Heat source unit and refrigeration device having low-stage and high-stage compressors with four-way switching valve
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Solution Overview
Problem
Existing refrigeration apparatuses face challenges in efficiently switching between cooling and heating operations, particularly in managing the flow paths and pressures within the refrigerant circuit, which can lead to damage to components like four-way switching valves and affect the reliability and efficiency of the system.
Innovation Solution
The proposed solution involves a heat source unit with a configuration that includes a high-stage compressor, a low-stage compressor, and a four-way switching valve, controlled by a controller that adjusts the operation of the compressors and switching valves to manage pressure differences and reduce the load on the switching valves, thereby preventing damage and improving reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the four-way switching valve switches flow paths while both compressors are operating, then the refrigeration cycle can switch between cooling and heating modes, but the pressure difference across the valve causes impact forces that may damage the valve
Solution Approach 1:
The controller stops the low-stage compressor before switching the four-way switching valve, and starts it after the valve switching is complete. This preliminary action sequence prevents the impact force generated by simultaneous compressor operation during valve switching, thereby protecting the valve from damage while maintaining the ability to switch between cooling and heating modes.
2Productivity
If the low-stage compressor is stopped during heating operation, then the high-stage compressor can operate independently to provide heating, but the refrigerant flow path must be switched which requires activating the four-way switching valve under pressure differential
Solution Approach 1:
The controller performs preliminary actions by stopping the low-stage compressor and activating the four-way switching valve in a controlled sequence before the high-stage compressor needs to operate independently. This ensures the refrigerant flow path is properly switched without subjecting the valve to damaging pressure differentials, maintaining both heating efficiency and valve reliability.
3Ease of operation
If the four-way switching valve is activated while pressure difference exists between suction and discharge sides, then flow path switching can occur, but the pressure difference generates impact force that reduces valve lifespan
Solution Approach 1:
The controller executes preliminary actions by coordinating the stopping of the low-stage compressor and the activation of the four-way switching valve before pressure differential builds up. This sequence ensures flow path switching occurs without excessive impact force, maintaining ease of operation while extending valve service life through reduced mechanical stress.
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 efficient switching between cooling and heating operations, reduces the risk of component damage, and enhances the reliability and efficiency of the refrigeration apparatus by managing pressure differences and optimizing the operation of the compressors and switching valves.
Implementation Method 1
a high-stage compressor (21) configured to suck and compress a refrigerant discharged from the low-stage compressor (23)
Implementation Method 2
a four-way switching valve (150) configured to switch a flow path of the refrigerant sucked into the low-stage compressor (23) and a flow path of the refrigerant discharged from the high-stage compressor (21)
Implementation Method 3
configured to perform a refrigeration cycle
Data Source
AI summary
A heat source unit connected to a utilization-side unit and configured to perform a refrigeration cycle includes a low-stage compressor, a high-stage compressor, a four-way switching valve, a low-stage pipe, and a controller. The low-stage pipe is provided in parallel with the low-stage compressor, and the refrigerant flows therethrough while the low-stage compressor is stopped. The controller outputs an instruction signal for actuating the four-way switching valve, to the four-way switching valve while the low-stage compressor is stopped and the high-stage compressor is operating.