Air Conditioner Bypass Flow Path Design for Faster Defrosting
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Solution Overview
Problem
Refrigeration cycle apparatuses with low discharge temperature refrigerants, such as R290, face challenges in shortening defrosting time due to reduced heat exchange efficiency between the refrigerant and the outdoor heat exchanger.
Innovation Solution
An air conditioning apparatus with a main circuit, first and second bypass flow paths, and a flow path selection device that directs refrigerant flow during heating and defrosting operations to increase refrigerant temperature and enhance heat exchange efficiency at the outdoor heat exchanger.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If refrigerant with low discharge temperature (e.g., R290) is used, then global warming potential is reduced, but heat exchange efficiency with outdoor heat exchanger decreases and defrosting time increases
Solution Approach 1:
The system performs preliminary heating of the refrigerant through the suction bypass flow path before defrosting. By circulating refrigerant through the suction bypass, the refrigerant temperature is raised in advance, ensuring that when defrosting occurs, the refrigerant has sufficient temperature difference with the outdoor heat exchanger to achieve rapid frost removal, thus solving the time loss issue while maintaining use of low-GWP refrigerants
Solution Approach 2:
The system dynamically changes the temperature parameter of the refrigerant by switching between different flow paths. During defrosting operation, the flow path selection device directs refrigerant through the suction bypass to increase its temperature, creating a larger temperature difference with the frosted heat exchanger surface, thereby enhancing heat exchange efficiency and reducing defrosting time without changing the refrigerant type
2Use of energy by moving object
If refrigerant discharge temperature is low, then energy efficiency in heating mode is improved, but heat exchange capacity during defrosting decreases
Solution Approach 1:
The system dynamically adjusts the refrigerant flow path based on operational mode. During heating, refrigerant flows through the main circuit for efficient heat exchange. During defrosting, the flow path selection device switches to route refrigerant through the suction bypass, dynamically changing the system configuration to optimize for defrosting heat exchange capacity while maintaining heating efficiency during normal operation
Solution Approach 2:
The suction bypass flow path acts as an intermediary that temporarily stores and heats refrigerant before it is used for defrosting. This intermediary path allows the system to build up refrigerant temperature during non-defrosting periods, then utilize this pre-heated refrigerant for rapid defrosting, effectively decoupling heating efficiency from defrosting capacity
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 solution enables faster defrosting by increasing the refrigerant's discharge temperature, improving heat exchange efficiency and reducing defrosting time regardless of the refrigerant type, while also reducing global warming potential and maintaining compressor reliability.
Implementation Method 1
an amount of heat exchange per unit time decreases
Implementation Method 2
temperature difference between the refrigerant and the outdoor heat exchanger is small and an amount of heat exchange per unit time decreases
Implementation Method 3
refrigerant circulates in the order of a compressor, a first heat exchanger, a first expansion valve, and a second heat exchanger
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
An air conditioning apparatus (100) includes: a main circuit (30); a first bypass flow path (B1) configured to communicate a pipe at a first expansion valve (6a) side of a second heat exchanger (7) with a pipe at a discharge side of a compressor (1); a second bypass flow path (B2) configured to communicate a pipe at a suction side of the compressor (1) with the pipe at the discharge side of the compressor (1); and a first flow path selection device (20) configured to selectively flow the refrigerant discharged from the compressor (1) to at least one of a first heat exchanger (5), the first bypass flow path (B1), and the second bypass flow path (B2). During a heating operation, the first flow path selection device (20) is configured to select at least the first heat exchanger (5). During a defrosting operation, the first flow path selection device (20) is configured to select at least the first bypass flow path (B1) after selecting at least the second bypass flow path (B2). With such a configuration, there can be provided an air conditioning apparatus that allows defrosting in a short time.