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The effect of streamwise conduction on the entropy generation of low-Peclet-number nanofluid flow in circular microchannel heat sinks under exponentially decaying wall heat flux with constant pumping power condition is analytically studied. Mathematical models with and without streamwise conduction term in the energy equation are developed and closed-form solutions are obtained. Due to the dramatic...
The large scale penetration of electric vehicles (EVs) will introduce technical challenges to the distribution grid, but also carries the potential for vehicle-to-grid services. Namely, if available in large enough numbers, EVs can be used as a distributed energy resource (DER) and their presence can influence optimal DER investment and scheduling decisions in microgrids. In this work, a novel EV...
Fuel blends that contain biodiesel are known to produce greater NOx (nitrogen oxide) emissions in diesel engine exhaust than regular diesel, and this is one of the key barriers to the wider adoption of biodiesel as an alternative fuel. In this study, a water-containing ABE (acetone–butanol–ethanol) solution, which simulates products that are produced from biomass fermentation without dehydration processing,...
The share of renewable energies in electricity and heat supply besides the conventional energy resources gains more importance. Accordingly, the efficiency and flexibility of modern thermal power plants should be further improved. To design such a system, it is necessary to generate detailed computer models that can accurately predict the power plant behaviour during fast transients, part loads and...
A new hybrid system mainly consists of a molten carbonate fuel cell (MCFC) and a Stirling heat engine is established, where the Stirling heat engine is driven by the high-quality waste heat generated in the MCFC. Based on the electrochemistry and non-equilibrium thermodynamics, analytical expressions for the efficiency and power output of the hybrid system are derived by taking various irreversible...
In the present study, optimization of rhombic drive mechanism used in a beta-type Stirling engine is performed based on a dimensionless theoretical model toward maximization of shaft work output. Displacements of the piston and the displacer with the rhombic drive mechanism and variations of volumes and pressure in the chambers of the engine are firstly expressed in dimensionless form. Secondly, Schmidt...
Local governments and property developers are increasingly seeking robust models for strategic planning of retrofitting residential energy systems. Strategic planning here infers making decisions on technology upgrades at the concept design stage. This represents a problem with many degrees of freedom. Optimization models offer a solution. The presentation of the tool RESCOM is the focus of this paper,...
An IGCC (integrated gasification combined cycle) is a widely used electrical power generation system that allows for a variety of feedstocks with high efficiencies. In this study, a 300 MW class IGCC plant was simulated using the PRO/II software package, and thermodynamic analysis was performed. The simulated results were compared to the basic design data for a 300 MW Class IGCC demonstration plant...
In this study, the exergetic performance of a baffled type solar air heater has been evaluated theoretically. A detailed parametric study was done to investigate the effect of variation of fin and baffle parameters, number of glass covers, bottom insulation thickness and inlet air temperature at different mass flow rates on the exergy efficiency. The results indicated that attaching fins and baffles...
The aim of this study is to model and design a hybrid renewable energy system for the remote area in Ras Musherib located in the western region of Abu Dhabi. The hybrid system, which consists of photovoltaic (PV) array, wind turbines, batteries and diesel generators, is designed to meet three known electric loads, 500 kW, 1 MW, and 5 MW to be able to fulfill the primary load for 250, 500 and 2500...
This paper discusses an ameliorated sample entropy-based capacity estimator for PHM (prognostics and health management) of Li-ion batteries in electrified vehicles. The aging datasets of eight cells with identical chemistry were used. The sample entropy of cell voltage sequence under the well-known HPPC (hybrid pulse power characterization) profile is adopted as the input of the health estimator....
Numerical simulation for natural convection flow in fluid filled enclosures with curved side walls is carried out for various fluids with several Prandtl numbers (Pr = 0.015, 0.7 and 1000) in the range of Rayleigh numbers (Ra = 103–106) for various cases based on convexity/concavity of the curved side walls using the Galerkin finite element method. Results show that patterns of streamlines and heatlines...
Gas/particle two-phase flow experiments at different over-fire air ratios were conducted using a 1:20 small-scale model of a down-fired 350 MWe superficial utility boiler designed with multiple injections and multiple staging combustion technology. The mean velocity, fluctuating velocity and particle volume flux were measured using particle dynamics anemometer measurements. None of four conditions...
The current numerical study is conducted to analyze melting in a rectangular closed enclosure by subjecting the bottom wavy surface to a uniform temperature. The cavity vertical walls and the top wall are insulated while the bottom wall is maintained at temperature TB = 38.3 °C. The enclosure was filled by solid Gallium initially at temperature Ti = 28.3 °C. A numerical code is developed using an...
Growth of the hydrogen market has motivated increased study of hydrogen production. Understanding how biomass is converted to hydrogen gas can help in evaluating opportunities for reducing the environmental impact of petroleum-based fuels. Using an atmospheric-pressure microwave plasma reactor coupled with species-selective analysis, experiments are conducted at microwave power levels of 800, 900...
This case study is aimed to investigate how the injector fouling can influence both the injection system and engine performances. In particular, the presence of deposits in the nozzle of the injector could affect the injection system performance along its life. The investigation was carried out on transparent compression ignition engine equipped with the head of a commercial multi-cylinder engine...
For the last years, PV (photovoltaic) generation has been having an important impact on LV (low voltage) and MV (medium voltage) grids in Spain, due to the increasing number of installations. As power monitoring of the generation is in most cases not required, utilities are forced to make assumptions on PV power generation in order to perform network planning studies for both peak demand and contingency...
Energy investments in Poland are currently focused on supercritical coal-fired unit technology. It is likely, that in the future, these units are to be integrated with carbon capture and storage (CCS) installations, which enable a significant reduction of greenhouse gas emissions into the atmosphere. A significant share of the energy market in Poland is constituted by coal-fired combined heat and...
The exhaust gases contain large amounts of unburned hydrocarbons during cranking without combustion. The effects of unburned hydrocarbon recirculation on ignition and combustion during diesel engine cold starts were investigated using both experiments and simulations. Experiments were conducted on a single-cylinder DI (direct injection) diesel engine equipped with a common rail injection system. The...
This study attempts to estimate the economic value of residential electricity use in the Republic of Korea. According to micro-economic theory, the economic benefit of residential electricity consumed is the sum of the actual residential electricity price and the additional WTP (willingness to pay) for the consumption. We apply the dichotomous choice contingent valuation method to assess the additional...
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