Three-Way Modulating Valve With Nonlinear Bypass Temperature Control
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Solution Overview
Problem
Existing temperature control systems for spacecraft environments, which use large three-way modulating valves to control air temperature by modulating the flow of cooling fluid through a heat exchanger, face challenges due to the large size of the valves and linear changes in flow rates, which do not efficiently manage the non-linear response of the heat exchanger.
Innovation Solution
A three-way modulating valve positioned upstream of the heat exchanger on the cooling fluid line, with a non-linear flow bypass ratio and pressure drop profile, allows for infinitely variable flow rates between 0 and 100%, reducing the valve size and maintaining constant hydraulic resistance, achieved through a unique shape of valve windows that change flow rates and pressure drop in a non-linear manner.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a large three-way modulating valve is used to control the flow of cooling fluid through a heat exchanger, then the temperature control capability is sufficient, but the valve size becomes large and the system complexity increases
Solution Approach 1:
The valve body is divided into multiple flow paths including a first flow path through the heat exchanger and a second flow path bypassing it. The valve member segments the cooling fluid flow to distribute it between these paths, allowing temperature control without requiring a single large valve component.
Solution Approach 2:
The three-way modulating valve performs multiple functions: it controls the flow rate of cooling fluid through the heat exchanger, provides a bypass path for temperature compensation, and maintains system pressure. This multi-functionality allows adequate temperature control with a more compact valve design.
2Ease of operation
If a linear change in flow rate is used to modulate the cooling fluid, then the valve operation is simple, but the non-linear response of the heat exchanger cannot be compensated
Solution Approach 1:
The system incorporates feedback through temperature sensors that monitor the temperature of the first fluid downstream of the heat exchanger. This feedback signals to the control system to adjust the valve position, compensating for non-linear heat exchanger response and achieving linear temperature control through iterative adjustment.
Solution Approach 2:
The valve transition from static linear control to dynamic modulation where the flow rate is continuously adjusted based on temperature feedback. The valve operates in a dynamic manner, changing its opening position in response to real-time temperature measurements to compensate for non-linear heat exchanger characteristics.
3Temperature
If the valve position is changed to modulate flow rate, then the temperature control is achieved, but the hydraulic resistance varies causing system instability
Solution Approach 1:
The valve is designed with specific geometric parameters including flow area ratios and passage dimensions that maintain relatively constant pressure drop characteristics across different valve positions. By carefully selecting these parameters, the valve modulates flow rate while minimizing variations in hydraulic resistance, thereby maintaining system stability.
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 solution enables a linear temperature response in the cooled air while reducing the valve size and maintaining constant system hydraulic resistance, allowing for a more efficient and cost-effective temperature control system, suitable for manned spacecraft applications.
Implementation Method 1
a system controls the temperature of the air being delivered into a spacecraft environment by passing the air through a heat exchanger to cool the air with a cooling fluid
Data Source
AI summary
A temperature sensor for a first fluid senses a temperature of the first fluid downstream of a heat exchanger. A supply for a second fluid changes a temperature of the first fluid. The supply for the second fluid passes through the heat exchanger. A valve is positioned upstream of the said heat exchanger on the supply for the second fluid, and controls a flow rate of the second fluid diverted into a bypass line compared to a flow rate of the second fluid directed through the heat exchanger, with the three-way valve controlled by a control in response to feedback from said temperature sensor. The valve changes the respective flow rates delivered into the bypass line and through the said heat exchanger in a non-linear manner with a change in valve position. A manned spaceship is also disclosed.