In this paper, the effects of injection parameters on combustion and particulate size distribution of partially premixed combustion (PPC) fuel with n-butanol were investigated experimentally. High concentrations of particle emission for the n-butanol PPC combustion are observed. The particle sizes are primarily concentrated within 64nm. With the advance of the start of injection (SOI) timing, more particles are formed and the particulate size distribution curve shifts towards right (larger size). In addition, the pilot-main injection strategy can effectively reduce the maximum pressure rise rate (MPRR). Furthermore, through adopting appropriate injection parameters, the MPRR and particle number can be reduced simultaneously, while still maintaining a comparable indicated thermal efficiency compared to the single injection strategy.
Ultra-high heat flux cooling has become a research hotspot owing to its wide application in thermal engineering fields. Only by exploring its internal physical mechanism and calculating the CHF (critical heat flux) of different surfaces, can the necessary theoretical basis be provided for the design and optimization of pool boiling heat exchange in engineering applications. Previous models cannot accurately predict CHF value due to the limitations of their physical models. In this paper, a new theoretical physical model was obtained to predict CHF value of pure liquid on a heated surface. The theoretical model proposed a new CHF trigger mechanism based on the bubble behavior near the heater surface. A three-dimensional force balance of a separated bubble was analyzed at CHF condition to derive the analytical correlation for CHF value. The correlation considers the effect of hydraulic pressure, surface tension, liquid properties as well as the contact angle of the heater surface. The predicted values of CHF value on heated surfaces obtained from the present model were found in agreement with existing experimental data within a wide range. It is shown that CHF is mainly affected by factors of adhesion force and hydraulic pressure.
Aiming at the demand of comprehensive vulnerability assessment in shipboard power system security defense, the paper proposed a vulnerability status description model of shipboard power system. The structure and physical properties of shipboard power network were fully analyzed. The product space which was called shipboard power network comprehensive vulnerability index set was established by degrees, betweenness, maximum connection sub-diagram scale, reliability indexes. Secondly, the normalized index sets were compactness and thepnormon the compactness sets were continuous were proved in this paper. The norm of vulnerability index was vulnerability output equation of shipboard power system. Using the norm on the product space, multi-scale integrated shipboard power network vulnerability norm was proposed, and the comprehensive structure performance evaluation of the shipboard power system network was formed. The index describes the change tendency of the shipboard power network comprehensive vulnerability. Finally, the test on a certain type of shipboard power network demonstrates the validity of the model.
Microthrusters are special category of propulsion device used to propel micro sized satellites. It is designed as per the mission requirements. There are various kinds of propulsion requirements such as continuous mode operation for orbit transfer (from one planet to another), orbit shift or adjustment for asteroid mining, pulsed mode operation for attitude control of satellites, and gravitation or solar drag compensation in orbit. Continuous mode operation is a high propellant consuming operation and designed cautiously to reach the destination with onboard available propellant. While pulsed mode operation is widely used for LEO (Low earth orbit) applications, where gravitation drag, atmospheric drag and solar drags are dominating. This paper focuses on the pulsed mode operation of vaporization liquid microthruster in vacuum operating condition. The pulsed mode operation involves timely thrust generation for the fine tuning of the positioning of the microsatellites. The operational timing in this mode of operation ranges from milliseconds to a few seconds at maximum. The operating time is decided based on the adjustment requirement for the positioning of the microsatellites. Vaporizing liquid microthrusters use green propellant to produce thrust. Tests are conducted under vacuum condition to simulate the actual space conditions and corresponding results are plotted. Results has shown a maximum thrust value of 290 μN at 1 sec of valve operating time, 335 μN at 2 seconds, 413 μN at 3 seconds, 524 μN at 4 seconds and 590 μN at 5 seconds of valve operating time for 200°C of a constant VLM temperature respectively. The effect of the dibble volume has also been discussed for the vaporization liquid microthruster using di-ionized water as liquid propellant.
In this paper, the performance of the moving average and moving median load estimation techniques is investigated using aggregated measurements of domestic smart meters. The load estimation techniques were tested using forward and backward walk approaches. Forward walk aims to estimate future load measurements using past measurements while backward walk estimates missing past measurements of the load using more recent measurements. Simulation results show that the moving average combined with forward walk produces load estimates with higher accuracies than the moving median and backward walk.
Electricity thefts in connivance with employees of electricity distribution companies, remain the Achille’s heel of power sector, addressing which continue to be the holy grail. The lackluster performance of technological measures to curb electricity thefts highlights the need to investigate the human aspectstoo. That’s what this study aims at. The findings, grounded in the responses of the nineteen employees of the Indian electricity distribution companies, detail the factors that induce employees to collude with consumers in electricity theft.
Omnipresent charging infrastructure is a requisite for ensuring smooth transition to e-mobility. Reliable, sustainable, cost-effective and photovoltaic (PV) panel based charging of EV batteries could be befitting solution. This paper presents a PV module-integrated converter for EV charging station which can track maximum power point besides providing requisite high gain boost in voltage to a usable value even under intermittent conditions, i.e. insolation variation and partial shading conditions. The current control scheme evacuates the maximum available power amidst intermittent conditions. The performance of the system is evaluated under Matlab/Simulink environment. Presented simulation results show close conformity with design and validates the effectiveness of the system proposed.
In the past four decades, oil sands production in Canada has increased dramatically. More recently, Canada has developed carbon emission reduction targets to meet its Nationally Determined Contributions and Mid-Century Strategy to reduce GHG emissions. Quantification and assessment of GHG emissions from the oil sands industry – a high emitter – is necessary to track progress toward meeting emissions reduction and technology development. This study uses GCAM, an integrated assessment model, to examine the energy consumption of oil sands extraction and upgrading. Five traditional and cogeneration extraction technologies are compared in model simulations for energy cost and nonenergy (operating) cost. Results show that energy consumed by oil sands production will triple by 2050 because of the expected increase in oil sands production. Cogeneration technologies result in reduced CO2 emissions.
This work proposes a novel design incorporating a passive heat recovery device into a windcatcher and investigates its performance using numerical and experimental analysis. Numerical modelling and experimental testing were used to characterise the radial blade design of the heat recovery rotary wheel in terms of performance. Two configurations of the radial blades provide data that can be used to assess how air velocity is affected by the design, the pressure drop across the device and the heat transfer capabilities of the radial blades. To further assess the potential of the proposed devices, it was incorporated into a multi-directional windcatcher ventilating a small room. Despite the blockage of the rotary heat recovery wheel, it was able able to provide adequate ventilation. In addition to sufficient ventilation, the heat in the exhaust airstreams was captured and transferred to the incoming airstream, raising the temperature between 0.5-4K depending on the indoor/outdoor conditions, this passive recovery has the potential to reduce demand on space heating systems.
Owing to the rapid development of the global economy, the demand for energy and water resources is the main global challenge in the 21st century. This article focuses on the consumption and transfer of the water resources in China’s West–East electricity transmission project. The input–output method is employed to construct a water footprint assessment model for this project. Results show that 606.4 billion kWh of electricity and 2.5 billion m3 of virtual water were transferred from the western to eastern region in 2016. Coordinated policy making the optimal use of water resources for energy generation needs to be further discussed for promoting sustainable regional development.