Dual-Compressor Refrigerant Routing for Low-Temperature Cooling

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Air conditioning apparatuses face efficiency decreases during cooling-based operations at low outdoor temperatures due to increased temperature differences between outdoor air or water and refrigerant in indoor heat exchangers acting as condensers.

Innovation Solution

An air conditioner configuration that switches between two operation modes based on outdoor temperature, where at low temperatures, the refrigerant discharged from one compressor bypasses the first indoor heat exchanger acting as a condenser and flows through the second outdoor heat exchanger as a condenser and the second indoor heat exchanger as an evaporator, optimizing compression ratios and efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the outdoor heat exchanger acts as a condenser during cooling-based operation, then the cooling capacity is improved, but the operation efficiency decreases due to increased temperature difference between outdoor air and refrigerant at low outdoor temperatures

Engineering Contradiction:
Improvecooling capacityVSAvoidoperation efficiency
Core Design Contradiction:
PowerVSLoss of energy

Solution Approach 1:

The patent divides the refrigerant discharge path into two separate paths: one path goes to the indoor heat exchanger acting as a condenser, and the other path goes through the outdoor heat exchanger acting as a condenser. This segmentation allows different compression ratios to be applied to different refrigerant flows, optimizing efficiency while maintaining cooling capacity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent dynamically adjusts the compression ratio of the compressor based on outdoor temperature conditions. At low outdoor temperatures, the system operates in a first operation mode with a higher compression ratio to maintain efficiency, while at higher temperatures, it switches to a second operation mode with a lower compression ratio. This dynamic adjustment resolves the contradiction between maintaining cooling capacity and preserving operation efficiency.

Inventive Principle:
Principle #15Dynamics

2Loss of energy

If the compression ratio is increased to maintain efficiency at low outdoor temperatures, then the operation efficiency is improved, but the cooling capacity may be reduced

Engineering Contradiction:
Improveoperation efficiencyVSAvoidcooling capacity
Core Design Contradiction:
Loss of energyVSPower

Solution Approach 1:

The patent applies different compression ratios to different refrigerant flows based on their destination and operating conditions. The first refrigerant flow to the indoor condenser receives a compression ratio optimized for that specific heat exchanger, while the second refrigerant flow through the outdoor condenser receives a different compression ratio suited for outdoor conditions. This local optimization allows the system to maintain both efficiency and cooling capacity simultaneously.

Inventive Principle:
Principle #3Local quality

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 enhances operation efficiency during cooling-based operations at low outdoor temperatures by maintaining high compression ratios for one compressor and low ratios for the other, thereby improving overall performance compared to conventional systems.

Implementation Method 1

heat exchangers... perform heat exchange between refrigerant and air or water

Methodology Applied
Scientific EffectHeat conduction: Conduction (thermal)

Implementation Method 2

heat exchangers... perform heat exchange between refrigerant and air or water

Methodology Applied
Scientific EffectConvection: Convection

Implementation Method 3

compressor... discharge high-temperature high-pressure refrigerant

Methodology Applied
Scientific EffectCompression: Compression

Implementation Method 4

indoor heat exchanger acting as a condenser... outdoor heat exchanger acting as a condenser

Methodology Applied
Scientific EffectCondensation: Condensation

Implementation Method 5

expansion valve... supply low-temperature low-pressure refrigerant

Methodology Applied
Scientific EffectPressure drop: Pressure Drop

Data Source

PatentEP3534082B1Air conditioner
Publication Date: 2021.04.21 MITSUBISHI ELECTRIC CORP
  • EP3534082B1 patent drawingFigure 1
  • EP3534082B1 patent drawingFigure 2(a)~2(b)
  • EP3534082B1 patent drawingFigure 3

AI summary

An air conditioner is provided that has high operation efficiency during cooling-based operation on a low outdoor temperature condition. The air conditioner includes a refrigeration cycle having a refrigerant circuit in which a first compressor (1) and a second compressor (2) are connected in parallel, and the first compressor (1), the second compressor (2), a first outdoor heat exchanger (3), a second outdoor heat exchanger (4), a first indoor heat exchanger (5), a second indoor heat exchanger (6), and expansion valves (16, 17) are connected by pipelines. When the air conditioning apparatus is operated in a first operation mode in which the second outdoor heat exchanger (4) and the first indoor heat exchanger (5) are operated as condensers and the second indoor heat exchanger (6) is operated as an evaporator, refrigerant discharged from the first compressor (1) flows through the first indoor heat exchanger (5), the expansion valves (16, 17), and the second indoor heat exchanger (6) in order while bypassing the first outdoor heat exchanger (3) and the second outdoor heat exchanger (4). Refrigerant discharged from the second compressor (2) flows through the second outdoor heat exchanger (4) and then flows through the second indoor heat exchanger (6) while bypassing the first indoor heat exchanger (5).