Vapor Cycle Machine Bypass System for Filter Dryer Pressure Loss
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Solution Overview
Problem
Vapor cycle machines (VCMs) face operational disruptions due to the degradation or failure of refrigerant filtration and drying (FDF) components, which can lead to increased pressure loss, reduced flow, and efficiency reduction, potentially causing flight delays or cancellations in aircraft applications.
Innovation Solution
A bypass system with a bypass loop and valve is implemented, allowing partial or complete rerouting of refrigerant flow around the FDF components, enabling continuous operation even during critical filter dryer end-of-life or failure conditions, using a manual or automatic electromechanical bypass valve and secondary FDF components to maintain filtration and drying functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If refrigerant filtration and drying components are used to remove moisture and contaminants, then system reliability is improved, but pressure loss increases and flow decreases over time
Solution Approach 1:
The system is divided into two parallel paths: a primary path through the FDF component and a secondary bypass path. This segmentation allows the refrigerant to be filtered and dried when the FDF is functional, while providing an alternative route when pressure loss becomes excessive, thus resolving the contradiction between reliability and pressure loss.
Solution Approach 2:
The bypass path is pre-configured and ready for use before the FDF component fails. The control system monitors pressure differential across the FDF and automatically redirects flow through the bypass path when degradation is detected, preventing complete system failure and maintaining operation during the transition period.
2Reliability
If refrigerant filtration and drying components operate continuously, then system availability is improved, but component wear increases and maintenance requirements increase
Solution Approach 1:
The system dynamically switches between using the FDF component and the bypass path based on real-time monitoring of pressure differential and operating conditions. The control system adjusts the bypass valve position to optimize the balance between maintaining system availability and preserving FDF component life, extending the interval between maintenance operations.
3Reliability
If a bypass path is added to the refrigerant circuit, then system availability during FDF failure is improved, but device complexity increases
Solution Approach 1:
An electronically controlled valve acts as an intermediary device to manage flow distribution between the FDF path and bypass path. This single control element simplifies the overall system architecture compared to mechanical bypass arrangements, reducing complexity while maintaining the ability to switch paths based on FDF performance.
4Reliability
If the bypass valve is opened to redirect refrigerant flow, then continuous operation is maintained, but filtration and drying function is reduced
Solution Approach 1:
The bypass valve can be positioned to provide partial bypass flow rather than complete bypass, allowing the FDF component to continue providing filtration and drying functions at reduced capacity. This partial action maintains system operation while preserving as much contaminant removal capability as possible, delaying the need for complete FDF replacement.
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 bypass system allows for extended operation of VCMs, preventing shutdowns and maintaining air conditioning and refrigeration capabilities, reducing maintenance and repair costs, and enhancing system availability, while minimizing additional component wear and potential failures.
Implementation Method 1
A bypass valve receives liquid refrigerant flow from the inlet line and routes the liquid refrigerant flow into the bypass line
Implementation Method 2
An orifice positioned in the bypass line limits flow in a manner consistent with normal flow through the refrigerant filter/dryer
Implementation Method 3
a vapor cycle machine with a compressor feeding a condenser, a receiving tank, an expansion valve, and an evaporator
Data Source
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AI summary
A filter dryer functions bypass system (26) in a vapor cycle machine (10) includes a refrigerant filter/dryer (18) receiving a flow of liquid refrigerant from an inlet line (17) and expelling the liquid refrigerant to an outlet line (19). A bypass line (32) interconnects the inlet line and the outlet line and a bypass valve (30) is configured to divert a portion or all of the flow of liquid refrigerant from the inlet line into the bypass line. A condition sensor (46) provides a status signal (48) indicative of refrigerant filter dryer condition and the bypass valve is operable responsive to the status signal.