Study On Measurement Of Biomass Combustion Temperature Field Based On Digital Holography

Biomass is a kind of energy-saving and environmental protection resource with large reserves and renewable resources.As the core reaction area of combustion,the temperature of the flame is one of the key indicators to characterize the performance of the fuel.In recent years,methods for measuring the temperature of biomass combustion have emerged in an endless stream,but most of these methods cannot be measured in real time and in full quantities.Based on the above considerations,this paper takes the online detection of biomass combustion temperature field as the theme,and uses the advantages of digital holographic technology to be non-contact,non-destructive and real-time in the whole field to achieve the purpose of real-time and full measurement of flame temperature.It lays the foundation for online measurement of biomass combustion temperature field based on digital holographic temperature measurement technology,and also provides new ideas for the means of in-depth study of material combustion mechanism.The main research contents are as follows:(1)Combined with Mckenna flat flame burner,the biomass combustion temperature field measurement system based on digital holography is designed and built.Through the experiment,the working condition of methane-oxygen mass fraction ratio of 0.9 was selected as the experimental condition of biomass combustion,and the optimal selection of the stability of the experimental combustion environment was realized.(2)An automatic spectrum extraction method is proposed to realize the extraction of the positive phase spectrum of biomass combustion package.Calculate and compare the MSE,PSNR,SSIM,edge retention ability and fidelity of a variety of commonly used filters,select wavelet denoising,and propose wavelet threshold denoising on the basis of which to realize the filtering of the experimental phase,and use the least squares method to realize the unpacking of the parcel phase.(3)The Abel ring belt method was used to reconstruct the combustion temperature field of six biomass species,and the temperature of the fixed point in the field was measured by the K-type thermocouple verification device,and the error analysis of the experimental results was carried out.The relative error is within 6%,the average error is about 2.78%,and the experimental results verify the applicability and feasibility of digital holographic technology for temperature field distribution measurement.At the same time,digital holograms can measure the full temperature field in real time rather than the temperature at a certain point.The flame temperature and combustion cycle are positively correlated with the biomass hydrocarbon content,the combustion cycle is negatively correlated with the ash content,and the influence of ash on the combustion cycle is much greater than the impact of the hydrocarbon content.The oxygen concentration content in biomass increased,and the ignition delay time,volatile combustion time and carbon combustion time of biomass fuels all showed a downward trend.This project verifies the feasibility and real-time fullness characteristics of digital holographic technology for biomass combustion temperature field research,and also provides new ideas for further understanding the research methods of biomass ignition and its combustion mechanism.