Oxy-fuel combustion of coal pyrolysis gas has recently been proposed to serve as internal heat source of a vertical low-temperature pyrolysis furnace, in order to make the output pyrolysis gas nearly free of nitrogen and widely useful. To keep the pyrolysis temperature and the heat carrier gas volume unchanged from air combustion to oxy-fuel combustion, the equivalence ratio has to be increased up to 8. To explore the flame temperature and species variation at this ultra-rich condition, freely propagating premixed oxy-fuel flames of a typical coal pyrolysis gas at equivalence ratios of 0.5–10 are numerically studied with detailed chemistry. It is found that super-adiabatic flame temperatures (SAFT) occur at equivalence ratios larger than 3 for the considered pyrolysis gas and the SAFT magnitude is 294 K at equivalence ratio of 8. Due to the high H₂ mole fraction (46%) in the pyrolysis gas, preferential diffusion plays a negligible role in the SAFT feature. Global net production of CO and H₂ by the rich combustion only occurs at moderate equivalence ratio ranges, which are 1.5–8 and 3–5.5 respectively for the two species. At equivalence ratio of 8, the three fuel components are all net consumed following the mole ratio of CH₄:CO:H₂ = 1:0.07:0.84. Kinetic analysis reveals three factors responsible for the reaction mechanism change with the increase in equivalence ratio. Firstly, the lack of H-radical and the decrease in temperature result in the disappearance of the H₂ production peak in the initial stage. Secondly, HO₂ attack to CO prevails and hence contribution of CO oxidation in the initial stage increases. Thirdly, the long lasting OH attack to CO and H₂ leads to the weakened CO and H₂ production rate in the final stage. ... Read more

Having a healthy built environment becomes increasingly important, especially under the effects of COVID-19. This paper intends to combine sustainable goals based on climate change with passive design principles to achieve a healthy built environment regarding the building performance of residential buildings. The Yuedao Residential Community in the Lingnan area was taken as an example for the research. Based on relevant standards of healthy buildings, the thermal, light, and acoustic environment requirements were determined. The methods of building performance simulation and on-site measurement were used to quantify the research object environments. Then, the outcomes were obtained based on these standards. As observed, the thermal environment’s adaptive thermal comfort level was level III. It was hot indoors, but the light and acoustic environments met the requirements. Building designs based on a built environment optimized by external shading systems aim to solve problems through building performance simulation and qualitative analysis. After optimization, the thermal environment improved. According to the literature review, this research focused on a healthy built environment with a sustainable passive design in terms of building performance. A research workflow was established that could be used for more practical research, with abundant research methods. The problems were solved to varying degrees, and the Lingnan architectural culture was preserved. Moreover, this research filled the gap in interactive research on healthy built environments with sustainable passive design regarding building performance ... Read more