Helical Flash Tank 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 phase density to vapor phase density ratio.
Innovation Solution
A phase separation apparatus with a cylindrical shell and an auger assembly featuring a helical spiral member within the shell, which separates two-phase refrigerant flows into vapor and liquid phases by utilizing density differentials and minimizing intermixing through a continuous spiral fluid flow passage, with vapor phase rising and liquid phase descending, and includes a support tube and end caps for structural integrity.
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 achieved, but the apparatus becomes bulky and heavy
Solution Approach 1:
The flash tank interior is segmented into multiple functional zones using a divider plate: a separation chamber for initial phase separation, a settling chamber for completing separation, and a baffle system to control fluid flow patterns. This segmentation enables effective phase separation in a compact volume by creating distinct functional regions that work together.
Solution Approach 2:
The invention introduces vertical dimensionality through a multi-level baffle arrangement and elevated outlet pipes. The liquid outlet pipe is positioned at the bottom while the vapor outlet pipe extends to the top, creating vertical flow paths that maximize separation efficiency within a compact horizontal footprint, effectively utilizing three-dimensional space.
2Volume of moving object
If the flash tank is made compact, then size restrictions are met, but structural durability under vibration is compromised
Solution Approach 1:
The flash tank is constructed as an assembly of multiple components (tank body, divider plate, baffle elements, inlet/outlet connections) that can be manufactured separately and then assembled. This modular segmentation allows each component to be optimized for its specific function while maintaining overall structural integrity, making the system more durable under vibration.
Solution Approach 2:
The divider plate and baffle elements are pre-positioned and secured within the tank during assembly to create a rigid internal framework before the tank is put into service. This preliminary structural arrangement ensures that the internal components can withstand vibration and movement forces without compromising the tank's compact design.
3Adaptability or versatility
If carbon dioxide is used as refrigerant, then natural refrigerant benefit is achieved, but phase separation becomes difficult due to low density ratio
Solution Approach 1:
The invention creates localized regions with different flow characteristics within the flash tank. The divider plate and baffle elements generate areas of high velocity and low velocity zones, creating local conditions that enhance phase separation even when the overall density ratio is low. This local quality variation compensates for carbon dioxide's low liquid-vapor density ratio.
Solution Approach 2:
The internal geometry of the flash tank, including the baffle arrangement and outlet positioning, is designed to create dynamic flow patterns that adapt to the low density ratio characteristics of carbon dioxide. The elevated outlet pipes and angled baffles promote continuous circulation and mixing that enhances separation efficiency for refrigerants with low density differentials.
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
Effectively separates refrigerant phases in a compact and lightweight form, reducing sloshing and intermixing due to vibration, enhancing the natural separation of vapor and liquid phases and maintaining system efficiency in transport refrigeration applications.
Implementation Method 1
separates two-phase refrigerant flows into vapor and liquid phases by utilizing density differentials and minimizing intermixing through a continuous spiral fluid flow passage, with vapor phase rising and liquid phase descending
Implementation Method 2
minimizing intermixing through a continuous spiral fluid flow passage
Data Source
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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.