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Abstract: Direct observation of transient swelling and shrinkage behavior of raw coals and processed coals was conducted by using a digital camera with a long focus lens, and quantitative description of swelling and shrinkage was resulted from subsequent image processing. The results showed that the raw and processed coals in pyrolysis behaved differently. The shrinkage of the processed coals was quite different, the maximum volumetric shrinkage ratio at 1000°C as in the range of 32–38% with swelling ratios less than 5%, and the volumetric swelling ratio increased and the shrinkage ratio decreased with the increase of coal sample density. The maximum volumetric swelling ratio of the raw coals was more prominent than those of the processed coals. The raw coal A2 showed a maximum swelling ratio of 20–85% and the raw coal B2 showed a maximum swelling ratio of 25–45%. The volumetric swelling ratios decreased and the shrinkage increased with the decrease of the sample size. It is considered that the different pyrolysis behaviors were mainly due to the variation in their macroscopic structures. However, the similar swelling and shrinkage curves of coal samples were observed for the same raw or processed coals. In addition, the effect of volatile matter on the volumetric shrinkage ratios would be weakened if the raw coal was crushed into powder and then pressed into processed coal samples. Scanning electron microscope analysis showed that the structure of coke after pyrolysis was also different. [Copyright &y& Elsevier]

With the increasing penetration of renewable energy (RE) generation in power systems, RE companies are gradually accepted as regular players in electricity markets. Compared with the conventional way, RE generation promotes economic and environmental protection, but also brings uncertainty to power systems. Hydrogen storage stations (HSSs) can alleviate RE's fluctuating generation. Moreover, the integration of hydrogen and electricity has superiorities to mitigate the spatial imbalance of the RE distribution and achieve higher energy efficiency. To this end, the framework of a local integrated electricity - hydrogen market is designed in this paper. Trading mechanisms among RE generation companies (GenCos), HSSs, power distribution company and other hydrogen-related participants are first introduced, based on which the mathematical models are presented. A two-stage market clearing model is then proposed to determine the optimal trading amount and allot profits based on Shapley value. A simple case shows that by participating in proposed market, the power deviation between offering and available capacity of GenCos decreases by 69.5% and 86.0%, respectively, while the profit of HSSs and GenCos is $ 1.60 × 103 within a week. Therefore, cooperating with the hydrogen market can be a potential way for power systems to integrate high proportion of RE. [ABSTRACT FROM AUTHOR]