Expansion Vessel Air Separation for Track-Bound Vehicle Cooling
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Solution Overview
Problem
Cooling systems for track-bound vehicles face challenges with air entrainment, which reduces flow, causes vibrations, noise, and corrosion, and makes de-airing difficult, leading to incomplete filling and false liquid level indications, requiring costly service units and staff training.
Innovation Solution
An expansion vessel with an air-cushion and a porous body in the by-pass creates a low flow velocity zone for air bubble separation, minimizing air in the main loop and allowing automatic de-airing, while valves regulate pressure and a level indicator ensures proper filling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal bellow is used in the expansion vessel to prevent air existence, then air prevention is improved, but the cost and complexity increase and reserve volume is restricted
Solution Approach 1:
The invention extracts the air separation function from the main cooling loop by introducing a dedicated by-pass circuit with an expansion vessel. Air bubbles are extracted from the cooling liquid and accumulated in the expansion vessel, separating the de-airing function from the primary cooling function. This eliminates the need for complex metal bellow structures while effectively preventing air in the system.
Solution Approach 2:
The by-pass circuit acts as an intermediary between the main cooling loop and the expansion vessel. Cooling liquid with air bubbles flows through the by-pass, allowing air to rise and separate in the expansion vessel before the liquid returns to the main loop. This intermediary circuit simplifies the overall system structure while achieving reliable air removal.
2Reliability
If de-airing is performed manually with separate service units, then air removal is improved, but maintenance cost and time increase
Solution Approach 1:
The expansion vessel with by-pass circuit enables self-service de-airing. As cooling liquid circulates through the by-pass, air bubbles automatically rise and accumulate in the expansion vessel due to gravity and reduced flow velocity. The system continuously removes air without external intervention, eliminating the need for manual service units and reducing maintenance time to minimal periodic draining.
Solution Approach 2:
The de-airing process operates continuously as cooling liquid constantly circulates through the by-pass circuit. Air removal is an ongoing process rather than a periodic manual operation, ensuring the system maintains optimal air-free conditions throughout operation without requiring intermittent maintenance interventions.
3Productivity
If cooling liquid flows at high velocity in the main loop, then cooling performance is improved, but air entrainment and turbulence increase
Solution Approach 1:
The cooling circuit is segmented into a main loop for high-velocity cooling and a by-pass for low-velocity de-airing. The main loop maintains high flow velocity for effective cooling, while the by-pass provides a separate path where cooling liquid slows down, allowing air bubbles to rise and separate without compromising main loop cooling performance.
Solution Approach 2:
Different flow conditions are created in different parts of the system: high velocity in the main loop for cooling efficiency, and low velocity in the by-pass/expansion vessel for air separation. This local differentiation of flow characteristics allows both high cooling performance and effective de-airing to coexist without compromise.
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 design enhances de-airing efficiency, eliminates the need for separate service units, and allows for a larger volume variation, preventing air-induced performance degradation and corrosion, thus improving system reliability and reducing maintenance costs.
Implementation Method 1
creates a low flow velocity zone for air bubble separation, minimizing air in the main loop
Implementation Method 2
a pump configured to make a cooling liquid to circulate in said loop to cool equipment of said vehicle
Implementation Method 3
a heat sink configured to let the cooling liquid absorb heat dissipated in said equipment mounted thereon
Implementation Method 4
a heat exchanger configured to emit heat absorbed from said equipment by said cooling liquid
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A cooling system to be arranged on board a track-bound vehicle has a cooling liquid circulating main loop with a pump (6), a heat sink (3) and heat exchanger (7). It has also a by-pass (9) configured to conduct a minor portion of the cooling liquid flow past part of the main loop and an expansion vessel (10) forming part of said by-pass. The expansion vessel is configured to have an air-cushion (14) in the volume thereof above a surface of said cooling liquid therein. The expansion vessel has a porous body surrounding a rising portion of an inlet tube (16) with apertures.