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The process of fuel droplet evaporating is one of the most important factors that directly affect the efficiency of the combustion process. Therefore, the current study reviews previous studies that focused on the process of evaporation of a drop of fuel. The review is divided into points. The first part is concerned with modeling of the evaporation process under different initial condition and temperature of the droplet. The second part present the experimental studies concerned with measuring the evaporation time of the droplet, as well as the shape of the droplet during the evaporation process. Most of the studies related to this subject can be divided into three categories: The first category is the studies that are concerned with the process of heating the droplet and studying the evaporation time for different types of fuels or by adding nanomaterials to the fuel and studying their effect on the evaporation process. The second category is the studies concerned with the mechanics of droplet evaporation and the study of droplet shape. The third category is the studies that focus on studying the effect of initial conditions, such as temperature and pressure, as well as the concentration of gasses surrounding the drop and their types. There are other studies concerned with projecting the electric field onto the drop during the evaporation process and studying its effect.

Simple Kalina cycle system (SKCS) is used for low temperature, intermediate temperature and high temperature heat recoveries. However, its efficiency is rather low. Therefore, a modification is suggested to improve its efficiency. In this work a computer program is developed to predict the energy-exergy performance of a modified Kalina Cycle System (MKCS) using aqua ammonia solution. It consists of heat recovery vapor generator (HRVG), condenser, heat exchanger, separator, turbine, throttling valve, absorber and pump. The modification is implemented by introducing a heat exchanger (HE) between the separator and expansion valve. This HE is used to reheat the work solution which comes from the pump by the high temperature hot weak solution which comes from the separator. The effect of many operating conditions such as dryness fraction (DF) at separator inlet, low pressure and ammonia (NH3) mass fraction with constant high pressure on cycle performance is studied. The results show that the modified cycle efficiency is higher than the simple cycle efficiency by about 33.6% while the net power by about 27.8%. The highest efficiency and highest net output power are 14.7% and 0.5641 kW respectively. The exergy efficiencies for modified Kalina and simple Kalina are 24.8% and 11.7% respectively.

Hydrogen is a clean fuel for internal combustion engines since it produces only water vapor and nitrogen oxides when it burns. In this research, hydrogen is used as a blending fuel with diesel to reduce pollutants emission and to improve performance. It is inducted in the inlet manifold, of a single cylinder, four stroke, direct injection, water cold diesel engine, type (Kirloskar). Hydrogen blending is done on energy replacement basis. A special electronic unit is designed and fabricated to control hydrogen blending ratio. The maximum achieved ratio is 30% of input energy and beyond that engine operation becomes unsatisfactory when the air temperature is 20 oC and injection timing of -35o CA which represent the first part of this work. Inlet air heating system is built and added in the experimental work. The heating system allows to increase the air temperature up to 100 oC. A heating of air to 60 oC with injection timing of -30o CA and 55% of hydrogen blending is executed in the second part of this study. Tests are done with 17.5 compression ratio and 1500 rpm. The brake specific fuel consumption is reduced by 29% and 46%, the engine thermal efficiency is increased with 16% and 21% for the 1st and 2nd part respectively. The pollutant emissions of carbon oxides, UHC, and smoke opacity are dramatically decreased by 19.5%, 13%, and 45% respectively for the 1st part and 41%, 38% and 65.6% for the 2nd part while NOx emission is increased by 10% and 25% for the 1st and 2nd part respectively.

Testing, designing and fabricating a friendly vapor absorption cooling system was the main purpose of the present study using water and methanol as a working fluid. Various Iraqi environmental conditions (Hilla City) are the operating conditions under which the test rig experiment was performed. The temperature of the heat source, condenser, absorber and evaporator, is the involved property in the test calculations. The system is tested during June and July 2019. The results show that the COP of the absorption cooling system ranged from 0.22 to 0.38 while the range of temperature drop in evaporator is (9.8 °C–15.8 °C). Condensation and absorption temperatures are under 45 °C while the maximum temperature of the driving water was 85 °C. The results also show that the generator temperature had a great effect on the system performance.

Flame stability, environmental changes and fossil fuel shortage represent major challenges to any successful combustion device utilization. In this study, the stability zone of laminar premixed ILPG/ -air flames was investigated experimentally. Non-swirling burners with different diameters (10, 12.5, and 17 mm) were employed to characterize the flashback and blow-off limits. Different hydrogen blends (0%-50%) at equivalence ratios (ER) (0.6-1.4) were used. The results show that maximum flashback limits occurred at ER slightly richer than stoichiometric, with the mixture flow rate at a flashback of (3.75, 7.25 and 14) LPM for the 50% hydrogen blending ratio and a burner diameter of (10, 12.5 and 17 mm), respectively. When hydrogen blending was 50% at stoichiometric condition, the critical velocity gradient at flashback increased from (469.9-650.8 1/s) with 10 mm diameter, and the critical velocity gradient at blow-off increased from (1538-2936 1/s). It was observed that the flashback limits decreased with increasing burner diameter. Its limit increased with increasing hydrogen addition to the ILPG. The blow-off limit increased with increasing fuel concentration. This paper further presents the stability zone for ILPG/air combustion for a non-swirling burner with a 10-mm diameter and different hydrogen blends. It was found that the stability zone was narrow on the lean combustion side and enhanced with increasing diameter and hydrogen addition.

The aim of this experimental work is to study the effect of nanoparticles added to diesel fuel on engine performance characteristic. Nano fuels are prepared by adding Al2O3 or TiO2, both with particle size less than 45nm of diesel fuel. Four doses of each type namely (25, 50, 100 and 150) ppm are prepared. These nanoparticles are blended with diesel fuel in varying volume fraction by the means of an electric mixer and an ultrasonicator. The Nano fuels are (DF+Al2O3) and (DF+TiO2). Physicochemical properties of nano fuels are measured and compared with these of neat diesel. The study shows that the addition of nanoparticles to diesel fuel improves its physical properties such as cetane number, thermal conductivity and viscosity. The influence of nanoparticles addition is very clear on the engine performance. The results show that the performance parameters are improved for example, brake thermal efficiency is increased from 19.4% for diesel to 21% and 25% for DF+Al2O3 and DF+TiO2 respectively, the brake specific fuel consumption (BSFC) is decreased by 8% and 20% for DF+Al2O3 and DF+TiO2 respectively, the brake specific energy consumption (BSFC) is decreased by 8% and 20% for DF+Al2O3 and DF+TiO2 respectively at 25ppm and 75% load. The exhaust gas temperature is 382°C for pure diesel while it is 417°C for DF+Al2O3 and 353°C for DF+TiO2. The peak pressure for pure diesel is 62 bar and it increases with DF+Al2O3 to 66.2 bar as for DF+TiO2 the peak pressure decreases to 57.2 bar at full load and 150ppm.

Hydrogen is a clean fuel for internal combustion engines as it produces only water vapor and nitrogen oxides when it burns. In this research, hydrogen is used as a blending fuel with diesel to reduce pollutants emission and to improve performance. It is inducted in the inlet manifold, (continuous manifold induction), which is of a single cylinder, four stroke, direct injection, variable compression ratio water cold diesel engine, type (Kirloskar). This technique of hydrogen blending is selected because of its simplicity and low cost. Hydrogen blending is built on the basis of energy replacement. A special electronic unit is designed and fabricated to control hydrogen blending ratio. The maximum achieved ratio is 30% of input energy and beyond that the engine operation becomes unsatisfactory. Tests are done with 17.5 compression ratio and 1500 rpm. The brake specific fuel consumption is reduced by 29% and the engine thermal efficiency increased by 16% at these operating conditions. The pollutant emissions of carbon oxides, UHC, and smoke opacity are dramatically decreased by 19.5%, 13%,and 45% respectively while NOx emission increased by 10%.

In this study a flat plate solar air heater with a shallow duct is analyzed experimentally. The collector consists of a 4.5m long air duct with a (20×5)cm cross-sectional area. The air duct consists of four channels so that the collector becomes more compact. The collector is studied under the weather conditions of Hilla city – Iraq with latitude and longitude equal 32.3° N and 44.25° E respectively and it is tilted by 45° with the horizontal plane. The effect of the air mass flow rate on the collector performance is also studied.The performance of the collector is analyzed with and without porous media stuffing. The measured parameters are the air and absorber temperatures, air speed and pressure drop. The temperatures are measured by means of type (K) thermocouples as this type covers the temperature range of the studied system. The values of the temperature are displayed by temperature data logger devices. The air speed and pressure drop are measured by digital anemometer and manometer devices respectively. The results of the studied system show that as the air mass flow rate increases, the temperature of both the flowing air and the absorber decrease, whilst the efficiency of the collector increases. The results also show that the addition of the steel wool porous material inside the air duct increases the temperature of both the flowing air and the absorber, and by that increases the efficiency of the collector. The porous media also caused an increase in the pressure drop between the outlet air and the atmosphere. This pressure drop increased with the increase in the air mass flow rate

In the present study, a solar collector is designed and constructed. The collector consists of parabolic trough of mild steel sheet and a helical coil receiver fabricated using copper tube positioned at the focal line of the trough. The copper tube is coated with black paint to increase its absorptivity. The system is fabricated and tested at Babylon University site in Hila city Iraq (32.4°latitude, 44.4° longitudinal) using water as working fluid under outdoor condition. The system is operated as a closed loop water circulation with a storage tank of 30 liter capacity contains 8 liters of water. Tests are carried out during the period from October to November 2018. The tests are performed with different circulation flow rate (1,1.5,2) l/min. Results show that the maximum helical coil surface temperature with non-circulation is 107.2 °C at 1.00 PM from 25th September and 75 °C with circulation at flow rate 1.5 l/min at 2.00 PM from 9th October. The maximum mean storage water temperature is 73.8 °C for flow rate 1.5 l/min at 2.00 PM from 9th October, 70.5°C for flow rate 1 l/min at 2.00 PM from 8th October and 69.1 °C for flow rate 2 l/min at 1.50 PM from 24th October.

Precise measurement and prediction of flame speed and laminar burning velocity are essential for premixed combustion properties characterization, turbulent combustion models validation, progress, and validation of chemical kinetic models. Besides, the problem of lack of fossil fuel, planet pollution, and production of several fuel alternatives led researchers to reexamine the process of combustion and optimize fuel consumption. So, it would be necessary to know the change of laminar burning velocity and flame speed with thermodynamic conditions to understand the impression of practical applications in all combustion systems as working pressures and temperatures are extensively higher than the atmospheric conditions. Several investigations work regarding flame speed and laminar burning velocity had been achieved. However, a detailed literature review of methods and techniques used to measure these two parameters and the effect of operating factors for different fuels focusing on biofuels is presented in this paper for ease of reviewing.

The response surface methodology - central composite design matrix (RSM-CCD) is applied to make experiment design and response optimization for CIE engine fulled by different methanol-biodiesel-diesel blending ratios. The 5% biodiesel has enhanced methanol-diesel miscibility by about twelve folds. A full factorial design is employed to build the experimental tests of the performance and exhaust emissions for CIE run by methanol/biodiesel/diesel fuel. The statistical tests are used to check the significance of models by p-value test, adeq. Precision test, Predicted R2, and adjusted R2. With a maximum error of 6%, models of the BTE, CO, UHC, CO2, and NOX are showed a good agreement between predicted and experimental results. The optimization indicated that engine load is a master input factor affecting the responses.

Making use of the superior thermal properties of nanofluids is now very common, especially with regard to the cooling of photovoltaic panels to improve overall efficiency. In this work, a novel cooling system manufactured from 3 mm aluminium was attached to the rear of a monocrystalline photovoltaic module, and two volumetric concentrations of SiC/Water nanofluid were tested with different flow rates. These tests were carried out under outdoor climatic conditions in middle of Iraq at Babylon University (32.46 °N, 44.42°E) during both winter and summer. A theoretical model was thus developed in SolidWorks and simulated using ANSYS 18.2. The maximum enhancements in electrical and overall efficiency were found to be 50% and 82.41% in March with a 0.5% nanofluid concentration and 2 L/min flow rate, while the minimum enhancements were 35.4% and 34.01% in June, with a 0.1% nanofluid concentration and 0.5 L/min flow rate. The theoretical results showed good approximation to the experimental results, and the average deviation percentage of electrical efficiency for a photovoltaic/thermal system with nanofluid on 27 March was 5.58%, while on 3 June it was 11%.

An experimental study on the laminar burning velocity of the premixed liquefied petroleum gas (LPG)/hydrogen/air flames was conducted in a constant volume chamber that centrally ignited at various initial pressures (0.1–0.3 MPa) and initial temperature of (308 K). In addition, the tested equivalence ratios of range from (0.8–1.3), and the investigated blends of hydrogen were (0–80%) by volume. Experimental data of laminar burning velocity, flame thickness, stretch rate, and laminar flame speed and combustion pressure of LPG flames with various blends of H 2 have been presented. The constant volume chamber has been designed and constructed specially for this study, as this method considered the most precise one to measure laminar burning velocity. A mixing chamber, ignition control, data acquisitions and high-speed Schlieren photography were used. Experimental results have been shown that the effect of hydrogen addition becomes noticeable when the hydrogen blend is larger than 60%. When hydrogen blending is 80%, adiabatic flame temperature increases about (40 K), the laminar flame speed of LPG also increases from (2.2–4.75 m/s) and laminar burning velocity from (31–59.5 cm/s). While flame thickness decreases from (0.15–0.07 mm) for stoichiometric mixture at atmospheric pressure. Increasing initial pressure from 1 bar to 3 bar reduces the stretched laminar flame speed of LPG-air mixture from (2.2–1.5 m/s), and laminar burning velocity also decreases from (31–20 cm/s). In contrast, combustion pressure increases from (5–25 bar). Equivalence ratio has a more dominating effect on adiabatic temperature, density ratio and flame thickness than hydrogen does. Correlations between hydrogen blend and initial pressure are derived from LPG–air mixtures.

For photovoltaic panels, high temperature has a major effect, reducing electrical efficiency and decreasing the panel’s life span. In this work, an aluminum pocket collector was manufactured and fixed to the rear side of a photovoltaic panel to form a photovoltaic/thermal system (PV/T). A SiC/water nanofluid was used as coolant fluid with two volumetric concentrations (0.1 and 0.5%). The experiments were conducted outdoors at Babylon University (32.46 °N,44.42°E) in March. Different flow rates of SiC/Water nanofluid were tested (0.5,1,1.5 & 2 LPM). A comparison was made with another, identical, PV panel under the same conditions. SiC/water nanofluid had a noticeable effect on output power and results showed that the maximum enhancement in electrical efficiency was 33.27% with 0.5 % SiC/Water nanofluid and flow rate of 2 LPM,. and the maximum overall efficiency was 92.43 %.

Flame speed is an important aspect of fuel combustion characteristics. It affects combustion system design and performance. In this study, a laboratory experimental rig has been built to investigate the effect of equivalence ratio of gasoline-air mixture in a centrally ignited constant volume combustion chamber on flame speed at an initial pressure of 1bar and an initial temperature of 483 K using high speed flame photography technique. The results of the outwardly expanding spherical flame showed that the flame speed depends on both equivalence ratio and flame radius. It decreases slightly with the increase of flame radius and increases with the equivalence ratio until slightly larger than stiochiometric and then decreases. The flame speed reached 1.45 m/s at Φ= 0.8, (1.6) m/s at Φ= 1 and 1.27 m/s at Φ= 1.5

The problem of non-equilibrium heat conduction in a semi-infinite medium subjected to a step change in temperature is analyzed thermodynamically using the extended irreversible thermodynamic approach. The results show clearly the wave nature of the dimensionless temperature distribution, Stanton number and the dimensionless entropy change profiles. The non-equilibrium profiles approach the equilibrium profiles as the speed of wave propagation is increased. The results also show that the non-equilibrium temperature is higher than the equilibrium temperature but the difference decreases as the wave propagation speed increases.

Soot formation and burnout were studied at atmospheric pressure in co-flowing, axisymmetric, buoyant laminar diffusion flames and double flames of liquefied petroleum gases (LPG)–air mixtures. In diffusion flames, two different fuel flow rates were examined. In double flames, three different primary air flow rates were examined. A soot sampling probe and a thermocouple were used to measure the local soot mass concentration and flame temperature, respectively. Flame residence time was predicted using a uniformly accelerated motion model as a function of axial distance of the flame. The increase of primary air flow rate was found to suppress the energy transfer from the annular region, at which the soot is produced, to the flame axis. The time required to initiate soot formation at the flame axis becomes longer as the primary air is increased. The trend rate of soot formation was found to be similar along the flame axis in all tested diffusion flames. The increase of primary air by 10% of the stoichiometric air requirement of the fuel results in a 70% reduction in maximum soot concentration. The final exhaust of soot, which is determined by the net effect of soot formation and burnout, is much lower in double flames than that in diffusion flames.

A thermal reactor was designed and built to produce coal from date stones by pyrolysis. Five specimens of coal have been prepared at different maximum charring temperatures. It was found that, as the temperature increases, the properties of coal are improved (the percentage of carbon content increases). It was also found that, at 700°C, the percentage of carbon content remains constant. The coal prepared at this temperature was used as a filtering medium in an adsorption filter to purify the exhaust gases of a two stroke spark ignition engine. The results showed that the filter has a high adsorption ability for CO and CO 2 gases. An ORSAT apparatus was used to measure the concentration of CO and CO 2 in the exhaust gases before and after the filter. The filter reduced the concentration of CO and CO 2 by 62 and 59%, respectively.

Experiments were carried out to evaluate the influence of the addition of hydrogen to the inlet air on the performance of a single cylinder direct injection diesel engine. Hydrogen was injected in the inlet manifold. The addition of hydrogen was done on energy replacement basis. It was found that the addition of hydrogen improves the combustion process due to superior combustion characteristics of hydrogen in comparison to conventional diesel fuels. It was also found that 10% energy replacement improves the engine thermal efficiency by about 40% and reduces the sfc by about 35% however the volumetric efficiency was reduced by about 35%., {"references":["L.M. Das ( Hydrogen Engine; Research and development Programs in\nIndian Institute of Technology ), International Journal of Hydrogen\nEnergy, Vol.27, No.9, PP.953-965, 2002.","Polasek Milos, Macek Jan and Takats Michal ( Hydrogen Fueled Engine\nProperties of Working Cycle and Emission Potentials ), SAE Paper No.\n020373, 2002.","Mihaylov Milen and Barzev Kiril,( Investigation of The Effects of\nHydrogen Addition on Performance and Exhaust Emissions of Diesel\nEngine ) ,FISITA World Automotive Congress,23-27 May ,2004\n,Barcelona ,Spain .","S.J. Lee , Yi HS and E.S. Kim , ( Combustion Characteristics of Intake\nPort Injection Type Hydrogen Fueled Engine ), International Journal of\nHydrogen Energy Vol.20,No.2,pp.317-322,1995.","N. Saravanan, and G.Nagarajan ( Performance and Emission Study in\nManifold Hydrogen Injection With Diesel as an Ignition Source For\nDifferent Starts of Injection ), Renewable Energy, Vol.34,No.1, pp. 328-\n334 , 2009.","Mohamed Fadhil Al-Dawoodi, ( Modeling of a Four Stroke Diesel\nEngine Operated With Hydrogen Blended Diesel Fuel ) , M.Sc. Thesis,\nUniversity of Babylon,","Iraq,2006.","Li Jing-Ding , Lu Ying-Qing and Du Ting-Shen, ( Improvement on\nCombustion of Hydrogen Fueled Engine ), International Journal of\nhydrogen energy ,Vol.11,No.10,pp.661- 668, 1986 .","S.Bari, and Mohammad M. Esmail ( Effect of H2/O2 Addition in\nIncreasing The Thermal Efficiency of a Diesel Engine ), Fuel, Vol. 89,\nPP. 378-383, 2010.\n[10] Tomita Eiji, et.al ( A Study on Hydrogen Combustion Ignited With Light\nOil in a Dual Fuel Engine ), Proceedings of The Fourth JSME-KSME\nThermal Engineering Conference, Oct. 1-6, 2000, Kobe, Japan.\n[11] N.Saravanan, and G. Nagarajan ( An Experimental Investigation of\nHydrogen Enriched Air Induction in a Diesel Engine), International\nJournal of Hydrogen Energy, Vol.33,No.2,PP.1769-1775, 2008.\n[12] Internal Combustion Engine Test Bed , Instruction Manual, Didacta\nCompany . 2001, Italy www.didacta.com\n[13] R.Sirens, and S.Verhelst ( A Hydrogen Fueled V-8 Engine For City\nBus Applications ), International Journal of Automotive Technology,\nVol. 2 No. 2 PP. 39-45, 2001."]}