Multi-Indoor AC Evaporating Temperature Control for Humidity Balance

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Solution Overview

Problem

In air-conditioning systems with multiple indoor units connected to an outdoor unit, the uniform control of evaporating temperature leads to excessive cooling and dehumidification, especially when load differences exist among units, resulting in inefficient energy use and reduced comfort.

Innovation Solution

An air-conditioning system with a control mechanism that adjusts the target evaporating temperature based on temperature and humidity sensors' data, allowing for thermo-ON/OFF operations of indoor units and conveying fans to optimize cooling and dehumidification according to the specific needs of each space, ensuring energy efficiency and comfort.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the upper limit evaporating temperature is set to ensure a predetermined amount of dehumidification, then dehumidification performance is improved, but excessive dehumidification occurs and comfort deteriorates

Engineering Contradiction:
Improvedehumidification performanceVSAvoidexcessive dehumidification
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies dynamics by making the upper limit evaporating temperature adjustable rather than fixed. The control means dynamically resets the upper limit evaporating temperature based on real-time detection of whether both thermo-ON and thermo-OFF indoor units are operating. When both states coexist, the system resets the temperature limit to prevent excessive dehumidification, thereby adapting to changing operational conditions to maintain comfort while ensuring adequate dehumidification performance.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter of evaporating temperature based on operational conditions. By detecting the coexistence of thermo-ON and thermo-OFF indoor units, the system modifies the upper limit evaporating temperature parameter to prevent excessive dehumidification. This parameter adjustment allows the system to maintain reliable dehumidification when needed while avoiding over-dehumidification that would compromise comfort.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If the upper limit evaporating temperature is set to ensure a predetermined amount of dehumidification, then dehumidification performance is improved, but energy consumption increases due to excessive air-conditioning

Engineering Contradiction:
Improvedehumidification performanceVSAvoidenergy consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The system dynamically adjusts the upper limit evaporating temperature based on the operational state of indoor units. When both thermo-ON and thermo-OFF units are detected, the control means resets the temperature limit to prevent unnecessary air-conditioning operation. This dynamic adjustment ensures that dehumidification performance is maintained when required while avoiding excessive energy consumption from unnecessary cooling operations.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The control system automatically detects the operational states of indoor units and self-adjusts the upper limit evaporating temperature without external intervention. When both thermo-ON and thermo-OFF units coexist, the system autonomously resets the temperature parameter to optimize the balance between dehumidification performance and energy consumption, eliminating the need for manual parameter adjustment.

Inventive Principle:
Principle #25Self-service

3Device complexity

If uniform evaporating temperature control is applied to all indoor units, then system simplicity is maintained, but excessive cooling occurs at units with small load

Engineering Contradiction:
Improvecontrol system simplicityVSAvoidexcessive cooling
Core Design Contradiction:
Device complexityVSLoss of energy

Solution Approach 1:

The patent implements feedback control by detecting the operational states (thermo-ON/thermo-OFF) of individual indoor units and using this information to adjust the upper limit evaporating temperature. When both thermo-ON and thermo-OFF units are detected, the system provides feedback by resetting the temperature limit to prevent excessive cooling at units with small load, thereby reducing energy loss while maintaining relatively simple control logic.

Inventive Principle:
Principle #23Feedback

4Ease of operation

If indoor units operate without considering individual load requirements, then operational simplicity is maintained, but cooling becomes excessive and comfort deteriorates

Engineering Contradiction:
Improveoperational simplicityVSAvoidexcessive cooling
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The control means incorporates feedback by automatically detecting whether both thermo-ON and thermo-OFF indoor units are operating simultaneously. Based on this detection, the system automatically resets the upper limit evaporating temperature to prevent excessive cooling at units with small load. This feedback mechanism maintains ease of operation by eliminating the need for manual intervention while effectively preventing harmful excessive cooling that would deteriorate comfort.

Inventive Principle:
Principle #23Feedback

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 prevents excessive air-conditioning, reduces energy consumption, and enhances comfort by dynamically adjusting the air-conditioning capacity to match the specific requirements of each indoor unit, thereby improving overall energy savings and user comfort.

Implementation Method 1

an evaporating temperature of a refrigerant at which at least a predetermined amount of dehumidification is obtained at an indoor heat exchanger

Methodology Applied
Scientific EffectEvaporation: Evaporation

Implementation Method 2

a conveying fan conveying conditioned air

Methodology Applied
Scientific EffectConvection: Convection

Data Source

PatentEP2863139B1Air conditioning system
Publication Date: 2020.07.08 MITSUBISHI ELECTRIC CORP
  • EP2863139B1 patent drawingFigure 1
  • EP2863139B1 patent drawingFigure 2
  • EP2863139B1 patent drawingFigure 3~4

AI summary

An air-conditioning system A includes: an air-conditioning apparatus B in which indoor units 6a and 6b are connected to an outdoor unit 1; a conveying fan 14; and control means 12 for controlling the air-conditioning apparatus B and the conveying fan 14 on the basis of a target evaporating temperature. The control means 12 resets an upper limit of the target evaporating temperature when: a control determination temperature difference which is a difference between a set temperature and a temperature of an air-conditioned space 5 is within a predetermined range; a humidity of the air-conditioned space 5 is equal to or lower than a predetermined value; and a thermo-ON indoor unit and a thermo-OFF indoor unit are present together in the same air-conditioned space 5.