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Hydropower remains, by a wide margin, the largest source of renewable electricity around the world, and hydropower dams supply a greater source of commercial energy than the world's fleet of nuclear power plants. Yet far less attention has been paid to the political, security, and governance elements underlying the continued use and growth of hydropower. Theorists from many disciplines—political geography,...
This study examined the torrefaction performance of Jatropha-seed residue after mechanical screw-press extraction of oil (denoted as JME) at fixed torrefaction temperature (Tr) of 533, 553 and 573 K in the torrefaction time (tr) range of 10–60 min. The characteristics results of torrefied JME (JMET) indicated that the mass yield decreases while dry-basis high heating value (HHD) increases with increasing...
The solid desiccant heat pump (SDHP) system is a novel thermodynamic appliance, intended to improve the energy efficiency of the conventional air conditioning. In the SDHP, desiccant coated heat exchangers are adopted as the evaporator and the condenser instead of the conventional sensible heat exchangers. This article aims to investigate the performance of the SDHP under typical weather conditions...
This paper presents a new coordination framework to optimize the joint operation of pumped-storage unit, irrigation system and intermittent wind power generation in an agricultural microgrid. The microgrid is an agricultural complex connected to the medium voltage network. This complex contains a farm needing water to be irrigated every day. The irrigation system has two large scale reservoirs located...
A fully validated with solid experimental results numerical study regarding the hydrogenation process of rectangular metal hydride beds under effective internal heat management is presented and analysed. Three different geometries equipped with plain embedded heat management tubes are introduced and examined. For each geometry, five different values of metal hydride thickness are studied and additionally,...
In order to utilize the waste heat of blast furnace slag more effectively, the multi-stage slag waste heat recovery system was proposed. This study employed the life cycle assessment to evaluate the environmental performance of the proposed system. Meanwhile, the economic feasibility of the system was analyzed in terms of capital cost and return analysis. Based on the current status of the environment,...
An exploratory study is presented considering the effect of eight different binary mixtures that serve as working fluid for a transcritical Rankine cycle operating with or without recuperator – the binary mixtures considered are composed by CO2, a natural fluid, and a secondary fluid (i.e., R134a, R32, R152a, R41, R161, R1234ze(E), R1234yf, R1270). The secondary component selection was based on its...
This research presents piston expander for low-pressure (1–10 bars) power generation to use with organic Rankine cycle and compressed air storage system. The mathematical model is analyzed to show behavior of main parameters such as pressure ratio and charge/discharge volumes where these parameters influence to the work and an isentropic efficiency base on dimensionless analysis. The main contributions...
The duct storage (DST) model is one of the most widely used borehole heat exchanger (BHE) models owing to its fast calculation scheme and usability. However, the DST model can simulate only regularly placed BHEs, particularly in cylindrical borefield configurations. As a possibility to describe irregular borefield configurations by adjusting BHE spacing has been reported, we propose optimal values...
Physics-based model has been regarded as a promising alternative to equivalent circuit model due to its ability to describe internal electrochemical states of battery. However, the rigorous physics-based model, namely pseudo-two-dimensional (P2D) model, is too complicated for online application in embedded battery management system. In this paper, to simplify the P2D model, a series of polynomial...
Data envelopment analysis (DEA), rough set theory (RS) and fuzzy artificial neural network (FANN) are combined as DEA-RS-FANN procedure to explore the effects of influencing factors on energy efficiency in China's provincial industry sectors. The analysis begins with the DEA technique to evaluate energy efficiency in provincial industries, followed by fuzzy c-means (FCM) algorithm to classify energy...
Through the application of flexible Time-of-Use (ToU) tariffs, demand side management (DSM) can be facilitated in order to alleviate grid congestion problems and potential network reinforcement. In this work, a novel approach to derive ToU tariffs for residential prosumers is described and the potential impact is verified in a pilot network within the distribution grid of Cyprus comprised of three...
Optimisation models have been extensively used for finding optimal configuration and operation of distributed energy technologies. The main objective in most of these models is to find the optimal configuration of distributed energy technologies that will meet a certain energy demand with the least cost and emissions. Local grid constraints are not considered in the optimisation of distributed energy...
The operating principle of condensing boilers is based on exploiting heat from flue gases to pre-heat cold water at the inlet of the boiler: by condensing into liquid form, flue gases recover their latent heat of vaporization, leading to 10–12% increased efficiency with respect to traditional boilers. However, monitoring the energy efficiency of condensing boilers is complex due to their nonlinear...
This research was undertaken to evaluate different inverse models for predicting power output of solar photovoltaic (PV) systems under different practical scenarios. In particular, we have investigated whether PV power output prediction accuracy can be improved if module/cell temperature was measured in addition to climatic variables, and also the extent to which prediction accuracy degrades if solar...
Micro survey data is used to explore the impact of firm-specific characteristics on firms' access to energy in 138 developing countries. The results show that firm-specific characteristics (age, size, sector of activity, location, ownership, etc.) are broadly significant predictors of firms' access to energy. In addition, energy supply conditions are also significant predictors of firms' energy constraints...
Mature hydrocarbon fields co-produce significant volumes of water. As the produced water increases over the life of the field, the project's operating costs increase (due to greater water management expenditure), while the oil revenues decrease. Typically, these waste streams of water have temperatures of 65–150 °C. The combination of moderate temperatures and large water volumes may be suitable for...
Thermoporoelastic effects during heat extraction from low permeability geothermal reservoirs are investigated numerically, based on the model of a horizontal penny-shaped fracture intersected by an injection well and a production well. A coupled formulation for thermo-hydraulic (TH) processes is presented that implicitly accounts for the mechanical deformation of the poroelastic matrix. The TH model...
This work aims to detect the impact of fundamentals and regulatory reforms on the Greek Wholesale Electricity Market, applying SARMAX/GARCH models. The System Marginal Price (SMP) is considered a stochastic, nonlinear process, reflecting not only the effects of endogenous/fundamental market factors but also the effects of exogenous variables including regulatory reforms, which also affect the market...
The present work mainly focuses on the thermodynamic and exergoeconomic comparisons between the novel single-pressure multi-stage CDTPCs (carbon dioxide transcritical power cycles) and single-pressure single-stage CDTPC for engine waste heat recovery. A method based on exergy fuel distribution is proposed to calculate the fuel cost for the bottoming CDTPCs. Parametric analysis is conducted to study...
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