Current Issue : April-June Volume : 2024 Issue Number : 2 Articles : 5 Articles
Implementing successful aggregated charging strategies for electric vehicles to participate in the wholesale market requires an accurate battery model that can operate at scale while capturing critical battery dynamics. Existing models either lack precision or pose computational challenges for fleet-level coordination. To our knowledge, most of the literature widely adopts battery models that neglect critical battery polarization dynamics favoring scalability over accuracy, donated as constant power models (CPMs). Thus, this paper proposes a novel linear battery model (LBM) intended specifically for use in aggregated charging strategies. The LBM considers battery dynamics through a linear representation, addressing the limitations of existing models while maintaining scalability. The model dynamic behavior is evaluated for the four commonly used lithium-ion chemistries in EVs: lithium iron phosphate (LFP), nickel manganese cobalt (NMC), lithium manganese oxide (LMO), and nickel cobalt aluminum (NCA). The results showed that the LBM closely matches the high-fidelity Thevenin equivalent circuit model (Th-ECM) with substantially improved accuracy over the CPM, especially at higher charging rates. Finally, a case study was carried out for bidding in the wholesale energy market, which proves the ability of the model to scale....
We investigate the energetic advantage of accelerating a quantum harmonic oscillator Otto engine by use of shortcuts to adiabaticity (for the expansion and compression strokes) and to equilibrium (for the hot isochore), by means of counter-diabatic (CD) driving. By comparing various protocols with and without CD driving, we find that, applying both type of shortcuts leads to enhanced power and efficiency even after the driving costs are taken into account. The hybrid protocol not only retains its advantage in the limit cycle, but also recovers engine functionality (i.e. a positive power output) in parameter regimes where an uncontrolled, finite-time Otto cycle fails. We show that controlling three strokes of the cycle leads to an overall improvement of the performance metrics compared with controlling only the two adiabatic strokes. Moreover, we numerically calculate the limit cycle behavior of the engine and show that the engines with accelerated isochoric and adiabatic strokes display a superior power output in this mode of operation....
Based on the survey, the majority of fishermen in Indonesia choose to use land engines as propulsion for the main engine and auxiliary engine on ships because in terms of the price of land engines, they are much cheaper than ship engines produced by marine engine factories. Therefore, not a few workshops that often serve land engine modifications for further use as ship propulsion. Regulations regarding the use of land engines as ship's main engines in Indonesia are currently not widely regulated in the Classification Agency regulations. Heat exchanger that supports the cooling system for optimal use of land engines on ships. Furthermore, the heat exchanger design process with a heat transfer load of 17,416 Watt was carried out using the LMTD method and obtained a heat transfer area value of 1,204 m2 with a staggered arrangement configuration. From the results of the CFD simulation, the temperature value at the hot water outlet is 51.39 C....
Electric vehicles and photovoltaic power stations can play an important role in replacing fossil fuels. This article presents a case study on the placement of charging stations powered by photovoltaic energy along an important highway in Brazil. A demand model was adopted to elaborate three scenarios for 2030 with different participation levels of electric vehicles in the Brazilian market. An optimized allocation model was used to derive the location and number of charging stations required to meet the charging demand. The results provided a list of adequate locations for installing the charging stations and offered insights into the consumed electricity and greenhouse gas emissions that could be mitigated by these actions. A financial analysis was conducted, and it was determined that the charging costs, based on the Internal Rate of Return calculation, were 10%. These costs were compared to the fueling costs of other traditional vehicles. The results showed that the costs can be 72% lower than the cost of refueling current conventional automobiles. The results of this study can serve as a reference in the public policy debate, as well as for investors in fast charging stations....
In view of the difficulty of a diesel engine starting in a plateau environment, this paper analyzed three factors that affect diesel engine starting by literature review and theoretical analysis, deeply analyzed the mechanism of the plateau environment on the diesel engine starting process, and introduced auxiliary measures for diesel engine starting in a plateau environment so as to further study how fast and reliable starting has laid a solid theoretical foundation....
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