Oil-Separating Cooling Circuit for Passive Refrigerant Flow

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Solution Overview

Problem

Conventional cooling devices face inefficiencies in both active and passive cooling modes due to lubricant oil deposition and increased viscosity, which impede heat exchange and circulation, particularly in passive cooling where gravity-driven flow is insufficient to overcome flow resistance.

Innovation Solution

A cooling device design featuring a compressor, condensing unit, and evaporator with a vertically oriented second fluid by-pass line that separates lubricant oil from the compressed cooling agent, allowing it to be recycled back to the compressor, thereby preventing deposition and ensuring efficient operation in both active and passive cooling modes with reduced flow cross-section and pressure drop.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If lubricant oil is transferred together with compressed cooling agent to downstream elements, then the cooling device operates in active cooling mode, but lubricant oil deposits within condensing unit and evaporator reducing heat exchange efficiency and blocks flow through expansion device

Engineering Contradiction:
Improvecooling performanceVSAvoidheat exchange efficiency
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent extracts lubricant oil from the cooling agent flow using a centrifugal separator located in the liquid line between condenser and evaporator. The separator removes lubricant oil droplets from the liquid cooling agent through centrifugal force, preventing oil deposition in the evaporator and maintaining heat exchange efficiency while allowing continuous operation in active cooling mode

Inventive Principle:
Principle #2Taking out (Extraction)

2Adaptability or versatility

If lubricant oil content at condensing unit, evaporator and connecting tubes is high, then viscosity of cooling agent increases, but force of gravity is not enough to support circulation during passive cooling mode

Engineering Contradiction:
Improvepassive cooling mode operationVSAvoidflow resistance
Core Design Contradiction:
Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The centrifugal separator extracts lubricant oil from the cooling agent before it reaches the evaporator and connecting tubes. By removing lubricant oil from the liquid cooling agent, the separator prevents viscosity increase and maintains low flow resistance, enabling gravity-driven circulation during passive cooling mode operation

Inventive Principle:
Principle #2Taking out (Extraction)

3Reliability

If conventional oil separating elements are used to separate lubricant oil from cooling agent, then some lubricant oil is removed, but lubricant oil can still migrate and be retained at heat exchangers especially evaporator

Engineering Contradiction:
Improveheat exchanger performanceVSAvoidcooling efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent employs a centrifugal separator that uses centrifugal force (a hydraulic principle) to separate lubricant oil from liquid cooling agent. This mechanical separation method is more effective than conventional oil separating elements, achieving nearly complete removal of lubricant oil and preventing its migration to heat exchangers, thereby maintaining both reliability and productivity

Inventive Principle:
Principle #29Pneumatics and hydraulics

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 recycles lubricant oil, preventing deposition and maintaining thermal performance in both cooling modes by ensuring continuous lubricant oil return to the compressor, enhancing the device's ability to operate efficiently in passive cooling by reducing flow resistance and maintaining heat exchange efficiency.

Implementation Method 1

the separating portion is adapted to physically separate lubricant oil from the compressed cooling agent during the active cooling mode, so that the lubricant oil is collected in the second fluid by-pass line, wherein when, at the separating portion, compressed gaseous cooling agent containing lubricant oil enters the interior of the second fluid by-pass line through an end of the first fluid line, wherein said end portion penetrates a wall of said second fluid by-pass line, wherein the lubricant oil is separated from the compressed gaseous cooling agent by the effect of gravity

Methodology Applied
Scientific EffectGravity: Gravitation

Data Source

PatentEP4115127B1Cooling device
Publication Date: 2024.04.24 HUAWEI DIGITAL POWER TECH CO LTD
  • EP4115127B1 patent drawingFigure 1
  • EP4115127B1 patent drawingFigure 2
  • EP4115127B1 patent drawingFigure 3

AI summary

A cooling device (100) comprising a cooling circuit (101) comprising a compressor (105), which is adapted to compress cooling agent in the cooling circuit (101) during an active cooling mode, wherein the compressed cooling agent contains lubricant oil from the compressor (105); a condensing unit (111), which is connected to the compressor (105) by a first fluid line (107) of the cooling circuit (101); an evaporator (103), which comprises a top part (103-1), a bottom part (103-2), and a plurality of evaporating tubes (103-3) connecting the top part (103-1) with the bottom part (103-2), wherein the top part (103-1) is connected to the condensing unit (111) by a second fluid line (113) of the cooling circuit (101), and wherein the bottom part (103-2) is connected to the compressor (105) by a third fluid line (117) of the cooling circuit (101).