Abstract

Urban population growth and extreme weather events challenge the balance of energy supply and demand, stressing power grids and leading to higher prices and potential blackouts. Addressing these challenges requires sustainable and resilient energy systems. This research aims to develop a methodology to optimize urban infrastructure energy resilience by integrating urban-scale building energy modeling (UBEM) with smart grid technologies. The methodology encompasses building energy analysis, renewable energy optimization, and systems-level integration. Using the Toyosu area of Tokyo as a case study, the research examines a normal baseline with 2023 historical weather data and an extreme weather scenario with future climate datasets. Each case contains 11 input variables and 4 output variables, with 6 input variables used in UBEM to generate the load profile. The study employs the REopt tool to identify optimal combinations of renewable energy and storage technologies. Simulation results demonstrate the feasibility of the proposed methodology, providing insights into enhancing urban energy system resilience and achieving sustainability goals. The proposed methodology allows for a more robust and dynamic response to fluctuations in energy demand and supply that is particularly critical during extreme weather events which are becoming more frequent due to climate change.

Abstract

Bipolar plates are integral to the functionality of anion exchange membrane electrolysis cells, with the flow field design being a critical determinant of heat and mass transfer, as well as electron conduction within the cell. This paper establishes a simulation model for anion exchange membrane electrolysis cells and analyzes the influence of the geometric structure of the serpentine flow field on the performance of the electrolysis cells based on the trade-off relationship between heat transfer, mass transfer, electron conduction. The results indicate that the dominant factors affecting current density when changing the channel width are electron potential and temperature. The smaller the channel width, the higher the electron potential and temperature, and the higher the current density. When the changing factor is the number of inlets in the flow field, the higher the liquid saturation, the higher the current density. Therefore, the current density is ranked as follows: 1-path serpentine flow field >3-path serpentine flow field >2-path serpentine flow field. Therefore, when the voltage is 2 V, the 1-path serpentine flow field with a channel width of 0.6 mm has the highest current density, which is 10.8% higher than the 2-path serpentine flow field with the lowest current density.

Abstract

Injecting CO2 into low-permeability reservoirs can synergistically enhance oil recovery and achieve carbon sequestration goals. The miscibility between CO2 and crude oil during the displacement process is influenced by pore scale and water saturation. To elucidate the characteristics of multiple types of miscibility in CO2 flooding at different water saturation levels in the low-permeability reservoirs of Block H in the JY Oilfield and to guide the design and parameter optimization of CO2-EOR schemes, we conducted CO2-crude oil phase behavior experiments, established a compositional model for CO2 flooding numerical simulation in low-permeability reservoirs, and proposed standards and characterization methods for the classification of multiple types of CO2-crude oil miscibility states under different water saturation levels. The influence of gas injection factors on miscibility state transitions was also determined. The study results indicate that Block H of the JY Oilfield contains medium-light crude oil with a saturation pressure of 4.762 MPa and a minimum miscibility pressure of 17.26 MPa. Under different water saturations, four types of CO2-crude oil miscibility states exist. As water saturation increases, the miscibility pressure threshold rises, and oil recovery decreases. Pore size and residual water significantly affect the miscibility state, with higher water saturation reducing the effectiveness of CO2 in improving crude oil mobility. Increasing the number of pore volumes injected and using high-purity CO2 favor achieving miscible and fully miscible flooding, resulting in high displacement efficiency and increased ultimate recovery. The study concludes that CO2-EOR scheme design for low-permeability reservoirs should prioritize blocks with medium to low water saturation and optimize injection and production parameters based on reservoir structure characteristics. For blocks with higher water saturation, employing near-miscible to miscible flooding at lower pressures can significantly reduce development costs and maximize economic benefits.

Abstract

In response to the problem of using cooling fluid to cool the bottom surface of components or devices, this study adds charged particles to the cooling fluid and regulates the heat flow by adjusting the electric field strength. In order to explore the microscopic mechanism of the effect of electric field strength on the heat transfer process in micro- and nano-fluidic channels, the convective heat transfer characteristics of argon fluid cooling on a platinum wall under different electric field strengths are simulated using the molecular dynamics method. A molecular dynamics (MD) model for the convective heat transfer of argon fluid in microchannels is established and the heat transfer process is simulated under different electric field strengths. The radial distribution functions (RDFs), vibrational density of states (VDOS) and atomic distribution functions of the atoms in the system are calculated, and the microscopic mechanism of convective heat transfer between argon fluid and platinum wall is analyzed. The influence of electric field intensity on the temperature and velocity distribution of the argon fluid is studied. The variation law of Nusselt number (Nu) and its controlling effect on the direction of the heat flow are analyzed. The results show that increasing the electric field intensity can improve the convective heat transfer characteristics in microchannels. Compared with no electric field, when the electric field intensity is 2.0V/nm, the Nu at the bottom and the top surfaces are increased by 42% and 56%, respectively. The temperature difference between the inlet and outlet is increased by 22.4%, the external temperature is reduced by 109.2K.

Abstract

The lifetime and performance of battery energy storage system depend on the temperature uniformity between batteries. In order to meet the temperature requirements in high discharge rate scenarios, this study proposes a novel composite cooling system. Based on the battery module, a thermal management system integrating PCM cooling, air cooling and liquid cooling is established. The influence of liquid cooling layout and flow direction on temperature uniformity is discussed. The flow parameters of air cooling and liquid cooling are optimized by orthogonal analysis. The results show that liquid-cooled longitudinal flow has better temperature uniformity than cross flow. When the liquid cooling flow direction is completely countercurrent, the maximum temperature difference is reduced to 4.35 K, and the improvement effect is 12.47%. After further auxiliary air cooling with inlet velocity of 0.4 m/s, the maximum temperature difference is reduced to 4.13 K. In general, this study can provide a new idea for BTM of high-rate discharge scenarios.

Abstract

In order to make full use of the latent heat of phase change material (PCM) and reduce loss of active cooling power consumption, based on synergy idea, this study discusses the influence of three air supply strategies of air-cooling start time, air-cooling stop time and air-cooling velocity on the composite cooling effect. Based on the entropy weight method, the optimal air supply strategy in the above three schemes is selected. The results show that after optimizing the air supply strategy, the PCM utilization rate of three schemes is increased by 52.50%, 29.13% and 31.44% respectively. The loss of air-cooling power consumption is reduced by 52.61%, 18.72% and 31.44% respectively. In particular, the strategy of adjusting the inlet velocity of battery module has the best comprehensive target performance, and the OP value is 0.64. The maximum temperature and maximum temperature difference after discharge are 307.55 K and 2.66 K, respectively. In general, it is feasible to optimize the composite cooling scheme based on the idea of synergy.

Abstract

The idea so-called Realizing Smart Energy Sharing (realSES) will contribute in development of a comprehensive management platform for energy sharing/trading in smart communities involving many connected prosumers. The designed and developed prototype is finally going to proof the concept of the state-of-the-art 5G-enabled renewable energy trading platform, integrated in microgrids, equipped with artificial intelligence and machine learning, as well as blockchain technologies to facilitate the prosumer ecosystem in the future distributed energy world. In this paper, after an overview on the realSES architecture, a simplified example of managing and optimizing energy production within a typical hybrid system, as an integral part of the realSES platform, is briefly outlined. More details and discussion can be provided in the extended version of this study.

Abstract

Underground hydrogen storage (UHS) in shale reservoirs is increasingly recognized as a significant method for hydrogen storage, with H2 adsorption on reservoir rocks playing a crucial role in this process. In this work, we utilized molecular simulation techniques to investigate the adsorption behavior of H2 in the slit nanopores of shale organic kerogen and specifically analyzed the effects of gas pressure, pore size, reservoir temperature, and kerogen maturity on H2 adsorption performance. The results indicate that H2 forms a strong adsorption layer on the kerogen pore surfaces, and this layer density increases with rising pressure. The surface excess adsorption amount of H2 increases initially with pressure and then decreases slowly after reaching a critical pressure. H2 exhibits stronger adsorption performance in smaller pores, and higher temperatures are unfavorable for further H2 adsorption. Due to the chemical composition differences among various types of kerogen, the H2 adsorption capacity decreases with increasing maturity. However, the H2 recovery efficiency remains above 90% under the same conditions. In practical applications of H2 storage in shale reservoirs, it is advisable to prioritize strata with higher organic maturity. Additionally, it is essential to consider the impacts of reservoir pressure and temperature based on realistic conditions to select the most suitable reservoir depth for H2 storage. This study reveals the gas adsorption phenomena involved in UHS at the molecular level, providing insights into the optimal selection of H2 storage shale reservoirs.

Abstract

In the realm of wet process electrode development for Proton Exchange Membrane Fuel Cells (PEMFCs), the rheological characteristics of the catalyst slurry play a pivotal role in shaping the coating appearance. The intricate interplay between solvated ionomers and catalysts gives rise to diverse and complex interactions, which in turn exert specific functions on aggregates, thus influencing the fluid properties significantly. This investigation utilizes rheological assessments to scrutinize the fluctuations in shear viscosity, viscoelastic behavior, and thixotropic properties of various water/alcohol slurries. The findings suggest that ethanol molecules, with their higher polarity, augment the surface potential of slurry aggregates, concomitantly diminishing slurry viscosity and compromising coating uniformity. This, however, leads to surface imperfections while enhancing the polarization efficiency of the membrane electrodes under high current densities, elevating the voltage output from 0.624V to 0.646V at 2A cm-2. Conversely, n-propanol molecules, relatively less polar, intensify the slurry’s viscosity and ameliorate surface flaws in the coating, thereby reducing the extra-large pore, exhibiting elevated polarization voltage at lower current densities, raising the voltage from 0.851V to 0.866V at 0.2A cm-2.

Abstract

To capture the transformation mechanism from adsorption to capillary condensation in nanostructures,argon adsorption on regularly arranged nanostructures model is established based on Monte Carlo and molecular dynamics simulation in this work. The variation of clusters and the effect of surface wettability during adsorption and capillary condensation are examined. Results indicate that the adsorption starts with the filling of the adsorption site by the single molecular cluster. The atoms in the bulk vapor coalesce with a single molecular cluster to form the multi molecular cluster after the adsorption site is filled. And the coalesce of clusters induces the formation of liquid film. Subsequently, the bending of the liquid film brings a negative pressure to the bulk liquid, which induces the onset of capillary condensation. During this process, the number of single clusters decreases rapidly, while the number of multi molecular clusters increases. With the decrease of surface wettability, the argon atoms tend to gather at the bottom of nanostructures, directly forming into multi molecular clusters. Finally, the adsorption and capillary condensation map exhibit that the critical relative pressure decrease from 0.6 to 0.2 as the surface wettability parameter increase from 0.33 to 0.67. And the increase in spacing leads to an increase in critical relative pressure.