Plastic Waste Upcycling for Generation of Power and Methanol: Process Simulation and Energy–Exergy–Economic (3E) Analysis

To address the global issue of plastic waste, the waste to wealth technique is under investigation. Four processes, known as INP-CC (incineration with carbon capture and power generation), GFP-CC (gasification with carbon capture and power generation), INP-ME (incineration with methanol and power cogeneration), and GFP-ME (gasification with methanol and power cogeneration), which include both traditional and innovative methods, have undergone development, simulation, and comprehensive comparison through techno-economic analysis. GFP-CC and GFP-ME are particularly favored for their energy efficiencies of 43.47 and 34.91%, respectively, in comparison to INP-CC (17.6%) and INP-ME (6.89%). Exergy flow diagrams reveal that the incinerator, gasifier, and combustion chamber account for over 50% of the exergy loss, highlighting their potential for intensification. However, from an economic standpoint, without a larger subsidy fee ($84 per ton) or higher methanol selling price ($550 per ton), processes GFP-ME and INP-ME are not economically attractive due to a negative net present value over 20 years. A sensitivity analysis of key economic parameters demonstrates that the price of methanol and hydrogen has the greatest impact on process economic performance. It appears that process INP-ME is more resilient in terms of economic performance when subjected to the same level of fluctuations in methanol and hydrogen prices, in comparison to GFP-ME

Sustainable Retrofit Design of Natural Gas Power Plants for Low-Grade Energy Recovery

Large amounts of low-grade energy in natural gas power plants are not being efficiently recovered or used. They are often emitted directly to the environment. It is quite challenging to retrofit natural gas power plants for the integration of low-grade energy recovery and further optimize power generation, production and supply of hot and cold energy, and pipeline networks for cold energy distribution as a total site. In this study, we present a process superstructure for the sustainable retrofit of natural gas power plants to recover low-grade energy and deliver it to different users. The waste energy sources include cold energy from liquefied natural gas, pressure energy from pipeline natural gas streams, and low-grade heat from low-pressure steam in power plants. A mixed integer nonlinear programming framework is formulated to optimize the process structure to minimize the total annual cost and maximize the exergy efficiency to obtain the best sustainable retrofit process for low-grade energy recovery. The optimization framework includes models of the existing gas turbines and boilers and the new pipeline network and refrigeration system. The mathematical framework is applied to a real industrial example, and the power consumption for cold energy production is significantly reduced by 32%. The ratio of different energy sources and the distance of cold energy distribution are investigated, and different optimization results are analyzed. Finally, exergy analysis is suggested to evaluate the sustainability of the retrofit. According to the results of the exergy analysis, the total exergy efficiency under the minimum total annual cost is increased by 6.172%

DataSheet_1_Generation of macro-vortices in estuarine compound channels.pdf

We report the results of a numerical investigation of the flow structure and mechanism of macro-vortex generation in estuarine compound channels. The Finite-Volume Coastal Ocean Model (FVCOM) was implemented to simulate tidal currents in compound channels, e.g., the Lantau Channel, which lies in the middle of the Pearl River Estuary (PRE). Results showed that the velocity magnitude in channels was significantly larger than that of floodplains during the ebb and flood phases, resulting in a high-velocity gradient at the depth discontinuity. Vorticity and Q-criterion were used to analyze the macro-vortex distribution inside the PRE. Massive macro-vortices were generated along the compound channels where high vorticity was also detected. The across-estuary sections with single and multiple channels were selected as representatives to analyze velocity distribution during ebb and flood tides. To characterize the channel flow, the ratio of the main channel depth of the Lantau Channel to floodplain depth (Rh) was calculated using the topography information and surface elevation of sections. It was found that there existed a channel segment where the flow periodically changed between shallow flow (Rh > 3) and intermediate flow (2hh greatly influenced the generation of macro-vortices. Transverse dispersive stresses were calculated to evaluate the longitudinal momentum transfer in the lateral direction. We found that the dispersive stresses could play an important role in the redistribution of momentum in addition to barotropic and baroclinic transport. This paper revealed the mechanism of the dynamic generation of macro-vortices in the estuarine compound channel, serving as a valuable example in understanding natural compound channel flows.</p

Additional file 1 of Association of sodium-glucose cotransporter 2 inhibitors with risk of major adverse cardiovascular events in type 2 diabetes patients with acute coronary syndrome: a propensity score‑matched analysis

Additional file 1: Figure S1. Kaplan–Meier curves to plot the cardiovascular outcomes in the matched population. A Kaplan–Meier curve for all-cause death. B Kaplan–Meier curve for MI. C Kaplan–Meier curves for stroke. D Kaplan–Meier curve for revascularization. E Kaplan–Meier curve for stroke. MI, myocardial infarction

Quantitative Structure–Property Relationship Analysis for the Prediction of Propylene Adsorption Capacity in Pure Silicon Zeolites at Various Pressure Levels

This work is devoted to the development of quantitative structure–property relationship (QSPR) models using various regression analyses to predict propylene (C3H6) adsorption capacity at various pressures in zeolites from a topologically diverse International Zeolite Association database. Based on univariate and multilinear regression analysis, the accessible volume and largest cavity diameter are the most crucial factors determining C3H6 uptake at high and low pressures, respectively. An artificial neural network (ANN) model with five structural descriptors is sufficient to predict C3H6 uptake at high pressures. For combined pressures, the prediction of an ANN model with pore size distribution is pleasing. The isosteric heat of adsorption (Qst) has a significant impact on the improvement of the prediction of low-pressure gas adsorption, which finely classifies zeolites into high or low C3H6 adsorbers. The conjunction of high-throughput screening and QSPR models contributes to being able to prescreen the database rapidly and accurately for top performers and perform further detailed and time-consuming computational-intensive molecular simulations on these candidates for other gas adsorption applications

Video_1_Generation of macro-vortices in estuarine compound channels.mp4

We report the results of a numerical investigation of the flow structure and mechanism of macro-vortex generation in estuarine compound channels. The Finite-Volume Coastal Ocean Model (FVCOM) was implemented to simulate tidal currents in compound channels, e.g., the Lantau Channel, which lies in the middle of the Pearl River Estuary (PRE). Results showed that the velocity magnitude in channels was significantly larger than that of floodplains during the ebb and flood phases, resulting in a high-velocity gradient at the depth discontinuity. Vorticity and Q-criterion were used to analyze the macro-vortex distribution inside the PRE. Massive macro-vortices were generated along the compound channels where high vorticity was also detected. The across-estuary sections with single and multiple channels were selected as representatives to analyze velocity distribution during ebb and flood tides. To characterize the channel flow, the ratio of the main channel depth of the Lantau Channel to floodplain depth (Rh) was calculated using the topography information and surface elevation of sections. It was found that there existed a channel segment where the flow periodically changed between shallow flow (Rh > 3) and intermediate flow (2hh greatly influenced the generation of macro-vortices. Transverse dispersive stresses were calculated to evaluate the longitudinal momentum transfer in the lateral direction. We found that the dispersive stresses could play an important role in the redistribution of momentum in addition to barotropic and baroclinic transport. This paper revealed the mechanism of the dynamic generation of macro-vortices in the estuarine compound channel, serving as a valuable example in understanding natural compound channel flows.</p

Integrated Energy-Harvesting System by Combining the Advantages of Polymer Solar Cells and Thermoelectric Devices

A polymer solar cell-thermoelectric (PSC–TE) hybrid energy-harvesting system was designed and fabricated, which realizes harvesting electricity from solar light and solar heat simultaneously. A series of measurements has been performed to study the relationship between the PSC–TE hybrid system and individual devices. The PSC–TE system improved the total power output compared with individual PSCs when a temperature gradient across TE module was introduced. The physical process that determines the overall power generation of the PSC–TE hybrid system was also studied and analyzed. The optimal power output of PSC–TE hybrid system is given, which can act as a guideline for further optimizing the hybrid energy-harvesting system. Interestedly, we demonstrate that the hybrid system can drive a commercial light-emitting diode by effectively utilizing solar energy, while it cannot be realized by an individual device. The hybrid system is proved to be a more efficient way for obtaining electricity by integrating multiple devices with different functions

The occurrence of PAHs and flame-retardants in air and dust from Australian fire stations

Firefighters are exposed to a wide range of chemicals whilst on duty, including polycyclic aromatic hydrocarbons (PAHs), organophosphate flame-retardants (OPFRs), and polybrominated diphenyl ethers (PBDEs). These groups of chemicals are related to combustion emissions. PAHs are formed during combustion. OPFRs and PBDEs are flame-retardants and are inadvertently released during combustion. Exposure to these chemicals occurs when attending fire scenes, and firefighters can track these chemicals back into fire stations leading to further exposure. The objective of this study was to understand the concentrations of PAHs, OPFRs, and PBDEs in fire stations, to evaluate factors that affect chemical concentration, and to assess how air and dust could contribute to firefighters’ relevant exposure risk. Concentrations of 13 PAHs, 9 OPFRs, and 8 PBDEs were quantified in fire station dust (n = 49) and air (n = 15) samples collected between November 2017 and February 2018. The median ∑13PAH concentration was 15 ng m−3 and 3.1 µg g−1 in air and dust, respectively, while the median ∑9 OPFR concentration was 56 ng m−3 in air and 84 µg g−1 in dust, and ∑8 PBDE had a median concentration of 0.78 ng m−3 in air and 26 µg g−1 in dust. The estimated daily intakes through dust and air for ∑13 PAHs, ∑9 OPFRs, and ∑8 PBDEs in firefighters were 3.6, 17, and 1.6 ng (kg body weight)−1 day−1, respectively. The worst-case estimated daily intakes were only 2% of the reference dose for individual chemicals. Pearson’s correlations with chemical concentration for several PAHs, OPFRs, and PBDEs were found between the number of years since fire stations were last renovated, as well as the storage locations of firefighting ensembles. These results suggest chemicals are brought back to fire stations from fire scenes and that they are accumulating in fire stations. They also suggest soiled firefighting ensembles are a source of these chemicals in fire stations and that their proximity to the rest of the station determines the extent to which they contribute to chemical concentrations in fire stations.</p

Solution-Processable Star-Shaped Photovoltaic Organic Molecule with Triphenylamine Core and Benzothiadiazole−Thiophene Arms

Solution-Processable Star-Shaped Photovoltaic Organic Molecule with Triphenylamine Core and Benzothiadiazole−Thiophene Arm

New Gasoline Absorption–Stabilization Process for Separation Intensification and Flowsheet Simplification in Refineries

A new gasoline absorption–stabilization process (GASP) is presented to intensify the separation process and significantly simplify the conventional GASP flowsheet. The conventional GASP includes four columns and recycling streams between refinery units, which makes the process very complex. In this study, the solubility and volatility of the C5–C11 hydrocarbons are discussed and a new indicator is presented to represent the performance of supplementary absorbent streams. The best suitable components are then found. A new flash tank is introduced into the GASP to obtain the suitable absorbent components to intensify the absorption process. As a result, the original secondary absorption column and the large recycling streams between the units are canceled. The conventional and new GASPs are simulated and optimized, respectively. Heat exchanger networks are designed for the two processes. The new process can significantly reduce the total annual cost by 11.24% as opposed to the conventional process