Cool Drying Heat Exchanger Control to Prevent Condensate Freezing

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Solution Overview

Problem

Existing cool drying devices face challenges in accurately measuring the lowest gas temperature (LAT) within the heat exchanger, leading to potential freezing of condensate, inefficiencies in coolant control, and increased costs due to reliance on flow sensors and external temperature measurements.

Innovation Solution

A device with a measuring element positioned inside the secondary part of the heat exchanger to accurately measure the LAT or dew point, combined with a control unit that determines load conditions based on coolant temperature, allowing for timely and efficient control of the control valve to prevent freezing and adjust cooling capacity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If measuring elements are positioned on the outside of the heat exchanger to measure LAT, then the device structure is simpler, but the measurement precision is insufficient and freezing may occur

Engineering Contradiction:
Improveease of positioning measuring elementsVSAvoidLAT measurement accuracy
Core Design Contradiction:
Ease of manufactureVSMeasurement precision

Solution Approach 1:

The measuring element is nested inside the secondary part of the heat exchanger, placing the measurement device within the actual measurement environment to directly capture the lowest gas temperature without external interference, thereby resolving the contradiction between measurement accuracy and positioning ease

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The measuring element acts as an intermediary positioned within the gas flow path to directly sense the LAT, eliminating the need for external measurements that are prone to error and freezing issues

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of operation

If measuring elements are positioned outside the heat exchanger, then installation is easier, but the control response time is delayed

Engineering Contradiction:
Improveease of installationVSAvoidcontrol response time
Core Design Contradiction:
Ease of operationVSLoss of time

Solution Approach 1:

The measuring element is installed inside the heat exchanger's secondary part, embedding the sensor within the process flow to eliminate transmission delays and provide real-time LAT data for immediate control action

Inventive Principle:
Principle #7Nested doll (Nesting)

3Object-affected harmful factors

If the cooling capacity is reduced by controlling coolant flow, then freezing is prevented, but the device complexity increases due to control valves and bypass pipes

Engineering Contradiction:
Improvefreezing preventionVSAvoidcontrol system complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The control unit receives real-time LAT signals from the measuring element and automatically adjusts the control valve to regulate coolant flow, creating a closed-loop feedback system that prevents freezing while maintaining relatively simple device architecture

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system uses its own measured LAT data to automatically control the cooling capacity through the control valve, enabling self-regulation without requiring complex external control mechanisms

Inventive Principle:
Principle #25Self-service

4Measurement precision

If the measuring element is positioned inside the secondary part of the heat exchanger, then the measurement precision and response time are improved, but the device complexity increases

Engineering Contradiction:
ImproveLAT measurement accuracyVSAvoiddevice structural complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The measuring element is nested within the existing secondary part structure of the heat exchanger, utilizing the available space without requiring separate external housing or complex mounting arrangements, thus minimizing additional device complexity while maximizing measurement accuracy

Inventive Principle:
Principle #7Nested doll (Nesting)

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

Accurate and timely measurement of LAT or dew point enables optimal control of the cooling process, preventing freezing and adjusting to varying loads without the need for a flow sensor, reducing costs and improving operational efficiency.

Implementation Method 1

at least one measuring element is a measuring element for measuring the lowest gas temperature (LAT) or the dew point of the gas in the secondary part of the heat exchanger

Methodology Applied
Scientific EffectTemperature measurement:

Implementation Method 2

the control unit is provided with an algorithm that determines whether the device is operating at zero load or full load... and in the event of zero load, controls the control valve only on the basis of the signal from the measuring element for measuring the coolant temperature

Methodology Applied
Scientific EffectFluid flow control:

Implementation Method 3

cool drying is based on the principle that by reducing the gas temperature, the moisture in the gas condenses

Methodology Applied
Scientific EffectCondensation: Condensation

Implementation Method 4

the primary part is the evaporator of a cooling circuit... which cooling circuit is filled with a coolant

Methodology Applied
Scientific EffectHeat transfer: Conduction (thermal)

Data Source

PatentEP2477726B1Device and method for cool drying.
Publication Date: 2013.12.04 ATLAS COPCO AIRPOWER NV
  • EP2477726B1 patent drawingFigure 1
  • EP2477726B1 patent drawingFigure 2

AI summary

Device for cool drying gas, which device comprises a heat exchanger (2) whose primary part is the evaporator (3) of a cooling circuit (4) and the gas to be dried is guided through the secondary part of the heat exchanger (2) to cool the gas and to condense water vapour out of the gas, whereby at least one bypass pipe (11) is provided (5) with a control valve (12) which is controlled by a control unit (14) as a function of signals received from a measuring element (15) for measuring the lowest gas temperature (LAT) or the dew point of the gas in the secondary part of the heat exchanger (2), whereby this measuring element (15) is positioned directly inside the secondary part of the heat exchanger (2), and a measuring element (16) for measuring the temperature of the coolant in the evaporator (3).