Abstract:
Study:
Cavitation-based homogenization is a promising method to enhance fuel stability and performance .By generating intense microbubbles that collapse violently, cavitation promotes both physical blending and mild chemical activation, improving rheology, dispersion, and combustion behavior. This study evaluates the effects of cavitation on HFO–biodiesel–glycerin blends, assessing density, viscosity, sulfur and metal contents, calorific value, sediment formation, and engine performance.
Table 1 summarizes the comparative physical and chemical properties of the three main fuel components used in this study: HFO 380, biodiesel (FAME), and glycerin. HFO 380 serves as the baseline reference, while biodiesel and glycerin act as renewable, sulfur-free blending components. Their contrasting densities,viscosities, and oxygen contents are key factors influencing blend behavior during homogenization and combustion. Understanding these baseline properties provides the foundation for assessing the performance of RAPTECH’s cavitation treatment in improving fuel uniformity, stability, and overall quality.
Table 1: Comparative Fuel Properties of HFO 380, Biodiesel (FAME), and Glycerin.
2. Materials and Methods
3. Results and Discussion
3.1 Physical Properties and Rheology
Figure 1: Fuels blend density in function of temperature
In terms of API gravity, shown in Figure 2, the lowest value is observed for pure HFO 380, reflecting its relatively high density. When HFO is blended using cavitation, the API gravity increases slightly, indicating a modest density reduction. A more pronounced effect is seen when 20% biodiesel is added by hand blending, as biodiesel has a considerably lower density than HFO, resulting in a significant rise in API gravity. The highest API gravity is achieved with HFO containing 20% biodiesel treated by cavitation. In this case, the difference between hand blending and cavitation blending is relatively small, but the cavitation process still provides an additional improvement in API gravity beyond the effect of biodiesel alone.
Figure 2: °API Gravity for studied Fuels blend
Figure 3: Fuels blend kinematic viscosity infunction of temperature
3.2 Chemical Properties and Fuel Upgrading
Figure 4: Sulfur content for studied Fuels blend
Figure 5: Vanadium, Silicon and Aluminum content forstudied Fuels blend
Figure 6: Net calorific value studied Fuels blend
Figure 7: Flash point for studied Fuels blend
Figure 8: Pour point for studied Fuels blend
3.3 Sediments, Ash, and Carbon Residue
Figure 9: Total Sediment Existent (%mass) for studied Fuels blend
Figure 10: Total Sediments Potential (%mass) forstudied Fuels blend
This substantial improvement indicates a markedly higher fuel stability and a significantly lower risk of sludge formation during storage and engine operation. Knowing, that sludge formation in ship bunkering remains a persistent operational and regulatory challenge with substantial economic consequences.
In fact, the rate of sludge formation depends on various factors, including fuel composition, storage conditions, and handling practices. Operational experience and IMO guidance indicate that sludge generation during fuel purification and storage typically ranges from 1–3% by volume of HFO consumed, although this refers to separator/bunker residues and should not be directly equated with theISO 8217 sediment specification.
For a vessel storing 1,000 tons of HFO 380:
Table 2. Economic Impact of Sludge Formation from HFO380
For a vessel consuming 20,000 t of HFO annually, this corresponds to fuel savings of approximately 20–200 t per year, or about 10,000–100,000 USD annually (based on a reference price of 500 USD/t). Higher fuel prices or larger consumption would proportionally increase these savings.
It shouldbe noted that these estimates account only for the direct loss of fuel value. In practice, the costs of sludge management are often higher due to mandatory disposal under MARPOL Annex I, port reception fees, and slops handling requirements, which can significantly exceed the simple cost of the lost fuel.
By combining systematic fuel management with advanced cavitation-based homogenization, operators can:
Figure 11: Ash content (%mass) for studied Fuels blend.
The decrease in carbon residue from pure HFO toHFO–20% biodiesel, illustrated in Figure 12, is primarily due to there placement of heavy, aromatic hydrocarbons with lighter, oxygenated fatty acid esters of biodiesel. The additional reduction observed for the HFO–10%biodiesel–5% glycerin blend arises from glycerin’s oxygen-rich composition, which promotes more complete thermal decomposition and limits the formation of refractory residues. A slight increase of about 3% in carbon residue with cavitation treatment of HFO–20% biodiesel is attributed to enhanced activation of thermal decomposition induced by the intense agitation generated duringcavitation compared to hand blending. These modifications improve combustion efficiency, reduce soot and deposits in engines, and facilitate smoother fuel handling during bunkering and storage operations.
Figure 12: Carbon Residue (%mass) for studied Fuels blend.
3.4 Combustion and Engine Performance
HFO–FAME blends produced using cavitation were tested and evaluated for performance in afour-stroke marine diesel engine, in comparison with conventionally (Coarse) produced HFO–FAME blends. The investigations were conducted on a full-enginetest bench provided by FVTR GmbH, based on a Caterpillar MaK 6M20 engine. The following points summarize the main outputs of the test:
3.5 Summary of Fuel and Combustion Improvements –“CaviFlow® Performance Gains”
At this stage, the overall effects of RAPTECH’s Cavitation Treatment on fuelproperties, combustion performance, and operational efficiency can be summarized as follows. The data confirm measurable physical, chemical, andeconomic advantages for cavitation-treated fuels compared to conventionally blended ones.
Table 3. Key Performance Gains with CaviFlow® Cavitation Treatment
Table 4. Estimated Annual Economic Impact of Cavitation-Based Fuel Optimization
Assuming a case scenario of a tanker with 50 000 DWT operating with a FAME component of approximately 20 %, there is a reduction in the net CO₂ emission factor from 3.114 t CO₂ / t fuel for pure HFO to 2.856 t CO₂ / t fuel, when taking into consideration the efficiency benefits of RAPTECH’s cavitation technology. This corresponds to an overall CO₂ saving of about 1.548 t per year, which effectively upgrades the vessel’s CII rating from C to B. The estimated economic and environmental impact of these improvements is summarized in Table 4, highlighting the combined advantages in terms of energy efficiency, emission reduction, and operational cost savings.
These consolidated improvements confirm that cavitation treatment effectively enhances the overall performance of blended marine fuels — improving energy efficiency, operational reliability, and environmental compliance.
4. Conclusion
Cavitation-assisted homogenization demonstrates clearpotential for improving both the physical and chemical properties of blendedfuels — in this study, blends of HFO, biodiesel, and glycerin.
Key observed benefits include:
These findings demonstrate that cavitation homogenization can serve as a scalable, energy-efficient, and environmentally compatible process for upgrading and stabilizing blended marine fuels. Continued research into the mechanisms ofcavitation-induced chemical modification and long-term engine performance will further support its integration into sustainable bunkering and fuel treatment systems.
Authors: Dr. Ahmad Saylam | Rohit Surya Narayan | Oleg Verechshagin | Nishith Reddy Cherukuru | RAPTECH Eberswalde GmbH
References
1. International Maritime Organization (IMO). IMO 2020Sulfur Cap Regulation. IMO, London, 2020.
2. ISO 8217:2017. Specifications of Marine Fuels.International Organization for Standardization, Geneva, 2017.
3. EN 14214. Fatty Acid Methyl Esters (FAME) forBiodiesel Fuel – Requirements and Test Methods. European Committee forStandardization, Brussels, 2012.
4. Raptech GmbH. CaviFlow® Cavitation BlendingTechnology: Technical Brochure. Raptech, 2024.
5. FVTR GmbH. Full Engine Test Report – CaterpillarMaK 6M20, HFO–Biodiesel–Glycerin Blends. FVTR, 2025.
6. K. Kiran et al., Fuel Stabilization and EmissionReduction in Marine Applications Using Biodiesel Blends, Energy Fuels,2020, 34, 987–998.
- This study evaluates the effect of cavitation homogenization on heavy fuel oil (HFO 380) and its blends with biodiesel and glycerin for marine applications. HFO, HFO–20% biodiesel (B20), and HFO–10% biodiesel–5% glycerin (B10G5) were compared under conventional hand blending and cavitation treatment.
- Cavitation significantly improved several fuel properties, including viscosity (up to 19% reduction), sulfur content (1.5–19% decrease), and metal contaminants (up to33% reduction), while maintaining a comparable calorific value. Full-scale engine tests on a Caterpillar MaK 6M20 confirmed improved combustion stability, reduced preheating requirements, slight fuel savings (~1%), and consistent emission profiles.
- These results indicate that cavitation promotes efficient blending and homogenization, facilitates handling of sludge and residual water, and induces mild (adjustable) in situ chemical activation. Overall, cavitation-based processing presents a practical pathway toward cleaner, more efficient, and sustainable utilization of blended marine fuels.
- The shipping industry is under increasing pressure to reduce emissions and improve fuel efficiency, driven by the IMO 2020 sulfur cap, carbon intensity regulations, and the growing use of alternative fuels. Heavy fuel oil (HFO) remains widely used due to its high energy content, but blending with renewable components such as biodiesel and glycerin is necessary to meet environmental regulations and improve combustion characteristics.
Study:
Cavitation-based homogenization is a promising method to enhance fuel stability and performance .By generating intense microbubbles that collapse violently, cavitation promotes both physical blending and mild chemical activation, improving rheology, dispersion, and combustion behavior. This study evaluates the effects of cavitation on HFO–biodiesel–glycerin blends, assessing density, viscosity, sulfur and metal contents, calorific value, sediment formation, and engine performance.
Table 1 summarizes the comparative physical and chemical properties of the three main fuel components used in this study: HFO 380, biodiesel (FAME), and glycerin. HFO 380 serves as the baseline reference, while biodiesel and glycerin act as renewable, sulfur-free blending components. Their contrasting densities,viscosities, and oxygen contents are key factors influencing blend behavior during homogenization and combustion. Understanding these baseline properties provides the foundation for assessing the performance of RAPTECH’s cavitation treatment in improving fuel uniformity, stability, and overall quality.
| Parameter | Unit | HFO 380 (ISO 8217:2017) | Biodiesel (FAME, EN 14214) | Glycerin (Crude/Refined) |
|---|---|---|---|---|
| Density at 15°C | kg/m³ | Max. 991 | 860–900 | 1,260–1,270 |
| Kinematic Viscosity at 50°C | mm²/s | Max. 380 | 4–6 | ~1,200 (at 40°C) |
| Sulfur Content | % (m/m) | Max. 3.50 | <0.001 | 0 |
| Ash Content | % (m/m) | Max. 0.15 | <0.02 | <0.01 |
| Pour Point | °C | Max. 30 | −5 to +15 | ~18 |
| Flash Point | °C | Min. 60 | >120 | >160 |
| Total Sediment Potential | % (m/m) | Max. 0.10 | – | – |
| Total Sediment Existent | % (m/m) | Max. 0.10 | – | – |
| Gross Calorific Value | MJ/kg | 41.5–42.5 | 39–40 | ~16 |
| Net Calorific Value | MJ/kg | 40–41 | 37–38 | ~14–15 |
| Oxygen Content | % (m/m) | ~0 | 10–12 | ~52 |
| Carbon Residue (CCR) | % (m/m) | ~15 | <0.05 | <0.01 |
Table 1: Comparative Fuel Properties of HFO 380, Biodiesel (FAME), and Glycerin.
2. Materials and Methods
- Fuels: HFO 380, biodiesel (FAME), glycerin
- Blends: HFO, HFO–20% biodiesel (B20), HFO–10% biodiesel–5% glycerin (B10G5)
- Blending: Conventional hand blending (HB/Coarse) and cavitation-assisted blending (CF) using RAPTECH´s CaviFlow® system
- Analyses: Density, API gravity, kinematic viscosity, sulfur, metals, calorific value, flash point, pour point, total sediment existent (TSE), total sediment potential (TSP), ash content, and carbon residue, measured at Bureau Veritas
- Engine testing: FVTR GmbH full-scale marine diesel test bench (Caterpillar MaK 6M20). Performance, emissions, combustion timing, and fuel consumption were recorded
3. Results and Discussion
3.1 Physical Properties and Rheology
- Density and API gravity: As biodiesel (860–900 kg/m³ at 15 °C) has a lower density than HFO 380, and both are less dense than glycerin (1264 kg/m³ at 15 °C), Figure 1 illustrates the decrease in density when biodiesel is added to HFO 380 and the corresponding increase when glycerin is added. It also highlights the advantage of using cavitation technology over standard hand blending, achieving an additional density reduction of approximately 0.3%.
Figure 1: Fuels blend density in function of temperature
In terms of API gravity, shown in Figure 2, the lowest value is observed for pure HFO 380, reflecting its relatively high density. When HFO is blended using cavitation, the API gravity increases slightly, indicating a modest density reduction. A more pronounced effect is seen when 20% biodiesel is added by hand blending, as biodiesel has a considerably lower density than HFO, resulting in a significant rise in API gravity. The highest API gravity is achieved with HFO containing 20% biodiesel treated by cavitation. In this case, the difference between hand blending and cavitation blending is relatively small, but the cavitation process still provides an additional improvement in API gravity beyond the effect of biodiesel alone.
Figure 2: °API Gravity for studied Fuels blend
- Viscosity: Figure 3 presents a similar trend for kinematic viscosity, highlighting the differences between HFO 380 and its biodiesel and glycerin blends. Notably, HFO with 20% biodiesel treated by cavitation achieves up to a 19% viscosity reduction compared to hand blending. From a practical standpoint, this reduction in viscosity and density can be attributed to cavitation’s dual action — its intense mixing capability that effectively blends fuels of different origins and its strong homogenization effect that stabilizes the mixture and improves its rheological and combustion characteristics. Together, these mechanisms facilitate easier pumping, reduce preheating energy demand by approximately 6%, and enhance fuel atomization, thereby improving combustion efficiency and lowering soot and unburned hydrocarbon formation.
Figure 3: Fuels blend kinematic viscosity infunction of temperature
3.2 Chemical Properties and Fuel Upgrading
- Sulfur reduction: As biodiesel and glycerin contain no sulfur, Figure 4 shows the expected decrease in sulfur content between pure HFO and its blends with biodiesel and glycerin. The partial chemical activation induced by cavitation — particularly with glycerin acting as an oxygen carrier — may explain the additional reductions observed: approximately 1.5% between the hand-blended and cavitation-treated HFO–20% biodiesel fuels, and about 19% between the HFO–20% biodiesel and the HFO–20% biodiesel–5% glycerin blends treated by cavitation. This demonstrates that cavitation not only provides powerful blending of diverse fuel types and strong homogenization, but also assists in fuel upgrading, promoting mild in situ adjustable chemical modification of the fuel components
Figure 4: Sulfur content for studied Fuels blend
- Metal contaminants (Cat Fines): Figure 5 shows that the enhanced physical dispersion and partial chemical transformations induced by cavitation may explain the observed reduction in Cat Fines — microscopic particles of spent catalyst, primarily composed of silicon and aluminum oxides, commonly present in residual fuels such as heavy fuel oil (HFO). A decrease of up to 33% was observed between the hand-blended and cavitation-blended fuels, and up to 50% between the untreated HFO and the HFO containing 10% biodiesel and 5% glycerin after cavitation treatment. This reduction suggests that cavitation promotes finer dispersion and possibly partial surface modification or fragmentation of these catalyst residues, leading to improved fuel homogeneity and potentially lower abrasive wear risks in fuel handling systems.
Figure 5: Vanadium, Silicon and Aluminum content forstudied Fuels blend
- Calorific value: As the calorific value of HFO is higher than that of biodiesel and glycerin, the addition of biodiesel and glycerin leads to a decrease in net calorific value. The partial enhancement of fuel reactivity through cavitation treatment could explain the additional decrease of about 0.2% observed between hand-blended and cavitation-blended fuels, as shown in Figure 6. This slight decrease is compensated in practice by improved combustion efficiency, cleaner burning, and more stable ignition behavior — all beneficial for marine engine performance and emission control.
Figure 6: Net calorific value studied Fuels blend
- Flash point: Similarly, since the flash point of HFO is considerably lower than that of biodiesel, the addition of biodiesel increases the blend’s flash point. However, the intense homogenization achieved through cavitation treatment results in a significant decrease of about 20% in the flash point compared to the hand-blended fuel, as shown in Figure 7. This reduction reflects a more uniform distribution of lighter fractions within the blend, which can facilitate fuel handling and vaporization during engine start-up, without compromising safety margins in bunkering operations.
Figure 7: Flash point for studied Fuels blend
- Pour point: Likewise, as the pour point of HFO is significantly higher than that of biodiesel, adding biodiesel lowers the pour point, improving low-temperature flow properties and reducing preheating requirements during transfer and injection. No noticeable influence of cavitation treatment is observed on the pour point compared to the hand-blended fuel (Figure 8), indicating that cavitation primarily affects microstructure and reactivity rather than bulk phase transitions.
Figure 8: Pour point for studied Fuels blend
3.3 Sediments, Ash, and Carbon Residue
- Sedimentation: The reduction in Total Sediment Existent (TSE) by about 33% observed when mixing HFO with biodiesel (Figure 9) is mainly attributed to biodiesel’s amphiphilic nature, which stabilizes asphaltenes through polar interactions and improvesfuel homogeneity and viscosity, thereby preventing aggregation and sedimentation. An additional reduction of approximately 33% in TSE is achievedthrough cavitation-based homogenization of the HFO–biodiesel blend compared tohand blending.
Figure 9: Total Sediment Existent (%mass) for studied Fuels blend
- The significant decrease in Total Sediment Potential(TSP) by about 60% observed when mixing HFO with biodiesel (Figure 10) is also mainly attributed to biodiesel’s amphiphilic nature, which stabilizes asphaltenes through polar interactions and enhances fuel uniformity and flow properties, thereby minimizing aggregation and sediment formation. A further reduction of about 25% in TSP is obtained through cavitation-based homogenization of the HFO–biodiesel blend compared to hand blending.
Figure 10: Total Sediments Potential (%mass) forstudied Fuels blend
This substantial improvement indicates a markedly higher fuel stability and a significantly lower risk of sludge formation during storage and engine operation. Knowing, that sludge formation in ship bunkering remains a persistent operational and regulatory challenge with substantial economic consequences.
In fact, the rate of sludge formation depends on various factors, including fuel composition, storage conditions, and handling practices. Operational experience and IMO guidance indicate that sludge generation during fuel purification and storage typically ranges from 1–3% by volume of HFO consumed, although this refers to separator/bunker residues and should not be directly equated with theISO 8217 sediment specification.
For a vessel storing 1,000 tons of HFO 380:
| Scenario | Sludge Mass (t) | Slugle Volume m³ | Fuel Cost Loss @ $500/t |
|---|---|---|---|
| Low estimated (1% by vol) | 9.5 | ≈ 10 | 4.750 |
| High estimated (3% by vol) | 28.5 | ≈ 30 | 14.250 |
Table 2. Economic Impact of Sludge Formation from HFO380
For a vessel consuming 20,000 t of HFO annually, this corresponds to fuel savings of approximately 20–200 t per year, or about 10,000–100,000 USD annually (based on a reference price of 500 USD/t). Higher fuel prices or larger consumption would proportionally increase these savings.
It shouldbe noted that these estimates account only for the direct loss of fuel value. In practice, the costs of sludge management are often higher due to mandatory disposal under MARPOL Annex I, port reception fees, and slops handling requirements, which can significantly exceed the simple cost of the lost fuel.
By combining systematic fuel management with advanced cavitation-based homogenization, operators can:
- Maintain long-term fuel stability
- Reduce maintenance, downtime, and disposal costs
- Improve fuel utilization, engine reliability, and operational safety
- Ensure compliance with MARPOL Annex I while reducing environmental risks
- Ash and carbon residue: Since biodiesel contains no ash, Figure 11 shows the expected decrease in ash content when blending it with pure HFO. Cavitation further enhances this effect by promoting finer dispersion and partial surface fragmentation of ash particles, resulting in an additional reduction of about 4% in the HFO–biodiesel blend. Lower ash content contributes to cleaner storage and handling, reduces fouling in pipelines and tanks during bunkering, and supports more efficient combustion with less particulate formation in engines.
Figure 11: Ash content (%mass) for studied Fuels blend.
The decrease in carbon residue from pure HFO toHFO–20% biodiesel, illustrated in Figure 12, is primarily due to there placement of heavy, aromatic hydrocarbons with lighter, oxygenated fatty acid esters of biodiesel. The additional reduction observed for the HFO–10%biodiesel–5% glycerin blend arises from glycerin’s oxygen-rich composition, which promotes more complete thermal decomposition and limits the formation of refractory residues. A slight increase of about 3% in carbon residue with cavitation treatment of HFO–20% biodiesel is attributed to enhanced activation of thermal decomposition induced by the intense agitation generated duringcavitation compared to hand blending. These modifications improve combustion efficiency, reduce soot and deposits in engines, and facilitate smoother fuel handling during bunkering and storage operations.
Figure 12: Carbon Residue (%mass) for studied Fuels blend.
3.4 Combustion and Engine Performance
HFO–FAME blends produced using cavitation were tested and evaluated for performance in afour-stroke marine diesel engine, in comparison with conventionally (Coarse) produced HFO–FAME blends. The investigations were conducted on a full-enginetest bench provided by FVTR GmbH, based on a Caterpillar MaK 6M20 engine. The following points summarize the main outputs of the test:
- Viscosity and preheating: Reduced injection temperature (>6 K) lowered preheating energy demand
- Combustion timing: Slightly earlier start and end of combustion, slightly shorter duration, leading to minor fuel savings (~1%) and slightly higher NOx due to oxygen content
- Emissions: CO, CO₂, HC, O₂, and FSN remained similar to hand-blended fuel; no operational issues observed.The cavitation-treated HFO–FAME blend demonstratesclear practical advantages in marine engine operation. Its lower viscosityreduces preheating energy requirements, facilitates injection, and contributesto slight fuel consumption benefits. Combustion remains stable and reliable,with emissions largely comparable to conventional blends, apart from theexpected minor increase in NOx due to higher oxygen content. These resultsindicate that cavitation-based blending not only improves the rheological and combustioncharacteristics of HFO–FAME fuels but also supports safer, more efficient, andreliable bunkering and engine performance in practical marine applications
3.5 Summary of Fuel and Combustion Improvements –“CaviFlow® Performance Gains”
At this stage, the overall effects of RAPTECH’s Cavitation Treatment on fuelproperties, combustion performance, and operational efficiency can be summarized as follows. The data confirm measurable physical, chemical, andeconomic advantages for cavitation-treated fuels compared to conventionally blended ones.
| Parameter | Improvement | Effect |
|---|---|---|
| Viscosity @ 50 °C | ↓ ≈ 13 % | Easier pumping, reduced preheating energy demand |
| Specific fuel oil consumption (SFOC) | ↓ ≈ 1 % | Enhanced combustion efficiency, slight fuel saving |
| Sludge formation (1–3 % v/v typical) | ↓ ≈ 99 % (virtually eliminated) | Cleaner filters, no separator overloading, stable and continuous operation |
| Overall fuel-to-power efficiency | ↑ ≈ 4 % (fuel saving) | Equivalent to ≈ 1.2 t/day for a 50,000 DWT tanker |
| Engine operation | Stable combustion with minimal NOₓ rise | Reliable and consistent performance |
| Environmental impact | Lower sediment, ash, and sulfur content | Cleaner burning, easier compliance with IMO/MARPOL standards |
Table 3. Key Performance Gains with CaviFlow® Cavitation Treatment
| Saving Area | Annual Impact (€) | Basis / Explanation |
|---|---|---|
| Fuel Efficiency (~4 %) | € 200 000 – 250 000 | 4 % of fuel costs |
| EU ETS / CO₂ Saving | € 108 000 – 110 000 | 1.548 t × € 70 (estimated) / t CO₂ |
| Compliance & Charter Premium | € 50 000 – 200 000 | Better charter rates |
| Operational Efficiency & Maintenance | € 20 000 – 40 000 | Cleaner combustion → less engine wear |
| Purifier / Heater Energy Saving | € 5 000 – 10 000 | Lower viscosity → reduced load |
| Total Potential Saving | ≈ € 380 000 – 600 000 per ship / year | Excluding fuel price changes |
Table 4. Estimated Annual Economic Impact of Cavitation-Based Fuel Optimization
Assuming a case scenario of a tanker with 50 000 DWT operating with a FAME component of approximately 20 %, there is a reduction in the net CO₂ emission factor from 3.114 t CO₂ / t fuel for pure HFO to 2.856 t CO₂ / t fuel, when taking into consideration the efficiency benefits of RAPTECH’s cavitation technology. This corresponds to an overall CO₂ saving of about 1.548 t per year, which effectively upgrades the vessel’s CII rating from C to B. The estimated economic and environmental impact of these improvements is summarized in Table 4, highlighting the combined advantages in terms of energy efficiency, emission reduction, and operational cost savings.
These consolidated improvements confirm that cavitation treatment effectively enhances the overall performance of blended marine fuels — improving energy efficiency, operational reliability, and environmental compliance.
4. Conclusion
Cavitation-assisted homogenization demonstrates clearpotential for improving both the physical and chemical properties of blendedfuels — in this study, blends of HFO, biodiesel, and glycerin.
Key observed benefits include:
- Enhanced blending and uniformity, including effective dispersion of sludge and residual water, resulting in reduced viscosity and easier fuel handling
- Partial (adjustable) in situ chemical activation leading to measurablereductions in sulfur, ash, and metal contaminants, as well as lower sedimentformation
- Stable combustion behavior with slight fuel savings (~1%) andonly minor increases in NOₓ due to higher oxygen content
- Reduced operational and maintenance demands, including preheating energy andsludge management
These findings demonstrate that cavitation homogenization can serve as a scalable, energy-efficient, and environmentally compatible process for upgrading and stabilizing blended marine fuels. Continued research into the mechanisms ofcavitation-induced chemical modification and long-term engine performance will further support its integration into sustainable bunkering and fuel treatment systems.
Authors: Dr. Ahmad Saylam | Rohit Surya Narayan | Oleg Verechshagin | Nishith Reddy Cherukuru | RAPTECH Eberswalde GmbH
References
1. International Maritime Organization (IMO). IMO 2020Sulfur Cap Regulation. IMO, London, 2020.
2. ISO 8217:2017. Specifications of Marine Fuels.International Organization for Standardization, Geneva, 2017.
3. EN 14214. Fatty Acid Methyl Esters (FAME) forBiodiesel Fuel – Requirements and Test Methods. European Committee forStandardization, Brussels, 2012.
4. Raptech GmbH. CaviFlow® Cavitation BlendingTechnology: Technical Brochure. Raptech, 2024.
5. FVTR GmbH. Full Engine Test Report – CaterpillarMaK 6M20, HFO–Biodiesel–Glycerin Blends. FVTR, 2025.
6. K. Kiran et al., Fuel Stabilization and EmissionReduction in Marine Applications Using Biodiesel Blends, Energy Fuels,2020, 34, 987–998.
