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We report a simple strategy to prepare novel 2-dimensional graphene analog MoS 2 /MWCNT (molybdenum disulfide/multi-walled carbon nanotube) composites as electrode material for supercapacitor. The MoS 2 /MWCNT composites exhibit superior electrochemical performance to pure MWCNT and MoS 2 . The composite shows a high specific capacitance of 452.7 F g −1 at a current...
This work is aimed at looking into the impact of the solar spectrum distribution on the energy yield of some PV (photovoltaic) materials on both monthly and annual time scales. The relative spectral responses of eight different PV solar cells – representative of each considered technology – have been selected. Modeling solar spectra in four sites located in the north hemisphere together with a 12-month...
This paper presents the system efficiency optimization scenarios of basic and regenerative supercritical ORCs (organic Rankine cycles) using low-GWP (global warming potential) organic compounds as working fluid. A more common refrigerant, i.e. R134a, was also employed to make the comparison. A 150-°C, 5-bar-pressurized hot water is used to simulate the heat source medium. Power optimization was equally...
Temperature–entropy diagrams combined with a pinch point analysis are introduced, providing a vivid and detailed tool to analyse two-step thermochemical water-splitting processes. The impacts of different temperature and pressure conditions, as well as different water conversion rates, are studied. Further, requirements regarding the entropy change in the redox material to reach desired process conditions...
In this paper, a quantum neural network (QNN) is used as controller in the adaptive control structures to improve efficiency of the maximum power point tracking (MPPT) methods in the wind turbine system. For this purpose, direct and indirect adaptive control structures equipped with QNN are used in tip-speed ratio (TSR) and optimum torque (OT) MPPT methods. The proposed control schemes are evaluated...
This article presents a new EROI (energy return on investment) factor named the ideal EROI, or EROI ide , that provides the theoretical upper boundary of the EROI of a given system. The EROI ide is the ratio between the inputs within the EROI stnd boundaries and the theoretical maximum output from a given system; i.e, all losses are omitted and the maximum theoretical energy...
Thermal management of fuel is very important for the cooling system of an advanced engine. In order to study the 3-D phenomena of fuel flow with cracking reaction in the cooling channels and their effect on the utilization of fuel heat sink, numerical models of cracking fuel flow in an asymmetrically heated rectangular tube are built on the basis of the real fuel thermophysical properties using commercial...
In the present paper, a numerical study is presented to investigate the cascade utilization of waste heat in sinter cooling bed. With the aid of CFD (computational fluid dynamics), a two-dimensional unsteady mathematical model, which would significantly reduce the computational time, is established to describe three-dimensional steady flow and heat transfer in sinter cooling bed. The Brinkman–Forchheimer...
Using a bypass to redirect a small flow through the in-house DH (district heating) substation directly to the return pipe is a commonly used but energy-inefficient solution to keep the DH network “warm” during non-heating seasons. Instead, this water can be redirected to the bathroom FH (floor heating) to cool down further and thus reduce the heat lost from bypass operation while tempering the bathroom...
Wind energy is becoming a top contributor to the renewable energy mix, which raises potential reliability issues for the grid due to the fluctuating nature of its source. To achieve adequate reserve commitment and to promote market participation, it is necessary to provide models that can capture daily patterns in wind power production. This paper presents a cyclic inhomogeneous Markov process, which...
The biomass wastes from the palm oil industry offer great potential for large-scale power generation in Malaysia. It has been estimated that 85.5% of available biomass in the country comes from oil palm agriculture. The introduction of the FiT (Feed-in Tariff) regime in 2011, which superseded the underperforming SREP (Small Renewable Energy Power) scheme, is expected to catalyse and accelerate the...
This paper presents a new and efficient method for solving EPD (economic power dispatch) problem. To solve this problem we have combined two meta-heuristic methods, the FFA and the mGA. The acceleration of the convergence speed, the improved solution quality and the balance between exploration and exploitation are achieved with FFA–mGA approach. The searching process starts with the FFA by initializing...
The definition of criteria for the benchmarking of similar entities is often a critical issue in analytical studies because of the multiplicity of criteria susceptible to be taken into account. This issue can be aggravated by the need to handle multiple data for multiple facilities. This article presents a methodological framework, named the Em+DEA method, which combines emergy analysis with Data...
This study reports the performance of a demonstrated 2304 m 2 solar-heated greenhouse equipped with a seasonal thermal energy storage system in Shanghai, east China. This energy storage system utilises 4970 m 3 of underground soil to store the heat captured by a 500 m 2 solar collector in non-heating seasons through U-tube heat exchangers. During heating seasons, thermal energy...
A new silica encapsulation technique toward n-octadecane PCM (phase change material) was developed through sol–gel synthesis using sodium silicate as a silica precursor. Fourier transform infrared spectra confirm the chemical composition of the synthesized microcapsules, and wide-angle X-ray scattering patterns indicate good crystallinity for the n-octadecane inside silica microcapsules. Scanning...
China is currently in the stage of industrialization and urbanization, which is characterized by rigid energy demand and rapid growth of energy consumption. China's transport industry is of high energy consumption and high pollution. Therefore, energy issues in the industry are particularly of concern to all parties. In this paper, a trans-log production function model for China's transport industry...
HEN (heat exchanger network) retrofitting is useful to reduce energy consumption in the existing process industries. In this study, several ERS (exchanger reassignment strategies) for HEN retrofitting are proposed and tested by performing single objective optimization on retrofit problems using IDE (integrated differential evolution). A reassignment strategy which includes practical considerations...
A comprehensive numerical model was developed to predict the electrochemical performance of solid oxide fuel cell (SOFC). The multi-component Lattice Boltzmann (LB) model based on kinetic theory for gas mixtures combined with a representative elementary volume (REV) scale LB algorithm based on the Brinkman equation for flows in porous media, the Butler–Volmer equation and Ohm's law were adopted to...
The advent of distributed renewable energy supply sources and storage systems has placed a greater degree of focus on the operations of the LV (low voltage) electricity distribution network. However, LV networks are characterised by having much higher variability in time series demand meaning that modelling techniques solely relying on iterative forecasts to produce a next day demand profile forecast...
Concentrated solar power presents the drawback of decreasing radiation capture efficiency as the temperature of the receiver increases, because thermal losses increase as well. Low temperature at the receiver is an advantage for radiation concentrators, as they present high capture efficiency, but this fact changes into a drawback because of the low efficiency of the thermodynamic cycles working with...
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