Shanmuga Priya at Indian Institute of Technology Guwahati for the award of the degree of Doctor of Philosophy was carried out under our supervision in the Department of Mechanical Engineering, Indian Institute of Technology Guwahati. Sree Sree Shivakumara Swamiji Head of Sree Siddaganga Mutt, for his blessings with holiness for the completion of this thesis along with Dr.
INTRODUCTION
- Emission and its standards
- Effects of exhaust pollution
- Solutions to meet energy demand and emission issues
- Advantages and limitations of a diesel engine
- Biodiesel and its limitations
- Diesel additives and combustion catalysts
- Ceria as an oxidation catalyst
- Possible effects of nanoparticles deposition emission and environmental implications
- Organization of thesis
The metal-based catalysts are manufactured in the form of organometallic compounds or nanoparticles. Chemical composition and surface characteristics – The toxicity of nanoparticles depends on the chemical composition of nanoparticles and the composition of chemicals adsorbed on their surfaces.
![Figure 1.2 Global energy related emission as on 2009 [source: EIA]](https://thumb-ap.123doks.com/thumbv2/azpdfnet/10441677.0/18.893.159.742.357.759/figure-global-energy-related-emission-2009-source-eia.webp)
LITERATURE REVIEW
Ceria- zirconia solid solutions
It was observed that the reducible Ce4+ and its thermal stability increased with Zr/Ce ratio, Vlaic et al. It was observed that the thermal stability of CeO2-ZrO2 increased with Zr/Ce ratio.
Ceria – zirconia with other metals
2009] prepared the CeO2-ZrO2-La2O3-Al2O3 catalyst by co-precipitation method, which was found to have high thermal sintering effect, OSC improvement and reduction temperature. 2010] suggested that the CeO2-ZrO2-Al2O3 solid solution was expected to retain the excellent textural properties and thermal stability in addition to its attractive OSC when the sample was prepared by co-precipitation method.
Evaluation of OSC of a material
21 TGA The weight change observed during the TGA was monitored under N2 or dry air in temperature. OSC was measured by injecting oxygen pulses into the sample bed, Masui et al.
Nanoparticles characterization
- Structural characterization
However, the individual phases of Al2O3 and ZrO2 were not detected by XRD, which confirmed that alumina and zirconia were well dispersed in CeO2 crystal lattice, and CeO2 - ZrO2 - Al2O3 was a homogeneous solid solution. 2010] observed the peaks for CexZr0.5-xAl0.50O1.75 (0.05≤x≤0.45), which were identical to the cubic fluorite structure of Ce1-xZrxO2 solid solution (Joint Committee on powder diffraction standards- JCPDS -18)- 27 and it is confirmed that Zr4+ doped into the CeO2 crystal lattice during the formation of the solid solution by co-precipitation and sol-gel methods.
Synthesis of nanofluid
They synthesized a nanofluid with deionized water, where gum arabic was used as a surfactant. The nanofluid was prepared by vigorous manual mixing of the liquid and nanoparticles, and then an ultrasonic disruptor was used to prevent agglomeration.
Quality characterization of nanofluid
- Dispersion stability of nanofluid
- Fuel properties
2010] reported that nanofluid viscosity increased with the addition of cerium nanoparticles to Jatropha-based biodiesel. The change in surface tension of the nanofluid against water was found to have a negligible effect on the heat transfer characteristics.
Experimental studies on engine performance and emission level
It was concluded that the combustion behavior of the nano suspension was better than the micron suspension. 2011] also reported that fuel vaporization time was reduced by metal oxide nanoparticles leading to reduced physical lag.
Technical gap
Objectives of the work
The studies on nanoparticles and nanofuels involve various analytical instruments and experimental techniques to confirm their properties. A range of different analytical instruments and techniques are used at various stages of development and testing of the nanoparticles and nanofuel, which are discussed in detail below.
Raw materials
This chapter aims to discuss the different techniques used and different methods used for the preparation of nanoparticles starting with the materials used, the methods followed to synthesize the nanoparticles and the nanofuel, the procedure followed to nanofuel in an IC engine and field trials in commercial diesel generators. .
Synthesis of nanoparticles
Based on the OSC data of the nanoparticles synthesized by the techniques discussed above, the sol-gel technique was followed for further investigation. Furthermore, the samples were calcined in a muffle furnace at 800 °C for 7 hours, which was termed as aged samples.
Synthesis of nanofuel
In the case of the magnetic stirring technique for synthesizing nanofuel, a magnetic stirrer of the production: IKA C-Mag, model: HS7 was used. In the case of the combined technique for synthesizing nanofuel, the combination of tip sonicator and magnetic stirrer was used alternately for 30 min.
Characterization of nanoparticles
- Structural analysis - X-Ray diffractometer (XRD)
- Lattice vibration studies- Raman spectroscopy
- Image studies - Transmission electron microscope (TEM)
- Oxygen storage capacity studies- Thermogravimetric analyzer (TGA)
- Thermal expansion studies – Thermomechanical analyzer (TMA)
The weight loss of the sample during the second heating cycle was used to calculate the OSC of the solid solution. A thermomechanical analyzer (TMA/SS6000, Seiko Instruments) was used to measure the thermal expansion of the sample in the temperature range from 30 to 1000 °C at a heating rate of 10 °C/min.
Quality characterization of nanofuel
- Dispersion stability studies- UV-Vis Spectrophotometer
The duration of the relative stability test was chosen based on the refilling of the fuel tank in each automotive system. As nanoparticle aggregation and sedimentation occur simultaneously, the relative stability of the nanochar changes continuously and was thus studied first on an hourly basis and then on a daily basis to find the rate of nanoparticle sedimentation in the liquid. It was chosen because electrons could undergo several possible transitions of different energy in all compounds except alkanes.
Characterization of nanofuel
- Surface tension study - Tensiometer
- Flash and Fire point temperature measurement - Pensky-Martens open type
- Thermal conductivity measurement - KD 2 pro Thermal properties analyzer
- Viscosity measurement- Rheometer
The ignition temperature and fire point of the nanofuel were measured using the open-type Pensky-Martens apparatus, which is shown in Figure 3.14. The flash point temperature of a volatile liquid is the lowest temperature at which it can vaporize to form a flammable mixture in air. The fire point temperature is assumed to be about 10 ºC higher than the flash point temperature.
Performance and emission studies in an Internal Combustion Engine
- IC engine Test rig
- Emission studies - Gas Analyzer and emission monitor
Exhaust emissions such as hydrocarbons, CO, CO2 and NOx were measured using a portable gas analyzer and emission monitor (Kane Quintox, KM9106) which is shown in Figure 3.18. The hydrocarbon, CO and NOx emissions were measured in ppm (parts per million) and the CO2 emissions were measured as a percentage.
Field Study
RESULTS AND DISCUSSION
It was observed that the crystallite size of CexZr1-xO2 solid solutions prepared by sol-gel technique was less than that of the COP synthesis technique. In general, it was observed that the OSC of sample synthesized by sol-gel technique is higher than that of the same synthesized by COP technique. It was also noted that the size of crystallites was found in sol-gel technique.
It was found that the crystallite size of all samples is smaller than that of Ce0.6Zr0.4O2 (CZ3). The crystallite size of aged CZM solid solutions was found to vary from 3.9 to 3.4 nm. In the case of old CZL samples, it was found that the size of the crystallites increased significantly compared to the fresh samples.
Quantitative studies on oxygen storage capacity (OSC) of CZY and CZM solid
It was observed that the OSC of the solid solutions was affected by the concentration of dopant elements in ceria. In the case of CZL, it was found that the OSC of CZL2 was 44% lower than that of CZ3 solid solution. Since the OSC of CZA2, CZM2, CZB3, CZL2, and CZN1 was found to be highest in CZA, CZM, CZB, CZL, and CZN solid solutions, respectively, the specific surface area study was focused on these solid solutions only.
TEM studies on high OSC solid solutions
The crystallites were found to be equiaxed and spherical in shape with a size of approximately 4 nm. It was observed that the crystallite size was less than 5 nm and agreed well with the XRD results. It was observed that the shape and size of the test sample were uniform.
Qualitative confirmation of OSC
- Lattice vibration studies
- Studies on thermal expansion
- Lattice defects confirmation
For example, the improvement in oxygen mobility of Ce0.6Zr0.4O2 was noticed due to the introduction of Al3+. The above observation confirms that the structure of Ce0.6Zr0.4-xMnxO2 has not changed due to aging. The thermal expansion of Ce0.6Zr0.4-xAl1.3xO2 samples against temperature is shown in Figure 4.26.
Optimization of surfactant and synthesis technique to prepare nanofuel
- Influence of surfactant on the stability of nanofuel
- Influence of preparation technique on the relative stability of nanofuel
- Accelerated relative stability study
It was observed that the relative stability of nanochar was observed to be 100% at all concentration for a period of 2 h. It is observed that the relative stability of nanochar was observed to be within 93% after 72 hours of aging for all concentration of CeO2 dispersed nanochar. The stability of the nanochar synthesized by the tip sonication technique was found to be high compared to that of the sample prepared through.
Optimization of ceria concentration for the performance enhancement of an
It was calculated from diesel, which was observed to increase to 0.06 wt. The mechanical efficiency was found to be high in the case of cerium oxide dispersed diesel at all concentrations compared to diesel. It was observed that the mechanical efficiency of an engine was found to be increased at all load conditions compared to diesel.
Studies on high OSC nanoparticles dispersed diesel
- Studies on the dispersion stability of nanofuel
- Characterization of nanofuel
2012], the stability of the CeO2-based nanofuel was found to be the lowest compared to the rest of the nanofuel. The viscosity of nanofuel was found to be high compared to that of diesel, which was also observed by Keblinski et al. It was found that the viscosity of sprayed diesel CZA3 is lower compared to that of CeO2, CZ3,.
Engine performance with high OSC nanoparticle (0.06 wt. %) dispersed diesel
- Engine performance studies
- Exhaust gas analysis using high OSC nanoparticles (0.06 wt. %) dispersed diesel
Field trial on nanofuels
It is observed that the FWHM is decreased, resulting in higher crystallite size compared to that of fresh samples. It was noted that the peaks observed for the aged samples were found to be weak compared to those of fresh samples. By comparing equation (4.8) and (4.9), the relationship between centrifugation time and normal aging time was obtained, which is given in equation (4.10).
At all concentrations, the stability of CeO2-type nanochar was found to be the lowest compared to the remaining nanochar. The friction force of an engine was found to be less for all types of nanofuels compared to diesel. It has been observed that the mechanical efficiency of an engine has increased by 12.0,.
Hydrocarbon reduction was found to be high for all types of nanofuels compared to diesel fuel and follows.
CONCLUSIONS AND FUTURE SCOPE
Scope of future work
Fabrication and characterization of Ce0.7Zr0.3O2 nanorods that have high specific surface area and large oxygen storage capacity. Synthesis and characterization of Nd3+ doped Ce0.6Zr0.4O2 and its doping significance in oxygen storage capacity. Influence of the ion beam of the doping element on studies of the oxygen storage capacity in Ce0.6Zr0.4O2.
