Outdoor Heat Exchanger Staging for Defrost Without Heating Loss
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Solution Overview
Problem
Air conditioners face issues with decreased heating performance during defrosting operations, cold drafts, and frost formation between heat exchangers due to temperature differences, leading to unreliable heating and reduced efficiency.
Innovation Solution
The air conditioner employs a multi-stage refrigerant flow path with alternately performing heat exchangers and an overlap pipe system to prevent frost formation between adjacent heat exchangers, allowing continuous heating during defrosting and maintaining high heating performance by controlling refrigerant flow through bypass and overlap valves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If defrosting operation is performed by switching refrigerant circulation direction, then frost on outdoor heat exchanger is removed, but indoor temperature decreases causing cold draft and heating performance drops below 400
Solution Approach 1:
The outdoor heat exchanger is divided into multiple sections (first, second, third sections) with independent refrigerant flow paths. This allows selective defrosting of specific sections while others continue heating, preventing overall heating performance drop and cold drafts.
Solution Approach 2:
The system dynamically switches refrigerant flow paths using flow channels and valves to enable different operational modes (heating, defrosting, simultaneous heating and defrosting) based on real-time conditions, maintaining heating performance while removing frost as needed.
2Object-affected harmful factors
If outdoor heat exchanger operates as condenser during defrosting, then defrosting is effective, but large temperature difference with adjacent evaporator causes frost band formation on interface
Solution Approach 1:
An intermediate heat exchanger section is positioned between the condenser and evaporator sections. This intermediate section acts as a thermal buffer, reducing the temperature difference at the interface and preventing frost band formation while allowing effective defrosting to occur.
Solution Approach 2:
Different sections of the outdoor heat exchanger are assigned different functions (condensing, intermediate, evaporating) with optimized local properties. The intermediate section specifically addresses the interface problem by having different thermal characteristics than adjacent sections, preventing frost bands locally while maintaining overall system effectiveness.
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 minimizes temperature differences between heat exchangers, prevents frost bands, and ensures continuous heating performance of 750 or more during defrosting operations, enhancing the reliability and efficiency of the air conditioner.
Implementation Method 1
the refrigerant flowing in the outdoor heat exchanger sucks heat and evaporates
Implementation Method 2
exchange heat of outdoor air and a refrigerant
Implementation Method 3
the heat exchanger for performing defrosting operation operates as a condenser
Data Source
Figure 1
Figure 2
Figure 3(a)~3(c)
AI summary
An air conditioner includes a plurality of heat exchangers provided to form an internal refrigerant flow path of an outdoor heat exchanger in multiple stages, a bypass pipe configured to branch refrigerant discharged from a compressor and to guide the refrigerant to the plurality of heat exchangers, flow pipes branched from the bypass pipe and extending to refrigerant pipes provided in the plurality of heat exchangers and overlap pipes branched from a flow pipe connected to any one of the plurality of heat exchangers and extending to a flow pipe connected to another heat exchanger.