Shell-and-Tube Evaporator Lubricant Return for Compressor Lubrication
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Solution Overview
Problem
Existing refrigeration chillers face challenges in maintaining adequate lubricant supply and viscosity for compressor bearings due to lubricant mixing with refrigerant, leading to inefficient lubrication and pressure drops, as conventional oil separators do not fully separate lubricant from refrigerant effectively.
Innovation Solution
A refrigeration system design incorporating a shell-and-tube style evaporator and a heat sink connected via a lubricant return line, which induces flow by evaporating refrigerant in the lubricant-refrigerant mixture, ensuring lubricant return to the compressor and improving viscosity through heat exchange, thereby enhancing lubrication and reducing parasitic losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an oil separator is used to separate lubricant from refrigerant, then lubricant separation is achieved, but the lubricant viscosity decreases due to refrigerant mixing and pressure drop occurs in the compressed refrigerant
Solution Approach 1:
The patent extracts the lubricant return function from the traditional oil separator location and places it in the evaporator, where lubricant is recovered along with refrigerant vapor without causing pressure drop in the high-pressure line. The evaporator acts as both a heat exchange device and a lubricant recovery point.
Solution Approach 2:
The patent introduces a lubricant return line as an intermediary pathway that allows lubricant to be transported from the evaporator back to the compressor without requiring high-pressure separation. This intermediary system avoids the pressure drop issue by operating at low pressure.
2Reliability
If lubricant is separated from refrigerant using conventional separators, then some lubricant recovery is achieved, but the lubricant viscosity is reduced due to refrigerant mixing
Solution Approach 1:
The patent changes the temperature parameter of the lubricant by routing it through the evaporator where it is cooled, thereby increasing its viscosity. The lubricant is cooled from ambient temperature to evaporator temperature, transforming its physical properties for better lubrication.
Solution Approach 2:
The patent performs preliminary cooling of the lubricant in the evaporator before it returns to the compressor. This preliminary action ensures that the lubricant is already at the optimal temperature and viscosity when it reaches the compressor, eliminating the need for additional cooling systems.
3Reliability
If lubricant is returned to the compressor, then adequate lubrication is maintained, but parasitic losses and noise increase
Solution Approach 1:
The system uses the evaporator's cooling function to simultaneously cool the lubricant and drive the thermosiphon effect, eliminating the need for separate lubricant cooling systems or pumps. The refrigerant vapor rising naturally creates the flow驱动力, making the system self-service and reducing parasitic losses.
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, improving lubrication quality, reducing noise, and minimizing parasitic losses by creating a thermosiphon effect, which maintains adequate lubrication and enhances compressor performance.
Implementation Method 1
a heat sink and a lubricant return line connecting the second outlet port to the suction port, wherein the lubricant return line is in heat exchange relationship with the heat sink such that heat is rejected from the heat sink to the lubricant-liquid refrigerant mixture
Implementation Method 2
evaporate the liquid refrigerant in the lubricant-liquid refrigerant mixture to induce flow of the evaporated refrigerant and the lubricant
Implementation Method 3
minimizing parasitic losses by creating a thermosiphon effect, which maintains adequate lubrication and enhances compressor performance
Data Source
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.