Refrigeration device unit, heat source unit, and refrigeration device
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Solution Overview
Problem
The use of a four-way switching valve in refrigerant circuits for supercritical carbon dioxide cycles results in increased level differential pressure, leading to loud impulsive sounds during refrigerant flow path switching.
Innovation Solution
Employing an electrically driven rotary-type flow path switching mechanism with three-way valves and an electric motor to control refrigerant flow, combined with a control unit that adjusts compressor operation and pressure differences before switching, reducing the level differential pressure and torque requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a four-way switching valve is used in supercritical carbon dioxide refrigerant circuits, then refrigerant flow path switching is enabled, but loud impulsive sounds occur due to increased level differential pressure
Solution Approach 1:
The patent divides the flow path switching function into multiple three-way valves (first three-way valve and second three-way valve) instead of using a single four-way switching valve. Each three-way valve handles a portion of the refrigerant flow independently, which reduces the pressure differential across each valve during switching, thereby eliminating loud impulsive sounds while maintaining complete flow path switching capability.
2Object-generated harmful factors
If level differential pressure is reduced before switching, then noise is reduced, but compressor operation must be adjusted
Solution Approach 1:
The control unit performs preliminary action by stopping the compressor or reducing its operating frequency before actuating the three-way valves to switch refrigerant flow paths. This preliminary compression reduction equalizes the pressure differential across the valves, preventing loud noise during switching. After the valves are switched, the compressor is restarted or its frequency is increased back to the required level.
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 significantly reduces noise and torque during refrigerant flow path switching, enhancing operational silence and efficiency in refrigeration systems using supercritical carbon dioxide.
Implementation Method 1
a flow path switching portion (71) to be driven by an electric motor (74)
Implementation Method 2
a refrigeration cycle in which a pressure above a critical pressure is applied to a refrigerant such as carbon dioxide (hereinafter, also referred to as a super critical cycle)
Data Source
Figure 1
Figure 2(A)~2(B)
Figure 3
AI summary
A switching mechanism (TV1, TV2, TV3, TV4, FV) includes an electric motor (74), a flow path switching portion (71) to be driven by the electric motor (74), a first port (P1) connected to a high-pressure flow path (7, 24, 28b, 31, 32) of a refrigerant circuit (6), a second port (P2) connected to a low-pressure flow path (8, 25, 28a, 33, 34) of the refrigerant circuit (6), and a third port (P3) connected to a predetermined flow path of the refrigerant circuit (6). The switching mechanism (TV1, TV2, TV3, TV4, FV) is switched between a first state in which the first port (P1) communicates with the third port (P3) and a second state in which the second port (P2) communicates with the third port (P3) in such a manner that the electric motor (74) drives the flow path switching portion (71).