Two-Phase Fluid Loop Pressure Control for Cavitation Prevention
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Solution Overview
Problem
Current methods for controlling pressure in two-phase fluid loops with mechanical pumping fail to guarantee minimum subcooling, leading to cavitation risks and temperature cycling issues, and do not optimize operational constraints, resulting in inefficient thermal management and component stress.
Innovation Solution
A device and method for dynamically regulating pressure in a two-phase fluid loop with mechanical pumping, using temperature and pressure sensors to adjust the saturation temperature, ensuring liquid-only conditions at the pump and minimizing subcooling, and controlling temperature variations to prevent cavitation and fatigue in dissipative equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If simple pressure control is used to maintain maximum pressure level, then the pressure regulation is simple, but minimum subcooling is not guaranteed leading to cavitation risks
Solution Approach 1:
The control device continuously measures the actual pressure in the fluid loop and compares it with the desired pressure setpoint. Based on this feedback, the mechanical pump's operating point is adjusted to maintain pressure within a range that ensures minimum subcooling and prevents cavitation, while avoiding excessive pressure that would limit dissipative equipment temperature range.
Solution Approach 2:
The invention changes the control parameter from simple maximum pressure maintenance to dynamic pressure regulation that ensures minimum subcooling. The control device adjusts the mechanical pump's operating point based on actual pressure measurements, thereby controlling the saturation temperature and ensuring liquid-only conditions at the pump inlet to prevent cavitation.
2Temperature
If high pressure is maintained to increase saturation temperature, then the temperature transport capacity increases, but temperature cycling and fatigue stress on equipment increase
Solution Approach 1:
The invention implements dynamic pressure control that adapts to varying thermal conditions. Rather than maintaining constant high pressure, the control device adjusts the mechanical pump's operating point in real-time based on actual pressure measurements, thereby dynamically controlling saturation temperature to limit thermal cycles while maintaining adequate heat transport capacity.
Solution Approach 2:
The control system uses feedback from pressure measurements to regulate saturation temperature. By comparing actual pressure with desired pressure ranges, the system adjusts the pump operation to maintain saturation temperature within limits that prevent excessive thermal cycling, thereby protecting equipment from fatigue stress.
3Temperature
If flow rate is increased to transport all power in single-phase loop, then temperature differences are reduced, but the mass of the loop increases significantly
Solution Approach 1:
The invention utilizes phase transitions (evaporation and condensation) in the two-phase fluid loop to transport thermal power efficiently. The mechanical pump circulates liquid refrigerant to the evaporator where it evaporates, absorbing heat from dissipative equipment. This phase change mechanism enables effective heat transport without requiring the high flow rates needed in single-phase systems, thereby reducing loop mass.
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 ensures stable operation by maintaining sufficient subcooling to prevent cavitation, optimizing thermal management, and reducing thermoelastic stresses, thereby enhancing the reliability and efficiency of the fluid loop and dissipative equipment.
Implementation Method 1
an evaporator, through which the fluid circulates and evaporates to a partially gaseous state (called two-phase) under the effect of the energy supplied by the dissipative equipment
Implementation Method 2
a condenser, through which the fluid in partially gaseous form circulates at the inlet and transforms into liquid fluid
Implementation Method 3
a pump, arranged between the outlet of the condenser and the inlet of the evaporator, intended to set the fluid in motion in the closed circuit from the evaporator to the condenser in partially gaseous form and from the condenser to the evaporator in liquid form
Data Source
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AI summary
The invention relates to a device (10) for controlling the pressure of a fluid in a mechanically pumped two-phase fluid loop, comprising a closed circuit (11) in which a heat transfer fluid (20) circulates, an evaporator (12) through which the fluid circulates in liquid form (20-liq), the evaporator (12) being configured to transform the fluid in liquid form (20-liq) into fluid in a partially gaseous form (20-g), a condenser (15) through which the fluid, the condenser (15) being configured to transform the fluid in a partially gaseous form (20-g) into fluid in liquid form (20-liq), a pump (18), disposed between the condenser (15) and the evaporator (12), intended to move the fluid in the closed circuit (11) from the evaporator (12) to the condenser (15) in a partially gaseous form (20-g) and from the condenser (15) to the evaporator (12) in liquid form (20-liq), a fluid reservoir (19) connected to the closed circuit (11),intended to compensate for variations in fluid volume in the closed circuit (11); the control device (10) being characterized in that it comprises a means for controlling (26) the pressure adjustment device (25) or the saturation temperature, as a function of a measured value (24, 29) of fluid pressure or saturation temperature and a setpoint value of pressure or saturation temperature, said setpoint value of pressure or saturation temperature being variable according to a measured value (22) of the temperature of the fluid in liquid form (20-liq) and a maximum value of the temperature of the reservoir (19) or of the maximum pressure in the closed circuit (11) over a predefined period,