Energy plays a vital role in rural development. However, the price of oil has crossed $100 per barrel in the international market and is expected to rise further. A large proportion of the energy used is from oil, but an alternative to partial or total energy consumption is determined by the substation. Alternative energy sources must be economically viable and environmentally friendly. In recent years, the use of cleaner alternative fuels such as natural gas, methanol, and hydrogen has become more popular, as a solution to environmental problems including the global warming and shortage of crude oil reserves in the world. Reduction in power is one of the important issues in converting a gasoline engine to CNG (Fathollah et al., 2013). Alternatives to petroleum-derived fuels for internal combustion engines must be developed due to the depletion of fossil fuel resources. Since compressed natural gas (CNG) is far more plentiful than petroleum, it can be a great alternative fuel (Andrei et al., 2019). It has a high H/C ratio and a high research octane number, leading to cleaner exhaust gasses than those produced by classic fuel combustion. It also has high anti-knocking proprieties but lower flame speed and shorter flammability range (Ma et al., 2010). Due to its relatively high octane number, natural gas has recently been seen as a clean alternative fuel for spark-ignition (SI) engines. In comparison with gasoline, the thermal efficiency and emissions would have increased with the mild burning of natural gas, which is primarily composed of methane, in SI engines. Natural gas enables higher pressure ratio combustion without banging thanks to its high research octane number (RON) of over 120. Due to its high hydrogen-to-carbon ratio, it also emits far less CO₂ than conventional hydrocarbon fuels (Saad et al., 2014). The combustion cycle is the most significant and complicated step in the SI four-stroke engine. The fact that the chemical energy of the fuel is transformed into thermal energy during this cycle has a substantial impact on engine performance and pollutant emissions. The duration of combustion is a crucial factor in determining the best combustion process during the combustion cycle. When the combustion time is too lengthy, more thermal energy is wasted due to a longer heat transfer time to the cylinder and piston, or when the combustion time is too short, the fuel will not be entirely burned, preventing the fuel’s chemical energy from being fully transformed into heat energy (Nguyen et al., 2019). A comprehensive review of natural gas as a transportation fuel which is a promising alternative fuel is needed. Although port-injected CNG technology has been tried and tested, it has not become as popular as conventional fuels. One of the reasons besides the lack of infrastructure and refueling stations is the lower torque and power output compared with gasoline in bivalent vehicles. This is due to lower volumetric efficiency as gaseous fuels replace incoming fresh air resulting in lower torque and power (Khan et al., 2016). Mixing devices used in gas engines, generally referred to as carburetors, for mixing air and gaseous fuels are commonly attached to the intake manifold of an internal combustion engine. In a gas carburetor, the mixing of air and gaseous fuels needs to be in a proper ratio for a particular engine load and speed. In designing the producer gas carburetor, simplicity and ruggedness have always been considered as a basic requirement to achieve easy adjustment and reproducible performance (Ani et al., 2006). At a wide throttle position, brake power, torque, and mean effective pressure are typically higher for gasoline and CNG, while CNG operation results in lower brake power, torque, and mean effective pressure. Around low speeds and high speeds, CNG emits less NO, but at 3,000–3,500 rpm, the emission rises. Compared with gasoline, CNG was proven to have lower CO emissions (Saad et al., 2014). Internal combustion engine power and torque are primarily influenced by the mass of the fuel mixture in the engine’s cylinders and, of course, the fuel’s composition. Therefore, compared with other engine parameters, volumetric efficiency plays one of the most crucial roles when dealing with diverse fuel qualities in the same engine (Sulaiman et al., 2013). When the distance between the mixer and the input manifold is small and the mixing time is sufficient, mixing chambers with a higher volume than just a T-joint tube allow longer air and fuel retention time within the chamber. Because the flow velocities are relatively lower, more time may be spent mixing, allowing for the use of a straightforward mixing chamber. Biomethane will be used directly in natural gas engines. Although biomethane is a cleaner fuel than biogas and could be carried across a farm more readily, using biogas to power pumps rather than converting the pumps to run on biomethane is probably still more economical. When compared with gasoline and kerosene, biogas offers a cheap alternative fuel that offers a greater total pump efficiency (58% at 2,500 rpm engine speed). Biogas is used to power an SI engine that powers a water irrigation pump (Abdel-Galil et al., 2008). The main representative exothermic reactions (REXRs) within the high heat release (HHR) region and the dominant formation reactions of CH₂O and OH, which are known as the indicators of low heat release (LHR) and high heat release (HHR), respectively, were not significantly affected by the more advanced NG start-of-injection (SOI) timing, which resulted in a higher heat release rate (HRR) (Li et al., 2021).

This article presents the results for the types of mixers used in mixing natural gas with air to operate the irrigation pump. It was produced in the workshop of the Department of Agricultural Engineering/Faculty of Agriculture, Ain Shams University, in Egypt. The following materials and methods were used.

To assess the effect of experimental factors and the performance of the engine and pump work using different types of fuel (gasoline–natural gas) at different engine speeds and for all types of mixers, with respect to operating the engine with natural gas, the operation was started with gasoline fuel by closing the gasoline valve and opening the gas valve gradually until the operation of the engine with gas stabilized naturally.

After preparing the engine and filling it with fuel, each water barrel with a capacity of 200 L and the tank of disposal measurement (40 L) was prepared and water hoses (the intake hose and the push hose) with a length of 3 m were installed for each of them with a valve with a diameter of 5.08 cm at the beginning of the push hose to control the amount of water leaving the pump. The engine was started with gasoline to determine the four shaft speeds (1,750 rpm, 2,300 rpm, 2,900 rpm, and 3,500 rpm) using the engine speed-measuring device.

The results here dealt with the analysis of technical indicators for the types of mixers used in mixing natural gas with air to operate the irrigation pump to save energy, and the analysis of the economic indicators for operating the irrigation pump was carried out.

In this article, an intensive study was presented to solve the deterioration of fuel economy by using natural gas. The goal of this study was to improve the fuel/air mixing and combustion process, and the main conclusions of this study can be summarized as follows:

1. Gasoline engines can be converted to work with natural gas with an efficiency of up to 89.5%. Through this research, a T-type mixer was used to mix natural gas with air.