The increase in refrigerated food demand, due to increase on urban population is involving the replacement of conventional diesel-powered transport refrigeration units (TRUs) by electrical-based auxiliary power units APUs, in an imperious. This paper presents a turnkey solution of a hydrogen-based APU for a refrigeration unit integrated in short haul trucks, for its use in the food industry.
The importance of renewable energy sources like solar energy in reducing carbon emissions and other greenhouse gases has contributed to an increase in grid integration. However, the intermittent nature of solar power causes reliability issues and a loss of energy balance in the system, which are barriers to solar energy penetration. This study proposes a unique three-step approach that identifies weather parameters with moderate to strong correlation to solar radiation and uses them to predict solar energy generation. The combination of an on-site weather station and a reliable local weather station produces relevant data that increases the accuracy of the forecasting model irrespective of the machine learning algorithm used. This data source combination is tested, along with two other scenarios, using the exponential Gaussian Process Regression machine learning algorithm in MATLAB. It was found to be the most effective algorithm with a Normalized Root Mean Square Error of 1.1922, and an R2 value of 0.66.
Hydrogen fuel cell vehicles (HFCVs) replacing internal combustion engine vehicles are a viable option to achieve net-zero carbon emission in transportation. Higher hydrogen storage pressure is necessary for increased recharge mileage, necessitating a hydrogen decompression mechanism. A unique pressure-lowering construction (Tesla-type orifice structure) is proposed in this study, in which Tesla-type channels are paralleled and incorporated into a standard orifice plate structure. A complete parametric analysis is used to optimize the Tesla-type orifice construction further. Compared to a standard orifice plate, at low inlet mass flow rates, the Tesla-type secondary orifice construction gives higher pressure drop performance. The presented study may provide a feasible technical structure for achieving high-efficiency hydrogen decompression in HFCVs.
Both effective utilization of renewable energy and multi-generation system are promising ways to reduce greenhouse gas emissions. This paper proposed a combined cooling, heating and power (CCHP) system, which is based on a basic system and consists of a transcritical CO2 cycle, an ejector refrigeration cycle, a domestic water heater and a thermoelectric generator. The parametric and comparative analyses are performed to show the system performance enhancement of the modification system. The multi-objective optimization is also conducted for the involved CCHP systems. Results show that compared to basic system, the novel system owns a higher exergy efficiency (30.75 VS 27.42%) and a lower total product unit cost (27.39 VS 32.28 $/GJ), confirming the obvious performance improvement.
The catalytic mechanism of Cu(111) surface on the pyrolysis of HFO-1234yf has been investigated by Density Functional Theory (DFT). Firstly, search for the most stable adsorption structure of HFO-1234yf and its pyrolysis products on the Cu(1 1 1) surface. Secondly, The most stable co-adsorption structure of the products of Path1-4 on Cu(1 1 1) surfaces was calculated. Finally, the transition state structure of Path1-4 were investigated. The results prove that the copper surface reduces the energy needed for the pyrolysis of HFO-1234yf.
Electric mobility can reduce energy consumption and polluting emissions and is one of the key elements of the current energy transition. Electric vehicles take over is hampered by different problems, above all the scarce diffusion of adequate recharging infrastructures. The objective of this paper is to design a smart system for the shared charging of electric vehicles. Such system minimizes the necessity of additional infrastructure by valorizing the electricity not used by a residential building. The effectiveness of such a system has been demonstrated in two realistic scenarios with a building consisting of 3 apartments and an elevator, a photovoltaic system, and up to 4 electric vehicles.
The upcoming transformation from internal combustion vehicles to electric vehicles in the private transport sector, together with the increasing demand for electricity, leads to challenges such as over-loading for the power grid. This study shows an economic analysis to what extent storage systems can be an alternative to conventional grid reinforcement. Current and predicted costs for storage systems are compared with the costs for cable replacement in the medium-voltage grid and correlations are derived. Accurate co-simulations of storage systems and the distribution grid allow these cost scenarios to be applied to use cases. The results show that the energy related costs for storage systems decrease about 38.5 % from 468 $/kWh to 288 $/kWh from 2020 to 2030. This leads to scenarios, mainly in urban distribution grids, where storage systems are an alternative to conventional grid reinforcement.
The combustion characteristics of a newly developed Clustered Porous Radiant Burner was investigated. Numerical simulations were performed at different equivalence ratios for a power input of 12.56 kW and the flame movement was analyzed by locating the maximum temperature points. Thermal nonequilibrium model was considered for the energy equations and the combustion was modelled by employing eddy-dissipation model. Surface combustion was reported for equivalence ratio 0.6, while the submerged combustion was obtained for equivalence ratios 0.7 to 0.85. Stable partially submerged combustion was obtained for equivalence ratio of 0.9. The burner was observed to be unstable when operated at an equivalence ratio of above 0.95. Numerically predicted result was in good agreement with the experimental data.
As highlighted by the European Union legislation, the building sector is considered crucial in order to achieve the expected objectives in terms of reduction in greenhouse gases emissions to net zero and below. Furthermore, the impact that user’s behavior has on the energy consumption of residential buildings and consequently on well-being and comfort is well documented. In these regards, the application of Building Automation and Control System (BACS) aims at achieving an improvement in the user’s indoor comfort conditions, as well as a significant reduction in energy consumption due to an optimization of its delivery. This study verifies the potentialities of BACS installation to two case studies; a nearly Zero Energy single-family house and an energy retrofitted apartment located in the Northern Italy. In detail, different scenarios were designed, combining different energy consumers’ profiles, and building automation systems configurations. In order to measure the feasibility of the projects, Cost-Benefit Analyses (CBA) were performed, comparing investment cost with energy savings and extra economic benefits. The latter were estimated through a survey in terms of consumers’ willingness to pay for the installation of smart devices in their homes through a contingent valuation in the iterative bidding format.
This paper proposed a piezoelectric wind energy harvesting method by vortex induced vibration (VIV) of axial bending vibrations of a flexible cylindrical cantilever shell. In the past decade, wind energy harvesting method by piezoelectric devices had been widely studied for alternative approach to the conventional wind turbines toward supplying power sources for ultra-low power electric devices which will be used for remote monitoring of large-scale structures. However, most of them were based on the combination of a rigid bluff body (BB) cylinder and a cantilever beam which contains piezoelectric element, and had problems of low power generation and durability against repeated loading. In the authors’ previous reports, a new Piezoelectric Cylindrical Shell Wind Energy Harvesting Flag (PCSWEHF) had been proposed as a flexible and durable power generation structure that utilizes VIV and power generation performance by circumferential bending motion of side-supported shell harvester was experimentally verified. In this study, we experimentally investigated the cantilever-type flexible structure based on the PCSWEHF by using prototypes with different parameters: the cross-sectional area of the cylindrical shell is constant, and the outer and inner radii of the shell are varied.