The Thermal Characteristics Measurement And Analysis Of Biomass Straw And DSC Curve Fitting

Biomass is a valuable resource in our country, thermal Characteristics is the basis of energy utilization.Collecting485biomass,which include317rice straw,46wheat straw and122rape straw in order to analyze biomass thermal characteristics in different regions and different types. Determination of specific heat capacity and thermal conductivity of samples at room temperature.Comparing and analysing biomass straw specific heat capacity and thermal conductivity of different regions and different types.Explore the influence of different moisture content, particle size, bulk density on its specific heat capacity and thermal conductivity. In addition, adopting reference method to determined the specific heat capacity of rice and wheat using DSC200F3type instrument.Making the statistics and analysis for specific heat capacity measurement results and DSC curves. Using the Gauss function, Polynomial function and Rational function to fitting the DSC curve of samples in MATLAB,then establish fitting model of the heat capacity of rice straw and wheat straw and make external authentication for the model. The study results are as follows:(1)Comparing of biomass straw specific heat capacity and thermal conductivity of different regions and different types. The results show that there exist significant differences between Hubei, Hunan and Yunnan of rice straw specific heat capacity.For the thermal conductivity of rice straw,there is no significant difference between Hubei and Hunan,but these two province have a very significant difference with Yunnan; For rape straw, Hunan and Sichuan have a very significant difference with Hubei Province in specific heat capacity and thermal conductivity and there is no significant difference between Hunan and Sichuan.Analysing thermal characteristics of different kinds of biomass straw,the results show that wheat straw and rape straw has no significant difference in the heat capacity but both of them have a very significant difference with rice straw;There exist Significant difference between rice straw and rape straw in thermal conductivity.However, There was no significant difference between the rice straw and wheat straw,the rape straw and wheat straw.(2)Investigating the influence on the thermal conductivity and specific heat capacity of different moisture content, particle size and bulk density.The results showed that, within a certain range, as the moisture content increases, the thermal conductivity is gradually increased, the moisture content has a significantly effect on the thermal conductivity of wheat straw and a very significant effect on the rice straw and rape straw; The specific heat capacity showes a decreasing trend,the moisture content was not significantly affect on the specific heat capacity of rice straw and has a very significantly affect on wheat straw. Rice straw sample is divided into five particle size samples which are>20mesh,20-40mesh,40-60mesh,60-80mesh and<80mesh screen. As the particle size decreases, the thermal conductivity is gradually increased, specific heat capacity of the sample of rice straw is firstly increased, and then reduced when<80mesh. Statistical analysis indicated that the size of the particle size has a significant effect on the thermal conductivity and specific heat capacity of rice straw. With the bulk density increased,the thermal conductivity coefficient values of wheat straw and rape straw are significantly increased. The bulk density have a significant effect on the thermal conductivity of rice straw and significant affect on the thermal conductivity of wheat straw and rape straw. However, with the change of the bulk density, specific heat capacity of the three straw samples don’t change significantly,the variance analysis also shows that the bulk density has no significant effect on the specific heat capacity of three straw samples.(3)Adopting reference method to determined the specific heat capacity of rice and wheat using DSC200F3type instrumen.Making the statistics and analysis for specific heat capacity measurement results and DSC curves. Using the Gauss function, Polynomial function and Rational function to fitting the DSC curve of samples in MATLAB,then establish fitting model of the heat capacity of rice straw and wheat straw and make external authentication for the model. The results show that rice straw specific heat capacity is between0.7886J/mg.K-6.5895J/mg.K while wheat straw specific heat capacity is between0.5831/mg.K-6.4835J/mg.K durning the temperature30℃to200℃and the temperature has a great influence on specific heat capacity, as well as by the geographical,variety and growing environment. The variation of rice straw and wheat straw DSC curve is basically the same and the curve shape is similar to the normal distribution curve which have apparent "tail" phenomenon; The heat capacity curve of rice straw and wheat straw can be described using a Gaussian function which have a high prediction accuracy. The correlation coefficient between the measured value and model predictive value of the specific heat capacity of rice straw is0.9986,and variance and standard deviation values are0.6481and0.0454while the correlation coefficient between the measured mean value and model predictive value of the specific heat capacity is0.9988,the SSE and RMSE are0.8312and0.0514.