International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395-0056
Volume: 12 Issue: 06 | Jun 2025
p-ISSN: 2395-0072
www.irjet.net
Diesel Preheating and Its Impact on Engine Performance – A Review Study Mr. B.S. Swami1, Prof. S.S. Kale2 1Mr. B. S. Swami M-Tech Student of Mechanical Engineering Department, N.K. ORCHID College of Engineering and
Technology, Solapur, Maharashtra, India.
2 Prof. S.S. Kale Mechanical Engineering Department, N.K. ORCHID College of Engineering and Technology,
Solapur, Maharashtra, India. ---------------------------------------------------------------------***--------------------------------------------------------------------operation through both mechanical and thermal Abstract - The performance and emission characteristics of interventions.
compression ignition (CI) engines are critically influenced by fuel properties, among which fuel temperature plays a significant role. This research explores the potential of preheating diesel fuel using recovered engine exhaust heat as a passive strategy to enhance engine efficiency and reduce harmful emissions. A custom-designed heat exchanger system was integrated into the fuel supply line to elevate the temperature of diesel without external energy input. The effects of varying fuel temperatures (30°C, 40°C, and 60°C) and compression ratios (15, 17.5, and 18) were systematically studied under different engine load conditions. Experimental results indicate that engine performance significantly improves with moderate preheating. The optimal performance was observed at 40°C fuel temperature and a compression ratio of 17.5, where brake power (1.81 kW), indicated power (4.41 kW), and thermal efficiency (30.02%) were maximized. Conversely, the lowest emissions of NO and CO were recorded at a higher temperature of 60°C and compression ratio of 18, indicating more complete combustion. These findings highlight a trade-off between performance and emission reduction, suggesting that the selection of operating parameters must be aligned with specific performance or environmental objectives. Overall, the study demonstrates that exhaust-driven diesel preheating is a viable, energy-efficient method for improving combustion quality, fuel economy, and emission characteristics in conventional diesel engines.
One of the critical factors affecting diesel engine performance is ignition delay, which is defined as the time interval between the start of fuel injection and the onset of combustion. A prolonged ignition delay can lead to uncontrolled combustion and higher peak pressures, causing knocking, increased mechanical stress, and emission of unburned hydrocarbons and nitrogen oxides (NOₓ). Several factors influence the ignition delay, including fuel properties (such as viscosity, volatility, and cetane number), intake air conditions, engine temperature, and injection parameters. Among these, fuel temperature is a significant yet relatively underexplored variable that directly affects fuel atomization, spray penetration, and mixing with air. Diesel fuel, by its nature, has high viscosity and moderate volatility. At ambient temperatures, particularly in colder climates, these characteristics hinder proper atomization during injection, leading to poor air-fuel mixing, incomplete combustion, and reduced engine efficiency. Preheating diesel fuel can significantly alter its physical properties—lowering viscosity and increasing vaporization rate—which facilitates better atomization and more uniform mixing in the combustion chamber. These improvements potentially result in reduced ignition delay, more stable combustion, lower fuel consumption, and reduced emissions.
Key Words: Diesel Engine, Fuel preheating, Performance testing, Knocking, Pollution.
Recent studies have shown that moderate preheating of diesel (typically in the range of 40°C to 100°C) can lead to measurable improvements in combustion quality and engine performance. However, the degree of improvement is often context-specific and depends on engine type, fuel composition, heating method, and operating conditions. Additionally, excessive preheating can reduce fuel density and calorific value, which may adversely affect engine power output and thermal efficiency. Therefore, an optimal preheating temperature range must be determined experimentally for each engine configuration.
1.INTRODUCTION Internal combustion (IC) engines, particularly diesel engines, continue to dominate the fields of transportation, agriculture, and power generation due to their robustness, high thermal efficiency, and fuel economy. Diesel engines operate on the principle of compression ignition, where the fuel is injected into highly compressed air in the combustion chamber, leading to spontaneous ignition. While diesel engines are widely used and well-understood, the growing emphasis on reducing fuel consumption, enhancing engine efficiency, and complying with increasingly stringent emission norms has renewed interest in optimizing engine
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In this regard, utilizing waste heat from the engine exhaust to preheat the fuel presents an attractive solution, combining performance enhancement with energy recovery. By
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