Flash Tank Spiral Separation for Vibrating CO2 Refrigerant Flow
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Solution Overview
Problem
Mobile refrigerant vapor compression systems operating in a transcritical cycle face challenges in compact, lightweight, and durable phase separation due to vibration and size restrictions, especially when using carbon dioxide as a refrigerant with low critical temperature and low liquid to vapor density ratio.
Innovation Solution
A phase separation apparatus with a flash tank featuring an auger assembly and helical spiral fluid flow passage within a shell, which separates two-phase refrigerant flow into vapor and liquid phases, utilizing a fluid inlet and outlets to manage the density differential and reduce intermixing caused by vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a conventional flash tank is used for phase separation, then separation function is provided, but the apparatus is bulky and heavy, which is unsuitable for mobile refrigeration systems with space and weight restrictions
Solution Approach 1:
The flash tank is segmented into distinct functional zones: an upper vapor separation chamber with vapor outlet, a lower liquid accumulation chamber with liquid outlet, and a central auger assembly. This segmentation allows each zone to perform its specific function efficiently while maintaining compact overall dimensions suitable for mobile applications.
Solution Approach 2:
The flash tank employs a cylindrical shell with curved end caps, creating a compact three-dimensional configuration that maximizes internal volume while minimizing external footprint. The curved geometry also helps distribute vibration stresses uniformly throughout the structure, improving reliability under mobile operating conditions.
2Weight of moving object
If the flash tank is reduced in size for mobile applications, then space and weight restrictions are met, but structural durability under vibration and movement becomes compromised
Solution Approach 1:
The flash tank utilizes a cylindrical shell construction that provides high strength-to-weight ratio. The shell geometry naturally resists vibration and movement stresses while maintaining minimal weight, making it ideal for mobile refrigeration systems where both weight and durability are critical.
Solution Approach 2:
The auger assembly is positioned along the central vertical axis of the cylindrical shell, creating a balanced, symmetric configuration that distributes mechanical stresses uniformly during vibration and movement. This balanced arrangement prevents stress concentration points that would compromise structural integrity.
3Adaptability or versatility
If carbon dioxide is used as refrigerant in transcritical cycle, then environmental benefits are achieved, but the low liquid to vapor density ratio makes phase separation difficult
Solution Approach 1:
The auger assembly rotates to dynamically agitate the two-phase refrigerant mixture, enhancing the separation process. This dynamic action compensates for the low density differential of CO2 by creating mechanical forces that promote phase separation, ensuring efficient operation with transcritical refrigerants.
Solution Approach 2:
The system operates by changing pressure parameters across the expansion device, creating a two-phase mixture that then separates in the flash tank. The pressure reduction from supercritical to subcritical range fundamentally changes the refrigerant's phase behavior, enabling separation despite CO2's low liquid-to-vapor density ratio.
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 apparatus effectively separates refrigerant phases, reducing intermixing and enhancing the natural separation of vapor and liquid phases, thus improving the efficiency and reliability of transcritical refrigerant vapor compression systems in mobile applications.
Implementation Method 1
a helical spiral member extending about the vertical support tube and defining in association with the shell a continuous spiral fluid flow passage within the interior volume
Implementation Method 2
separates a two-phase fluid flow into a liquid phase portion and a vapor phase portion... utilizing a fluid inlet and outlets to manage the density differential
Implementation Method 3
an auger disposed within the interior volume and extending along a central vertical axis of the shell... defining in association with the shell a continuous spiral fluid flow passage
Data Source
AI summary
A phase separation apparatus is provided for separating a two-phase fluid flow into a liquid phase portion and a vapor phase portion. The phase separation apparatus may be applied to the separation of a two-phase refrigerant flow in a refrigerant vapor compression system operating in a transcritical cycle.