Fluid Compressibility Measurement Using Dual Piston Pump

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Solution Overview

Problem

Existing methods for determining fluid compressibility in systems, such as those used in liquid chromatography, face inaccuracies due to volumetric effects and system-specific offsets, which can be challenging to account for without additional equipment or specific measurements.

Innovation Solution

A method that calculates fluid compressibility by determining volume differences between initial and compressed states at different pressures, using a dual piston pump system where both the primary and secondary reciprocating pumps are fluidically coupled, allowing for continuous operation and high accuracy without requiring additional equipment or specific measurements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional methods measure absolute volumes to determine compressibility, then the measurement process is simple, but dead volume and system offsets reduce measurement precision

Engineering Contradiction:
Improvecompressibility measurement accuracyVSAvoidmeasurement system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the volume measurement into two distinct components: dead volume (system-specific offset) and stroke volume (piston displacement). By measuring these separately and using only the stroke volume difference for compressibility calculation, the method eliminates dead volume interference while maintaining measurement simplicity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent uses the secondary piston as a copy of the primary piston to perform reference measurements. The secondary piston measures the same fluid compression under identical conditions, allowing the system to cancel out common-mode errors and isolate the compressibility effect from system-specific offsets.

Inventive Principle:
Principle #26Copying

2Measurement precision

If a dual piston pump system is used to determine compressibility, then measurement accuracy improves by eliminating dead volume effects, but the device complexity increases

Engineering Contradiction:
Improvecompressibility determination accuracyVSAvoidpump system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The dual piston pump system serves multiple functions: it delivers fluid at controlled flow rates for chromatography operations and simultaneously determines fluid compressibility through coordinated piston measurements. This multi-functionality justifies the added complexity by providing both operational and measurement capabilities in one system.

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

Solution Approach 2:

The system uses its own piston movements and internal volume changes to determine compressibility, without requiring external measurement equipment. The pump system self-diagnoses fluid compressibility properties through its operational parameters, eliminating the need for separate measurement apparatus.

Inventive Principle:
Principle #25Self-service

3Productivity

If compressibility is determined during regular system operation, then productivity is maintained, but measurement reliability may be compromised by operational variations

Engineering Contradiction:
Improvesystem operational continuityVSAvoidcompressibility determination reliability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The system continuously monitors piston positions and flow rates, using this feedback to calculate compressibility in real-time. The control system adjusts operational parameters based on measured compressibility values, ensuring reliable determination even during dynamic operational conditions by constantly adapting to system state changes.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system performs preliminary calibration measurements during system initialization or maintenance periods to establish baseline compressibility values. These pre-determined values are then used to correct and validate measurements taken during regular operation, ensuring reliability across different operational phases.

Inventive Principle:
Principle #10Preliminary action

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 accurate determination of fluid compressibility during regular system operation, eliminating undesired volumetric effects and system-specific offsets, and can be applied to fluid separation systems for maintaining solvent composition and flow rate consistency under changing conditions.

Implementation Method 1

compressing a first volume of the fluid to a first compressed volume at a second value of pressure

Methodology Applied
Scientific EffectCompression: Compression

Data Source

PatentEP2430309B1Determining fluid compressibility while delivering fluid
Publication Date: 2013.09.04 AGILENT TECHNOLOGIES INC
  • EP2430309B1 patent drawingFigure 1~2D
  • EP2430309B1 patent drawingFigure 3
  • EP2430309B1 patent drawingFigure 4A~4B

AI summary

A method for determining compressibility of a fluid is described. The method comprises starting at a first value of pressure and compressing a first volume of the fluid to a first compressed volume at a second value of pressure, starting at the first value of pressure and compressing a second volume of the fluid to a second compressed volume at the second value of pressure, determining a first volumetric difference corresponding to a difference between the second volume and the first volume, determining a second volumetric difference corresponding to a difference between the second compressed volume and the first compressed volume, and determining a value of compressibility of the fluid from a ratio derived from the second volumetric difference and the first volumetric difference.