multiple channels, with each channel having a first section providing most of the hydraulic resistance and a second section for volume delay, allowing for independent viscosity-independent distribution of partial flows, ensuring predictable and reproducible mixing even with varying fluid viscosity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional mixers are used to blend mobile phase constituents, then mixing is achieved, but fluctuations in mixing ratio occur leading to baseline noise and poor reproducibility
Solution Approach 1:
The mobile phase flow is divided into multiple parallel flow channels (at least three channels), each receiving a portion of the inlet flow. The flow distributor segments the inlet flow distribution ratio among channels is 1:2:1 or 1:3:1, allowing independent control and stabilization of mixing ratios in each channel, thereby reducing fluctuations and improving reproducibility
Solution Approach 2:
A flow distributor is introduced as an intermediary device between the inlet and flow channels to precisely control and stabilize the distribution ratio of inlet flow to each channel. This intermediary component ensures constant flow distribution ratios (1:2:1 or 1:3:1) despite variations in inlet flow conditions, eliminating baseline noise and improving analysis reproducibility
2Adaptability or versatility
If pump operation controls mobile phase composition, then blending is achieved, but mixing ratio fluctuations occur during gradient mode due to varying viscosity
Solution Approach 1:
The system maintains constant mixing ratios (1:2:1 or 1:3:1) across different viscosity conditions by using flow channels with specifically designed hydraulic resistances. The first flow section provides dominant hydraulic resistance while the second flow section provides volume delay, ensuring that viscosity changes during gradient mode do not affect the distribution ratio, thus maintaining composition stability
Solution Approach 2:
The flow distributor is designed in advance with specific hydraulic resistance characteristics in the first flow section to predetermine the flow distribution ratio. This preliminary design ensures that regardless of subsequent viscosity changes during gradient operation, the mixing ratio remains constant at the predetermined values (1:2:1 or 1:3:1)
3Ease of manufacture
If flow channels have uniform design, then manufacturing is simple, but viscosity-independent flow distribution cannot be achieved
Solution Approach 1:
Different sections of the flow channels have different functional qualities: the first flow section is designed with dominant hydraulic resistance (narrower cross-section) to control flow distribution, while the second flow section has larger volume for delay functionality. This local differentiation enables viscosity-independent flow distribution while maintaining manufacturability through standardized components
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 mixer achieves homogeneous and predictable fluid mixing, independent of fluid viscosity, enhancing separation performance and reproducibility in HPLC applications, particularly during gradient mode, by ensuring consistent flow distribution and delay profiles.
Implementation Method 1
a first flow section (260A-260L, 260C, 260D-260K) providing a dominant hydraulic resistance for the respective flow channel
Implementation Method 2
a second flow section (270B-270L, 270C, 270D-270K) coupled in series with the first flow section (260A-260L, 260C, 260D-260K) of the respective flow channel, having a volume delaying a propagation of the fluid from the first flow section (260A-260L, 260C, 260D-260K) to the flow combiner (240) by a time required by the respective partial flow to pass the volume of the respective second flow section (270B-270L, 270C, 270D-270K)
Data Source
AI summary
A mixer for mixing a fluid having a property varying along a flow direction of the fluid includes an inlet configured for receiving an inlet flow, an outlet configured for providing an outlet flow, and a plurality of flow channels coupled between the inlet and the outlet. The mixer also includes a flow distributor for distributing the inlet flow into the plurality of flow channels so that each flow channel receives a partial flow from the inlet flow, and a flow combiner for combining the partial flows from the plurality of flow channels to the outlet flow. Each flow channel has a first flow section having a hydraulic resistance substantially representing a hydraulic resistance of the flow channel. One or more of the flow channels each have a second flow section coupled in series with the first flow section of the respective flow channel.