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A small-scale separated-type biomass gasification system composed of a screw pyrolyzer, a steam tar reformer, an air-steam char fluidized bed gasifier, and a spent char combustor with heat carrier particles circulating is designed to convert woody biomass into combustible gas which can be applied for gas-engine power generation. In this study, the simulation results of this system based on two biomass pyrolysis routes, i.e., fast and slow pyrolysis, are analyzed and compared. During the simulations, the empirical equations as well as the main experimental data from the published literature are applied to analyze the elemental, mass, and energy balances of each process by using sets of assumptions at a certain condition to predict final energy efficiency and the potential electricity generated from the system. As a result, 12.5 kg/h of wood biomass feeding to this system has power generation ability of 16.8 kWe and 16.3 kWe with cold gas efficiencies of 73.8% and 71.7% for the fast and slow pyrolysis routes respectively. Comparison of product yields and compositions obtained in the present system with the reported data shows that the prediction gives a reasonable accuracy which could indicate what occur within the system. The calculation methods presented in this study could be utilized for preliminary engineering design of comprehensive biomass thermal conversion processes.

Energy crisis and environmental pollution are great challenges to the sustainable development of human society. In response to increasingly stringent emissions regulations, scientists are actively seeking solutions, such as the exploitation of new energy. In recent years, natural gas has attracted wide attention because of its environmental advantages over the traditional diesel engine. In addition, the higher exhaust temperature of natural gas engine gives it a good potential for waste heat recovery, especially in cascade utilization system. To recover the available energy of natural gas engine at multiple temperatures, an integrated system consisting of supercritical carbon dioxide Brayton cycle, double effect absorption refrigeration system and Kalina cycle is established in this study. After verifying the model accuracy of three sub-cycles, we analyze and discuss the influence of major parameters on system performance in detail, as well as carrying out the dynamic response analysis of waste heat recovery system, After the completion of multi-objective optimization, the thermodynamic and economic analysis indicate that the output power increased by 15.33% and the payback period shortened by 25.6%. Therefore, it can conclude that the new scheme is a practicable approach to recover waste heat of natural gas engines.

Facing the energy shortage and environmental pollution problems in the world, a high-efficiency fuel cell scheme combined with waste heat recovery is regarded as an optimal selection of auxiliary power generation equipment for ships. In this study, a novel system, comprising solid-oxide-fuel-cell-preheating subsystem, homogeneous charge compression ignition engine and organic Rankine cycle, is designed and analysed. First, the mathematical model is established and verified to ensure the reliability of simulation results. Then, the effect of relevant parameters on homogeneous charge compression ignition engine performance is observed, and the optimal zeotropic working fluid of organic Rankine cycle is determined according to the exhaust temperature. Finally, the thermodynamic and economic analysis are carried out. The results indicate that the performance of the new system is better than that of the traditional combined system using gas turbine. Thermal efficiency and exergy efficiency of the system are more than 63.6% and 61.3%, which is about 18.76% and 17.95% higher than that of simple cell. In addition, the payback time is about 2.98 years, which is about half of the traditional combined system and can fully meet the economic requirements. This novel system can be a new selection of marine auxiliary power generation equipment.

Fuel cell technology has the superiorities of long-term energy storage and instant power generation, as well as a clean and harmless reaction process. Microfluidic fuel cell is developed on the basis of membrane fuel cell, aiming at eliminating the life and cost of proton membrane by utilizing laminar flow characteristics. Microfluidic fuel cell has a broad application prospect in mobile electronic devices due to its inherent small size and higher power density. The main objective of this work is to investigate the vapor-feed microfluidic fuel cell performance under the influence of vibration in different properties. Meanwhile, fuel utilization and exergy efficiency are introduced to make a comprehensive efficiency analysis of the cell. In order to complete these studies, a three-dimensional model of vapor-feed microfluidic fuel cell is established in numerical simulation software and the vibration physical field is applied. The simulation results are compared with the experimental data to verify the reliability, after which the cell performance between the two vibration orientations under the effects of multiple parameters like intensity, frequency and phase is studied. The simulation results show that vibration has a positive but limited effect on vapor-feed microfluidic fuel cells, either power output or energy efficiency.