The Approach of Compensation of Air Refractive Index in Thermal Expansion Coefficients Measurement Based on Laser Feedback Interferometry

We present the thermal expansion coefficient （TEC） measurement technology of compensating for the effect of variations in the refractive index based on a Nd： YA G laser feedback system, the beam frequency is shifted by a pair of aeousto-optic modulators and then the heterodyne phase measurement technique is used. The sample measured is placed in a muffle furnace with two coaxial holes opened on the opposite furnace walls. The measurement beams hit perpendicularly and coaxially on each surface of the sample. The reference beams hit on the reference mirror and the high-refiectivity mirror, respectively. By the heterodyne configuration and computing, the influences of the vibration, distortion of the sample supporter and the effect of variations in the refractive index are measured and largely minimized. For validation, the TECs of aluminum samples are determined in the temperature range of 29-748K, confirming not only the precision within 5 × 10-7 K-1 and the accuracy within 0.4% from 298K to 448K but also the high sensitivity non-contact measurement of the lower reflectivity surface induced by the sample oxidization from 448 K to 748 K.

Investigation of the Effects of a Large Percentage of Dried Sludge on the Operation of a Coal-Fired Boiler

A 600 MW coal-fired boiler with a four-corner tangential combustion mode is considered here to study the combustion features and pollutant emissions at different loads for large-percentages of blending dried sludges.The influence of the over-fired air(OFA)coefficient is examined and the impact of the blending ratio on the boiler operation is explored.The results show that for low blending ratios,a slight increase in the blending ratio can improve the combustion of bituminite,whereas a further increase leads to the deterioration of the combustion of blended fuels and thus reduces the boiler efficiency.Enhancing the supporting capability of the secondary air effectively reduces the slagging degree in the bottom ash hopper and improves the burnout rate of coals.For a large-percentage blending case at full load,it is found that the OFA coefficient must be reduced appropriately,otherwise,a secondary high-temperature combustion zone can be generated in the vicinity of the furnace arches,causing high temperature slagging and superheater tube bursting.Considering the influences of combustion and pollutant emissions,the recommended OFA coefficient is 0.2.Blending dried sludge under low loads increases the flue gas temperature at the furnace exit.While reducing the flue gas temperature in the main combustion region,which is beneficial to the safe operation of the denitrification system.Increasing the blending ratio and reducing load lead to an increase in NOx concentration at the furnace exit Sludges with low nitrogen content are suggested for the practical operation of boilers.

Cylinder Pressure Prediction of An HCCI Engine Using Deep Learning

Engine tests are both costly and time consuming in developing a new internal combustion engine.Therefore,it is of great importance to predict engine characteristics with high accuracy using artificial intelligence.Thus,it is possible to reduce engine testing costs and speed up the engine development process.Deep Learning is an effective artificial intelligence method that shows high performance in many research areas through its ability to learn high-level hidden features in data samples.The present paper describes a method to predict the cylinder pressure of a Homogeneous Charge Compression Ignition(HCCI)engine for various excess air coefficients by using Deep Neural Network,which is one of the Deep Learning methods and is based on the Artificial Neural Network(ANN).The Deep Learning results were compared with the ANN and experimental results.The results show that the difference between experimental and the Deep Neural Network(DNN)results were less than 1%.The best results were obtained by Deep Learning method.The cylinder pressure was predicted with a maximum accuracy of 97.83%of the experimental value by using ANN.On the other hand,the accuracy value was increased up to 99.84%using DNN.These results show that the DNN method can be used effectively to predict cylinder pressures of internal combustion engines.

Effects of Optimized Operating Parameters on Combustion Characteristics and NO_(x)Emissions of a Burner based on Orthogonal Analysis

To optimize the structure of the burner,improve the combustion performance,and reduce the emission of NO_(x),a self-circulating low NO_(x)combustion technology was used to design a new type of flue gas self-circulating low NO_(x)burner.Based on previous research on the numerical model of combustion and the composition of mixed gas on combustion and NO_(x)emissions,the effect of various factors on the ejection coefficient of the flue gas self-circulating structure was analyzed using the orthogonal test method,and the burner operating parameters,such as preheating temperature and excess air coefficient,were deeply studied through the three-dimensional finite element numerical model in this paper.The results show that the diameter ratio of the nozzle and the length of the cylindrical section of the flue gas self-circulating structure have great influence on its ejection and mixing ability.The optimal ejection coefficient was 0.4829.Overall,the amount of NO_(x)emissions greatly increased from 6.23×10^(-6)(volume fraction)at the preheating temperature 973 K to 3.5×10^(-3)at preheating temperature 1573 K.When the excess air coefficient decreased from 1.2 to 1,the maximum combustion temperature decreased from 2036.3 K to 1954.22 K,and the NO_(x)emissions decreased from 352.29×10^(-6)to 159.73×10^(-6).

Experimental Analysis on Influencing Factors of NO_(x)emission in Gas-Fired Heating and Hot Water Combi-Boilers

To study the influencing factors of NO_(x)emission in gas-fired heating and hot water combi-boilers,a boiler with the maximum heat input of 26.0 k W was selected,and influencing factors including flue restrictor diameter,fan power,nozzle aperture,nozzle ejection distance and air relative humidity on NO_(x)formation were determined.The NO_(x)test rig has been built and the concentration of NO_(x)at the rated heat input and the NO_(x)weight value(NO_(x))_(pond)with different heat input in the dry flue gas have been tested respectively according to the test methods in Chinese national standard GB 25034-2010.The results show that with the increase of the diameter of flue restrictor at exhaust outlet,the NO_(x)concentration at the rated heat input and the NO_(x)weight value(NO_(x))_(pond)with different heat input in the dry flue gas decreased by 26.9%and 5.9%;with the increase of the diameter of flue restrictor at air intake inlet,the NO_(x)and(NO_(x))_(pond)decreased by 36.5%and 16.0%;with the increase of fan power,the NO_(x)and(NO_(x))_(pond)can be decreased by 48.4%and 16.1%;with the increase of ejection distance of nozzle,the NO_(x)and(NO_(x))_(pond)decreased by 7.7%and 6.8%;with the increase of aperture of nozzle,the NO_(x)and(NO_(x))_(pond)increased by 5.2%and 2.3%;with the increase of air relative humidity,the NO_(x)decreased by 16.4%and the(NO_(x))_(pond)basically remains unchanged.The analysis of the influence factors of NO_(x)emission can be provided as reference for the optimization design of combi-boilers with low NO_(x)emission.

Analysis of the influencing factors of PAEs volatilization from typical plastic products

The primary emphasis of this research was to investigate the foundations of phthalate（PAEs） pollutant source researches and then firstly confirmed the concept of the coefficient of volatile strength, namely phthalate total content in per unit mass and unit surface area of pollutant sources. Through surveying and evaluating the coefficient of volatile strength of PAEs from typical plastic products, this research carried out reasonable classification of PAEs pollutant sources into three categories and then investigated the relationship amongst the coefficient of volatile strength as well as other environmental factors and the concentration level of total PAEs in indoor air measured in environment chambers.Research obtained phthalate concentration results under different temperature, humidity,the coefficient of volatile strength and the closed time through the chamber experiment. In addition, this study further explored the correlation and ratio of influencing factors that affect the concentration level of total PAEs in environment chambers, including environmental factors, the coefficient of volatile strengths of PAEs and contents of total PAEs in plastic products. The research created an improved database system of phthalate the coefficient of volatile strengths of each type of plastic goods, and tentatively revealed that the volatile patterns of PAEs from different typical plastic goods, finally confirmed that the coefficient of volatile strengths of PAEs is a major factor that affects the indoor air total PAEs concentration, which laid a solid foundation for further establishing the volatile equation of PAEs from plastic products.