The experimental setup aimed to analyze the combustion characteristics of both Liquefied Petroleum Gas (LPG) and Hydrogen-Enriched LPG (HHO) systems, with a focus on understanding their performance efficiency and emissions profiles (Usman et al [9)]. Central to this setup is the use of an LPG tank as the main fuel source, providing a stable fuel base for combustion experiments. Coupled with a commercial LPG burner equipped with adjustable flame control capabilities, this setup allows for precise regulation of LPG flow and flame intensity, ensuring controlled combustion conditions necessary for accurate experimentation (Adam J. Gee et al. [10]). Two HHO generators were also included in the setup, introducing a mixture of hydrogen and oxygen into the system. This addition presents a new element, offering the opportunity to investigate the combustion dynamics and efficiency of this HHO additive hydrogen technology (Zhe Zhao et al. [11]).
In order to comprehensively assess the performance and characteristics of LPG and HHO combustion systems, a multifaceted monitoring approach has been carefully designed. Key to this approach were strategically placed gas flow meters, which accurately measure the flow rates of both LPG and HHO. These devices provide valuable data regarding the mass/volume of gases entering the combustion chamber, allowing for a deeper understanding of the combustion process. Additionally, an array of thermocouples has been strategically positioned throughout the system to monitor flame temperatures. By capturing temperature profiles at critical points, this setup enables one to gain insights into the thermal dynamics during the entire combustion cycle and access combustion efficiencies. Furthermore, a gas analyzer has been integrated into the system in order to obtain exhaust gas emissions. This sophisticated instrument examines combustion by-products, ensuring a comprehensive evaluation of combustion performance. Gas emissions such as CO and UH were measured to understand the environmental impact of both LPG and HHO combustion (Gregory Sherman et al. [12]). Together, this integrated monitoring system enables one to conduct a thorough analysis to optimize combustion processes and contribute to a more efficient and environmentally conscious utilization of LPG and HHO.
During the experiments, safety precautions were put in place to protect both personnel and equipment. This involved ensuring there were fire extinguishing equipment readily available to deal with any unexpected fires. The experiments were conducted in a controlled environment equipped with proper ventilation systems to reduce the risk of gas build-up and manage potential by-products effectively.
In the initial stages of the study, focus was on establishing the infrastructure necessary to perform the experiments precisely and safely. This involved the design and construction of an open-side/end stainless-steel tube fitted with an LPG burner, which served as the cornerstone of the investigation (as shown in Fig. 1). The tube, measuring 2 meters in length, 17 centimeters in diameter, and 3 mm thickness, was crafted with precision to ensure both durability and resistance to corrosion, vital for the extended duration of the study. Key to this setup was the integration of the Baltur BTG-3 LPG burner, renowned for its adaptability and efficient utilization of LPG at 30 mbar pressure, with a power range spanning from 16.6 to 42.7 kW. To facilitate accurate temperature monitoring, high-temperature J-type thermocouples were strategically placed at intervals of 20–25 cm along the tube. Additionally, to ensure comprehensive data collection, a gas flow meter, a precision mass balance and a Pico DAQ system were used.
2.1 Temperature Profiles along the open-side/end SS tube
The impact of introducing HHO gas on the performance of an open-side/end stainless steel tube equipped with an LPG burner (see Fig. 1) was investigated, aiming to gather qualitative insights into combustion. This analysis focused on several key parameters to observe any noticeable changes. Initially, the flame color was closely observed, specifically looking for any transition from its typical yellowish color to blueish upon the introduction of HHO gas. Furthermore, the flame temperature was recorded, comparing readings between scenarios without and with HHO gas to identify any differences. Additionally, examination extended to the preliminary assessment of emissions, particularly the levels of Unburned Hydrocarbons (UH) and Carbon Monoxide (CO) in the exhaust gases. These findings contribute to a deeper understanding of the potential effects of HHO gas supplementation on combustion processes, offering valuable insights for further research and application in various industrial applications.
Figure 2 shows the thermal images of the flames without (left image) and with the introduction of HHO gas into LPG burners (right image). HHO gas, a blend of hydrogen and oxygen, offers distinct advantage due to its higher flame speed. This promotes improved combustion characteristics and higher heat-generated compared to using LPG alone. By introducing HHO gas alongside LPG, the combustion process becomes more efficient, leading to better utilization of fuel and more heat generated. This synergy between HHO gas and LPG shows a potential for enhancing the performance of burners across various applications, highlighting its potential to contribute to cleaner and more effective combustion processes.
Furthermore, Fig. 3 shows the Temperature profiles inside the SS tube without HHO gas and after the introduction of the HHO gas. Due to higher efficiency, more heat is generated and the corresponding temperatures are higher in the case of the introduction of the HHO gas.
2.2 Qualitative Flame Observation in an Open-side/end tube
Figure 4 shows the quality of the flame without and with the HHO gas. The pure LPG flame appears yellowish blur, suggesting an incomplete combustion reaction. In contrast, with HHO gas, the LPG + HHO flame becomes blueish-clean, indicative of complete combustion. This scenario also exhibits higher temperatures along the SS tube in comparison to using LPG alone as shown previously in Fig. 3. Additionally, in the case of HHO gas, the flame appears shorter due to its enhanced flame velocity completing the combustion process faster, thus shortening the flame-combustion length. These observations underscore the role of HHO in promoting cleaner combustion and elevating thermal dynamics within the SS tube setup. At the same time, preliminary exhaust gas emissions’ analyses indicated much less Unburned Hydrocarbons (UH) and Carbon Monoxides (CO), something that was further investigated qualitatively during the experiments on the boiler.