CO2 Pump Temperature Control for Chromatography Mass Flow

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Solution Overview

Problem

Maintaining a consistent mass flow rate of CO2 in carbon dioxide-based chromatography systems is challenging due to the high compressibility of CO2, which causes changes in density and mass flow rate with pressure changes within the CO2 pump.

Innovation Solution

The system dynamically adjusts the temperature of the CO2 pump using a pressure sensor and computing system to maintain a consistent mass flow rate by retrieving target temperature values from a database and generating temperature control commands to control heaters or coolers, thereby compensating for pressure changes without altering the pump stroke volume.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If pressure changes within the CO2 pump are allowed to occur, then the pump can adapt to varying chromatography conditions, but the mass flow rate of CO2 changes due to high compressibility

Engineering Contradiction:

Improvepressure adaptationVSAvoidmass flow rate consistency

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The system changes the temperature parameter of the CO2 pump in response to pressure changes. When pressure increases, temperature is increased to expand the CO2 and maintain constant density and mass flow rate. This parameter coupling (temperature adjustment based on pressure) resolves the contradiction by allowing pressure adaptation while maintaining flow consistency.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The system implements a feedback control mechanism where pressure sensors continuously monitor pump pressure, and the controller adjusts the temperature accordingly to maintain constant mass flow rate. This closed-loop feedback ensures that pressure variations do not compromise flow consistency.

Inventive Principle:

Principle #23Feedback

2Reliability

If temperature of the CO2 pump is dynamically adjusted, then mass flow rate consistency is maintained, but system complexity increases

Engineering Contradiction:

Improvemass flow rate consistencyVSAvoidtemperature control system

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The system introduces a temperature control intermediary (heating/cooling mechanism) between the pressure changes and the CO2 fluid. This intermediary allows indirect control of mass flow rate through temperature adjustment, which is simpler and more reliable than direct mechanical control of pump parameters.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system replaces potential mechanical adjustments to pump stroke volume or speed with a thermal control mechanism. By using heating elements and temperature sensors instead of mechanical modifications, the system achieves mass flow rate control with simpler, more reliable components.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If temperature control mechanisms are added to the CO2 pump, then mass flow rate can be maintained, but energy consumption increases

Engineering Contradiction:

Improvemass flow rate consistencyVSAvoidpump energy consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The temperature control operates periodically or incrementally rather than continuously at maximum capacity. The controller adjusts temperature in steps or cycles based on pressure feedback, reducing overall energy consumption while maintaining mass flow rate consistency.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The system makes small, targeted temperature adjustments rather than large continuous changes. By coupling temperature changes directly to pressure changes, the system minimizes energy input while achieving the necessary compensation for pressure variations.

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 approach allows for precise control of the mass flow rate of CO2, ensuring a constant flow rate despite changes in delivery pressure, thereby maintaining the intended chromatography composition and efficiency.

Implementation Method 1

the temperature of a CO2 pump can be dynamically adjusted in order to compensate for changes in delivery pressure of the CO2 pump in order to maintain a consistent mass flow rate

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

measuring a change in pressure within a CO2 pump using a pressure sensor

Methodology Applied

Scientific EffectPressure measurement:

Implementation Method 3

cool the CO2 pump using a coolant

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS11143634B2Systems, devices, and methods for controlling the temperature of a CO2 pump

Publication Date: 2021.10.12 WATERS TECHNOLOGY CORP

AI summary

Methodologies, systems, and computer-readable media are provided for controlling the mass flow rate within a CO2 based chromatography system. The pressure within a CO2 pump is measured and received at a computing system, and the computing system retrieves a target temperature value corresponding to the new pressure measurement within the CO2 pump. The computing system then generates a temperature control command that controls a CO2 pump heater or cooler in order to achieve the target temperature value at the CO2 pump. Thus, a target mass flow rate of CO2 from the CO2 pump is achieved by adjusting the temperature of the CO2 pump in response to changes in pressure.