Numerical Study on the Effect of Fuel Rich n-Heptane on In-Cylinder Fuel Reforming Characteristics in an HCCI Engine

The effect of in-cylinder fuel reforming on an n-heptane homogenous charge compression ignition engine has been studied. A dedicated cylinder without a complex control system is proposed for fuel enrichment reforming, which can provide part of the power for the engine. The effects of different reforming species on engine performance and chemical reaction have been simulated by a numerical study. By comparing the combustion characteristics of n-heptane with different equivalence ratios in the reformer cylinder, the optimal n-heptane equivalence ratio has been determined. The enrichment of n-heptane produces sufficient hydrogen (H2) and carbon monoxide (CO), while the hydrocarbon content of the reforming species was low. It was found that the addition of reforming species retards the combustion phase of n-heptane, thereby providing a means of controlling engine performance. In addition, the laminar flame speed and the adiabatic flame temperature of n-heptane increased by adding H2 and CO. Fuel reforming reduced the emission of ethylene, propyne, allene, propylene, butadiene, and nitrogen oxide, but it increased the emissions of acetylene and CO. Moreover, chemical, dilution, and thermodynamic effects of the reforming gas have been studied. The results showed that the chemical effect of the reforming species was less significant than the dilution and thermodynamic effects. These simulation results showed that in-cylinder fuel reforming can effectively improve engine performance and thereby reduce emissions.

Modeling And Optimization Study of PEMFC Fueled With Ammonia Reforming Gas

The storage of high-purity hydrogen has been a technical challenge limiting the large-scale application of fuel cells. Ammonia is an ideal hydrogen storage carrier with a storage mass density of up to 17 wt% and can be easily liquefied for storage and transportation, but ammonia requires complex separation equipment to re-generate high-purity hydrogen, which greatly reduces its advantages in hydrogen storage. Therefore, the development of direct ammonia reforming gas fuel cells, which can avoid complicated pure hydrogen separation equipment, has a very meaningful impact and can greatly expand the application of fuel cells. In this paper, we study the modeling simulation of ammonia reforming gas-fueled proton exchange membrane fuel cell (PEMFC) based on the preliminary experiments, and the concentration-dependent Butler-Volmer electrochemical model is used to simulate the ammonia reforming gas-fueled PEMFC. Firstly, the concentration-dependent Butler-Volmer electrochemical model was improved by adding a correction factor for the concentration difference polarization based on the characteristics of the experimental data to obtain a correction factor of 1.65 based on the experimental data; secondly, the effect of the anode channel length on the fuel cell performance was investigated. The results show that: firstly, the improved concentration-dependent Butler-Volmer electrochemical model can better match the experimental results; secondly, the anode channel length has less effect on the maximum power density and hydrogen concentration in the exhaust gas, and the current density gradient increases with decreasing anode channel length, but the fuel flow resistance decreases. The results of the study can provide a reference for the simulation study of PEMFC using ammonia reforming gas as fuel.

Biogas Reforming Conversion Character on Microwave-heating Carbon Receptor

Objectives:Methane (CH₄) and carbon dioxide (CO₂) are the main components of biogas and are produced from biomass gasification. These two gases are a by-product gases that can be used as an energy source and is known as a greenhouse gas that affects global warming. In order to convert the gas which is the main cause of global warming into high-quality fuel energy, the microwave reforming characteristic research was conducted. In this study, the reforming characteristics of microwave carbon receptor pyrolysis-gasification gas were investigated. In addition, reforming gas conversion characteristics according to the reforming temperature, flow rate, and CH₄ / CO₂ ratio, which are the main influence variables, were studied.Methods:Experiment was achieved in a microwave convertor which was installed a quartz tube reactor. The reactor was irritated by a microwave energy to heat carbon receptor in a sample basket which was placed at the center of the quartz tube. A simulated gas mixture of methane and carbon dioxide was fed into the carbon receptor in the reactor, and a reformed product gas was collected and analyzed using a GC-TCD.Results and Discussion:In the case of microwave reforming of a mixture gas of carbon dioxide and methane, hydrogen and carbon was produced by thermal decomposition of methane. The produced carbon was adsorbed to the receptor and interfered with the catalytic activity. The attached carbon was reacted with the carbon dioxide by gasification reaction to produce carbon monoxide, and was cleaned to maintain a constant reforming conversion.Conclusions:As a result, the conversion rate and the product gas yield were high when the receptor bad reforming temperature was high and the space velocity in the convertor was low. The increase in methane in the simulated gas resulted in low conversion due to carbon adsorption.

Study of Microstrain and Stress in Non-Planar Palladium Membranes for Hydrogen Separation

Palladiums tubular membranes are developed to operate up to 400 °C, for the synthesis of H2 and for the separation of CO2 in Water Gas Shift (WGS) processes and reforming gas of methane [. Palladium has FCC lattice that allows the separation of hydrogen from carbon dioxide through a solution-diffusion mechanism [. To ensure high selectivity in the separation process, the functional Pd layer on the porous substrate of the membranes must have a microstructure with low defects and free from residual stresses [.MicroXRD measurements were performed to evaluate the effect of the stress-relief heat treatment, carried out for different time and temperatures, on the palladium layer. Microstrains were assessed before and after stress-relief by the Williamson-Hall method [. The use of microdiffraction was mandatory considering the tubular shape of membranes. The data were corrected for elastic anisotropy of palladium and the altered Williamson-Hall method was successfully applied.The XRD two-dimensional (2D) images and the integrated spectra collected from the samples allowed to study also the evolution of Pd microstructure and the reduction of micro-stresses due to stress relief. The results of the study allowed to identify the optimal thermal profile for the heat treatment of palladium membranes.

Shaft Furnace Direct Reduction Technology - Midrex and Energiron

Coke constitutes the major portion of ironmaking cost and its production causes the severe environmental concerns. So lower energy consumption, lower CO2 emission and waste recycling are driving the iron and steel industry to develop alternative, or coke-free, ironmaking process. Midrex and HYL Energiron are the leading technologies in shaft furnace direct reduction, and they account for about 76% of worldwide production. They are the most competitive ways to obtain high quality direct reduced iron (DRI) for steelmaking. Therefore, in the present paper, some detailed information about these two processes are given. Much attention has been paid on process scheme, the feedstock, DRI product, heat recovery, reforming gas, hot discharge and transportation, and by-product emission. Its very important for direct reduction development in both natural gas-rich counties and natural gas-poor counties.

KAJIAN PRODUKSI HIDROGEN DENGAN ENERGI NUKLIR PROSES TERMOKIMIA SIKLUS IODINE-SULFUR DAN PROSES HIBRIDA SIKLUS BELERANG

KAJIAN PRODUKSI HIDROGEN DENGAN ENERGI NUKLIR PROSES TERMOKIMIA SIKLUS IODINE-SULFUR DAN PROSES HIBRIDA SIKLUS BELERANG. Makalah ini membahas perbandingan produksi hidrogen dengan energi nuklir untuk 2 buah teknologi proses produksi hidrogen yaitu proses termokimia siklus iodin-sulfur dan proses hibrida siklus belerang (HyS). Tujuan dari studi ini adalah untuk memahami karakteristik produksi masing-masing proses. Hal yang menarik dari kedua proses adalab dua-duanya mengoperasikan reaksi dekomposisi asam sulfat. Jika proses termokimia siklus 1-S mengandalkan proses dekomposisi HI untuk menghasilkan hidrogen, proses HyS mengandalkan proses elektrolisis campuran air dan SO2 untuk menghasilkan hidrogen. Prediksi keekonomian menunjukkan bahwa biaya produksi hidrogen pada proses 1-S sedikit lebih mahal dibandingkan dengan proses HyS, tetapi kedua proses mempunyai efisiensi termal yang relatif sama. Dibandingkan dengan proses konvensional elektrolisis, kedua proses mempunyai efisiensi termal yang jauh lebih tinggi. Meskipun saat ini biaya produksi hidrogen kedua proses masih relatif jauh lebih mahal dibandingkan dengan proses steam refonning gas alam, namun di masa depan jika terjadi kelangkaan gas alam (sehingga mahal), kedua proses akan kompetitif. Dari sisi bahan baku, kedua proses lebih menguntungkan dibandingkan dengan proses steam reforming gas alam, karena air sebagai bahan baku relatif jauh lebih melimpah.