Refrigeration Cycle Pressure Reduction for Stable Compressor Restart
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Solution Overview
Problem
Existing refrigeration cycle devices face challenges in stably restarting the compressor when the main circuit downstream of the compressor is in a high-pressure state.
Innovation Solution
The refrigeration cycle device incorporates a check valve and a control unit that executes a pressure reduction operation when predetermined conditions are met, utilizing a subcooling circuit and expansion valves to stabilize the pressure before restarting the compressor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the compressor is stopped while the main circuit downstream is in a high-pressure state, then the system can maintain high pressure for efficient refrigeration, but the compressor cannot be restarted stably due to excessive back pressure
Solution Approach 1:
The control unit executes a pressure reduction operation before compressor restart by opening the expansion device to reduce the first pressure in the high-pressure circuit. This preliminary pressure reduction prevents excessive back pressure during restart, enabling stable compressor operation while maintaining the benefit of high-pressure refrigeration during operation.
2Stress or pressure
If a check valve is installed downstream of the compressor to maintain pressure, then pressure retention is improved, but the system lacks a mechanism to reduce pressure for stable restart
Solution Approach 1:
The expansion device acts as an intermediary mechanism between the high-pressure circuit and the compressor. By controlling the opening of the expansion device, the system can selectively reduce pressure in the high-pressure circuit when needed for restart, while maintaining pressure retention during operation through the check valve.
Solution Approach 2:
The control unit dynamically changes the pressure parameter in the high-pressure circuit by controlling the expansion device opening. This parameter change enables the system to transition between pressure retention mode (during operation) and pressure reduction mode (before restart), resolving the contradiction between pressure maintenance and restart capability.
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 allows for stable compressor restarts by reducing pressure in the high-pressure circuit, preventing sudden overload and ensuring reliable operation.
Implementation Method 1
The check valve is provided in the main circuit on the downstream side of the compressor in the flow direction of the refrigerant
Implementation Method 2
an expansion device... The pressure reduction operation is an operation of reducing a first pressure of the main circuit on the downstream side of the check valve
Implementation Method 3
a compressor... The pressure reduction operation is an operation of reducing a first pressure of the main circuit on the downstream side of the check valve
Implementation Method 4
a first heat exchanger... and a second heat exchanger... The main circuit allows a refrigerant to flow through the compressor, the first heat exchanger, the expansion device, and the second heat exchanger
Data Source
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AI summary
A refrigeration cycle device according to an embodiment includes a main circuit, a check valve, and a control unit. The main circuit connects a compressor, a first heat exchanger, an expansion device, and a second heat exchanger in a loop to allow a refrigerant to flow thereto. A downstream side in a flow direction of the refrigerant is defined as a first side and an upstream side in the flow direction of the refrigerant is defined as a second side. The check valve is provided in the main circuit on the first side of the compressor. The control unit controls execution of a pressure reduction operation when a predetermined condition is satisfied and an operation of the compressor is stopped. The pressure reduction operation is an operation of reducing a first pressure of the main circuit on the first side of the check valve.