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Energy and climate market policy is inherently multiobjective and multilevel, in that desired choices often conflict and are made at a higher level than influenced actors. Analyzing tradeoff between reducing emissions and keeping fuel prices low, while seeking compromise among producers, traders, and consumers is the crux of the policy problem. This paper aims to address this issue by combining multiobjective...
CHP (Combined heat and power) production in connection with DH (district heating) systems has previously demonstrated a significant reduction in primary energy consumption. With extended installation of intermittent sustainable sources, such as eg. wind turbines rather than thermal units, the changed distribution of generation technologies may suggest a reconsideration of optimum for DH network temperatures,...
Kinetics of cellulose hydrothermal carbonization was investigated over different reactions times and temperatures, developing a first order-reaction model, where chemical and heat transfer processes were connected and resolved simultaneously. According to the model, mass species evolutions are described by sigmoid curves and the presence of an induction period confirms the importance of taking into...
This paper presents an experimental study on the self-ignition of H2 under different oxidation conditions and to explore how H2 assists CO oxidation in a CO2-diluted stoichiometric stream via a catalytic reactor filled with lab-made catalyst. We characterize the light-off process by measuring the temperature time profile and radial temperature distribution at the reactor exit, the axial temperature...
DI (direct injection) gas engines aim at providing clean and efficient combustion. Mixture quality control and hydrocarbon emission reduction are key development challenges in such engines. Here, a CFD (computational fluid dynamics) study of the DI gas injection process is carried out. The aim is to provide knowledge that aids e.g. engine designers in i) extending the lean limit at part load conditions...
This paper aims at improving the clarity and coherence of PV (photovoltaics) technical potential assessment, that is, calculation of the electricity that can be supplied by large-scale deployment of PV systems. A step-by step method, compiling the main variables and processes involved, and including the packing factor in the technical potential equations, is proposed for this purpose. The influence...
This study aims towards the development of an optimised design of a centrifugal blower consisting of various fan ribs, based on performance assessments following changes in the shape of its internal components. Various components, such as the external cases and the rotating fan ribs placed in a variety of operating conditions, are evaluated numerically and experimentally. Evaluation is based on performance...
A solid oxide fuel cell-gas turbine (SOFC-GT) hybrid system supplying liquid fuel as ethanol exhibits promise as an auxiliary power unit. In this study, the recirculation of anode and cathode exhaust gas in the SOFC-GT system is proposed to improve the efficiency of heat management in the SOFC-GT hybrid system. The key operating parameters, such as fuel utilization factor and the cell and GT temperatures,...
In this paper, the first and second-laws efficiencies are applied to performance analysis of an irreversible Miller cycle. In the irreversible cycle, the linear relation between the specific heat of the working fluid and its temperature, the internal irreversibility described using the compression and expansion efficiencies, the friction loss computed according to the mean velocity of the piston and...
The goal of this paper is to showcase a modelling exercise, conducted for the Republic of Macedonia, a non-Annex I country under UNFCCC and a candidate for EU membership, by making use of MARKAL energy system model. Baseline Scenario and three groups of mitigation scenarios have been developed until 2050, reflecting different types of targets with different levels of ambition regarding CO2 emissions...
Indirect energy consumption accounts for a large proportion of the all energy used in processes to make the final products and thus exerts huge pressure on environment. Structural analysis of indirect energy flow network is a prerequisite for solutions to energy related problems. The aim of this study is to reveal the structure of indirect energy flow network and its change from 1993 to 2007. To this...
This paper presents an innovative method for modeling energy hubs based on energy flow between its constituent elements. Using this method, modeling of energy hubs with different elements and connections is facilitated. Also, an appropriate mixed integer nonlinear programming model is presented for short term 24-hour scheduling an energy hub, in which, the objective is to fulfill daily cooling, heating...
The provision of ancillary services in the smart grid by electric vehicles is attractive to grid operators. Vehicles must be aggregated to meet the minimum power requirements of providing ancillary services to the grid. Likely aggregator revenues are insufficient to cover the additional battery degradation costs which would be borne by an existing electric vehicle owner. Moreover, aggregator revenues...
Using thermal energy balance, this paper analyzes and investigates the thermal performance of a U-tube solar collector whose temperature thermal energy is high due to solar radiation. A working fluid of 20% PG (propylene glycol)–water is used. Solar collector efficiency was calculated and energy savings predicted for various nanofluids, such as MWCNT, Al2O3, CuO, SiO2, and TiO2. As a result, thermal...
A state-of-the-art, in terms of spatio-temporal resolution (about 10 km and on a hourly basis) and temporal span (35 years), wave hindcast is exploited to update existing assessments of wave energy potential in the Mediterranean Sea. The hindcast, covering the period 1979–2013, has been obtained using WavewatchIII with calibrated source-term parameters recently proposed by L. Mentaschi et al. (2015)...
This study calculates the LCOE (Levelized Cost of Energy) on the PSDA (Atacama Solar Platform) for a solar–solar energy mix with the objective of evaluate new options for continuous energy delivery. LCOE was calculated for three 50 MW (megawatt) power plants: A PV (photovoltaic), a CSP (concentrated solar power) plant with 15 h TES (thermal energy storage) and a hybrid PV-CSP plant constituted with...
Both new and existing buildings need to be adapted to climate change, in order to keep providing a comfortable and healthy indoor climate. Preferably, the adaptation measures applied at the building level scale do not require additional energy (i.e. passive measures). Previous studies showed that passive climate change adaptation measures can have a positive effect on thermal comfort in summer and...
Experimental investigations were conducted on a diesel engine to evaluate the effects of hydrogen addition on engine combustion, unregulated gaseous emissions and particulate emissions based on the Japanese 13-mode testing cycle. A diesel–hydrogen co-operated combustion strategy is proposed in which hydrogen is naturally aspirated into the diesel engine to substitute 10, 20 and 30% of the total fuel...
This study proposes a new renewable energy based multigeneration system, which integrates a solar PV/T system and a geothermal energy system to produce electricity and heat for power, heating, cooling, hot water and drying air, and investigates the design, analysis and assessment of this integrated system. The psychometric processes are utilized for obtaining required dry agent from the ambient air,...
The present study focuses on the pyrolysis characteristics of OPF (oil palm fiber) and OPFP (oil palm fiber pellet) in N2 and CO2 to evaluate the impacts of biomass pattern and carrier gas on the three-phase products. Three different reaction temperatures of 400, 450, and 500 °C along with 30 min pyrolysis are considered. The results indicate that OPFP pyrolysis gives a higher liquid yield when compared...
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