A battery-to-electrolyzer pathway for energy management in a hybrid battery/hydrogen microgrid

A RES-based microgrid with two simultaneous storage options - battery and hydrogen - is considered. While the battery pack serves as a short-term storage solution, the hydrogen-cycle (consisting of an electrolyzer, a hydrogen pressurized tank and a fuel cell stack) provides for a long-term (seasonal) storage in order to improve the system resilience and to allow off-grid operation for longer time. With respect to the most classical energy management approach, where energy is transferred either from PV to battery (as the priority transfer) or from PV to electrolyzer, the novel strategy adopted in this paper also adds the possibility of a battery-to-electrolyzer energy conversion route. This route is enabled whenever the energy stored in the battery is expected to overcome the estimated short-term energy needs. The novel strategy reveals significant potential to increase the hydrogen production during the summer months, by redirecting to the electrolyzer part of the excess energy that would be otherwise curtailed or transferred to an external grid. Application of the strategy during autumn and winter time reveals on the contrary a clear worsening of the microgrid performance and should be avoided

Energy and Seismic Rehabilitation of RC Buildings through an Integrated Approach: An Application Case Study

The high number of existing buildings in Italy without adequate seismic and thermal performances requires the definition of integrated retrofitting techniques in order to improve the seismic performance and to reduce energy losses at the same time. On one hand, an integrated approach appears mandatory considering that improving only the energy efficiency of nonseismic buildings leads to an increase of their exposure and, therefore, of their risk in the case of seismic events. On the other hand, seismic strengthening without an adequate thermal assessment and rehabilitation could compromise living comfort and energy maintenance costs. In this context, an application of integrated approach for the rehabilitation of reinforced concrete (RC) existing buildings has been proposed referring to a case study representative of the Italian building stock. Different configurations of infill panels have been considered in order to analyze both energy and seismic performance. Monthly quasi-steady state and hourly dynamic models have been used for the calculation of the energy need of buildings located in different Italian climate and seismic zones. Seismic performances have been evaluated by means of incremental nonlinear dynamic analysis (IDA). As-built and post-retrofit performances have been compared in order to evaluate the effectiveness of the proposed intervention solutions

Modeling and simulation of low current atmospheric and high-pressure helium plasma discharges

A plasma discharge in a Helium gas reactor at different pressures and at low currents (0.25–0.45 A) has been investigated by Computational Fluid Dynamic modeling coupled with the Maxwell’s equations. The results show different discharge dynamics across the pressure range (0.1–8 MPa), with an arc discharge obtained at high pressure and a low current arc discharge observed at atmospheric pressure. A large density gradient at higher pressure causes a strong natural convection effect in the reactor. This density gradient affects drastically the discharge shape and the velocity field at high pressures while at atmospheric pressure, a lower density gradient was observed resulting in a low velocity magnitude. It has been observed that the velocity magnitude is not affected by the electric current. The discharge electric potential has been calculated by considering the electrical characterization of the electrodes and numerical results have been compared with experimental results. The comparison shows a good agreement between the measured and calculated discharge electric potential at lower pressures. These devices can be used as plasma sources for wastewater treatment.The Royal Societyhttp://www.frontiersin.org/Physicsam2022Chemical Engineerin

Analysis of Electron Dynamics in Non-Ideal Penning Traps

In Penning traps that are used for particular applications, such as in ion pump technology, Larmor, bouncing and diocotron frequencies can be of the same order of magnitude. The paper deals with the dynamics of electrons confined in such devices starting from the study of the properties of the trajectories. In cases of interest, in which electron-neutral collision frequency is much smaller with respect to the characteristic frequencies of the motion, suitable time averages of the trajectories are introduced in order to simplify the analysis of the problem. In the work, time averages have been calculated in a simple way by using an approximate r−z decoupling of the effective potential. Results obtained with the method are presented and discussed in both linear and nonlinear regimesPenning trap, ergodic methods, electron dynamics, time-averag

Thermodynamic properties of high temperature air in local thermodynamic equilibrium: II accurate analytical expression for electron molar fractions

An extremely accurate analytical expression for electron molar fractions in LTE air plasma in the temperature range 50–20 000 K and in the pressure range 10^−3 ÷ 10^3 bar is reported. Results have been obtained by using self-consistent cutoff and inserting Debye-Huckel corrections