Refrigeration device
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Solution Overview
Problem
In refrigeration devices using carbon dioxide as a refrigerant, the pressure fluctuations caused by opening and closing solenoid valves lead to reverse refrigerant flow and oil confinement in evaporators, resulting in compressor oil depletion and performance deterioration.
Innovation Solution
The solenoid valve is positioned on the refrigerant downstream side of the evaporator, and a controller manages the expansion valve and solenoid valve to prevent reverse refrigerant flow by controlling their positions, ensuring the solenoid valve is closed when not in use and opening it for predetermined periods to facilitate oil return.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the solenoid valve is disposed on the refrigerant downstream side of the evaporator, then pressure fluctuations are reduced and the evaporator acts as a buffer tank, but reverse refrigerant flow occurs when the solenoid valve is closed and oil is confined in the evaporator
Solution Approach 1:
The solenoid valve is opened periodically for predetermined periods even during heating mode to prevent oil confinement. The controller opens the solenoid valve at predetermined timings to allow refrigerant and oil to flow back to the compressor, ensuring continuous oil circulation while maintaining pressure stability during normal operation.
2Adaptability or versatility
If the solenoid valve is closed to heat and use an interior of a display chamber, then heating function is achieved, but refrigerant reversely flows into the evaporator and oil is confined
Solution Approach 1:
During heating mode, the solenoid valve is not continuously closed but is opened periodically for predetermined periods. This periodic opening allows refrigerant and oil to flow back to the compressor, preventing oil confinement while still achieving the heating function by controlling the valve closure during non-operational periods.
3Ease of operation
If the solenoid valve is opened and closed frequently, then control responsiveness is improved, but pressure fluctuations increase causing harmful effects
Solution Approach 1:
The evaporator acts as a buffer tank (intermediary) between the solenoid valve and the compressor. This buffer capacity absorbs pressure fluctuations caused by frequent solenoid valve operations, allowing responsive control while preventing harmful pressure spikes from reaching the compressor.
4Reliability
If the solenoid valve is disposed upstream of the expansion valve, then liquid backflow prevention is achieved, but pressure fluctuations occur due to valve opening/closing
Solution Approach 1:
The evaporator serves as a buffer tank that mediates between the solenoid valve and the compressor. This intermediate buffer capacity smooths out pressure fluctuations generated by solenoid valve operations, maintaining pressure stability while the solenoid valve remains positioned upstream of the expansion valve for liquid backflow prevention.
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 prevents compressor oil depletion and performance issues by ensuring the solenoid valve is closed when not in use and opening it for predetermined periods to return confined oil, maintaining system efficiency and preventing overheating or excessive cooling.
Implementation Method 1
a solenoid valve (a liquid solenoid valve) is disposed on a refrigerant upstream side of the expansion valve disposed in each showcase
Implementation Method 2
a valve position of the expansion valve on a refrigerant upstream side of the evaporator of the showcase is controlled on the basis of a refrigerant superheat degree
Implementation Method 3
Evaporators to cool interiors of the display chambers are arranged in the showcases
Implementation Method 4
a refrigerant is distributed and supplied from a compressor to respective evaporators arranged in a plurality of showcases, thereby cooling interiors
Implementation Method 5
a compressor of a refrigerating machine unit installed, for example, outside the store
Data Source
Figure 1
Figure 2~3
AI summary
There is prevented burning or performance deterioration of a compressor which is caused by oil confined in an evaporator of a switchable showcase, when a solenoid valve is disposed on a refrigerant downstream side of the evaporator. A showcase 2A is a switchable showcase which is usable in switching a cooling mode to cool an interior of a display chamber, a non-cooling mode in which the interior of the display chamber is not cooled and/or a heating mode to heat the interior of the display chamber by an electric heater 63. A controller 57 of the showcase 2A controls a valve position of a low stage side expansion valve 34 and opens and closes a solenoid valve 37 in the cooling mode, and shuts off the low stage side expansion valve 34 and opens the solenoid valve 37 in the non-cooling mode and/or the heating mode.