Electronics cooling using lubricant return for a shell-and-tube style evaporator
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Solution Overview
Problem
Existing refrigeration chillers face challenges in maintaining adequate lubricant supply and viscosity for compressor surfaces due to lubricant mixing with refrigerant, leading to inefficient oil separation and pressure drops in the system.
Innovation Solution
A refrigeration system design incorporating a shell-and-tube style evaporator and a heat exchanger that creates a thermosiphon effect, allowing lubricant to return to the compressor in a superheated state, improving lubrication and reducing noise, while also ensuring efficient refrigerant flow and minimizing parasitic losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an oil separator is used immediately downstream of the compressor, then lubricant separation is improved, but pressure drop increases and lubricant viscosity decreases due to refrigerant mixing
Solution Approach 1:
The patent introduces a heat exchanger as an intermediary device between the evaporator and compressor. This heat exchanger serves as a mediator that transfers heat from the refrigerant to the lubricant, enabling lubricant return without requiring high-pressure oil separation. The heat exchanger mediates the thermal energy transfer that drives lubricant circulation while avoiding the harmful pressure drop and viscosity loss associated with traditional oil separators.
Solution Approach 2:
The patent extracts the lubricant from the refrigerant-lubricant mixture in the heat exchanger through thermal separation rather than mechanical separation. By removing heat from the mixture, the lubricant condenses and separates from the refrigerant vapor, allowing the lubricant to be returned to the compressor. This extraction method avoids the pressure drop and viscosity degradation problems of traditional oil separators.
2Reliability
If an oil separator is used immediately downstream of the compressor, then lubricant separation is improved, but lubricant viscosity decreases due to refrigerant mixing
Solution Approach 1:
The patent changes the thermal parameters of the lubricant by using a heat exchanger to remove heat from the refrigerant-lubricant mixture. This parameter change (temperature reduction) causes the lubricant to condense and increase in viscosity, making it suitable for return to the compressor. The heat exchanger enables precise control of the lubricant's thermal state, ensuring optimal viscosity without the refrigerant mixing problems of traditional separators.
3Reliability
If a heat exchanger is used for lubricant return, then lubricant viscosity is maintained and pressure drop is reduced, but system complexity increases
Solution Approach 1:
The patent makes the heat exchanger perform multiple functions: it serves as both the evaporator for refrigerant and the heat exchange surface for lubricant return. The same heat exchanger component that facilitates refrigerant evaporation also enables lubricant condensation and return through thermal energy transfer. This multi-functionality eliminates the need for separate oil separation equipment, reducing overall system complexity while maintaining reliable lubricant supply.
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
The system effectively recovers and returns lubricant to the compressor, enhancing lubrication, reducing noise, and improving compressor performance by maintaining lubricant viscosity and flow quality, thus addressing the issues of lubricant supply and refrigerant pressure drops.
Implementation Method 1
heat is rejected from the heat sink to the lubricant-liquid refrigerant mixture to evaporate the liquid refrigerant in the lubricant-liquid refrigerant mixture
Implementation Method 2
creates a thermosiphon effect, allowing lubricant to return to the compressor in a superheated state
Implementation Method 3
a heat exchanger that creates a thermosiphon effect
Implementation Method 4
the compressor configured to receive refrigerant from the suction port, compress the refrigerant, and discharge the compressed refrigerant
Implementation Method 5
the condenser connected to the discharge port and configured to receive the compressed refrigerant from the compressor and condense the compressed refrigerant
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A refrigeration system that induces lubricant-liquid refrigerant mixture flow from a flooded or falling film evaporator by means of the lubricant-liquid refrigerant mixture flow adsorbing heat from an electronic component.