Absorption Heat Pump Control Using Vapor Mixing Ratio Measurement
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Solution Overview
Problem
Absorption heat pumps face inefficiencies due to the variable mixing ratio of refrigerant vapor to solvent vapor, making it difficult to control and optimize their operation for best efficiency across different output levels.
Innovation Solution
Measuring temperature and pressure of the steam mixture after it's removed from the generator and before it enters the condenser allows for determination of the mixing ratio, enabling optimized control of the heat pump by adjusting the expansion valve and solvent throttle based on calculated manipulated variables to maintain optimal condensation and evaporation temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the heat pump operates at different outputs, then the mass flow through the generator varies, but the variable mixing ratio of refrigerant vapor to solvent vapor makes it difficult to control and maintain optimal efficiency
Solution Approach 1:
The patent implements a feedback control system where the mixing ratio of refrigerant vapor to solvent vapor is continuously measured and used to adjust the mass flow through the generator. This closed-loop control enables the heat pump to maintain optimal efficiency across different output levels by dynamically compensating for variations in vapor composition, thereby resolving the control difficulty associated with operating at variable outputs.
Solution Approach 2:
The patent changes the operating parameters of the heat pump system by adjusting the mass flow rate through the generator based on the measured mixing ratio. By dynamically modifying this parameter in response to varying output conditions and vapor composition, the system maintains optimal performance across different operating points, transforming a static control problem into a dynamic adaptive system.
2Productivity
If the steam mixture has higher water content at higher outputs, then the mass flow increases, but the purity of the steam mixture decreases affecting condensation temperature and efficiency
Solution Approach 1:
The control system uses feedback from the measured mixing ratio to adjust the mass flow through the generator, ensuring that even at higher outputs where water content naturally increases, the condensation process remains efficient. The system compensates for purity variations by dynamically controlling operating parameters, maintaining reliable condensation efficiency across the full output range.
Solution Approach 2:
The system takes preliminary action by measuring the mixing ratio before condensation and using this information to pre-adjust the mass flow and operating conditions. This anticipatory control prevents the negative effects of variable purity on condensation efficiency, counteracting the problem before it significantly impacts performance.
3Ease of operation
If temperature and pressure measurements are taken to determine mixing ratio, then control optimization is enabled, but measurement and control complexity increases
Solution Approach 1:
The patent introduces temperature and pressure measurements as intermediary parameters that indirectly provide information about the mixing ratio. Rather than directly measuring the complex vapor composition, the system uses these simpler, more readily obtainable measurements as mediators to infer mixing ratio and enable control optimization with relatively simple instrumentation.
Solution Approach 2:
The patent replaces complex direct composition measurement systems with simpler thermal and pressure sensing systems. By substituting mechanical or chemical analysis methods with temperature and pressure measurements, the system achieves control optimization while minimizing the addition of measurement and control complexity.
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 improves the efficiency of the absorption heat pump by ensuring optimal condensation and evaporation processes, maintaining the desired temperature difference and pressure levels, thus enhancing heat transfer and reducing energy consumption.
Implementation Method 1
a temperature T 1 of the steam mixture is determined by means of a temperature sensor (16)
Implementation Method 2
a pressure P 1 of the steam mixture is determined by means of a pressure sensor (14)
Implementation Method 3
condensed in a condenser, with condensation heat being supplied to a consumer through the condenser
Implementation Method 4
A fluid (steam or a mixture of steam and liquid) is generated from the completely or partially condensed vapor mixture and the fluid is expanded by means of an expansion valve
Implementation Method 5
The expanded fluid is fed to an evaporator for at least partial evaporation of the expanded fluid while absorbing heat from a heat source
Implementation Method 6
The fluid is then fed to an absorber, where it is mixed with a low-refrigerant solution and absorbed by it
Implementation Method 7
the generator is first heated using a heat source in order to expel a vapor mixture of refrigerant vapor and solvent vapor from a solution
Data Source
Figure 1
AI summary
The present invention relates to a method for controlling an absorption heat pump in a cyclic process. According to the invention, the temperature T1 and the pressure P1 of the extracted vapor mixture are measured at least intermittently and/or during a start-up phase of the absorption heat pump at a point after the extraction of a vapor mixture from a generator (20) and before its supply to a condenser (30), and the mixing ratio of the vapor mixture is determined from these data.