Refrigeration Cycle Bypass Pipe Control for Defrosting in Extreme Cold
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Solution Overview
Problem
Refrigeration cycle equipment faces challenges in performing heating operations effectively in extremely cold environments, as existing defrosting methods can damage the compressor by sucking in large amounts of liquid refrigerant, and there is a need for improved defrosting efficiency and safety.
Innovation Solution
A refrigeration cycle equipment with a bypass pipe line and an open/close valve controlled by a unit that opens only when the outdoor temperature exceeds a predetermined level during defrosting, preventing excessive compressor pressure and allowing safe heating operations in cold conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the bypass pipe is used to raise suction pressure during defrosting operation, then the defrosting efficiency is improved, but the compressor may be damaged by excessive liquid refrigerant suction in extremely cold environments
Solution Approach 1:
The control unit monitors outdoor temperature and dynamically adjusts the bypass valve opening degree based on temperature parameters. When outdoor temperature is below the predetermined threshold (e.g., -15°C), the bypass valve opening degree is limited to prevent excessive liquid refrigerant from entering the compressor, while still maintaining adequate defrosting function. This parameter-based control resolves the contradiction by adapting system behavior to environmental conditions.
Solution Approach 2:
The control unit continuously monitors outdoor temperature and uses this feedback to adjust the bypass valve operation. The temperature sensor provides real-time data that feeds back to the control logic, which then modulates the bypass valve opening degree accordingly. This closed-loop feedback mechanism ensures defrosting efficiency is maintained while preventing compressor damage in extreme cold conditions.
2Productivity
If the bypass valve opening degree is increased to improve defrosting performance, then the heating operation efficiency during defrosting is improved, but the risk of compressor damage increases
Solution Approach 1:
The system dynamically changes the bypass valve opening degree parameter based on outdoor temperature conditions. At moderate temperatures, a larger opening degree is permitted to maximize heating efficiency during defrosting. As temperature drops below the threshold, the opening degree is reduced to limit liquid refrigerant flow, thereby preventing compressor damage while maintaining adequate heating performance.
Solution Approach 2:
The bypass valve opening degree is made dynamic rather than fixed, allowing the system to adapt to varying outdoor temperature conditions. The control unit continuously adjusts the valve position based on real-time temperature data, optimizing the balance between heating efficiency and compressor protection. This dynamic adjustment resolves the contradiction by allowing high opening degrees only when safe.
3Adaptability or versatility
If the outdoor temperature is extremely low, then the heating operation is needed, but the conventional defrosting method becomes unsafe
Solution Approach 1:
The system introduces temperature-based parameter changes to the defrosting control logic. When outdoor temperature falls below the predetermined threshold, the bypass valve opening degree parameter is automatically adjusted to a safer value. This parameter adaptation allows the system to maintain heating operation capability in extreme cold while ensuring defrosting safety through controlled refrigerant flow.
Solution Approach 2:
The control unit performs preliminary assessment of outdoor temperature before initiating defrosting operation with full bypass valve opening. By checking temperature conditions in advance, the system prevents unsafe defrosting operations from occurring in the first place, thereby maintaining both heating capability and operational safety in extremely cold environments.
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
Enables efficient heating operations even in extremely cold environments by controlling the bypass pipe line to prevent compressor damage from excessive refrigerant suction, ensuring safe and effective defrosting and heating performance.
Implementation Method 1
perform a defrosting operation (reverse-defrost) to dissolve the frost adhering to the fins of the outdoor heat exchanger
Implementation Method 2
a compressor; a refrigerant pipe line which sequentially connects a compressor
Implementation Method 3
an expansion valve; a refrigerant pipe line which sequentially connects a compressor, a four-way valve, an outdoor heat exchanger, an expansion valve
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A refrigeration cycle equipment includes: a compressor (1); a four-way valve (2); an outdoor heat exchanger (3); an expansion valve (4); an indoor heat exchanger (5); a refrigerant pipe line which sequentially connects a compressor (1), a four-way valve (2), an outdoor heat exchanger (3), an expansion valve (4), and an indoor heat exchanger (5); a bypass pipe line (8) connecting a refrigerant pipe line between the outdoor heat exchanger (3) and the expansion valve (4) and a refrigerant pipe line between a suction port of the compressor (1) and the four-way valve (2); an open/close valve (9) provided for the bypass pipe line (8); an outdoor temperature sensor (17) provided for the outdoor heat exchanger (3) to detect an outdoor temperature; and a control unit (20) controlling the compressor (1), the four-way valve (2), the expansion valve (4), and the open/close valve mechanism (9). The control unit (20) controls the open/close valve mechanism (9) of the bypass pipe line (8) to be opened at a time when the outdoor temperature is detected to be more than a predetermined temperature in a defrosting operation of the refrigeration cycle equipment.