This paper was intended to delineate numerical research for hydrogen catalytic combustion over a circular cylinder. The wire/rod-type catalytic reactor is a simple geometry reactor with an economical design with less pressure loss. For the single rod in the reaction channel, the flow characteristic and the difference of conversion efficiency between non-gas-phase reaction and gas-phase reaction have been delineated in the present study. The flow field and the chemical reactions were numerically modeled using 2D Large Eddy Simulation combined with the gas-phase and surface reaction mechanisms. The results show that the current numerical simulation has been validated to precisely predict the vortex shedding and its frequency in the cold flows. Despite the variation trends being dominated by the upstream flow, the vortex shedding phenomena were affected by the flue gas generated from the rod surface. It can be seen from the linear relationship between the vortex shedding frequency of reacting flow and Reynolds Number. It is noted that the vortex shedding vanished if the gas-phase reaction was ignited in the reaction channel. In addition, the geometric modified conversion efficiency was proposed to delineate an indicator that could be potential for the optimization of rod-type catalytic reactor. In summary, the fundamental study of a rod in a 2D flow channel can provide information for optimizing the catalytic design or the rod array arrangement in the reactor. Moreover, the rod can also be a partial catalytic flame holder to ignite and stabilize the gas-phase reaction. The obtained results could be the potential for practical applications of rod-type catalytic combustion, catalytic gas turbine, hydrogen generation, partially catalytic reaction flame holder, and other catalytic reactions that can be appreciated. 相似文献
Enhanced hydrogen evolution was pursued in this work. Rhodobacter sp. (Rb) and Rhodopseudomonas palustris (Rp), single or mixed were used to extract hydrogen molecules from Chlorella fusca biomass. To elevate their fermentable contents, Chlorella was grown at nitrogen and/or phosphorus deprivation. Besides, cellulase and/or macerozyme, Triton X100 or sonicated yeast were applied for further biohydrogen fermentation. Utilizing hydrolysates of mineral deprived Chlorella cultures, Rb exhibited relatively higher cumulative hydrogen (4200 ml L?1) than Rp (2500 ml L?1) while mixed cultures attained significantly higher levels (4700 ml L?1). Triton or enzymes significantly enhanced hydrogen evolution, with more effectiveness of macerozyme than cellulase. A novel use of sonicated yeast, as enzymes pool, induced the highest significant collective H2 (up to 47 times that of microalgal supernatant). Sonicated yeast induced a remarkable hydrolysis of algae, as inferred from increased reducing sugars. However, hydrogen evolution efficiency exhibited poor proportionality with reducing sugars, indicating fermentation of other metabolites. 相似文献
In this study, the simultaneous use of nanofluid and phase changing material as a coolant for photovoltaic fluid collector system and its effects are investigated experimentally. Two types of nanofluid are taken for the consideration, that is, ZnO and CuO, which are water‐based fluid. The experiments are performed in five different types of photovoltaic thermal system conventional: PT, PVT (ZnO), PVT (CuO), PCM medium (PVT/PCM/ZnO), and PCM medium (PVT/PCM/CuO). The results are obtained for surface temperature, energy, and thermal efficiency, and it is compared with each other. Further, the effect of the nanofluid as the effective alternative for pure deionized water is measured. From the results, it is evident that the PVT/PCM/CuO system minted 15% high electric output compared with convention module. Furthermore, the addition of the CuO nanofluid increases the thermal output significantly up to 8% for PVT and 12% for PCM without energy consumption. It also found that the nanofluid increases the overall energy efficiency of the system compared with convention PV. 相似文献
Although the dielectric barrier discharge (DBD) has been widely considered and studied for ozone generation, only a few studies have examined the influence of the alternating voltage waveform on the ozone rate production. This paper analyses the influence of the voltage shape on the ozone concentration and the energy efficiency of a DBD cylindrical ozone generator. Three voltage signals were studied using a high-voltage amplifier: sinusoidal, triangular and rectangular signals with voltage values up to 8 kV and frequencies up to 1.1 kHz. The obtained results showed that the efficiency of the ozone generator depends strongly on the type of the voltage waveform. The maximum values of the energy efficiency and the ozone concentration were obtained with the triangular voltage signal. This wave shape configuration has been successfully used for discolouration of water contaminated by textile dye. 相似文献
Five types of photovoltaic (PV) modules were comparatively analyzed considering the electrical output, efficiency and relative loss in efficiency, based on infield data collected in a temperate mountain climate, over 14 months. The mono-, poly-crystalline silicon, CdTe, CIS and CIGS modules were mounted on two identical platforms, installed close to a row of buildings. Based on the data collected from individual or groups of modules on the two platforms, analyses focused on the photovoltaic output, considering: the mean monthly values; the influence of the neighboring buildings; the influence of the irradiance, temperature and wind in different seasons (winter, summer); the influence of tracking on each PV module type. The qualitative analysis shows that small PV platforms installed in the built environment require accurate investigations on the air currents with influence on snow and frost retention/melting and water vapor condensation. In the temperate climate, with snowy winters and rather warm summers, the best performing modules are of poly-crystalline silicon; among thin film modules, the best output corresponds to CIGS, while the steadiest efficiency corresponds to CdTe. Tracking has a “leveling” effect on the conversion efficiency, making the PV output more predictable during days with preponderant direct solar irradiance. 相似文献
先进绝热压缩空气储能系统(advanced adiabatic compressed air energy storage system,AA-CAES)是一种清洁、环保的大规模储能技术,能够为可再生能源并网及电网调峰提供新的解决方案。为了深入研究压气机模型对变工况下AA-CAES系统运行性能的影响,本文在传统模型的基础上添加了压气机效率模型。求解系统模型发现:相对于储气室最高压比,换热器效能对储能效率的影响较大,换热器效能每提高0.05,储能效率平均提高2.9%;随着储气室最高压比的上升,储能密度近似呈线性增加;AA-CAES系统在储能阶段,稳定运行的前两级压气机功率保持不变,非稳定运行的第3级压气机功率随储气室压比的升高而逐渐增大,储能阶段结束时第3级压气机耗功最多。 相似文献