In order to study the dynamic behavior of Engines a software was developed; the actual pressure and also the friction forces were considered in the governing equations. Considering the torque as the input, the crank speed and acceleration were calculated. The cylinder gas pressure was detected with a photo sensor installed in the spark plug. The predicted and actual crank velocities were compared and the differences were explained.

The transient period that lasts from Engine starting to achieve Engine coolant to its performance temperature is called warm-up. This study tries to decrease the time of warm-up period in a spark ignition Engine.To achieving to this goal, at first the coolant thermal operation should be analyzed. For that, Engine divided to seven major parts. These components are piston, cylinder block, cylinder head, Engine oil, cylinder block coolant, cylinder head coolant and radiator coolant. Because warm-up period is a transient period, one of the transient heat transfer analyze methods should be applied. The method that is used in this study is lumped thermal capacitance method. Using heat transfer rules including conduction and convection and ignoring radiation, the thermal equations of mentioned parts are calculated. These equations are nonlinear differential equations that can be arranged in form of a set of differential equations. Because of some complicated nonlinear terms in the differential equations, they can not be solved with analytical methods and so MATLAB software is applied to solve the differential equations set. After solving the differential equations set and finding the temperature changes of major parts, these answers should be validated. To verifying the accuracy of theoretical answers, the answers are compared whit experimental result of Engine test that is carried out in IPCO (Irankhodro Powertrain Company). After assuring of the correction and accuracy of theoretical method, some solutions are introduced to reduce the warm-up period. The criterion of warmup period is the thermal operation of Engine coolant. So, after applying these solutions, the temperature changes of coolant during warm-up period is calculated for each method and at the end, the advantages and deficiencies of each solution are discussed.

Increasing the volumetric efficiency of Internal Combustion Engines has always been one of the goals of the Engine designers. Utilizing turbocharged systems is one of the common ways to achieve this aim. In these systems, compact heat exchangers are used to reduce the temperature and increase the density of the air at the outlet of compressor. This article seeks out the best geometric layout for an aftercooler to have the lowest pressure drop and the highest temperature decrease of the passing air through the heat exchanger and at the same time leads to the lowest manufacturing cost. To obtain this purpose, a bar and plate heat exchanger is considered and after deriving all the geometric, flow and thermal equations, a comprehensive objective function is defined. Then, using the genetic algorithm method and considering six design variables, the best design values for variables are found to maximize the objective function. All calculations are done analytically and using coding in MATLAB software. The results show that the designed aftercooler beside an appropriate weight and a very low pressure drop, reduce the Engine inlet air temperature significantly and brings it to an acceptable level to enter the Engine.

The present study deals with a comparative evaluation of a single-zone (SZ) thermodynamic model and a 3D computationalfluid dynamics (CFD) model for heat release calculation in Internal Combustion Engines. The first law, SZ, model is based onthe first law of thermodynamics. This model is characterized by a very simplified modeling of the Combustion phenomenonallowing for a great simplicity in the mathematical formulation and very low computational time. The CFD 3D models, instead, are able to solve the chemistry of the Combustion process, the interaction between turbulence and flame propagation, the heat exchange with walls and the dissociation and re-association of chemical species. They provide a high spatial resolutionof the Combustion chamber as well. Nevertheless, the computation requirements of CFD models are enormously largerthan the SZ techniques. However, the SZ model needs accurate experimental in-cylinder pressure data for initializing theheat release calculation. Therefore, the main objective of an SZ model is to evaluate the heat release, which is very difficultto measure in experiments, starting from the knowledge of the in-cylinder pressure data. Nevertheless, the great simplicityof the SZ numerical formulation has a margin of uncertainty which cannot be known a priori. The objective of this paperwas, therefore, to evaluate the level of accuracy and reliability of the SZ model comparing the results with those obtainedwith a CFD 3D model. The CFD model was developed and validated using cooperative fuel research (CFR) Engine experimentalin-cylinder pressure data. The CFR Engine was fueled with 2, 2, 4-trimethylpentane, at a rotational speed of 600 r/min, an equivalence ratio equal to 1 and a volumetric compression ratio of 5. 8. The analysis demonstrates that, consideringthe simplicity and speed of the SZ model, the heat release calculation is sufficiently accurate and thus can be used for a firstinvestigation of the Combustion process.

The subjects of heat transfer and cooling system are very important topics in the Internal Combustion Engines (ICE). In modern cooling systems, low weight, small size and high compactness are the critical designing criteria that requires heat transfer enhancement. Boiling phenomenon which is occurred in the water jacket of the ICE is one of the methods to increase heat transfer in the coolant system of an ICE. A research has been shown that parameters such as material, temperature, and roughness of the heated surface have direct effect on the rate of heat transfer in a boiling phenomenon. In this paper the potential of boiling phenomenon and the effect of the surface roughness on the amount of heat flux removed by the coolant flow in the Engine water jacket is investigated experimentally. For this purpose the experiments was carried out in three different flow velocities and also three different surface roughnesses. Results show that the boiling and roughness of a hot surface will increase the heat removal significantly.

The work presented in this paper is an attempt to evaluate the exhaust emission characteristics of a hydrogen-ethanol dual fuel combination with different percents of hydrogen substitutions (i.e. 0-80% by volume and of 20% increment ) at three different compression ratios of 7:1, 9:1 and 11:1. Experimental investigations have been carried out on a computer interfaced with; four-stroke cycle, single-cylinder, compression ignition (CI) Engine, which was converted to spark ignition (SI) and carburetion, to suit ethanol fuel and a provision was made at the inlet manifold of the said Engine to induct hydrogen gas. The effect of hydrogen substitutions on CO, HC, NOx emissions at 7, 9 and 11 compression ratios were determined. It was found that, at 100% load, the percentage ofhydrogen substitution varied from zero to 80% and the NOX emissions increased by 58.62, 59.3, 62.74% for 7, 9, 11 compression ratios respectively. When the effect of compression ratio changed from 7:1 to 11:1 the same change took place in the percentage of substitution which was a reduction of CO and HC by 30.4 and 21.67%.

Good understanding of In-Cylinder Fluid Flow during the operation process has effective role in the Engine design. To aid the best operation, fuel consumption and environment pollution must be decreased. In recent years, various turbulence models are widely developed and used to predict the flow turbulence. In this paper, the effect of turbulence models in simulation of In-Cylinder fluid flow in a Combustion chamber has been investigated from the Inlet Valve Closing (IVC) to Exhaust Valve Opening (EVO). Comparison of the present simulation with the experimental data shows a considerable difference for various models. The results of simulation show that the Reynolds Stress Turbulence Model is better than the other turbulence models.

Abstract: In this investigation a two-dimensional airflow and heat transfer with sinusoidal boundary condition analysis was conducted. Both laminar and turbulent sinusoidal pipe flows were investigated numerically for Remax=2000, 10000, 20000 and 60000. The results are compared with experimental results of previous researchers [2], [5]. The RNG k – E turbulence model was used for turbulence modeling. After investigation of this turbulence model, since the flow inside the exhaustport of Internal Combustion Engine is sinusoidal, this model can be used for it [9, 10]. An available code, which is basis on finite volume and can solve Nervier-stokes equations on the structured "grids, is used After discretization equations on the control volume, physical properties flux on the control volume by means of first-order upwind difference scheme is calculated. The SIMPLE method was used for solving algebraic equations. Computational results are presented and discussed for velocity, pressure drop, wall shear, temperature, heat flux, and convection coefficient, for pipe flow and flow around exhaust valve.

Exergy analysis is a method of evaluating the contribution proportion of each process on transmission of initial availability of the system and determining the positions of useful energy losses. In this research exergic analysis of an Internal Combustion Engine equipped with turbocharger and intercooler is attended. To do this, at first, the procedure of performance simulation of the system components i.e. Engine, compressor, turbine and intercooler is briefly explained. Then by defining exergy terms and using related exergy equilibrium equations for open and closed systems necessary conceptual basis for exergy analysis, is introduced. Also exergo-economic analysis, as a powerful tool for cost study and optimization of complex energy systems is developed by combining the second law of thermodynamics concept with economic view points. The results show that Combustion process produces the most proportion of the system irreversibility. Furthermore, regarding exergo-economic parameters, Engine has the most suitable performance among the related components of the system.

About 30 to 40 percent of the total energy produced in Internal Combustion Engines is converted into useful mechanical work at best, and the rest is transferred to the environment through exhaust gases and Engine cooling systems. One effective way to overcome mentioned issue is to recover the exhaust gas heat of Internal Combustion Engines. In the present study, in order to recover the wasted energy from the ICE exhaust gases, use of Stirling Engine has been suggested. For this purpose, modeling of the Stirling Engine was performed by using the second-order method. To approach operating conditions of the stirling Engine to actual state, heat and working losses for each moment of the Engine movement were calculated separately and added to the modeling. The modeling of the Stirling Engine was performed for three operating pressures in different Engine speeds, depending on the thermal energy of the Internal Combustion Engine. The results show that, at best condition, Stirling Engine produce 5/8 to 10 horsepower and 20 to 22 N. m of torque. By adding these values to the IC Engine, we will see a significant increase in power and torque of the hybrid system. It is also possible to achieve a constant torque over a wide range of Engine speeds in hybrid Engine by using different operating conditions of stirling Engine.