In the wake of a global shift towards sustainable energy and heightened environmental stewardship, hydrogen energy stands out as a clean and efficient alternative, drawing significant interest for its potential. Industrial by-product hydrogen (IBPH), a key source in the burgeoning hydrogen economy, is poised for growth during the early to mid-stages of hydrogen economy, but currently grapples with substantial wastage and suboptimal utilization due to technological barriers and insufficient attention. A critical examination of the purification and utilization technologies for IBPH is thus imperative, offering practitioners in the hydrogen domain the insights necessary for a more strategic and efficacious harnessing of this resource. The present review delivers an exhaustive survey of cutting-edge separation and purification techniques tailored for IBPH. Additionally, it encapsulates the latest advancements in utilization technologies of IBPH across diverse sectors, presenting a methodical compendium of current innovations. The discourse extends to a probing analysis of the prevailing challenges and envisions the prospective landscape of the IBPH marketplace.

As one type of low-calcium cement, C₄A₃$-C₂S clinker consumes less energy and can utilize rich-MgO low-calcium limestone. The effect of rich-MgO low-calcium limestone on its calcination and properties is studied by means of f-CaO, XRD Rietveld refinement, TG-DTG and Lithofacies analysis. The results show that 3%∼5% MgO can promote the absorption of f-CaO and accelerate the formation of highly active monoclinic C₃S and C₄AF in clinker. When the MgO content is 7% and 8%, C₄A₃$-C₂S clinker calcined at 1380°C has excellent mechanical properties and its soundness is still qualified. This research shows that the rich-MgO low-calcium limestone can replace more than 50% of natural limestone to prepare C₄A₃$-C₂S clinker in cement industrial production.

In this study, the low idle operation is defined as the engine running at the lowest engine speed with a few slight loads. Idling is necessary for most vehicles, especially for buses and trucks that frequently travel long distances, as drivers often rest inside the vehicle. However, under idling conditions, weak air flow and low air-fuel ratio result in poor air to fuel mixture, ultimately causing incomplete combustion and the production of more harmful exhaust emissions. Bioethanol, as a low-carbon fuel, has great potential for application in diesel engines due to its unique properties. In this research, the influences of different diesel-bioethanol blends (BE0, BE5, BE10, BE15) on combustion and emissions of a diesel engine were investigated under idle conditions. The main results show that there was no phase separation phenomenon even up to 15% bioethanol was directly blended with diesel by volume. And adding bioethanol to diesel had no significant impact on combustion pressure peak, but it postponed the start of combustion (SOC). Surprisingly, the nitrogen oxide (NO_x) and smoke were simultaneously decreased by over 52% and 78% with the intervention of bioethanol, respectively.

The global critical issue in energy scarcity should be appropriately solved to realize a sustainable society. Effective use of Rankine cycle is one possible way since it provides most of worldwide electricity production. In this paper, theoretical analysis model of organic working fluids R717, R134a, R1234yf, R290, R245fa and R1233zd in Rankine cycle for maximum power generation in optimization operation using low-temperature heat sources are proposed and studied for development next generation green and zero-carbon energy generation system to promote the race to zero. Results show that temperatures of warm and cold water at inlet, mass flow rate of the warm water and performance of the evaporator play a key role to obtain the theoretical optimization operation conditions for maximum power generation. In the case of same initial conditions of temperatures of warm water (85°C) and cold water (15°C) at inlet, mass flow rate of the warm water (10 kg/s) and performance of the evaporator (100 kW/K), R717 has the best performance in terms of the maximum power output 56.0 kW with thermal efficiency of 8.6%, and the next is the R1233zd (54.4 kW, 8.3%), R245fa (54.0 kW, 8.2%), R134a (52.8 kW, 7.9%), R290 (52.7 kW, 7.9%), and R1234yf (51.7 kW, 7.7%). Here, it should be noticed that other optimization conditions are almost the same (mass flow rate of the cold water 9.1-9.2 kg/s; performance of the condenser 91∼92 kW/K) to get their maximum power output of ORC. In addition, it also known that low-GWP R1233zd (GWP: 1) can deserve the best option to replace R245fa (GWP: 950) and R1234yf (GWP: 4) also can replace r134a (GWP: 1430) since their optimization operation conditions are almost same.

The increasing utilization of CO₂ for synthesizing high-value fuels or essential chemicals is a potentially effective approach to mitigating global warming and climate change. Compared to thermal catalytic CO₂ conversion under harsh operating conditions (400∼500°C, 10 MPa), non-thermal plasma can overcome kinetic barriers and trigger reactions beyond thermal equilibrium at ambient temperature and pressure. In this study, the effects of operating conditions (discharge frequency, input power, and gas flow rate) and geometrical parameters (discharge length, discharge gap, and dielectric materials) have been extensively analyzed using typical cylindrical dielectric barrier discharge (DBD) plasma. The discharge characteristics changed by operating conditions (including waveforms of applied voltage and current) are compared, indicating higher applied voltage and lower gas flow rate can strengthen the filamentary discharges. The results demonstrate CO₂ conversion rate increases with the increase of applied voltage and the decrease of CO₂/H₂ ratio, achieving its maximum value of 43.0% at 20 mL/min. The highest energy efficiency of 3771.9 μg/kJ for CO generation is obtained at the applied voltage of 5.5 kV and gas flow rate of 40 mL/min, respectively. Besides, the structure of plasma reactor also impacts the performance of CO₂ conversion. On the one hand, the discharge gap has a significant role in the variation of CO₂ conversion and product selectivity, which is attributed to the electric field density and corresponding electron-induced reaction. On the other hand, the circulating water-cooling jacket was used to find out the influence of reaction temperature, which switched the product from CO to CH₄. This work will pave the way for a sustainable alternative towards future CO₂ conversion and utilization.

Methanol has received widespread attention as a kind of alternative fuel for internal combustion engines because of its wide range of sources, low price, low combustion emission pollution, and carbon neutrality. Meanwhile, the relatively developed diesel spray theories have a great reference value to theoretical analysis of high-pressure methanol injection. Based on the optical experiment of the methanol sprays under high-pressure injection conditions, the empirical models for predicting spray tip penetration, spray angle, spray area, and spray volume of diesel were used to calculate the parameters of the methanol sprays. These calculation values were then compared with the experimental values to establish empirical models of high-pressure methanol spray characteristics. On this basis, an assessment of the adaptability of the diesel spray similarity theory applied to the high-pressure methanol sprays was conducted under similarity conditions. The results show that Wakuri's model has the best predictive performance on the methanol spray tip penetration (the average relative error is 4.31%), and Inagaki's model provides the most precise predictions on the methanol spray angle (the average relative error is 2.63%). After correcting the constants, empirical models that can describe the methanol spray characteristics in this experiment were proposed. In terms of the similarity theory, the diesel spray similarity theory shows good adaptability to the spray tip penetration and spray angle of the high-pressure methanol sprays with nozzle diameters of 0.12 mm and 0.15 mm under similarity conditions. The above results can serve as a basis for extending diesel spray theory to methanol and for the upsizing or downsizing design of direct injection methanol engines with different bore sizes of the same series.

Globally, interest is shifting toward green energy due to its environmental appeal. Therefore, to promote energy and environmental conservation in drying, several solar dryers have been developed which offers limitless, clean, and free energy to dry agricultural product. Among these solar dryers, solar greenhouse dryers offer a very simple low-temperature, energy-efficient structure capable of drying large beds of crops by harnessing thermal radiation energy from the sun. To improve the thermal performance in the passive mode especially, several modification approaches have been adopted. This article, therefore, reviewed various possible modification methods that have been adopted to improve the thermal performance of the greenhouse, with a focus on the modification of the northern wall. The various strategies involved in the modification of the north wall structure include creating an opaque north wall with black painted materials, installing a reflective north wall using a mirror, integrating heat storage materials like pebbles or brick, integrating phase change materials into the north wall, digging the soil depth to form a north wall and creating a variable southern roof with a modified north wall. Modifying the northern wall showed higher drying chamber temperature compared to completely transparent convectional greenhouse dryers in all the studies. These modifications can increase the temperature of the modified greenhouse by 13.38∼21.10% for a natural convection solar greenhouse dryer compared to the conventional type. With this approach, the radiation losses from the northern wall can be minimized and the energy management system of the greenhouse can be optimized for higher performance, making it more sustainable and eliminating the use of fossil fuel in agricultural product drying.

The pressing need for substantial actions to address climate change is globally recognised, notably through initiatives like the Green Energy Transition (GET) to foster a sustainable future. Despite this global acknowledgement, traditional energy sources maintain their dominance in the worldwide energy sector, with fossil fuels and solid biomass accounting for about 75% of total global Greenhouse Gas (GHG) emissions. The escalating GHG emissions levels directly threaten the climate, leading to global warming and adverse environmental consequences. A systematic literature review was employed to comprehensively examine the conceptualisation and drivers of the GET. The study identified Economic, Social, Political/Legal, Technological, and Environmental factors as drivers of GET. The study revealed diverse perspectives among researchers in conceptualising the GET, with a prevailing consensus that it is a global shift from carbon-intensive to sustainable and low-carbon emission energy alternatives and associated technologies. Predominantly, sustainability transition theories emerged as the most frequently applied conceptual frameworks. Commonly utilised tools for data analysis included Autoregressive Distributed Lag and Generalized Methods of Moments. Recognising the critical role of GET in mitigating GHG emissions and addressing climate change, the results underscore the importance of addressing the identified factors propelling the transition.