Multi-Outdoor Unit Parallel Defrosting Without Four-Way Valve Reversal
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing air-conditioning systems face challenges in defrosting, as four-way valve reversing methods disrupt indoor comfort, and non-reversing methods using phase change materials are costly.
Innovation Solution
A multi-outdoor unit parallel type non-reversing defrosting system and control method, where outdoor units are arranged in parallel, with a bypass branch and solenoid valves to distribute heating and defrosting energy efficiently, allowing non-frosted units to assist in defrosting without reversing the system.
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 and comfort deteriorates
Solution Approach 1:
The system divides outdoor units into multiple independent parallel units, each capable of independent defrosting operations. When one outdoor unit requires defrosting, only that specific unit is isolated and defrosted while other units continue normal heating operations, thereby maintaining indoor heating continuity while achieving defrosting function.
Solution Approach 2:
The patent merges the defrosting function with continuous heating by allowing multiple outdoor units to work in parallel - some units perform heating while others perform defrosting simultaneously. The indoor heat exchanger receives heat from both heating units and defrosting units, ensuring continuous indoor heating output throughout the defrosting process.
2Ease of operation
If non-reversing defrosting with phase change materials is used, then indoor heating continuity is maintained, but system cost increases
Solution Approach 1:
The patent extracts the phase change material component from the system and replaces it with a simpler parallel outdoor unit configuration. Instead of using expensive phase change materials to store heat during defrosting, the system uses multiple outdoor units working in parallel, where defrosting heat is directly transferred to the indoor heat exchanger, achieving the same heating continuity effect at lower cost.
Solution Approach 2:
The patent replaces expensive phase change materials with a more economical solution using standard refrigerant cycles and simple solenoid valve control. The system uses temporary refrigerant flow redirection through bypass branches controlled by solenoid valves, eliminating the need for costly thermal energy storage materials while maintaining defrosting effectiveness.
3Reliability
If all outdoor units are reversed together for defrosting, then defrosting is achieved, but heating output is completely interrupted
Solution Approach 1:
The system segments outdoor units into independent defrosting zones, allowing selective defrosting of only the frosted units while other units continue heating operations. This is achieved through individual solenoid valve control for each outdoor unit's bypass branch, enabling granular defrosting management that preserves overall heating output.
Solution Approach 2:
Each outdoor unit is designed with multi-functionality, capable of both heating and defrosting operations independently. The parallel configuration allows any outdoor unit to switch between heating mode and defrosting mode as needed, providing system flexibility where units can serve multiple functions simultaneously or sequentially, maintaining overall system productivity.
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 indoor heating output during defrosting, maintains comfort, and reduces costs by effectively utilizing non-frosted outdoor units for defrosting without the need for costly phase change materials.
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
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
Data Source
Figure 1
Figure 2
AI summary
A multi-outdoor unit parallel type non-reversing defrosting system includes an indoor heat exchanger 1 and three or more outdoor units 2 arranged in parallel. The outdoor units 2 each include a compressor 21, a four-way valve 22, an outdoor heat exchanger 23, a first solenoid valve 24, and a bypass branch. Two ends of the bypass branch are respectively in bypass connection with a pipeline between the four-way valve 22 and the outdoor heat exchanger 23 and a pipeline between the first solenoid valve 24 and the indoor heat exchanger 1. The bypass branch is provided with a second solenoid valve 25 configured to control connection and disconnection of the bypass branch. When it is monitored that any outdoor unit 2 is abnormal in frosting, the outdoor units 2 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 1, and after the started outdoor units 2 run to a target frequency, the outdoor units 2 are correspondingly distributed and started as required on the basis of the heating energy requirement A and a defrosting energy requirement B of the frosted outdoor unit 2. Meanwhile, the bypass branch of the frosted outdoor unit 2 is controlled to be connected till it is monitored that defrosting is completed.