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[en] Highlights: ► We model thermodynamic ideal cycle of a new hybrid pneumaticcombustion engine. ► We optimize commands of all modes and calculate maps of fuel and air consumption. ► We evaluate fuel economy for Wind–Diesel system function of tank volume and wind penetration. ► We find up to 10% of fuel economy i.e. 80 t/year with 100% wind penetration. ► Fuel economy increases with wind penetration and with volume but has asymptotic value. -- Abstract: This paper presents an evaluation of an optimized Hybrid Pneumatic-Combustion Engine (HPCE) concept that permits reducing fuel consumption for electricity production in non-interconnected remote areas, originally equipped with hybrid Wind–Diesel System (WDS). Up to now, most of the studies on the pneumatic hybridization of Internal Combustion Engines (ICE) have dealt with two-stroke pure pneumatic mode. The few studies that have dealt with hybrid pneumatic-combustion four-stroke mode require adding a supplementary valve to charge compressed air in the combustion chamber. This modification means that a new cylinder head should be fabricated. Moreover, those studies focus on spark ignition engines and are not yet validated for Diesel engines. Present HPCE is capable of making a Diesel engine operate under two-stroke pneumatic motor mode, two-stroke pneumatic pump mode and four-stroke hybrid mode, without needing an additional valve in the combustion chamber. This fact constitutes this study’s strength and innovation. The evaluation of the concept is based on ideal thermodynamic cycle modeling. The optimized valve actuation timings for all modes lead to generic maps that are independent of the engine size. The fuel economy is calculated for a known site during a whole year, function of the air storage volume and the wind power penetration rate.
[en] Highlights: → IMEP is essential to estimate the indicated torque in internal combustion engine. → We proposed model which describes the IMEP-Low pressure and the IMEP-High pressure. → We studied the evolution of the IMEP with respect to the engine's variables. → We deduced the variables of influence that can be used to develop the models. → The IMEP model is compared to transient experimental New European Driving Cycle. - Abstract: Indicated Mean Effective Pressure models (IMEP) are essential to estimate the indicated torque in internal combustion engine; they also provide important information about the mechanical efficiency of the engine thermodynamic cycle which describes the conversion of the fuel combustion energy into mechanical work. In the past, many researches were made to improve the IMEP prediction and measurement techniques at different engine operating conditions. In this paper, we proposed a detailed IMEP model which separately describes the IMEP-Low pressure and the IMEP-High pressure of a modern diesel engine; the IMEP is the direct subtraction result between these two variables. We firstly studied the evolution of the IMEPHP and IMEPLP with respect to the engine's variables and then we deduced the variables of influence and the form of the equations that can be used to develop the models. Finally, the models' coefficients were determined based on experimental data collected on a steady state test bench and using the least square regression method. In addition, the IMEPHP model results were compared to transient experimental data collected on a chassis dynamometer test bench; the model results are in excellent agreement with the experimental data.
[en] Electricity in Canadian remote areas is, historically, produced using Diesel generators. Its total production cost is very high not only due to inherent cost of fuel but also due to transportation and maintenance costs. Moreover, the use of fossil fuels is a significant source of greenhouse gas emissions. Hybrid systems that combine wind turbines and diesel generators reduce fuel consumption, operational cost and pollution. Adding a storage element to this hybrid system increases the penetration level of renewable sources, i.e. the percentage of renewable energy in the overall production, and further improves fuel savings. Among all energy storage techniques, CAES (compressed air energy storage) has several advantages to be combined with hybrid WDS (wind-diesel systems), due to its low cost, high power density and reliability. In a previous work, we have exposed and have evaluated a new technique to transform the existing Diesel engine to a HPCE (hybrid pneumatic combustion engine), able to operate as a bi-source engine (compressed air and fuel). Based on ideal cycle modeling, we provided a first estimation of the annual fuel economy obtained with this multi-hybrid system (WDS–HPCE). As a continuity to this work, we will compare, in this article, several strategies of management of the CAES. We will demonstrate that one of these strategies that uses an algorithm based on wind speed forecast, is the most efficient. We will, also, provide an evaluation of the fuel economy generated by the WDS–HPCE, as a function of the wind power penetration ratio, the air-storage capacity, and the average wind speed on site. - Highlights: • We model thermodynamic cycle of a new hybrid pneumatic combustion engine. • we evaluate all ratios of pneumatic power to fuel power and select two highlighted. • we calculate maps of fuel and air consumption for the highlighted strategies. • We evaluate fuel consumption for each strategy and for a combination between both. • we get better fuel consumption without dissipating air except when it is exceeding
[en] This paper presents a brief review of the conventional and renewable energy statuses, in Lebanon, as well as of the principal problems facing the electricity of Lebanon Company (EDL). In addition, an analytical-critical review of the latest three official Lebanese electricity plans is presented. Furthermore, two future electricity generation plan-scenarios for Lebanon are investigated, where multi variables are examined, namely: cost, environment and tariff. First, an economical-environmental optimization is carried out, where two reasonable scenarios are introduced based on the fuel source of CCGT power plants. Results revealed that the investment in wind energy and natural gas for power production should be a main concern in the future. Second, an optimization of the average electricity tariff for each of the two investigated generation scenarios is studied, where three different approaches are illustrated. Results confirm that all tariff plans are acceptable and convincing, and that the use of natural gas in CCGT plants is always preferred against gasoil. Moreover, the optimized average tariff is maximally a double of the current EDL average tariff, which is very convincing compared with the actual cost of electricity for the current Lebanese electricity sector. - Highlights: ► Brief review of the conventional and renewable energy status in Lebanon. ► Illustration of the major problems facing “Electricity of Lebanon” (EDL). ► Review of electricity plans for Lebanon. ► Optimization of cost, pollution and tariff for electricity generation in Lebanon
[en] This paper presents a dynamic simulation model to predict the performance of an ASHPWH (air source heat pump water heater). The developed model is used to assess its performance in the Lebanese context. It is shown that for the four Lebanese climatic zones, the expected monthly values of the average COP (coefficient of performance) varies from 2.9 to 5, leading to high efficiencies compared with conventional electric water heaters. The energy savings and GHG (greenhouse gas) emissions reduction are investigated for each zone. Furthermore, it is recommended to use the ASHPWH during the period of highest daily ambient temperatures (noon or afternoon), assuming that the electricity tariff and hot water loads are constant. In addition, an optimal management model for the ASHPWH is developed and applied for a typical winter day of Beirut. Moreover, the developed dynamic model of ASHPWH is used to compare the performance of three similar systems that differ only with the condenser geometry, where results show that using mini-condenser geometries increase the COP (coefficient of performance) and consequently, more energy is saved as well as more GHG emissions are reduced. In addition, the condenser “surface compactness” is increased giving rise to an efficient compact heat exchanger. - Highlights: • Numerical modeling and experimental validation for ASHPWH (air source heat pump water heater). • Optimization of the ASHPWH-condenser length. • Comparison of the ASHPWH with conventional electric water heater according to energy efficiency and green gas house emissions. • Development of an energetic-economic optimal management model for ASHPWH. • Energetic and environmental assessment of ASHPWH with mini-tubes condensers
[en] In this paper, we are studying an innovative solution to reduce fuel consumption and production cost for electricity production by Diesel generators. The solution is particularly suitable for remote areas where the cost of energy is very high not only because of inherent cost of technology but also due to transportation costs. It has significant environmental benefits as the use of fossil fuels for electricity generation is a significant source of GHG (Greenhouse Gas) emissions. The use of hybrid systems that combine renewable sources, especially wind, and Diesel generators, reduces fuel consumption and operation cost and has environmental benefits. Adding a storage element to the hybrid system increases the penetration level of the renewable sources, that is the percentage of renewable energy in the overall production, and further improves fuel savings. In a previous work, we demonstrated that CAES (Compressed Air Energy Storage) has numerous advantages for hybrid wind-diesel systems due to its low cost, high power density and reliability. The pneumatic hybridization of the Diesel engine consists to introduce the CAES through the admission valve. We have proven that we can improve the combustion efficiency and therefore the fuel consumption by optimizing Air/Fuel ratio thanks to the CAES assistance. As a continuation of these previous analyses, we studied the effect of the intake pressure and temperature and the exhaust pressure on the thermodynamic cycle of the diesel engine and determined the values of these parameters that will optimize fuel consumption. -- Highlights: ► Fuel economy analysis of a simple pneumatic hybridization of the Diesel engine using stored compressed air. ► Thermodynamic analysis of the pneumatic hybridization of diesel engines for hybrid wind-diesel energy systems. ► Analysis of intake pressure and temperature of compressed air and exhaust pressure on pressure/temperature during Diesel thermodynamic cycle. ► Direct admission of compressed air reduces fuel consumption through positive work of low-pressure Diesel cycle and reduction of thermal losses. ► Optimization of air intake temperature/pressure and crankshaft angle to improve the ratio fuel consumption/mass of air.