Method for controlling level of liquid within an evaporator and a system thereof
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Solution Overview
Problem
Flooded type chiller systems face challenges in maintaining the optimal liquid refrigerant level in the evaporator, leading to inefficiencies and safety issues due to the high cost and complexity of using level sensors, as well as the degradation of system performance from oil carryover.
Innovation Solution
A method and system that measure and calculate various parameters to determine a virtual refrigerant level, allowing the expansion valve to control the refrigerant level without physical sensors, using a controller to maintain a pre-defined target level and manage oil carryover by adjusting the expansion valve operation based on calculated parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If level sensors are used to determine refrigerant level in the evaporator, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent creates a virtual copy of the physical level sensor by using a level gauge that provides visual indication of refrigerant level. This copying approach eliminates the need for expensive electronic level sensors while maintaining measurement capability through the gauge's visual display, directly resolving the contradiction between measurement precision and device complexity
Solution Approach 2:
The patent replaces expensive, complex electronic level sensors with a simple, inexpensive level gauge that can be easily installed and maintained. This substitution uses a low-cost component to achieve the same functional purpose, reducing overall system complexity and cost while maintaining adequate measurement precision
2Measurement precision
If level sensors are installed on the evaporator, then refrigerant level control is improved, but ease of manufacture and installation deteriorate
Solution Approach 1:
The level gauge serves as a simplified copy of electronic sensor systems, providing refrigerant level information without requiring complex electrical connections, mounting brackets, or integration with control electronics. This makes installation significantly easier while maintaining level control capability
Solution Approach 2:
The patent extracts the level measurement function from the complex electronic sensor system and implements it through a standalone level gauge that operates independently. This extraction eliminates the need for electrical harnesses, power connections, and complex mounting procedures, greatly simplifying installation
3Quantity of substance
If expansion valve opens to feed additional refrigerant, then refrigerant level is maintained, but oil carryover increases
Solution Approach 1:
The patent uses the level gauge to provide continuous visual feedback on refrigerant level, allowing the operator to monitor and adjust expansion valve operation to maintain proper levels without causing oil carryover. This feedback mechanism enables precise control that prevents the harmful effect of excessive refrigerant feeding
Solution Approach 2:
The system enables self-monitoring and self-adjustment of refrigerant levels through the level gauge, allowing the operator to maintain optimal levels and prevent oil carryover without requiring complex automated control systems. The visual feedback allows the system to self-regulate
4Measurement precision
If physical level sensors are used, then refrigerant level detection is accurate, but cost increases
Solution Approach 1:
The level gauge creates a visual copy of the refrigerant level information that can be read directly, eliminating the need for expensive electronic sensors. This copying approach provides accurate level detection at a fraction of the cost of electronic sensor systems
Solution Approach 2:
The patent substitutes expensive electronic level sensors with an inexpensive level gauge that provides adequate measurement precision for the application. This cost-effective component achieves the same functional goal without the high price tag of electronic sensing systems
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 approach reduces costs by eliminating the need for level sensors, stabilizes chiller operation, automatically manages oil carryover, and ensures efficient operation even with reduced water flow or refrigerant leakage, maintaining optimal refrigerant levels and heat transfer efficiency.
Implementation Method 1
The evaporator vaporizes the liquid refrigerant in shell and returns to a suction inlet of the compressor
Implementation Method 2
heat exchange with water in the tube causes it to become Low Pressure Refrigerant Vapour
Implementation Method 3
the condenser receives the compressed refrigerant gas and condenses to a liquid refrigerant
Data Source
AI summary
A method controls the level of liquid within an evaporator of a flooded-type chiller without level sensors. The flooded-type chiller includes at least one compressor, a condenser, an expansion valve and an evaporator. A number of sensors positioned in the system measures a number of first parameter information values. A controller calculates a number of second parameter information values based on the measured first parameter information values and further determines a virtual refrigerant level as a control signal based on the second parameter information values. Based on the determined virtual refrigerant level, the controller opens, closes or holds the expansion valve with respect to a dead zone for maintaining a pre-defined target refrigerant level so as to provide the desired refrigerant level and oil in the evaporator.