Refrigeration device
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Solution Overview
Problem
In typical binary refrigeration apparatuses, an abnormal increase in pressure occurs in the high-pressure side of the second refrigerant circuit when the compressor stops, due to the expansion tank being connected to the low-pressure side, leading to inefficiencies and increased costs as the expansion tank is often disabled, except in cases where the first refrigerant circuit cannot operate.
Innovation Solution
A refrigeration apparatus with a first and second refrigerant circuit, a cascade condenser, a receiver, a tank, and a bypass with a first on-off valve that opens when high-side pressure increases, directing refrigerant to the tank to prevent pressure buildup, and also serves as an oil tank to manage refrigerating machine oil levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the expansion tank is connected to the low-pressure side of the second refrigerant circuit, then the refrigerant can be collected during compressor stop, but the high-pressure side experiences abnormal pressure increase that cannot be avoided
Solution Approach 1:
The patent divides the refrigerant circuit into high-pressure and low-pressure sides, and connects the expansion tank to both sides through separate connections. This segmentation allows independent pressure management on each side, enabling the high-pressure side to be directly connected to the expansion tank for effective pressure relief while maintaining the low-pressure side connection for refrigerant collection during compressor stop.
Solution Approach 2:
The expansion tank serves as an intermediary component that mediates pressure management between the high-pressure and low-pressure sides of the refrigerant circuit. By connecting to both sides, it acts as a buffer that can absorb excess pressure from the high-pressure side while facilitating refrigerant return from the low-pressure side, thus resolving the conflicting pressure control requirements.
2Reliability
If the on-off valve is provided upstream of the evaporator to prevent refrigerant flow into the evaporator at compressor stop, then refrigerant flow is blocked, but the passage area for pressure relief is further reduced making abnormal pressure increase more serious
Solution Approach 1:
The patent extracts the pressure relief function from the main refrigerant flow path by providing a separate connection from the high-pressure side directly to the expansion tank. This allows the on-off valve to block refrigerant flow to the evaporator while the separate pressure relief path remains available to prevent abnormal pressure buildup, effectively separating the flow control function from the pressure management function.
3Device complexity
If the expansion tank is connected only to the low-pressure side, then the structure is simple, but the expansion tank is often disabled except when the first refrigerant circuit cannot operate, increasing costs
Solution Approach 1:
The patent makes the expansion tank universal by enabling it to serve multiple functions: it continues to function as an expansion tank for the low-pressure side while simultaneously serving as a pressure relief destination for the high-pressure side. This multi-functionality ensures the expansion tank remains operational and useful in various operating conditions, preventing it from being disabled and justifying its inclusion in the system.
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
Prevents abnormal pressure increases in the second refrigerant circuit's high-pressure side when the compressor stops, and functions as an oil tank to prevent compressor failure from oil shortages, reducing costs and improving operational efficiency.
Implementation Method 1
when a high-side pressure in the second refrigerant circuit increases to not less than a predetermined pressure, the bypass opens... directing refrigerant to the tank to prevent pressure buildup
Implementation Method 2
a cascade condenser formed by the first evaporator of the first refrigerant circuit and the second condenser of the second refrigerant circuit
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A refrigeration apparatus 100 includes a first refrigerant circuit 50 having a first evaporator 4, a second refrigerant circuit 60 having a second condenser 7, and a cascade condenser 15 formed by the first evaporator 4 and the second condenser 7. The second refrigerant circuit 60 of the refrigeration apparatus 100 includes a receiver 8, a tank 14, a bypass 13, and a bypass valve 13a. The receiver is disposed between the second condenser 7 and a second expansion valve 10. The tank 14 is connected to a second compressor 5 and stores excess refrigerating machine oil 18 in the second compressor 5 so as to adjust the amount of refrigerating machine oil 18 in the second compressor 5. The bypass 13 connects the receiver 8 and the tank 14 to each other. The bypass valve 13a is disposed in the bypass 13, opens the bypass 13 when a high-side pressure in the second refrigerant circuit 60 increases to a predetermined pressure or more, and closes the bypass 13 when the high-side pressure in the second refrigerant circuit 60 decreases to the predetermined pressure or less.