Lubrication and cooling system
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Solution Overview
Problem
In refrigeration and heat pump systems, the absorption of refrigerant by lubricating oil leads to reduced viscosity and lubricity, causing issues such as oil foaming and mechanical failures, particularly at elevated temperatures, which complicates the operation and longevity of compressors and bearings.
Innovation Solution
A pressure reducing device is introduced between the oil sump and the low-pressure side of the refrigerant system to lower the refrigerant pressure in the oil sump, reducing refrigerant dilution in the oil and maintaining higher oil viscosity and lubricity, while also applying this pressure reduction to the motor housing to enhance cooling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If refrigerant pressure in the oil sump is reduced, then refrigerant dilution in the oil is reduced and oil viscosity is maintained, but additional pressure reducing devices are required
Solution Approach 1:
The pressure reducing device is designed to serve multiple functions: it reduces refrigerant pressure in the oil sump to prevent oil dilution and maintain lubricity, while also enabling efficient motor cooling through enhanced refrigerant circulation. This multi-functionality justifies the added device complexity by addressing multiple system requirements simultaneously.
2Temperature
If refrigerant pressure in the motor housing is reduced, then motor cooling efficiency is enhanced, but system complexity increases
Solution Approach 1:
The pressure reducing device connected to the motor housing serves dual purposes: it reduces refrigerant pressure to enhance motor cooling efficiency while simultaneously managing refrigerant distribution in the system. This eliminates the need for separate cooling systems and reduces overall system complexity despite adding one device.
3Ease of manufacture
If standard chiller equipment is reused in heat pump systems, then cost is reduced, but operational range is extended to high temperatures
Solution Approach 1:
The pressure reducing device enables standard chiller equipment to operate in high-temperature heat pump applications by actively managing refrigerant pressure and temperature parameters. This allows the same equipment to adapt to different thermal conditions without modification, extending its operational range from cooling-only to both cooling and heating applications.
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 solution effectively mitigates the adverse effects of refrigerant absorption on oil viscosity and lubricity, reducing the risk of mechanical failures and extending the operational range of compressors and motors, especially in high-temperature heat pump applications, and allows for the reuse of standard chiller equipment in heat pump systems.
Implementation Method 1
a refrigerant pressure reducing device (409) between the sump and a low pressure region of the system reducing an amount of refrigerant mixed with the lubricant, the pressure reducing device lowering refrigerant gas pressure below that of the low pressure region of the system
Implementation Method 2
the refrigerant surrounding and cooling the motor
Implementation Method 3
a condenser (25) in fluid communication with the compressor that condenses the refrigerant gas into a high pressure liquid
Implementation Method 4
an evaporator (27) in communication with the expansion valve and with the compressor, the evaporator changing the state of liquid refrigerant to refrigerant gas
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A system for reducing the refrigerant pressure in an oil sump (10) or in a cavity (352) of a housing. The invention is particularly useful for reducing pressure in a compressor (23) for heat pump applications that has been validated for water chiller operations or in turbine and generator systems in ORC systems generating electricity using refrigerant, the ORC systems essentially being a heat pump application operating in reverse. An auxiliary compressor (509), an auxiliary condenser (709) or an ejector pump (609) may be used to reduce pressure in the oil sump (10), to separate refrigerant from oil. The auxiliary compressor (509), the auxiliary condenser (709) or the ejector pump (609) may also be used to reduce the pressure of refrigerant in the housing of a compressor in heat pump applications at temperatures and pressures at which the compressor was validated for water chiller applications and of the turbine and generator in ORC applications.