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

Corfou = Ithaque

Spitta Lentz, Tazerout M. Corfou = Ithaque. In: Revue des Études Grecques, tome 42, fascicule 197, Juillet-septembre 1929. pp. 288-298

Le déclin de l'Occident : esquisse d'un morphologie de l'histoire universelle. 2 : Perspectives de l'histoire universelle

467 p

Pollution duality in turbocharged heavy duty diesel engine

International audienceDiesel engine designers are faced with increasingly stringent social demands to reduce emissions while maintaining high performance. Several strategies are considered, such as the advanced fuel system, the cooled exhaust gas recirculation (EGR), the particulate filter, the NO(x) after-treatment, the oxidation catalyst, the advanced control techniques and the alternative combustion. These strategies have been tuned to achieve the lowest engine exhaust gas emissions. The major problem of diesel engine pollution is the NO(x) and soot formation. Their antagonistic evolution according to the air/fuel ratio is well-known, and requires a good compromise. In this article, a numerical investigation was carried out using the KIVA-3v code. The aim deals with the influence of some engine parameters on the performances and the pollutant (NO(x)-soot) formation of a turbocharged heavy duty direct injection diesel engine. The numerical Simulations were achieved to capture independently the effects of engine operating parameters such as the fuel injection timing, the fuel injection duration, the piston bowl diameter and the EGR rate. The obtained results are discussed and some conclusions are developed

Le déclin de l'occident : esquisse d'un morphologie de l'histoire universelle. 1 : Forme et réalité

411 p., ref. bib. : ref. et notes dissem

Thermodynamic analysis of reciprocating compressors

A global model for the thermodynamic analysis of reciprocating compressors is presented. The model is based on five main and four secondary dimensionless physically meaningful parameters. Expressions for the volumetric effectiveness, the work per unit mass and the indicated efficiency are derived. The model has been used in order to predict the performance of a reciprocating air compressor under various operating conditions. The model proves to be a very accurate and useful tool to analyse the compressor performance. The relative importance of the various losses and the influence of different parameters on the reciprocating compressor behaviour are discussed. Especially the in-cylinder residual mass fraction and the walt to fluid heat transfer influences on the reciprocating compressor performance are highlighted. (C) 2001 Editions scientifiques et medicales Elsevier SAS

Heat transfer correlation choice for two zone combustion model optimization in the case of natural gas si engines

Paper presented at the 7th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Turkey, 19-21 July, 2010.Owing to its both economical and environmental qualities, natural gas is one of the most interesting and promising available fuels for internal combustion engines. However, optimization of engine design requires extensive engine testing. Therefore, engine modeling codes are generally preferred for evaluating initial designs. Two-zone model is one of the most interesting simulation tools, especially for natural gas SI engines, due to the combustion type in this case. On the other hand, about one third of the fuel energy is transformed to heat loss from the chamber walls. Hence, the accuracy of the simulation depends on the precision of the heat transfer model. However, in the previous studies, using two-zone models, many choices are made for heat transfer evaluation and no choice influence study has been carried out. The current study aims to investigate the effect of the choice of the heat transfer correlation and provide an optimized choice for a more accurate two-zone combustion model in the case of natural gas SI engines. For this purpose, a computer simulation is used, and experimental measurements are used for comparison and validation.ksb201

Valorisation du biogaz par moteur à allumage commandé : Une approche méthodologique du dimensionnement

The size of an electric power plant using biogaz has to be achieved by the development of a model designed to integrate fuel quality and quantity evolutions throughout life duration of the power plant. A description by “grey box” for the biogaz combustion in spark ignition engines allows to estimate the electric power output. The biogaz composition is featured by “typical days”. The investment decision is generally based on economical criteria, the electric trade, the investment and the maintenance costs are introduced. Results show the optimal power output to install according to the available biogaz flow-rate. The “bottom price” for the electric power, which is the minimum price beneath such a project can not make any profit, is presented.Le dimensionnement d'une installation de production d'électricité utilisant du biogaz nécessite de mettre au point un modèle permettant d'intégrer les changements de quantité et de qualité du combustible durant la durée de vie de l'installation. Une description de type « boite grise » de la combustion du biogaz dans les moteurs à allumage commandé permet d'obtenir la puissance électrique produite en fonction du combustible. Les caractéristiques du biogaz sont modélisées par « journées types ». La décision d'investissement se faisant principalement sur un critère financier, cette analyse introduit la recette électrique, le coût de revient lié à l'investissement et la maintenance. Les résultats présentés permettent de connaître la puissance à installer en fonction du débit de biogaz. Une présentation du « prix plancher », prix minimum pour qu'un projet soit rentable, est présentée

Pollution duality in turbocharged heavy duty diesel engine

International audienceDiesel engine designers are faced with increasingly stringent social demands to reduce emissions while maintaining high performance. Several strategies are considered, such as the advanced fuel system, the cooled exhaust gas recirculation (EGR), the particulate filter, the NO(x) after-treatment, the oxidation catalyst, the advanced control techniques and the alternative combustion. These strategies have been tuned to achieve the lowest engine exhaust gas emissions. The major problem of diesel engine pollution is the NO(x) and soot formation. Their antagonistic evolution according to the air/fuel ratio is well-known, and requires a good compromise. In this article, a numerical investigation was carried out using the KIVA-3v code. The aim deals with the influence of some engine parameters on the performances and the pollutant (NO(x)-soot) formation of a turbocharged heavy duty direct injection diesel engine. The numerical Simulations were achieved to capture independently the effects of engine operating parameters such as the fuel injection timing, the fuel injection duration, the piston bowl diameter and the EGR rate. The obtained results are discussed and some conclusions are developed