Air Conditioning Load Control for Parallel Compressors and Injectors

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Solution Overview

Problem

Large air conditioning systems face challenges in determining and coordinating the supply and demand relationship between parallel components to achieve stable on-demand cooling/heating and improved energy efficiency, particularly when only part of the indoor heat exchange units are in use.

Innovation Solution

A control method that acquires actual cooling/heating capacity and temperature change rates to automatically learn the heat exchange load characteristic curve, allowing for adjustment of the number and rotational speeds of compressors and injectors to match steady state or desired loads, ensuring efficient operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If multiple parallel compressors and injectors are used to improve partial-load regulation ability, then energy efficiency is improved, but device complexity increases

Engineering Contradiction:
Improveenergy efficiencyVSAvoiddevice complexity
Core Design Contradiction:
Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The patent implements dynamic coordination control of multiple parallel compressors and injectors based on real-time load detection. The system dynamically adjusts the operating state of each component (on/off status, injection amount) according to the current cooling/heating load requirements, enabling the system to adapt to varying partial-load conditions and optimize energy efficiency while managing the complexity through intelligent control strategies

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes operational parameters (compressor speed, injector opening degree, refrigerant injection amount) to optimize performance at different load levels. By adjusting these parameters dynamically, the system can operate multiple parallel components at optimal points across a wide range of loads, improving overall energy efficiency without requiring excessive hardware complexity

Inventive Principle:
Principle #35Parameter changes

2Reliability

If parallel components are coordinated to achieve stable on-demand cooling/heating, then reliability is improved, but control complexity increases

Engineering Contradiction:
Improvestable on-demand cooling/heatingVSAvoidcontrol complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent employs feedback control mechanisms where the system continuously monitors the actual cooling/heating output and temperature change rates, then uses this information to adjust the operation of parallel compressors and injectors. This closed-loop feedback ensures stable on-demand performance while managing control complexity through systematic coordination strategies

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system performs preliminary learning to establish heat exchange load characteristic curves before actual operation. By pre-establishing the relationship between cooling/heating capacity and temperature change rates, the system can quickly determine the optimal combination of parallel components without complex real-time calculations, thereby improving reliability while reducing instantaneous control complexity

Inventive Principle:
Principle #10Preliminary action

3Manufacturing precision

If automatic learning of heat exchange load characteristic curve is implemented, then manufacturing precision is improved, but loss of time increases

Engineering Contradiction:
Improveaccuracy of load determinationVSAvoidlearning time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The system performs the heat exchange load characteristic curve learning during system installation or initial operation phases, establishing the load-characteristic relationship in advance. This preliminary action allows for accurate load determination during subsequent operations without requiring extended learning periods, thereby achieving high precision while minimizing operational time loss

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system automatically learns and establishes its own heat exchange load characteristic curves through self-service mechanisms, collecting operational data and fitting the characteristic curves without external intervention. This automated approach improves the accuracy of load determination while reducing the time burden on operators, balancing precision requirements with time efficiency

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP3708925B1Control method for air conditioning system and associated air conditioning system
Publication Date: 2023.04.26 CARRIER CORP
  • EP3708925B1 patent drawingFigure 1

AI summary

A control method for an air conditioning system is provided. The control method includes: S100, acquiring an actual cooling/heating capacity output by the air conditioning system, and acquiring an actual temperature change rate of an indoor heat exchange unit (200); S200, automatically learning a heat exchange load characteristic curve of the indoor heat exchange unit (200) based on the actual cooling/heating capacity and the temperature change rate; S300, acquiring a steady state load and/or a desired load of the indoor heat exchange unit based on the heat exchange load characteristic curve; and S400 adjusting the number of operating compressors and rotational speeds of compressors, and/or adjusting the number of operating injectors and opening degrees of injectors, based on the steady state load and/or the desired load. According to the control method for an air conditioning system, the output capacity of the entire system can be effectively coordinated so as to dynamically adapt to the current load demand.