Powder-size driven facile microstructure control in powder-fusion metal additive manufacturing processes.

Microstructure control in metal additive manufacturing is highly desirable for superior and bespoke mechanical performance. Engineering the columnar-to-equiaxed transition during rapid solidification in the additive manufacturing process is crucial for its technological advancement. Here, we report a powder-size driven melt pool engineering approach, demonstrating facile and large-scale control in the grain morphology by triggering a counterintuitive response of powder size to the additively manufactured 316 L stainless steel microstructure. We obtain coarse-grained (>100 µm) or near-monocrystalline microstructure using fine powders and near-equiaxed, fine-grained (<10 µm) microstructure using coarse powders. This approach shows resourceful adaptability to directed energy deposition and powder-bed fusion with no added cost, where the particle-size dependent powder-flow preheating effects and powder-bed thermophysical properties drive the microstructural variations. This work presents a pathway for leveraging feedstock particle size distribution towards more controllable, cost-effective, and sustainable metal additive manufacturing.

Assessment of gas generation and energy recovery from municipal solid waste in Kanpur city, India.

The study reported herein presents the methane generation potential from municipal solid waste (MSW) generated in Kanpur city using four established methods, namely: the IPCC Default Method (DM), EPER Germany, The IPCC First Order Decay (FOD) method, and the Modified Triangular Method (MTM). Results revealed that the average maximum and minimum emissions with respect to total MSW generated and considered over the study period were obtained in the IPCC Default Method (19.17Gg/year) and the MTM (1.00Gg/year), respectively. Furthermore, the sensitivity analysis carried out revealed that the MTM method is the least uncertain method in predicting the methane emissions. Energy generation using the Yedla method and the Stoichiometric method was also carried out, highlighting the potential for energy recovery using methane emissions. The total energy generation potential using the Yedla method over the entire study period was determined to be 924 TJ, with an increased potential of 30% between the periods of 2022 to 2031. According to the study, there exists significant potential for effectively managing the greenhouse gas emissions from open dumpsite by harnessing the methane produced and using it for energy generation.

Assessment of landfill gases by LandGEM and energy recovery potential from municipal solid waste of Kanpur city, India.

The world due to increased urbanization and globalization is facing major environmental challenges. Anthropogenic emissions of Greenhouse gases (GHG) like carbon dioxide and methane are on the rise and unsustainable which needs to be regulated. Open dumping of Municipal Solid Waste (MSW) contributes to generation of greenhouse gases like carbon dioxide and methane. This is because large fractions of the waste open dumped are organic in nature which undergoes anaerobic decomposition leading to generation of GHGs. In particular, methane has a high potential for energy generation and if utilized could be highly beneficial. The present study assesses the generation of landfill gases, primarily methane generation potential from MSW generated in Kanpur city using LandGEM 3.02 version model developed by USEPA for the period 2015-2030. It was observed from the study that the cumulative LFGs generation, methane emission and energy recovery potential estimated as 233.44 × 106 m3, 116 × 106 m3 and 858.14 × 106 MJ respectively. Uncertainty analysis carried out showed that variation in methane emissions maybe attributed to input parameters of k and Lo of the LandGEM model. The study shows that there exists high potential to control the greenhouse gas emissions by utilizing the methane generated for energy production.