Absorption Air Conditioner Pressure Control Against LiBr Crystallization
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Solution Overview
Problem
Existing absorption air-conditioning devices face challenges in accurately and efficiently controlling the concentration of absorbing fluids like lithium bromide to prevent crystallization and enhance reactivity, with existing methods being slow and less effective.
Innovation Solution
A method involving a control process that calculates the concentration of the absorbing fluid by measuring coolant vapor pressure and solution temperature, using a formula to adjust the head loss in the duct connecting the desorber and condenser, thereby managing the risk of crystallization and improving system reactivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the concentration of absorbing fluid is increased to prevent crystallization, then the reliability of the system is improved, but the productivity of the air-conditioning device deteriorates due to reduced cooling efficiency
Solution Approach 1:
The system continuously measures the concentration of absorbing fluid using a concentration sensor and compares it to reference values. When the concentration exceeds the upper reference value (indicating crystallization risk), the controller automatically adjusts the flow rate of absorbing fluid or activates the heater to reduce concentration. When concentration is below the lower reference value, the controller increases flow rate to enhance cooling. This closed-loop feedback mechanism dynamically maintains concentration within optimal ranges, simultaneously ensuring reliability (preventing crystallization) and productivity (maintaining cooling efficiency).
Solution Approach 2:
The system dynamically adjusts key parameters including the flow rate of absorbing fluid through flow rate control, the temperature of absorbing fluid via heater activation, and the concentration of absorbing fluid itself. By changing these parameters in response to real-time concentration measurements, the system optimizes the balance between preventing crystallization and maintaining cooling performance, resolving the contradiction between reliability and productivity.
2Productivity
If the concentration of absorbing fluid is decreased to improve cooling efficiency, then the productivity is improved, but the reliability deteriorates due to increased crystallization risk
Solution Approach 1:
The concentration sensor continuously monitors absorbing fluid concentration and provides feedback to the controller. When concentration drops below the lower reference value (indicating reduced crystallization risk but potentially insufficient cooling), the controller increases the flow rate of absorbing fluid to enhance cooling efficiency. When concentration rises toward the upper reference value, the controller reduces flow rate or activates heating to prevent crystallization. This real-time feedback enables dynamic optimization of the reliability-productivity tradeoff.
Solution Approach 2:
The system transitions from static concentration control to dynamic control by continuously adjusting the flow rate of absorbing fluid and heater activation based on real-time concentration measurements. This dynamic adjustment allows the system to adapt to changing operating conditions, maintaining optimal balance between preventing crystallization (reliability) and maximizing cooling efficiency (productivity) throughout operation.
3Reliability
If a complex control method is used to accurately manage concentration, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The system employs a concentration sensor that automatically measures absorbing fluid concentration and a controller that autonomously compares measurements to reference values and adjusts flow rate or heater activation without manual intervention. This self-service automated control achieves accurate concentration management (improving reliability) while eliminating the need for complex manual control procedures, effectively managing device complexity through automation.
Solution Approach 2:
The system replaces complex mechanical concentration adjustment mechanisms with electronic sensing and control. The concentration sensor electronically measures concentration, and the controller electronically adjusts flow rate valves and heater activation, substituting complex mechanical control systems with simpler electronic systems that achieve more precise control with fewer moving parts, thereby improving reliability while managing device complexity.
4Device complexity
If manual adjustment methods are used for concentration control, then the device complexity is reduced, but the speed of response deteriorates
Solution Approach 1:
The concentration sensor provides continuous real-time feedback on absorbing fluid concentration to the controller, which immediately processes the information and adjusts flow rate or heater activation. This automated feedback loop enables rapid response to concentration changes without manual intervention, significantly improving response speed while keeping the control system relatively simple through the use of basic sensing and actuation components.
Solution Approach 2:
The system automatically monitors concentration and adjusts parameters without requiring manual operation. The concentration sensor and controller work together to self-regulate the system, eliminating the time delay associated with manual measurement and adjustment while maintaining relatively simple device architecture through automated self-service control.
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 method allows for faster and more accurate control of the absorbing fluid concentration, effectively managing the risk of crystallization and enhancing the reactivity of the air-conditioning device, providing immediate and effective shutdown of condensation to prevent crystallization.
Implementation Method 1
The desorber receives heat, and this outside contribution permits the evaporation of the liquid coolant from the mixture
Implementation Method 2
This coolant fluid is then condensed in the condenser by cooling
Implementation Method 3
The liquid obtained is trapped and evaporated in the evaporator and thus produces the cold of the air-conditioning
Implementation Method 4
The absorber allows the solution fix the coolant fluid molecules and, in this way, to maintain a low pressure
Implementation Method 5
The solution/coolant fluid reaction is exothermic
Data Source
AI summary
The invention relates to an absorption air conditioner that comprises a desorber (100), a condenser, an evaporator and an absorber, wherein the absorbing fluid may consist of lithium bromide. The method comprises the following steps: calculating the concentration of the absorbing fluid solution at the outlet of the desorber (100); and comparing the calculated concentration with a predetermined critical value and, if the calculated concentration gets closer to the predetermined critical value, increasing the charge loss in the duct (20) connecting the desorber (100) to the condenser, which interrupts the condensation in the condenser and results in a pressure increase in the desorber that stops the desorption and in a concentration increase, the charge loss being on the other hand reduced for resuming the desorption when the calculated concentration deviates from the predetermined critical value. The invention can be used in automobiles and absorption air-conditioners.