In this study, quantitative analysis was conducted to study the changes in characteristics of surface functional groups of coal char under O2/CO2 atmospheres using Fourier transform infrared analysis. A drop tube furnace was explored. Besides, the effect of the oxygen‐containing functional group on the generation characteristics of NO emission was also investigated. The results showed that CH2/CH3 is highly influenced by the process and atmosphere of coal combustion. The burning of coal increases the contents of aromatic hydrogen and aromaticity on the surface of coal char particles, and it decreases the content of lipid hydrogen. The oxygen concentration exhibits a significant effect on the oxygen‐containing functional groups in coal char, which promotes the reduction reaction of NO. There is an optimum oxygen concentration of 30% that creates the best NO reduction effect caused by the oxygen‐containing functional groups.
In this study, naphthalene heat pipes were produced and filled with different materials to test the heat transfer performance. The relationship between the pipes' diameters, liquid content, wall temperature distribution, and transmission power was studied. An explosion test was designed to assess the operating temperature limit of the naphthalene heat pipes. The results demonstrated an optimum filling amount to optimize the pipes' heat transfer performance. In practical applications, it is very important to strictly control the wall temperature of naphthalene heat pipes. When the wall temperature of the evaporation section reaches approximately 600°C, they can easily explode.
To understand the interactions of coal particles on devolatilization, volatile burning, and char combustion, the combustion characteristics of two interacting equal-sized coal particles placed in the upstream and downstream configuration in a hot laminar flow are numerically investigated. A two-dimensional mathematical model was developed based on the wall surface reaction theory in the commercial software FLUENT. The numerical results show that the particle interaction has different effects on the coal ignition time and combustion characteristics of the upstream and downstream particles. The upstream coal particle undergoes a faster temperature rise, earlier coal devolatilization, and faster char burnout than the downstream one. With increasing the particle separation distance within a certain range, the temperature rise, coal devolatilization, and char combustion processes are further enhanced and weakened for the upstream particle and the downstream particle, respectively. There exists a critical particle separation distance beyond which the combustion processes of the two particles are similar to those of a single particle.
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