Outdoor Heat Exchanger Bypass Control for Stable Refrigerant Circulation
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Solution Overview
Problem
The air-conditioning apparatus disclosed in Patent Literature 1 faces a problem where the heat exchange amount of the outdoor heat exchanger is decreased, leading to insufficient refrigerant circulation due to throttling of the outdoor flow rate control device, resulting in refrigerant accumulation in the outdoor heat exchanger.
Innovation Solution
The apparatus includes a compressor, a flow switching device, an outdoor heat exchange unit with a first and second outdoor heat exchanger connected in series and parallel, respectively, and a bypass pipe with flow rate control devices to control the refrigerant flow, ensuring necessary refrigerant circulation by adjusting the flow rate control devices to maintain heat exchange amounts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the outdoor flow rate control device is throttled to decrease heat exchange amount, then heat exchange amount is reduced, but refrigerant circulation becomes insufficient
Solution Approach 1:
The outdoor heat exchange unit is divided into multiple heat exchangers (first outdoor heat exchanger and second outdoor heat exchanger) with separate flow rate control devices (first flow rate control device and second flow rate control device). This segmentation allows independent control of refrigerant flow to each heat exchanger, enabling precise adjustment of heat exchange amount while maintaining sufficient total refrigerant circulation through coordinated control of multiple pathways.
Solution Approach 2:
The system changes the flow rate parameters of refrigerant by adjusting the opening degrees of multiple flow rate control devices (first flow rate control device, second flow rate control device, and third flow rate control device in bypass pipe). By dynamically changing these flow parameters, the system can reduce heat exchange amount when needed while ensuring that the total refrigerant circulation remains sufficient for continuous operation.
2Quantity of substance
If refrigerant flow is throttled downstream of outdoor heat exchanger, then heat exchange amount decreases, but refrigerant accumulates in outdoor heat exchanger
Solution Approach 1:
The refrigerant flow path is segmented into multiple parallel pathways with independent control. Instead of a single throttling point downstream that causes accumulation, the system uses separate flow rate control devices for each heat exchanger and a bypass pipe with its own flow rate control device. This segmentation allows refrigerant to be distributed and controlled at multiple points, preventing accumulation in any single heat exchanger while achieving the desired heat exchange reduction.
Solution Approach 2:
The bypass pipe with the third flow rate control device acts as an intermediary pathway that provides an alternative route for refrigerant flow. When the main heat exchange pathways are throttled to reduce heat exchange amount, the bypass pipe allows additional refrigerant to circulate, preventing accumulation in the outdoor heat exchangers while still achieving overall heat exchange reduction through coordinated control of all flow rate devices.
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 configuration allows for secure refrigerant circulation even when heat exchange amounts are decreased, preventing refrigerant stagnation and maintaining operational efficiency by adjusting the flow rate control devices to direct refrigerant through the bypass pipe, thus preventing 'liquid back' and ensuring continuous operation.
Implementation Method 1
the first flow rate control device, the second flow rate control device and the flow control device are controlled
Implementation Method 2
an outdoor heat exchange unit (3), in which the outdoor heat exchange unit includes a first outdoor heat exchanger (3a)
Implementation Method 3
a compressor (1)
Data Source
AI summary
An air-conditioning apparatus that includes a compressor, a flow switching device, an outdoor heat exchange unit, an expansion section and an indoor heat exchanger, which are connected by pipes, in which the outdoor heat exchange unit includes a first outdoor heat exchanger, a first flow rate control device, a second outdoor heat exchanger, a second flow rate control device, a bypass pipe, the second outdoor heat exchanger, the second flow rate control device, a third flow rate control device, and a flow control device.