Predictions of distortion and hardness after heat treatment by numerical simulation are very useful for determining the optimum condition and for controlling the distortion of machinery parts. In this article, the combination method of orthogonal experiment and numerical simulation is used to optimize the standard heat treatment condition by reducing the distortion after carburizing quenching. A helical gear made of carburizing steel 20MnCrS5 is simulated using three-dimensional coupled analysis that is based on thermo-mechanical theory. The good agreement between the experiment and simulation is verified by the comparison between the experimental data and the simulated data. Firstly, the influencing factors of distortion after carburizing quenching are investigated and discussed. Four influence factors of heat treatment are selected as follows: carburizing time, the cooling time before 860°C, the holding time at 860°C, and the gear orientation during quenching. Next, selection of the optimal case is then determined by comparing the distortions. Finally, a new optimization method of minimum distortion after carburizing quenching is provided.

With the continuous expansion of the high‐purity hydrogen application range, the performance degradation of hydrogen storage alloy (HSA) caused by impurities has attracted widespread attention in producing pure hydrogen from biomass. In this study, the lanthanum‐rich mischmetal alloy's purification ability on hydrogen sulfide impurities and cycling performance were studied. The hydrogen with different concentrations of hydrogen sulfide was used to investigate the purification performance, which assumes the gas derived from biomass. Besides, a cycling experiment was designed to analyze cycling performance. The results show that the HSA could remove high concentrations of hydrogen sulfide entirely. It was also found that impurities of 1 ppm hydrogen sulfide had little effect on the HSA. With hydrogen sulfide concentrations of 100 ppm, the hydrogen storage capacity, absorption rate, and release rate were reduced, but they became a stable state from the second cycle. The performance degradation mechanism was analyzed by Energy Dispersive X‐Ray Spectroscopy (EDS) and X‐ray Photoelectron Spectroscopy (XPS​).

Pyrolysis is a pathway for hydrogen reproduction from sewage sludge. The critical problem in the indirect pyrolysis process is the lower heat transfer performance in the furnace. The circulation of heat media controls the heat transfer in the pyrolizer (e.g., heat carriers (HCs) in the form of alumina balls), which is essential in determining the heat transfer performance and ultimately determining the hydrogen yield. The temperature of the HCs and amount of hydrogen yield are low because the required temperature in the vessel is not satisfied. This study investigated the relationship between the operating conditions and HC temperature profile to determine the optimum conditions for sufficient HC heating. We discuss the HC performance aspects to achieve a more effective operation using low inputs. Using a computational fluid dynamics simulation, we assessed the effect of the inlet gas temperature, inlet gas flow rate, and furnace structure on the heat transfer performance. We validated our model using the test results from a demonstration plant. We observed that by increasing the hot gas inlet temperature by 51 °C, the heat loss was reduced by 2,170 MJ/h, and the thermal efficiency of the entire plant was improved by 5.46%. When the number of hot-gas inlets was split, the efficiency did not change, but the temperature dispersion of the HCs was small. This implied that tar generation, including that of liquid substances, was prevented. At the pyrolysis temperature of 600°C, the cold gas efficiency was 81.2 LHV%.

Hydrogen is a candidate of alternative fuels and evaluated for fuel cell (FC) applications. As a hydrogen storage system, metal hydride (MH) is attracting attention due to its high energy volume density and safety. To apply fuel cells and metal hydride to electrically power assisted bicycles, a previous study has evaluated load weight and power demand through experiments conducted on existing electrically power assisted bicycles. Focusing on such energy supply system, this study designs metal hydride cartridge and investigate temperature changing when exhaust heat from fuel cell is supplied to metal hydride, which release hydrogen with absorbing heat. First, the negative effect of the exhaust heat supply to the fuel cell on the fuel cell performance is investigated and we proposed the usage of method to mitigate the effect. Next, the structure of MH cartridge is designed from weight and volume of the MH cartridge and exhaust flow rate of the FC, and we proposed a structure in which multiple small cylinders are stacked. Finally, FC exhaust heat was supplied to the designed dummy cartridge, and the amount of heat supply according to the FC output and power generation time was evaluated.