Refrigeration system having a compressor driven by a magnetic coupling
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Solution Overview
Problem
Vapor-compression refrigeration systems with magnetic couplings face significant heat generation due to Joule losses from eddy currents in the separation wall, which is insufficiently cooled by convection, potentially degrading lubricants and requiring more effective cooling methods.
Innovation Solution
Direct injection of liquid refrigerant from the condenser onto the separation wall within the compressor housing to evaporate and absorb heat, utilizing a fluid conduit and injection ports or nozzles to enhance heat dissipation through phase change cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If magnetic coupling is used to transfer torque across the separation wall, then the compression mechanism can be driven from outside the hermetically sealed housing, but Joule losses from eddy currents generate excessive heat in the separation wall
Solution Approach 1:
The patent converts the harmful heat generated by Joule losses into a beneficial cooling opportunity by directing liquid refrigerant onto the hot separation wall. The refrigerant absorbs the excess heat through evaporation, transforming the harmful thermal energy into useful cooling effect while maintaining the external drive capability provided by the magnetic coupling
Solution Approach 2:
The patent utilizes the phase transition of liquid refrigerant from liquid to vapor as it contacts the hot separation wall. This phase change process absorbs large amounts of latent heat, efficiently removing the thermal energy generated by eddy currents in the separation wall without requiring complex active cooling systems
2Device complexity
If conventional forced convection cooling is used on the separation wall, then the cooling system is simple, but the cooling effectiveness is insufficient to prevent lubricant degradation
Solution Approach 1:
The patent replaces insufficient forced convection cooling with evaporative cooling using liquid refrigerant. The phase transition from liquid to vapor provides orders of magnitude higher heat transfer coefficients, effectively removing heat from the separation wall to maintain lubricant stability without requiring complex cooling infrastructure
Solution Approach 2:
The patent uses the refrigerant already present in the system to cool the separation wall, eliminating the need for separate cooling systems. The refrigerant serves dual purposes: its primary refrigeration function and its secondary function as a coolant for the separation wall, achieving self-service cooling
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 method significantly reduces the temperature of the separation wall, improving thermal management and preventing lubricant degradation, while being orders of magnitude more effective than conventional forced convection cooling.
Implementation Method 1
the liquid refrigerant from the condenser is evaporated on or adjacent the inside surface of the separation wall portion to thereby cool the separation wall portion
Implementation Method 2
evaporate and absorb heat, utilizing a fluid conduit and injection ports or nozzles to enhance heat dissipation through phase change cooling
Implementation Method 3
the compression mechanism is driven by a prime mover located outside the compressor housing through a magnetic coupling
Implementation Method 4
Joule losses from eddy currents in the separation wall
Implementation Method 5
a compressor which compresses a gaseous refrigerant
Implementation Method 6
a condenser which condenses the gaseous refrigerant into liquid form
Data Source
AI summary
A refrigeration system includes a compressor having a hermetically sealed housing and a compression mechanism which is positioned inside the housing; a condenser which is fluidly connected to the compressor; an evaporator which is fluidly connected between the condenser and the compressor; a magnetic coupling having a drive coupling half positioned outside the housing and a driven coupling half positioned inside the housing and separated from the drive coupling half by a separation wall portion of the housing; and a fluid conduit for communicating a portion of liquid refrigerant from the condenser to an inside surface of the separation wall portion. During operation, the liquid refrigerant from the condenser is evaporated on or adjacent the inside surface of the separation wall portion to thereby dissipate heat generated by magnetically induced eddy currents in the separation wall portion.