Refrigerant Supercooling Control in Multi-Unit Air Conditioning

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Solution Overview

Problem

Conventional air conditioning systems face issues with pressure loss and noise due to improper control of the supercooling expansion device, leading to insufficient refrigerant degree of supercooling and abnormal refrigerant states, which affect thermal efficiency and cause noise in indoor units.

Innovation Solution

Incorporating a supercooling heat exchanger and expansion device in the distribution unit, along with temperature and pressure sensors, to accurately control the degree of supercooling of liquid refrigerant, preventing conversion to gaseous state and ensuring efficient refrigerant flow.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If the liquid pipe length is increased to supply refrigerant to multiple indoor units, then the coverage area is improved, but pressure loss increases causing refrigerant to convert to gaseous state and generate noise

Engineering Contradiction:
Improvecoverage areaVSAvoidnoise
Core Design Contradiction:
Area of stationary objectVSObject-generated harmful factors

Solution Approach 1:

The supercooling expansion device performs preliminary expansion of liquid refrigerant before it enters the long liquid pipe. By reducing the refrigerant temperature and increasing its degree of supercooling in advance, the system compensates for the pressure loss that will occur during transport through the extended liquid pipe, preventing flash gas formation and noise at indoor units.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system changes the temperature parameter of the liquid refrigerant by introducing it to the supercooling expansion device, which lowers the temperature and increases the degree of supercooling. This parameter change allows the refrigerant to withstand the pressure loss in longer pipes without converting to gaseous state.

Inventive Principle:
Principle #35Parameter changes

2Stability of the object's composition

If the degree of supercooling is increased to prevent flash gas, then refrigerant flow stability is improved, but the risk of refrigerant shortage at indoor units increases

Engineering Contradiction:
Improverefrigerant flow stabilityVSAvoidrefrigerant quantity
Core Design Contradiction:
Stability of the object's compositionVSQuantity of substance

Solution Approach 1:

The supercooling expansion device operates with feedback control based on the actual degree of supercooling of the liquid refrigerant. The controller adjusts the expansion device opening degree according to measured supercooling values, automatically balancing between maintaining sufficient supercooling to prevent flash gas and avoiding excessive supercooling that would cause refrigerant shortage at indoor units.

Inventive Principle:
Principle #23Feedback

3Quantity of substance

If the supercooling expansion device opening degree is increased to supply more refrigerant, then refrigerant quantity is improved, but the degree of supercooling decreases causing flash gas formation

Engineering Contradiction:
Improverefrigerant quantityVSAvoiddegree of supercooling
Core Design Contradiction:
Quantity of substanceVSTemperature

Solution Approach 1:

The opening degree of the supercooling expansion device is made dynamically adjustable rather than fixed. The controller continuously adjusts the opening degree based on real-time measurements of the refrigerant's degree of supercooling, enabling the system to optimize both refrigerant quantity and supercooling degree according to actual operating conditions.

Inventive Principle:
Principle #15Dynamics

4Measurement precision

If precise control of supercooling expansion device is implemented, then refrigerant state accuracy is improved, but system complexity increases

Engineering Contradiction:
Improverefrigerant state accuracyVSAvoidcontrol system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The supercooling expansion device is designed to be self-regulating through feedback from the degree of supercooling measurement. The system automatically adjusts its own operation based on measured conditions without requiring complex external control mechanisms, achieving precise refrigerant state control while minimizing additional system complexity.

Inventive Principle:
Principle #25Self-service

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 configuration allows precise control of supercooling, preventing noise and maintaining thermal efficiency by ensuring accurate refrigerant state and flow, thus enhancing cooling and heating operations.

Implementation Method 1

a supercooling heat exchanger disposed between the liquid pipe and the indoor unit so as to supercool the liquid refrigerant flowing through the liquid pipe

Methodology Applied
Scientific EffectSupercooling: Supercooling

Implementation Method 2

a supercooling expansion device connected to the supercooling heat exchanger to adjust an opening degree in order to increase or decrease a degree of supercooling of the liquid refrigerant

Methodology Applied
Scientific EffectPressure drop cooling: Pressure Gradient

Data Source

PatentEP3358276B1Air conditioning system
Publication Date: 2022.05.18 LG ELECTRONICS INC
  • EP3358276B1 patent drawingFigure 1
  • EP3358276B1 patent drawingFigure 2
  • EP3358276B1 patent drawingFigure 3

AI summary

The present invention relates to an air conditioning system. The present invention relates to an air conditioning system comprising one or more over-cooling heat exchangers, an over-cooling expansion device, a temperature sensor, and a pressure sensor so as to accurately measure and control a current over-cooling degree value of a fluid coolant disposed between a fluid pipe and a plurality of indoor units and flowing thereinside.