Binary refrigeration device
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Solution Overview
Problem
Existing ultralow temperature binary refrigeration apparatuses face challenges with Ozone Depletion Potential (ODP) and Global Warming Potential (GWP), compatibility issues between refrigerants and oils, lubrication failures, and the need for oil separators, especially when using HFC refrigerants, which also require significant power and refrigerant amounts.
Innovation Solution
A binary refrigeration apparatus using propane in the high temperature cycle and a hydrocarbon with a boiling point of -80°C or lower, such as ethane, in the low temperature cycle, along with an oil return agent like n-pentane, eliminating the need for an oil separator and improving refrigerant stability and compatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If HFC refrigerants are used in the refrigeration apparatus, then Ozone Depletion Potential is reduced, but Global Warming Potential increases and compatibility issues with refrigerator oil occur
Solution Approach 1:
The patent changes the chemical composition parameters of the refrigerant from HFC to hydrocarbon (R-290 propane and R-170 ethane), which fundamentally alters both the ODP and GWP characteristics. This parameter change achieves zero ODP while maintaining acceptable GWP levels, resolving the contradiction between reducing ozone depletion and minimizing global warming impact.
Solution Approach 2:
The patent uses a composite refrigerant system combining R-290 and R-170 in specific proportions (70-90% R-290 and 10-30% R-170 by mass). This composite approach allows optimization of thermodynamic properties while maintaining environmental benefits, achieving both low ODP and controlled GWP through the synergistic combination of different hydrocarbon refrigerants.
2Reliability
If ester-based refrigerator oils are used with HFC refrigerants, then compatibility is improved, but hydrolysis occurs during use leading to performance deterioration
Solution Approach 1:
The patent changes the refrigerator oil type from ester-based to hydrocarbon-based (alkylbenzene or naphthenic oil), which fundamentally alters the chemical stability parameters. This change eliminates the hydrolysis issue that plagues ester oils while maintaining good compatibility with hydrocarbon refrigerants, thereby extending service life and improving reliability.
Solution Approach 2:
The patent achieves homogeneity between the refrigerant and refrigerator oil by using hydrocarbon-based oil that is chemically compatible with hydrocarbon refrigerants (R-290 and R-170). This homogeneous combination prevents chemical reactions like hydrolysis and ensures stable long-term operation, resolving the contradiction between compatibility and service life.
3Reliability
If alkylbenzene refrigerator oil is used with HFC refrigerants, then lubricity is maintained, but oil stagnation occurs in the cycle causing blockage
Solution Approach 1:
The patent changes the refrigerant type from HFC to hydrocarbon (R-290/R-170 mixture), which fundamentally alters the interaction parameters between refrigerant and alkylbenzene oil. This change improves oil circulation by preventing stagnation and blockage in the refrigeration cycle while maintaining adequate lubrication performance, resolving the contradiction between lubricity and ease of operation.
4Temperature
If cascade condenser is used to connect high and low temperature cycles, then ultralow temperature is achieved, but system complexity increases
Solution Approach 1:
The patent changes the refrigerant parameters in the low-temperature cycle to a hydrocarbon mixture (R-290 and R-170) with optimized boiling points. This parameter change allows the cascade condenser to achieve ultralow temperatures more efficiently, reducing the temperature differential required and simplifying the heat exchange process, thereby mitigating the complexity issue.
Solution Approach 2:
The patent uses a composite refrigerant mixture (R-290 and R-170) in the low-temperature cycle that provides optimized thermodynamic properties for cascade operation. This composite approach improves the efficiency of the cascade condenser, allowing ultralow temperature achievement with reduced system complexity compared to using single-component refrigerants.
5Ease of operation
If expansion tank is used to reduce pressure in low temperature cycle, then compressor startup is enabled, but device complexity increases
Solution Approach 1:
The patent extracts and eliminates the expansion tank component from the system by using a hydrocarbon-based refrigerant mixture (R-290 and R-170) that provides adequate pressure characteristics for direct compressor startup. This removal of the expansion tank simplifies the system while maintaining ease of operation, resolving the contradiction between startup capability and device complexity.
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 achieves ultralow temperatures without ODP or GWP concerns, enhances refrigerant stability, reduces the need for oil separators, and increases the Coefficient of Performance (COP), allowing for reduced refrigerant amounts or compressor power, while preventing lubrication failures and oil stagnation.
Implementation Method 1
connecting a high temperature refrigeration cycle and a low temperature refrigeration cycle via a cascade condenser
Implementation Method 2
flows through a dryer 21, a capillary tube 22, and into an evaporator 24 from an inlet pipe 23, and then exits from an outlet pipe 25 to return to the compressor 6
Implementation Method 3
the refrigerant passes through the pipe 20 in the cascade condenser 11 to condense, flows through a dryer 21, a capillary tube 22, and into an evaporator 24
Data Source
Figure 1~2
Figure 3
Figure 4(a)~4(g)
AI summary
Provided is an ultralow binary refrigeration apparatus, which cools an enclosed space to an ultralow temperature of -80°C or lower to be used for storing cells or microorganisms, for example, without posing worries in regard of Ozone Depletion Potential (ODP) and Global Warming Potential (GWP), and which is excellent in refrigerant stability, can dispense with an oil separator, and enables a reduction in the amount of refrigerant, or a reduction in the power output of the compressor. The object is achieved by a binary refrigeration apparatus configured by connecting a high temperature refrigeration cycle and a low temperature refrigeration cycle via a cascade condenser, which is characterized in that the high temperature refrigeration cycle is filled with propane as a refrigerant and a refrigerator oil, while the low temperature refrigeration cycle is filled with a hydrocarbon having a boiling point of -80°C or lower as a refrigerant, a refrigerator oil, and an oil return agent.