Study On Numerical And Experimental Performance Of A Vertical Falling-Film Absorption Heat Transformer

As energy consumption continues to grow and environmental pollution becomes more and more serious,China has set the goal of reaching a "carbon peak" by 2030 and becoming "carbon neutral" by 2060.In the energy consumption,the industrial sector accounts for up to 45%,but a considerable part of its energy input is discharged into the environment in the form of industrial waste heat.And industry,construction and transportation have a very large demand for cooling and heating load.The absorption heat transformer is a kind of efficient use of low temperature waste heat for temperature raising equipment,can meet the needs of high-quality steam and hot water in the industry.This paper focuses on the dynamic performance of the vertical falling-film absorption heat transformer,mainly including the mechanism of heat and mass transfer of vertical falling-film,experimental performance of variable flow and temperature parameters,dynamic performance in different operating stages and the integration of heat transformer system.This paper also analyzes the existing experimental data of the absorption heat transformer to analyze its steady and dynamic performance under different heat source water flow rate and temperature.The experimental analysis reveals the dynamic and steady state change rules of temperature,pressure,heat and other parameters in the process of changing heat source water temperature and flow rate,expounds the gradual change process of the absorption heat transformer,and deeply analyzes the influence process of heat source water temperature and flow rate change.In order to study the heat and mass transfer mechanism of the vertical falling film process,the paper design to build a single/multiple vertical tube falling film experiment platform and generatedabsorbed vertical falling-film experiment platform.From the falling film tube design and sensitive parameters analyzes of the two dimensions research vertical falling film process,this paper puts forward a new method that not destroys liquid membrane cases and can accurately measure the falling film tube inside and outside temperature,and provides guidance advice to form vertical falling-film absorption systems.In this paper,the lumped parameter method is used to establish the dynamic model of the absorption heat transformer.The model is verified with the experimental data of the existing experimental platform and relevant literature,and the model has good accuracy.In this paper,the model is used to study the dynamic performance under different operating states such as start-up,variable load and operation fluctuation,focusing on the response time and anti-fluctuation ability.In order to describe the storage of the solution,the characteristic time of solution storage is defined in this paper.The simulation results show that smaller solution reserves and larger solution mass flow rate are more favorable in the process of start-up and load changing.Large solution storage and small solution mass flow rate will increase the stability of the heat pump during the operation fluctuation.In the process of operation,the response time of the heat pump has a linear relationship with the characteristic time of solution storage.The fluctuation amplitude of the heat pump has a negative exponential relationship with the characteristic time of solution storage and is mainly related to the mass flow of the solution.On this basis,this paper proposes a new system integration method and control strategy of the absorption heat transformer.Simulation study shows that the new system has faster response speed and higher stability,which provides guidance for the subsequent operation of absorption heat transformers.