Multi-Unit Air Conditioner Load Control for Energy and Comfort

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Solution Overview

Problem

Air conditioners with multiple indoor units connected to a single outdoor unit face inefficiencies in energy consumption and comfort due to constant compressor operation and uneven cooling/heating capacities, leading to wasteful energy use and potential discomfort.

Innovation Solution

An air conditioner system with a detection sensor and control apparatus that adjusts target evaporation/condensation temperatures and refrigerant states based on the highest required capacity among indoor units, allowing for dynamic adjustment of cooling/heating capacities to match actual loads and maintain comfort.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the target value of evaporation temperatures is kept constant, then the compressor can maintain stable operation, but the compressor operates at higher rotations than necessary when indoor unit capacities are small, causing wasteful energy consumption

Engineering Contradiction:
Improvestable compressor operationVSAvoidcompressor energy consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent applies dynamics by making the target evaporation temperature variable rather than constant. The control device dynamically adjusts the target evaporation temperature based on the maximum required capacity among all indoor units, allowing the compressor to operate at appropriate speeds matching actual cooling demands while maintaining stable control through systematic adjustment of all indoor unit target temperatures

Inventive Principle:
Principle #15Dynamics

2Use of energy by moving object

If the target value of evaporation temperatures is changed according to the highest required capacity to save energy, then the compressor operates at appropriate rotations, but indoor units with small required capacities perform excessive cooling and comfort is reduced

Engineering Contradiction:
Improvecompressor energy consumptionVSAvoidcomfort in indoor units
Core Design Contradiction:
Use of energy by moving objectVSEase of operation

Solution Approach 1:

The patent applies local quality by providing individualized temperature adjustment for each indoor unit. The control device calculates and sets a specific target evaporation temperature for each indoor unit based on its required capacity relative to the maximum capacity, ensuring that each unit receives appropriate cooling matched to its local demand rather than uniform control

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent applies parameter changes by systematically adjusting the target evaporation temperature parameter for each indoor unit according to its capacity ratio. The control device modifies the target evaporation temperature parameter individually for each unit based on its required capacity, preventing excessive cooling in low-demand units while maintaining energy efficiency

Inventive Principle:
Principle #35Parameter changes

3Ease of operation

If the target value of refrigerant state is changed to lower cooling capacity when temperature drops below target, then comfort is maintained, but control complexity increases

Engineering Contradiction:
Improvecomfort maintenanceVSAvoidcontrol system complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent applies feedback by implementing a closed-loop control system that continuously monitors the cooling temperature in each indoor unit and adjusts the target refrigerant state accordingly. When the cooling temperature drops below the target by a predetermined value or more, the control device receives feedback and automatically changes the target refrigerant state to reduce cooling capacity, maintaining comfort through automatic regulation

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 optimizes energy consumption by reducing unnecessary compressor operation and ensures comfort by precisely controlling temperature delivery to each unit, balancing energy savings with reliable operation.

Implementation Method 1

a heat source unit (2) including a compressor (11)

Methodology Applied
Scientific EffectCompression: Compression

Implementation Method 2

performing a cooling operation using the heat source-side heat exchanger as a condenser

Methodology Applied
Scientific EffectHeat exchange: Heat Exchanger

Implementation Method 3

using the heat source-side heat exchanger as a condenser

Methodology Applied
Scientific EffectCondensation: Condensation

Implementation Method 4

using the utilization-side heat exchanger as an evaporator

Methodology Applied
Scientific EffectHeat exchange: Heat Exchanger

Implementation Method 5

using the utilization-side heat exchanger as an evaporator

Methodology Applied
Scientific EffectEvaporation: Evaporation

Implementation Method 6

a plurality of utilization units each including a decompressing device

Methodology Applied
Scientific EffectDecompression: Depressurisation

Data Source

PatentEP3587948B1Air conditioner
Publication Date: 2022.02.23 DAIKIN INDUSTRIES LTD
  • EP3587948B1 patent drawingFigure 1
  • EP3587948B1 patent drawingFigure 2
  • EP3587948B1 patent drawingFigure 3

AI summary

Provided is an air conditioner capable of achieving both energy conservation and comfort. An air conditioner (1) includes a detection sensor (26) detecting a state of air related to required capacities of a plurality of utilization units (3), and a control apparatus (30) acquiring the required capacities of the utilization units (3) based on a detection result of the detection sensor (26), setting target values (Tem, SHm) of each of an evaporation temperature (Te) in a utilization-side heat exchanger (16) adjusted by a compressor (11) and a predetermined refrigerant state (SH) adjusted by a decompressing device (15) in accordance with the highest required capacity and, when a cooling temperature (Tf) becomes lower than a target cooling temperature (Tfm) by a predetermined value (Δt) or more in one of the utilization units (3) other than the utilization unit (3) having the highest required capacity, changing the target value (SHm) of the refrigerant state (SH) such that a cooling capacity of the other utilization unit (3) is lowered.