Multi-outdoor unit parallel type non-reversing defrosting system and defrosting control method thereof
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing air-conditioning systems face issues with comfort during frosting, as four-way valve reversing methods disrupt indoor heating, and non-reversing defrosting methods using phase change materials are costly.
Innovation Solution
A multi-outdoor unit parallel type non-reversing defrosting system with an indoor heat exchanger and multiple outdoor units, each equipped with a compressor, four-way valve, outdoor heat exchanger, solenoid valves, and a bypass branch, allows for controlled distribution of heating and defrosting energy without reversing, using solenoid valves to manage bypass connections and prioritize non-frosted units for efficient defrosting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If four-way valve reversing method is used for defrosting, then defrosting function is achieved, but indoor heating stops causing poor comfort
Solution Approach 1:
The system divides outdoor units into multiple independent modules, each with its own defrosting capability. When one outdoor unit needs defrosting, only that specific unit undergoes the reversing process while other outdoor units continue normal heating operation, thus segmenting the defrosting impact and maintaining overall heating continuity.
Solution Approach 2:
The patent combines multiple outdoor units working in parallel to share the heating load. When one unit is reversed for defrosting, the other units compensate by increasing their heating output to maintain the total heating requirement, effectively merging their capacities to offset the temporary loss from the reversing unit.
2Ease of operation
If non-reversing defrosting method using phase change materials is used, then indoor heating continuity is maintained, but system cost increases
Solution Approach 1:
The system uses the refrigerant circulation system itself to perform defrosting by temporarily reversing the refrigeration cycle in the affected outdoor unit. The high-temperature refrigerant from the compressor is directed to the outdoor heat exchanger to melt frost, utilizing the system's own thermal energy rather than requiring external heating devices or phase change materials.
Solution Approach 2:
The patent changes the operating parameters of the refrigeration cycle dynamically. By controlling the four-way valve to reverse the refrigerant flow direction and adjusting the expansion valve opening degrees, the system transforms the outdoor heat exchanger from a cooling component to a heating component temporarily, enabling defrosting without adding physical defrosting devices.
3Reliability
If multiple outdoor units are reversed together for defrosting, then all frosted units are defrosted, but all indoor units must stop heating
Solution Approach 1:
The control system identifies and isolates only the specific outdoor units that require defrosting based on frost detection sensors. Each outdoor unit's defrosting process is independently controlled through individual four-way valve operations, allowing selective defrosting of only the affected units while leaving other outdoor units in normal heating mode.
Solution Approach 2:
The system dynamically adjusts the operating state of each outdoor unit based on real-time frost conditions. The control algorithm continuously monitors frost sensors and dynamically switches between heating mode and defrosting mode for individual units, optimizing the balance between defrosting completeness and heating output maintenance.
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 solution ensures continuous heating output for the indoor heat exchanger by utilizing non-frosted outdoor units for defrosting without reversing, maintaining comfort and reducing energy costs by prioritizing the minimum number of units needed.
Implementation Method 1
The bypass branch is provided with a second solenoid valve configured to control connection and disconnection of the bypass branch
Implementation Method 2
an outdoor heat exchanger, a first solenoid valve, and a bypass branch
Implementation Method 3
a four-way valve, an outdoor heat exchanger, a first solenoid valve, and a bypass branch. Four interfaces of the four-way valve are connected to a discharge end of the compressor
Data Source
AI summary
A multi-outdoor unit parallel type non-reversing defrosting system, which includes an indoor heat exchanger and three or more outdoor units arranged in parallel. The outdoor units each include a compressor, a four-way valve, an outdoor heat exchanger, a first solenoid valve, and a bypass branch. Two ends of the bypass branch are respectively in bypass connection with a pipeline between the four-way valve and the outdoor heat exchanger and a pipeline between the first solenoid valve and the indoor heat exchanger. The bypass branch is provided with a second solenoid valve configured to control connection and disconnection of the bypass branch. When it is monitored that any outdoor unit is abnormal in frosting, the outdoor units which are not frosted are correspondingly distributed and started as required on the basis of a current heating energy requirement A of the indoor heat exchanger.