Oil Separation Pocket in Refrigeration Circuits for Compressor Lubrication
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Solution Overview
Problem
In refrigeration circuits with ejectors, oil used for lubricating the compressor dissolves into the refrigerant and accumulates in the liquid phase, leading to a decrease in oil levels within the compressor, potentially causing it to run dry if not adequately replaced.
Innovation Solution
An oil separation device is implemented, featuring a refrigerant conduit with a larger diameter portion and a smaller diameter portion forming an oil separation pocket, where the oil is collected and then suctioned into an oil receiver using a pressure difference created by a low-pressure refrigerant return line, allowing for efficient oil extraction and retransfer to the compressor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oil is used for lubricating the compressor, then the compressor can operate reliably, but the oil dissolves into the refrigerant and accumulates in the liquid phase, leading to oil level decrease in the compressor
Solution Approach 1:
The patent extracts oil from the liquid refrigerant phase using a dedicated oil separation device. The device includes an oil separation pocket formed by a smaller diameter section extending into a larger diameter section of the refrigerant conduit, creating a separation zone where oil accumulates. An oil suction line then extracts the separated oil from this pocket, preventing it from accumulating in the gas-liquid separator and ensuring continuous oil supply to the compressor.
Solution Approach 2:
The patent introduces a gas-liquid separator as an intermediary component between the ejector and the evaporator. This separator divides the refrigerant flow into liquid and gas phases, with the liquid phase (containing dissolved oil) being separated and directed through an oil separation device. The separator acts as a mediator that enables the extraction of oil from the refrigerant stream without disrupting the overall refrigeration cycle.
2Loss of substance
If an oil separation device is implemented, then oil can be extracted and retransferred to the compressor, but the device complexity increases
Solution Approach 1:
The patent merges the oil separation function with the existing gas-liquid separator by integrating an oil separation pocket into the refrigerant conduit. The smaller diameter section of the conduit itself forms part of the separation structure, eliminating the need for a completely separate oil separation device. The oil suction line is connected to this integrated pocket, creating a compact combined system that performs both gas-liquid separation and oil extraction functions.
Solution Approach 2:
The oil separation device operates passively using the existing pressure differential in the refrigeration system. The oil suction line utilizes the pressure difference between the liquid phase (higher pressure) and the vapor phase (lower pressure) to automatically draw oil from the separation pocket without requiring an additional pump or active mechanical component. This self-service mechanism reduces device complexity while maintaining effective oil extraction.
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 solution effectively separates and retransfers oil from the suction circuit to the driving circuit, preventing compressor dry-running and maintaining lubrication, while being cost-effective and space-efficient without requiring additional moving elements like pumps.
Implementation Method 1
The ejector increases the suction pressure of a compressor by converting expansion energy into pressure energy while expanding the refrigerant to a reduced pressure
Implementation Method 2
The second portion having the second diameter extends into the first portion forming an oil separation pocket between the outer diameter of the second portion and the inner diameter of the first portion
Implementation Method 3
the oil extraction line connects the separation vessel to the oil receiver
Data Source
AI summary
An oil separation device (14) for separating oil from a refrigerant-oil-mixture in a refrigeration cycle (1), the oil separation device (14) comprises a first refrigerant conduit having at least a first portion (16) with a first diameter (d1); a second refrigerant conduit arranged downstream of and connected to the first refrigerant conduit, the second refrigerant conduit having at least a second portion with a second diameter (d2) being smaller than the first diameter (d1); wherein the second portion (18) of the second refrigerant conduit having the second diameter (d2) extends into the first portion (16) of the first refrigerant conduit forming an oil separation pocket (32) between the outer diameter of the second portion (18) and the inner diameter of the first portion (16); and a suction line (20) having an inlet end (19), which opens into the oil separation pocket (32) and is configured to suck oil from the oil separation pocket (32).