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This paper deals with the analysis of crude oil prices in the context of fractional integration and using bull and bear phases over monthly periods between September, 1859 to July, 2015. We examine both the log prices series as well as volatility, approximated by means of the absolute and the squared returns. The results for the whole sample indicate that the log-prices are nonstationary, with an...
The critical temperature (Tc) and boiling temperature (Tb) of working fluids are important selection criteria for the organic Rankine cycle (ORC) system. In this study, the ratio of Tb and Tc (Tbr) and the vapor expansion ratio (VER) model based on Claussius–Claperyron equation are introduced to compare and explain their effects on the maximum net output power (Wnet,max) and VER of ORC. The investigation...
The CO2 capture based on the MEA (monoethanolamine) absorption has been proved to be a practical and alternative method for the post-combustion CO2 capture. It is of benefit to the energy conservation of CO2 capture system to clarify the impacts of the absorbing column parameters on the system performance. Based on the representative elementary volume method and pseudo-single-liquid model, the computational...
This article presents the results of a 3-year field study into the yield and energy efficiency of maize, sweet sorghum, giant miscanthus, Amur silver grass, Virginia fanpetals and alfalfa with timothy grass grown in a farm in north-eastern Poland. The species with the highest DMY (dry matter yield) were the giant miscanthus (25.3 Mg ha−1 y−1) and maize (22.7 Mg ha−1 y−1). The production of 1 Mg of...
An accurate battery State of Charge estimation plays an important role in battery electric vehicles. This paper makes two contributions to the existing literature. (1) A recursive least squares method with fuzzy adaptive forgetting factor has been presented to update the model parameters close to the real value more quickly. (2) The statistical information of the innovation sequence obeying chi-square...
The energy sector is the major contributor to GHG (greenhouse gas emissions) in Ireland. Under EU Renewable energy targets, Ireland must achieve contributions of 40%, 12% and 10% from renewables to electricity, heat and transport respectively by 2020, in addition to a 20% reduction in GHG emissions. Life cycle assessment methodology was used to carry out a comprehensive, holistic evaluation of biomass-to-energy...
This study investigated the performances of five different substation configurations in single-family houses supplied with ULTDH (ultra-low-temperature district heating). The temperature at the heat plant is 46 °C and around 40 °C at the substations. To avoid the proliferation of Legionella in the DHW (domestic hot water) and assure the comfortable temperature, all substations were installed with...
The submicron characterization of transient heat-transfer processes at solid–liquid interfaces is of great importance in many areas of science and engineering. This paper reports on a technique that allows for the transient thermal imaging of the temperature field underneath a growing bubble during nucleate boiling with submicron spatial resolution. The boiling experiments were performed on a temperature-sensitive,...
The purpose of this study was to investigate the effect of turbulence on the power performance at the yawed and no-yawed flow conditions, focusing on the turbulence intensities and boundary layer in wind tunnel experiments. In this study, UMY02-T01-26 airfoil was developed, based on the body type of large aquatic animals. Turbulence inflow was generated by an active turbulence grid. Boundary layer...
Electrified powertrains/propulsion systems have gained a significant interest in transport industry to develop energy-efficient vehicular systems. In these powertrains, rechargeable energy storage systems (such as High Energy Batteries, Electrochemical Double-Layer Capacitors or High Power Batteries), electric motors, energy management strategies and advanced power electronics converters play an important...
Development of MCESs (Multi-Carrier Energy Systems) can make the energy supply more reliable and efficient. Due to the redundancy potential of these systems, in case of an energy carrier interruption, consumers may be able to supply part of their loads from other energy infrastructures. This paper presents an approach for evaluating the adequacy of MCESs considering the dependencies of energy carriers...
Integrating gas, electricity and residential heating sectors through hybrid heating technologies equipped with smart controls could provide energy system planning and operational benefits. Hybrid heaters combine different heating appliances in one device and can switch between those appliances during operation. Different configurations are possible: B-R (gas boiler-resistance), HP-B (heat pump-gas...
To alleviate the conflict between oil supply and demand, Chinese government has accelerated exploration and exploitation of alternative oil productions. STL (Shale-to-liquid) processes and CTL (coal-to-liquid) processes are promising choices to supply oil. However, few analyses have been made on their energy efficiency and economic performance. This paper conducts a detailed analysis of a STL process...
National targets for increased renewable energy are common-place internationally and small/micro-generation may help achieve such goals. Energy yields from such technologies however, are very location and site specific. In rural environments, the average wind speed is relatively high and the homogeneous landscape promotes laminar air flow and stable (relatively) wind direction. In urban environments...
BEER (Building energy efficiency retrofit) projects are initiated in many nations and regions over the world. Existing studies of BEER focus on modeling and planning based on one building and one year period of retrofitting, which cannot be applied to certain large BEER projects with multiple buildings and multi-year retrofit. In this paper, the large-scale BEER problem is defined in a general TBT...
This paper presents detailed techno-economic and environmental analyses of a SPM (solar photovoltaic microgrid) for remote communities. The SPM is modeled to support a yearly load growth of 2% over a project life of 25 years, with a base case demand of 63,875 kWh/yr. The PV and the battery performances are carefully evaluated. We use the unmet demand, loss of energy probability and the availability...
One of the major issues associated with the implementation of direct-current distribution systems is the design of a proper protection scheme. The fault current characteristics in direct-current distribution systems are quite different than those in conventional alternating-current grids. Thus, the performance of conventional protection schemes can adversely be affected, and it is necessary to modify...
The wake characteristics of wind turbines are of crucial importance for the optimum placement of multiple turbines. In this study, the wake development of a straight-bladed VAWT (vertical axis wind turbine) was investigated and compared in low-turbulence smooth and grid-turbulence flows. The wake fields in both flow regimes were measured with WTTs (wind tunnel tests). To further examine the flow physics,...
Marked-based emissions trading systems (ETS) are cost effective to facilitate emission abatement and are expected to play an essential role in international cooperation for global emission mitigation. In this analysis we discussed the impacts of a linked ETS in achieving the Intended Nationally Determined Contribution (INDC) emission reduction target in 2030 with a multi-regional computable general...
Natural convection of nanofluids around several pairs of hot and cold cylinders in an adiabatic enclosure is investigated numerically. Hot and cold cylinders are maintained at the different constant temperatures (Th > Tc) while the walls of the enclosure are thermally insulated. A parametric study is undertaken to explore the effects of the pertinent parameters, such as; Rayleigh number, size and...
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