s. jafarmadar

In this research, thermodynamic and thermoeconomic analysis of a new multigeneration system based on the Parabolic trough collector and the photovoltaic-thermal solar collectors is carried out to produce power, cooling, hot water, hydrogen and freshwater. The proposed system includes an organic Rankine cycle, double-effect absorption refrigeration system, PEM electrolyzer and the reverse osmosis desalination unit. Analysis of energy, exergy, thermoeconomics, as well as analysis of various parameters was done by using the EES software. The results show that the energy and second law efficiency of the system is 33.49% and 13.31%, respectively. The net power produced by the system is 1271.48 kW in which ORC turbine has the maximum share. Moreover, the coefficient of performance of the cooling system is achieved to be 1.097 by considering the basic assumptions. The hydrogen and freshwater production rates are 542.3 kg/day and 4.55 kg/s, respectively. Finally, the rate of exergy destruction in each part of the system shows that the highest rate of exergy loss occurs in the PTC collector and the organic Rankine cycle with the amount of 53575 kW and 1624 kW, respectively, and in the organic Rankine cycle, the thermoelectric generator unit and evaporator have the largest share of exergy losses.

Considering the high importance and necessity of replacing fossil fuels with renewable and environmentally friendly fuel sources, for many years researchers have been working on hydrogen production methods as one of the cleanest and most available alternative fuels. have focused their research. One of these studied methods is hydrogen production using water and aluminum. In the current research, thermodynamic analysis is done on this method and the Liebig condenser is the production process of thermodynamic analysis. The efficiency of the condenser and the whole system is calculated. In the next step, system failure factors are identified based on technical literature and experts' opinions, and using one of the multi-criteria decision making methods called the best-worst method, the identified factors are weighted and ranked, and the impact The most important index on system performance is studied and solutions to increase system efficiency are provided.

In the present study, a novel tri-generation system is proposed. The system produces heat, electric power, and cooling water using concentrated solar cells alongside thermoelectric coolers. The simulation of the system is performed analytically. A zerodimensional model for thermoelectric cooler is applied and the thermal resistance network model is used for a more accurate simulation of the cooling system of the concentrated solar cells. The results indicate that the system can deliver 270 kW electrical power and 2 kg/s of cold water flow in 10℃ and 10 kg/s of hot water flow in 50℃ using 1000× CPV panels with an overall surface area of about 2 m2 which are divided into 1×1 cm pieces. The parametric study conducted on the system for different hours of the day shows that solar radiation has a minimal effect on the output cold water temperature, but it strongly affects the generated power.

In this study, renewable energy sources including a high-temperature solar parabolic trough collector and geothermal water integrated with a modified Kalina cycle, a combined ORC-EJR cycle, an electrolyzer, an RO desalination unit, and a domestic water heater. SiO2 and TiO2 nanoparticles dissolved in Therminol VP1 are applied as the working fluid of the solar collector. A comparative analysis of introduced working fluids is performed from energy, exergy as well as cost analysis point of view to evaluate their efficiencies. Solar irradiation, ambient temperature, and collector inlet temperature were the parameters investigated to discover their effects on energy and exergy efficiency, solar collector outlet temperature, hydrogen production rate, and freshwater production rate. The highest generated outlet temperature of the solar collector outlet was 693.8 K obtained by Therminol VP1/SiO2 nanofluid. The maximum energy and exergy efficiencies of the proposed system were 36.69 % and 17.76 %, respectively. Moreover, it is found that by increasing the solar collector inlet temperature, the hydrogen production rate decreases while the water production rate increases.

The use of thermoelectric generators has a special place in recovering the waste heat of combustion gases. In the proposed model, a thermodynamic analysis with the effect of the thermoelectric generator module area on the performance characteristics of the device was studied. To develop the model, the properties of the thermoelectric generator were assumed to be temperature dependent. The convective heat transfer of water in the cold channel was also considered as variable. The effects of water flow regime and the module area were investigated both in the longitudinal direction and for five different values of the module rows on the functional characteristics of the device. The results showed that increasing the number of module rows and module area decreased the power and efficiency of energy and exergy and increased the rate of exergy destruction. The module area is also optimized in two different cases. One was done to achieve the maximum net power and the second to achieve the maximum ratio of maximum net power to the area module. The optimal area in the first and second cases were 0.4641m2 and 0.2207m2 , respectively.

The main purpose of this study is to evaluate the thermodynamic and economic performance of using a solar chimney and wind turbine to help generate electricity in a multigeneration system. The proposed system is designed to generate power, heating, cooling, hot water, and steam. Parametric studies were conducted to evaluate the effects of various parameters such as Brayton cycle turbine inlet pressure, organic Rankine cycle turbine inlet temperature, solar radiation, wind speed, and absorption refrigeration cycle evaporator temperature on the system efficiency. The effects of these parameters on the energy, exergy, and economic efficiencies of the whole system were investigated. The results showed that the highest energy efficiency and total exergy of the multigeneration system were 22.12% and 11.4%, respectively. Also, the total power generation capacity of the studied system was calculated to be 2103 kW. The results also depicted that the highest rate of exergy destruction for the main components of the system is found in the parabolic dish solar collector. Increasing the turbine inlet pressure, the average wind velocity of the wind turbine and, evaporator temperature increasing of absorption refrigeration cycle has a positive effect on the efficiency of the proposed system.

Active and passive methods are two main mechanisms of heat transfer improvement. The active methods use external forces to improve heat transfer. This investigation evaluates the thermal and frictional behavior of a circular tube containing a rotational shaft. Constant heat flux was exerted to the circular tube. The fluid inlet and outlet temperature as well as wall temperature of tubes were measured to calculate the hat transfer coefficient. The Re (Reynolds) number was between 800-2000. Also, the dimensionless rotational speed (Rs) had the values of 1,1.5, 2, 2.5 and 3. Results revealed that the rotational shaft could increase the Nu number. Up to %18. Also, the results showed that the rotational shaft could significantly increase the pressure drop and friction factor. The maximum increment of %78 was achieved for friction factor. It was revealed that the use of rotational shaft could be more efficient at low Re numbers and low dimensionless rotational speeds. Also, it was found that by the increment of Reynolds number and being in the transient regime the efficiency of the system would improve.

The present study aims to investigate the amount of exhaust gases emissions of a 4-cylinder gasoline-ignition engine. An experimental study of an ignition engine management system has been conducted for emissions optimization, using Winols specialized software. In order to achieve a steady state conditions in the experiments, the temperature of the water and engine oil before each test reached the engine's working temperature (90°C) to allow various parts of the engine to remain stable and the tests are performed in in-line engine operation. Two sets of tests with idle (850-900 rpm) and mid-range (2500 rpm) are considered. Experiments were performed for three identical engines with different mileages and obtained results were discussed. According to the obtained results, after applying changes to the engine management system, a 22% reduction in the unburned hydrocarbon emission in both cases was obtained. Furthermore, it is found that 31 and 5% reduction in carbon monoxide emissions in the idle and mid-range were obtained, respectively. As a result of applying these changes, there was a reduction of 1.4% in NOx emission in the idle case and a decrease in about 19% at 2500 rpm.

In this work, a numerical study has been carried out in order to investigate the effects of a micro combustor size on the exergy and energy efficiencies of a premixed hydrogen/air for a micro thermophotovoltaic system. For this purpose, six combustors in different sizes are designed, in which geometry dimensional size gradually reduced. The effects of the combustor size on the entropy, exergy, radiation power, and energy conversion efficiency are investigated. Also, mean and uniform wall temperature are discussed. In order to compare the entropy generation of each micro combustor, a dimensionless entropy generation rate is defined. The hydrogen/air combustion with 9 species and 19 reversible elementary reactions were simulated by using the Eddy Dissipation Concept (EDC) model. Results indicate the micro-combustor geometry size has important effects. A reduction of the combustor geometry size dimensionality causes an increase in average wall temperature and makes it uniform. Moreover, by decreasing micro combustor size, the radiation power efficiency increases from 41.96 to 45.62% and total energy conversion efficiency from 6.46 to 7.02%. The highest exergy efficiency, 38.63%, is achieved in the smallest micro combustor while the minimum exergy efficiency 33.22%, is obtained in the largest micro combustor.

Gaynarje spring is one of the hottest springs in the world and is located around Meshginshahr in northwest of Iran. Because of the water at temperature of 82 ºC, it is not appropriate to use this mineral water for swimming and bathing. In this study, in addition to lowering the water temperature to the appropriate swimming temperature (29 ºC), the hot water is used for power and natural gas production in a combined cycle based on Organic Rankine Cycle (ORC) and LNG cold. The proposed configuration has been studied thermodynamically and optimized for important performance parameters. For this purpose, mass, energy and exergy equations were developed for components and the whole system. Also, performance parameters were calculated. For achieving the best results, several working fluids are examined for the ORC. According to the obtained results R245fa as an ORC working fluid has the best performance from the thermodynamic viewpoint. Also, for optimum condition of the cogeneration cycle, net output power, natural gas production, thermal and exergy efficiencies were calculated to be 524.9 kW, 1.352 kg/s, 24.11 and 48.99%, respectively. The parametric study is also indicated that the performance parameters have optimum values with respect to the evaporator temperature.

In Iran, Sabalan geothermal power plant has been utilized with two wells having different and mass flow rates and thermal properties. In this study, in order to achieve the maximum power, four new configures; a single flash-binary, a double flash (I)–binary, a double flash (II)–binary and a triple flash-binary cycles were examined. These four configurations were initially investigated considering the effective parameters of energy and exergy analysis, and then optimization was performed using three working fluids. The results show that in the optimum state, the double flash (II)–binary using isobutane shows better results compared to the other three configurations. Furthermore, for the optimum case, the net power of 23084 kW, the thermal efficiency of 19.74%, the exergy efficiency of 75.7%, and the exergy destruction rate of 6250 kW were obtained which show an improvement in terms of energy and exergy for the Sabalan geothermal power plant compared to the previous studies.

Natural gas-diesel dual fuel combustion is a beneficial strategy for achieving high efficient and low emissions operation in compression ignition engines, especially in genset application heavy duty diesel engine at rated power. This study aims to investigate a dual fuel engine performance and emissions using premixed natural gas and early direct injection of diesel fuel. Due to the different reactivities of natural gas and diesel fuels, the mentioned dual fuel combustion is based on reactivity controlled compression igniton (RCCI) which is introduced whitin the cylinder. A six-cylinder direct injection (DI) diesel engine was properly modified to run on dual-fuel mode. Based on experimental study, comparative results are given for various operating modes; conventional diesel mode, convential dual-fuel mode, and RCCI mode; revealing the effect of combustion mode on performance and emission characteristics in a compression ignition engine. The results show that the conventional dual fuel combustion reduces nitrogen oxides (NOx) emissions but suffers from higher carbon monoxide (CO) and unburned hydrocarbon (HC) emissions in compared to conventional diesel mode at part load condition. Results of detailed assessment of different dual fuel modes with CFD model coupled with chemical kinetic mechanism reaveled that RCCI strategy led to higher combustion efficiency as well as lower HC and CO emissions compared to conventional dual fuel combustion at part load condition.

Environmental pollution and energy constraints have made engineers research a new method of ignition in the internal combustion engines. Also, the automotive industries are searching to replace SI and CI engines due to the strict regulations of international organizations actives in the eld of environment. (HCCI) is a suitable method for combustion in SI and CI engines. The HCCI engine uses a premixed air/fuel mixture that is pressed with high compression ratio. In the research, a CFD model has been used for the analysis of HCCI engine. In order to validate the model, we used the experimental results obtained from Dutez engines with Methane fuel and a secondary fuel injection diesel in 270oCAD position. Investigation showed that concordance between the model and experimental results is acceptable. Maximum cylinder pressure decreases with the increase of EGR. With an increase in EGR percentage, the rate of carbon black increases which it results from the incomplete combustion. Therefore, performance of EGR is acceptable within a certain range. Also, an increase of EGR reduces cylinder temperatures. Incomplete combustion causes a part of the air/fuel mixtures to leave the cylinder without participating in the combustion process. As a result, those parts of the air/fuel mixtures leave the cylinder without producing thermal energy. Increase of EGR rate reduces the amount of heat release due to incomplete combustion, but heat release increases even despite non-combustion. This performance is due to the increase of temperature which, in turn, causes the increase of cylinder density. As a result, heat release is produced even despite non-combustion. It is noteworthy that maximum heat releases occur under non-EGR condition. Change in the heat release rate regarding dierent EGR rates shows that the combustion occurs in dierent positions. The increase of EGR greatly reduces NOX emissions. So, EGR system can provide adequate eect on reducing NOX emissions.

Modern diesel engines should have higher pollutant emissions standards with better performance and by using split injection strategies which could optimize the air – fuel mixture, this purpose could be achieved. After achieving the successful validation between modeling and experimental results for both single and double injection strategies, for the first time and in this paper, double injection strategies with new nozzle configuration were used in which number of nozzle holes were doubled and located below the previous holes and then double injection strategies were implemented in a case that for each pulse of injections upper or below holes were used, then this study focused on the effects of the new nozzle configuration holes angle in each pulse of injections. This study confirms that split injection could decrease Nox emission, because it has lower maximum in-cylinder temperature than single injection case due to its separate second stage of combustion, also results showed that using new nozzle configuration with two rows of holes could be more effective in decreasing pollutant emissions without any significant effects on engine performance.

In this research, back-propagation (BP) and generalized regression (GR) GR neural networks are developed for predicting the performance and emissions of direct injection diesel engine fuelled with the mixtures of diesel and castor oil fuels. The neural network models for the engine were trained by using some of the experimental data. Experimental test are carried out on a semi-heavy duty Motorsazan MT4.244 direct injection diesel engine fuelled with blends of diesel fuel with 0%, 5%,10%,15%,20%, 30% of Castor oil%(by volume) at various speeds and loads. Then, the performance of these neural networks predictions are compared by comparing predictions with the experimental results which were not used in the training process. The comparison of the predicted values shows that the computational accuracy of both GR and BP neural networks are appropriate, however the GR presents slightly better performance with very faster training compared with the BP. therefore, it can be concluded that GR can be used to predict performance and emissions with high accuracy and faster training.

If an air flow is injected into a liquid fluid, many ambulant air bubbles are formed inside the fluid. Air bubbles move inside the liquid fluid because of the buoyancy force, and the mobility of these air bubbles makes sizable commixture and turbulence inside the fluid. This mechanism was employed to enhance the heat transfer rate of a horizontal double pipe heat exchanger in this paper. However it can be used in any other type of heat exchanger. Especially, this method can be expanded as a promising heat transfer improvement technique in automotive cooling system, for instance in radiator which contains of water or other liquid fluid. Bubbles were injected via a special method. Present type of air bubbles injection and also the use of this mechanism for double tube heat exchanger have not been investigated before. Results are reported for varying bubble inlet parameters. The main scope of the present work is to experimentally clarify the effect of air bubble injection on the heat transfer rate and effectiveness through a horizontal double pipe heat exchanger.

Artificial neural network was considered in previous studies for prediction of engine performance and emissions. ICA methodology was inspired in order to optimize the weights of multilayer perceptron (MLP) of artificial neural network so that closer estimation of output results can be achieved. Current paper aimed at prediction of engine power, soot, NOx, CO2, O2, and temperature with the aid of feed forward ANN optimized by imperialist competitive algorithm. Excess air percent, engine revolution, torque, and fuel mass were taken into account as elements of input layer in initial neural network. According to obtained results, the ANN-ICA hybrid approach was well-disposed in prediction of results. NOx revealed the best prediction performance with the least amount of MSE and the highest correlation coefficient(R) of 0.9902. Experiments were carried out at 13 mode for four cases, each comprised of amount of plastic waste (0, 2.5, 5, 7.5g) dissolved in base fuel as 95% diesel and 5% biodiesel. ANN-ICA method has proved to be selfsufficient, reliable and accurate medium of engine characteristics prediction optimization in terms of both engine efficiency and emission.

In the present work, multidimensional modeling of open-cycle process of OM355 engine was developed. Calculations for computational mesh were carried out. The results of the model were validated by experimentally measured in-cylinder pressure and the good agreement between calculations and measurements approved the trustworthy of numerical code. Results included pressure, temperature, emission and Rate of heat release diagrams were represented for the full cycle. Furthermore local flow field velocity vectors were indicated. The results show the importance of open-cycle simulations in automotive researches.

Nitrogen oxides (NOx) contribute to a wide range of environmental effects including the formation of acid rain and destroy ozone layer. In-cylinder high temperature flame and high oxygen concentration are the parameters which affect the NOx emissions. The EGR system is a very effective way for reducing NOx emission from a diesel engine (via reduction of these parameters), particularly at the high load of engine operation condition. In this study, the influence of EGR on diesel engine combustion, NOx/PM emissions, brake specific fuel consumption (BSFC), engine thermal efficiency, cylinder pressure and heat release rate (HRR) are analyzed and presented. The experiments have been conducted on a turbocharged DI diesel engine under full load condition at two different injection timings in order to distinguish and quantify some effects of Hot and Cooled EGR with various rates on the engine parameters. Experimental results showed that increase of EGR rate has a negative effect on air-fuel ratio. For a premixed combustion at constant boost pressure, ignition delay is increased leading to retardation of all combustion process, a low HRR peak and reduce of in-cylinder peak temperature. Using of Hot EGR reduces NOX emissions whereas PM emissions are increased. The advance of injection timing resulted in the reduction PM while both NOX emissions and fuel consumption were increased. The use of cooled EGR was more effective compared to the hot EGR. As a result, the EGR temperature has no significant impact on NOx emissions. With increasing EGR rate, unequal EGR distribution was increased in inlet port of cylinders while the reducing EGR temperature (cooled EGR) improved its distribution among the engine cylinders and decreased the EGR cylinder-to-cylinder variations.

Multidimensional modelling of open-cycle process of OM355 engine was developed. Calculations for computational mesh were carried out. The results of the model were validated by experimentally measured in-cylinder pressure and the good agreement between calculations and measurements approved the trustworthy of numerical code. Results included pressure, temperature, emission and Rate of heat release diagrams were represented for the full cycle. Further more local flow field velocity vectors were indicated. The results show the importance of open-cycle simulations in automotive researches.

Conventional compression ignition (CI) engines are known for their high thermal efficiency compared to spark ignited (SI) engines. Gasoline because of its higher ignition delay has much lower soot emission in comparison with diesel fuel. Using double injection strategy reduces the maximum heat release rate that leads to NOx emission reduction. In this paper, a numerical study of a gasoline fuelled heavy duty Caterpillar 3401 engine was conducted via three dimensional computational fluid dynamics (CFD) procedures and compared with experimental data. The model results show a good agreement with experimental data. To have a better design the effect of injection characteristics such as, the main SOI timing, injection duration and nozzle hole size investigated on combustion and emissions and an optimized point find. The results suggest an optimization in injection characteristics for simultaneous reduction of NOx and soot emissions with negligible change in IMEP.