Expansion Valve Feedback Control for Refrigerant Phase Management
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Solution Overview
Problem
Existing HVAC&R systems fail to adequately control the phase of refrigerant at various locations along the refrigerant circuit, such as within the condenser and evaporator, leading to decreased performance.
Innovation Solution
A vapor compression system with a heat exchanger, expansion valve, sensor, and controller that adjusts the expansion valve based on feedback from temperature sensors to maintain optimal refrigerant phase, pressure, and temperature differences within the condenser and evaporator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing HVAC&R systems use conventional expansion devices, then the system structure is simple, but the refrigerant phase control at various locations along the refrigerant circuit is inadequate, leading to decreased performance
Solution Approach 1:
The patent implements feedback control by using sensors to detect refrigerant conditions (temperature, pressure, phase) at various locations in the refrigerant circuit and using this information to dynamically adjust the expansion valve operation. The controller receives sensor signals and modifies expansion valve positioning based on actual refrigerant state, ensuring proper phase control while adapting to changing operating conditions.
Solution Approach 2:
The patent transitions from static expansion devices to dynamic control systems where the expansion valve position is continuously adjusted based on real-time refrigerant conditions. The system dynamically responds to changes in load, ambient conditions, and refrigerant state by modifying expansion valve opening to maintain optimal refrigerant phase and system performance.
2Productivity
If the expansion valve is adjusted to optimize refrigerant phase control, then the heat exchange capacity improves, but the system requires more complex control mechanisms and sensors
Solution Approach 1:
The controller uses feedback from temperature and pressure sensors to automatically adjust the expansion valve, eliminating the need for manual tuning and reducing the complexity of control mechanisms. The system self-regulates based on sensor inputs, optimizing heat exchange capacity while maintaining manageable system complexity through automated control.
Solution Approach 2:
The system performs self-adjustment of the expansion valve based on sensor feedback, eliminating the need for external intervention or complex manual control mechanisms. The automated control system monitors refrigerant conditions and independently makes adjustments to optimize heat exchange performance.
3Reliability
If temperature sensors are used to provide feedback for expansion valve control, then the system performance and efficiency improve, but the system cost and complexity increase
Solution Approach 1:
The temperature sensors serve multiple functions: they monitor refrigerant temperature for phase control, provide feedback for expansion valve positioning, detect abnormal operating conditions, and enable system diagnostics. This multi-functionality justifies the added complexity by providing comprehensive system monitoring and control capabilities from a single sensor system.
Solution Approach 2:
The sensor feedback system enables precise control of the expansion valve, improving system performance and efficiency. The continuous monitoring and adjustment based on sensor data ensures optimal refrigerant phase and heat exchange performance while the automated control reduces the need for additional complex control mechanisms.
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
Enhances the heat exchange capacity of the evaporator and overall system performance by adjusting the expansion valve to match temperature differences with set points, improving efficiency and operation across different operating conditions.
Implementation Method 1
a heat exchanger configured to facilitate heat transfer between a refrigerant and a conditioning fluid
Implementation Method 2
The condenser is configured to transfer heat from a refrigerant to a cooling fluid, an evaporator is configured to transfer heat from the refrigerant to a conditioning fluid
Implementation Method 3
The vapor compression system may circulate a working fluid, such as a refrigerant, which may change phases between vapor, liquid, and combinations thereof in response to heat transfer with other fluids
Implementation Method 4
an expansion valve configured to direct the refrigerant from the condenser to the evaporator
Data Source
AI summary
A vapor compression system includes a heat exchanger configured to facilitate heat transfer between a refrigerant and a conditioning fluid. The vapor compression system also includes an expansion valve disposed along a conduit coupled to the heat exchanger. The conduit is configured to direct a flow of the refrigerant into the heat exchanger. Additionally, the vapor compression system includes a sensor configured to provide feedback indicative of a temperature of the conditioning fluid exiting the heat exchanger and a controller including a memory and processing circuitry. The processing circuitry is configured to receive a signal indicative of the temperature of the conditioning fluid exiting the heat exchanger from the sensor and adjust operation of the expansion valve based on the signal.