Rabeea M. Ghazal

Industrial development and population growth have significantly escalated worldwide energy demand; in addition, the heightened consumption of primary energy sources such as hydrocarbons has profoundly impacted the atmospheric environment. Among all potential fuels, hydrogen provides the most significant advantages for energy supply and environmental sustainability. Nonetheless, the combustion of pure hydrogen has challenges related to its production, storage, and utilization. A more effective approach to improve combustion is to utilize hydrogen as an addition to fossil fuels. Hydrogen possesses numerous characteristics that render it a compelling fuel alternative. It possesses high energy density, offering triple the energy compared to liquefied petroleum gas. This indicates that hydrogen is able to deliver equal power output with reduced fuel usage, thus decreasing the fuel used and, consequently, greenhouse gasses linked to combustion. In this study, practical experiments and computer simulations were adopted to predict the behavior of some characteristics of the combustion of Iraqi liquefied petroleum gas, such as flame temperature and laminar burning velocity, in addition to the effect of changing the equivalence ratio and hydrogen enrichment at rates ranging between 5 and 20% at a constant atmospheric pressure and temperature. In the practical aspect, a counter-flow burner was developed at the Training and Workshops Center, University of Technology, Iraq, for the purpose of performing practical experiments. In addition, a MATLAB R2023b program code was developed based on flame front image frames to analyze data and measure flame parameters, i.e., laminar burning velocity, flame temperature, and flame front diameter. While the commercial CFD Ansys Fluent version 17.2 program was used to numerically simulate the premixed counter-flame, the steady laminar flame (SLF) was used. Also, in order to implement the continuity of the numerical simulation, the momentum and energy equations of the counter-flow burner were solved. The results showed that increasing the hydrogen percentage caused an increase in the laminar burning velocity as well as the flame temperature; when the hydrogen percentage in the mixture was 20%, the increasing percentages in the practical experiments were about 25% and 19.6%, respectively, and the percentages in the numerical simulation were about 22.6% and 20.5%, respectively. Also, changing the equivalence ratio from 0.4 to 1.4 had an effect on the shape, color, and method of flame spread, where at the higher percentage, the shape changed and the color concentration increased, meaning that the temperature rose and the method of spread changed to an irregular one. Additionally, several recommendations are suggested for future endeavors in this domain.

Hydrogen is a promising fuel because it has good capabilities to operate gas turbines. Due to its ignition speed, which exceeds the ignition of traditional fuel, it achieves a higher thermal efficiency while the resulting emissions are low. So, it was used as a clean and sustainable energy source. This paper reviews the most important research that was concerned with studying the characteristics of hydrogen combustion within incinerators and power generation equipment, where hydrogen was used as a fuel mixed with traditional fuel in the combustion chambers of gas turbines. It also includes an evaluation of the combustion processes and flame formation resulting from the enrichment of gaseous fuels with hydrogen and partial oxidation. A large amount of theoretical and experimental work in this field has been reviewed. This review summarizes the predictive and experimental results of various research interests in the field of hydrogen combustion and also production.

This study focused on exergo–conomic and parametric analysis for Taji station in Baghdad. This station was chosen to reduce the emission of waste gases that pollute the environment, as it is located in a residential area, and to increase the production of electric power, since for a long time, Iraq has been a country that has suffered from a shortage of electricity. The main objective of this work is to integrate the Taji gas turbine’s power plant, which is in Baghdad, with the Rankine cycle and organic Rankine cycle to verify waste heat recovery to produce extra electricity and reduce emissions into the environment. Thermodynamic and exergoeconomic assessment of the combined Brayton cycle–Rankine cycle/Organic Rankin cycle (GSO CC) system, considering the three objective functions of the First- and Second-Law efficiencies and the total cost rates of the system, were applied. According to the findings, 258.2 MW of power is produced from the GSO CC system, whereas 167.3 MW of power is created for the Brayton cycle (BC) under the optimum operating conditions. It was demonstrated that the overall energy and exergy efficiencies, respectively, are 44.37% and 42.84% for the GSO CC system, while they are 28.74% and 27.75%, respectively, for the Brayton cycle. The findings indicate that the combustion chamber has the highest exergy degradation rate. The exergo–economic factor for the entire cycle is 37%, demonstrating that the cost of exergy destruction exceeds the cost of capital investment. Moreover, the cost of the energy produced by the GSO CC system is USD 9.03/MWh, whereas it is USD 8.24/MWh for BC. The results also indicate that the network of the GSO CC system decreases as the pressure ratio increases. Nonetheless, the GSO CC system’s efficiencies and costs increase with a rise in the pressure ratio until they reach a maximum and then decrease with further pressure ratio increases. The increase in the gas turbine inlet temperature and isentropic efficiency of the air compressor and gas turbine enhances the thermodynamic performance of the system; however, a further increase in these parameters increases the overall cost rates.