Defrosting control method of multifunctional multi-split system with two four-way valves
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing multi-split air conditioner systems face challenges in defrosting the outdoor unit heat exchanger without affecting indoor unit performance, leading to reduced comfort and potential freezing of hydraulic modules during temperature conversions.
Innovation Solution
A defrosting control method utilizing two four-way valves to adjust the operation modes of indoor and hydraulic modules, including powering down the four-way valves, adjusting fan states, and optimizing electromagnetic and electronic expansion valves to ensure efficient defrosting without disturbing users or risking hydraulic module freezing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the outdoor unit heat exchanger is used as an evaporator for refrigeration during heating mode, then the outdoor unit can provide heating function, but the outdoor unit heat exchanger will be frosted when environment temperature is low, reducing heat exchange capacity
Solution Approach 1:
The system periodically switches between heating mode and defrosting mode. During defrosting mode, the four-way valve reverses the refrigerant flow direction, allowing the outdoor heat exchanger to function as a condenser and melt accumulated frost, thereby restoring heat exchange capacity while maintaining overall heating functionality
2Reliability
If the four-way valve is powered down to reverse for defrosting, then the outdoor unit heat exchanger can be defrosted, but the indoor units need to absorb heat as evaporator, reducing indoor environment temperature and affecting user comfort
Solution Approach 1:
The system segments the defrosting process by controlling individual indoor unit fans rather than shutting down all indoor units. The fan control unit selectively controls fans of indoor units to stop or continue operation based on their operational state, allowing defrosting to proceed while maintaining user comfort in occupied spaces
Solution Approach 2:
The fan control unit dynamically adjusts fan operation based on real-time system state. During defrosting mode, it determines which indoor units should maintain fan operation (those in refrigeration mode or recently operated) versus those that can stop (those in heating mode), creating a dynamic response that balances defrosting efficiency with user comfort
3Reliability
If air conditioner indoor units are converted into refrigeration state during defrosting, then defrosting can be performed, but if users power off the indoor units, it causes user complaints due to incomprehension
Solution Approach 1:
The system dynamically determines indoor unit fan operation based on their pre-defrosting state. Indoor units that were in refrigeration mode or recently operated maintain fan operation during defrosting, while those in heating mode stop fans. This dynamic approach prevents unexpected temperature changes for users and eliminates confusion or complaints
4Reliability
If hydraulic modules are converted into water refrigeration during defrosting, then defrosting can be performed, but if hydraulic modules are not in water heating originally, the water temperature becomes very low, causing risk of freezing and bursting pipeline
Solution Approach 1:
The controller performs preliminary assessment of hydraulic module operational state before initiating defrosting. It identifies which hydraulic modules were in water heating mode and maintains their fan operation during defrosting, preventing water temperature from dropping to freezing levels and avoiding pipeline damage
Solution Approach 2:
The system uses feedback from the hydraulic control unit about the operational state of hydraulic modules to make informed decisions during defrosting. Modules that were providing water heating maintain operation during defrosting, while others can be converted to refrigeration mode, creating a feedback-driven approach that prevents pipeline freezing
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 method enables fast and full defrosting of the outdoor unit while minimizing energy consumption and ensuring system reliability, maintaining user comfort by optimizing the operation of indoor and hydraulic modules during defrosting.
Implementation Method 1
the outdoor unit heat exchanger serves as a condenser, and a high temperature refrigerant discharged from a compressor is subjected to heat release by the outdoor unit heat exchanger. Therefore, the frost on the outdoor unit heat exchanger can absorb heat to be melted into water and flow away
Implementation Method 2
a high temperature refrigerant discharged from a compressor is subjected to heat release by the outdoor unit heat exchanger
Data Source
Figure 1~2
AI summary
Herein disclosed is a defrosting control method of a multi-functional multi-split system with two four-way valves. The multi-functional multi-split system includes an outdoor unit, at least one set of hydraulic modules, and at least one set of indoor modules. When the multi-split system is switched from a normal operation mode to a defrosting mode, a first four-way valve and a second four-way valve are powered down, and operation modes of each set of indoor modules and each set of hydraulic modules, the on/off state of fans of an indoor heat exchanger and a hydraulic heat exchanger, opening degrees of a first electromagnetic valve of the indoor heat exchanger and a second electromagnetic valve of the hydraulic heat exchanger, and the on/off state of the first electromagnetic valve and the second electromagnetic valve are correspondingly adjusted based on the previous operation modes of each set of indoor modules and each set of hydraulic modules.