Air-conditioning apparatus having first and second defrosting pipes
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Solution Overview
Problem
Existing air-conditioning systems face inefficiencies in defrosting processes, particularly in low-pressure defrosting where refrigerant evaporating temperature needs to be lower than outdoor air temperature, leading to low defrosting efficiency, and in high-pressure defrosting where subcooling increases, causing temperature distribution and prolonged defrosting times.
Innovation Solution
An air-conditioning apparatus with a compressor that injects refrigerant at intermediate compression stroke, a parallel configuration of outdoor heat exchangers, and pressure adjustment devices to manage refrigerant flow for efficient defrosting without stopping indoor heating, utilizing medium-pressure refrigerant to enhance defrosting capacity and reduce defrosting time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If low-pressure defrosting is used where refrigerant evaporating temperature is lower than outdoor air temperature, then heating can continue during defrosting, but defrosting efficiency becomes low
Solution Approach 1:
The patent changes the pressure parameter of refrigerant from low-pressure to medium-pressure during defrosting. By controlling the pressure adjustment device to maintain refrigerant pressure at a medium level (higher than evaporator pressure but lower than condenser pressure), the refrigerant temperature becomes higher than outdoor air temperature, enabling efficient heat transfer for defrosting while maintaining continuous heating operation.
2Productivity
If high-pressure defrosting is used where refrigerant pressure equals compressor discharge pressure, then defrosting capacity increases, but subcooling increases causing temperature distribution and prolonged defrosting time
Solution Approach 1:
The patent introduces a medium-pressure defrosting mode that adjusts refrigerant pressure to an intermediate level between low-pressure evaporator operation and high-pressure discharge. This medium pressure optimizes the balance between defrosting capacity and temperature uniformity, preventing excessive subcooling and temperature distribution while maintaining effective defrosting performance.
3Loss of time
If refrigerant flow rate to outdoor heat exchanger is increased for faster defrosting, then defrosting time decreases, but heating capacity during defrosting is reduced
Solution Approach 1:
The patent divides the outdoor heat exchanger into multiple independent sections, each with its own refrigerant flow control. This allows selective defrosting of only the frosted sections while other sections continue heating, thereby maintaining overall heating capacity while achieving efficient defrosting of affected areas.
Solution Approach 2:
The patent applies different refrigerant flow rates to different sections of the outdoor heat exchanger based on local frosting conditions. Sections requiring defrosting receive higher refrigerant flow, while non-frosted sections maintain normal heating flow, optimizing both defrosting efficiency and heating performance simultaneously.
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
The system enables efficient defrosting by optimizing refrigerant pressure and flow, maintaining continuous heating and improving defrosting capacity, reducing the time required for defrosting and minimizing temperature variations in the outdoor heat exchanger.
Implementation Method 1
a compressor configured to allow refrigerant to be injected into a portion located intermediate of a compression stroke, suck refrigerant having a low pressure, compress the refrigerant, and discharge refrigerant having a high temperature
Implementation Method 2
a plurality of outdoor heat exchangers connected in parallel and configured to exchange heat between outdoor air and the refrigerant
Implementation Method 3
a first pressure adjustment device configured to adjust the refrigerant passing through the first defrosting pipe to a medium pressure higher than the low pressure and lower than the high pressure
Data Source
AI summary
An air-conditioning apparatus includes: a compressor allowing refrigerant injection thereto and compress and discharge the refrigerant at a high temperature; an indoor heat exchanger exchanging heat between air and refrigerant; a first flow rate control device adjusting and controlling a flow rate of refrigerant; and a plurality of outdoor heat exchangers being in parallel to exchange heat between outside air and refrigerant, a first defrosting pipe allowing a branched part of the refrigerant discharged from the compressor to pass and flow into the outdoor heat exchanger to be defrosted; a reducing device adjusting a pressure of refrigerant passing through the first defrosting pipe to a medium pressure; a second defrosting pipe from which the refrigerant having passed through the outdoor heat exchanger to be defrosted is injected into the compressor; and a reducing device adjusting a pressure of refrigerant passing through the second defrosting pipe to an injection pressure.