Multi-objective optimization of CCHP system with hybrid chiller under new electric load following operation strategy

The performance of combined cooling, heating and power (CCHP) system is greatly affected by its operating strategy and design. In this paper, a new electric load following (NELF) strategy was developed. It is based on the alternation between absorption cooling and electric cooling according to the building energy requirements, for hybrid chiller based CCHP systems. A comparison of the new proposed strategy with the modified electric load following (MELF) and electric load following (ELF) strategies is performed. A multi-objective optimization approach based on genetic algorithm is carried out to predict the optimal capacity of CCHP systems. Performance criteria like primary energy consumption, annual total cost and carbon dioxide emission were considered as objective functions. The performances of these CCHP systems and operation strategies were examined and compared with the separated production (SP) system for a Mosque complex located in Algiers, Algeria. Results show that hybrid chiller CCHP based NELF strategy is the best choice, which can reduce the primary energy consumption by 34.45 GWh/year, annual total cost by 0.313 million €/year and carbon dioxide emission by 8.37 kton/year. Compared to the other configurations and strategies, the hybrid CCHP based NELF achieves better energetic, economic and environmental performance under the optimized conditions

Kinetic study of transesterification using particle swarm optimization method

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Experimental investigation of pistacia lentiscus biodiesel as a fuel for direct injection diesel engine

International audienceBiodiesel is currently seen as an interesting substitute for diesel fuel due to the continuing depletion of petroleum reserves and the environment pollution emerging from exhaust emissions. The present work is an experimental study conducted on a DI diesel engine running with either pistacia lentiscus (PL) biodiesel or its blends with conventional diesel fuel. PL biodiesel is obtained by converting PL seed oil via a single-step homogenous alkali catalyzed transesterification process. The PL biodiesel physicochemical properties, which are measured via standard methods, are similar to those of diesel fuel. A single cylinder, naturally aspirated DI diesel engine is operated at 1500 rpm with either PL biodiesel or its blends with diesel fuel for several ratios (50, 30 and 5 by v%) and engine load conditions. The combustion parameters, performance and pollutant emissions of PL biodiesel and its blends are compared with those of diesel fuel. The results show that the thermal efficiency is 3% higher for PL biodiesel than for diesel fuel. The emission levels of carbon monoxide (CO), unburned hydrocarbon (HC) and particulate matter are considerably reduced at full engine load (around 25%, 45% and 17% respectively). On the other hand, the brake specific fuel consumption (BSFC) and the nitrogen oxide (NOx) emissions. increase (around 10% and 4% respectively). (C) 2015 Elsevier Ltd. All rights reserved

Hydrogen supplemented natural gas effect on a DI diesel engine operating under dual fuel mode with a biodiesel pilot fuel

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Experimental investigation of DI diesel engine operating with eucalyptus biodiesel/natural gas under dual fuel mode

International audienceWith the gradual depletion of petroleum and environmental degradation, intensive research activity has been addressed to the utilization of alternative fuels in internal combustion engines. In the present work, an experimental investigation is carried out to study the effect of eucalyptus biodiesel and natural gas under dual fuel combustion mode on the performance and the exhaust emissions of a single cylinder DI diesel engine. The natural gas (NG) is inducted with the intake air through the inlet manifold. The liquid pilot fuel (eucalyptus biodiesel or diesel fuel) is injected into the combustion chamber to cover approximately 10% of the maximum power output. Then, keeping constant the pilot fuel flow rate, the power output is further increased using only natural gas. The combustion characteristics (cylinder pressure, ignition delay and heat release rate), performance and exhaust emissions of the dual fuel mode (NG-diesel fuel and NG-biodiesel) are compared with those of conventional diesel engine mode at various load conditions. The combustion analysis has shown that biodiesel as pilot fuel exhibits similar pressure-time history, with highest peak, as diesel fuel in conventional and dual fuel modes. The performance and pollutant emission results show that, compared to diesel fuel in dual fuel mode, the use of eucalyptus biodiesel as pilot fuel reduces the high emission levels of unburned hydrocarbon (HC), carbon monoxide (CO) and carbon dioxide (CO2) particularly at high engine loads. However this is accompanied by an increase in the brake specific fuel consumption (BSFC) and the nitrogen oxide (NOx) emissions, which can be explained by the lower calorific value and the oxygen presence in the molecule of the eucalyptus biodiesel, respectively. (C) 2014 Elsevier Ltd. All rights reserved

Recent advances toward mesoscopic quantum optomechanics

International audienceWe present a number of approaches, currently in experimental development in our research groups, toward the general problem of macroscopic quantum mechanics, i.e., manifestations of quantum noise and quantum fluctations with macroscopic (engineered and microfabricated by man) mechanical systems. Discussed experiments include a pendulum, a torsion pendulum, a ng-scale phononic-crystal silicon nitride membrane, a [Formula: see text] g-scale quartz resonator, and mg-scale mirrors for optical levitation. We also discuss relevant applications to quantum thermometry with optomechanical systems and the use of squeezed light to probe displacements beyond conventional quantum limits.</jats:p