Air conditioner and defrost control method therefor
Solution Overview
Problem
Air conditioners face inefficiencies in heating performance due to frost accumulation on outdoor heat exchangers during low temperatures, requiring separate defrost operations that disrupt heating and extend defrost times, especially for the lowermost heat exchange units.
Innovation Solution
An air conditioner design with a controller that sequentially defrosts outdoor heat exchange units from the top down, using expansion valves and hot gas valves to manage frost removal, allowing for differential defrost completion and finish times to minimize total defrost time and frost accumulation on the lowermost unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the air conditioner performs a separate defrost operation by switching the flow direction of refrigerant, then the frost on the outdoor heat exchanger is removed, but the heating operation is interrupted and heating performance deteriorates
Solution Approach 1:
The outdoor heat exchanger is divided into multiple heat exchange units (first, second, third units) with independent expansion valves and hot gas valves. This segmentation allows selective defrosting of specific units while others continue heating operations, preventing complete interruption of heating performance.
Solution Approach 2:
Instead of defrosting the entire outdoor heat exchanger, the patent applies partial defrost action by selectively defrosting only the lowermost heat exchange unit (third unit) where frost accumulation is most severe, while the upper units (first and second units) continue normal heating operation.
2Object-affected harmful factors
If the air conditioner defrosts the entire outdoor heat exchanger at the same time, then all frost is removed, but the total defrost time increases and heating operation is disrupted for longer periods
Solution Approach 1:
The defrost operation is segmented into sequential phases targeting different heat exchange units. The controller performs defrost on the third unit first, then the first unit, and finally the second unit, allowing overlapping defrost operations that reduce total defrost time while maintaining completeness.
Solution Approach 2:
The controller performs preliminary defrost action on the lowermost heat exchange unit (third unit) before other units, as this is where frost accumulates most severely. This preliminary action prevents frost from migrating to other units during subsequent defrost operations.
3Ease of operation
If the air conditioner uses conventional defrost control, then the defrost operation is simple to implement, but frost accumulates excessively on the lowermost heat exchange unit reducing defrost efficiency
Solution Approach 1:
The patent applies local quality by providing differential defrost control to different heat exchange units. Each unit has its own expansion valve and hot gas valve, allowing the controller to apply different defrost timing and duration to each unit based on its specific frost accumulation characteristics, particularly targeting the lowermost unit with extended defrost action.
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 approach reduces the total defrost time and ensures even defrosting of all heat exchange units, maintaining heating performance by minimizing frost on the lowermost unit and allowing simultaneous defrosting between adjacent units for enhanced reliability.
Implementation Method 1
N expansion valves respectively connected to the N heat exchange units
Implementation Method 2
N hot gas pipes respectively connected to the N heat exchange units; N hot gas valves respectively installed in the N hot gas pipes
Implementation Method 3
defrost the N heat exchange units
Data Source
AI summary
An air conditioner includes an outdoor heat exchanger in which N heat exchange units are spaced apart from one another sequentially in a vertical direction N expansion valves respectively connected to the N heat exchange units; N hot gas pipes respectively connected to the N heat exchange units; N hot gas valves respectively installed in the N hot gas pipes; and a controller configured to control the N expansion valves and the N hot gas valves to defrost the N heat exchange units, wherein the controller is configured to defrost a bottom heat exchange unit first, then defrost a top heat exchange unit, and defrost the heat exchange units located under the top heat exchange unit sequentially from a second highest heat exchange unit to the bottom heat exchange unit after defrosting the top heat exchange unit.