Experimental study of the transient properties of a diesel and castor biodiesel blend in a mini boiler with the optimal combustion efficiency

The researcher looks into alternative fuels because petroleum fuel is becoming increasingly scarce and energy demand is rising as a result of population expansion. In this work, experimental investigation of the transient characteristics of castor biodiesel and diesel is conducted. Castor crude oil was extracted with a Soxhlet apparatus. The crude oil is then transformed into biodiesel using potassium hydroxide as a catalyst in the esterification process. Different experimental procedures are employed for the small boiler (VITOLA 200) to ascertain the combustion performance, emission characteristics, and thermal efficiency with regard to time for blends of 10%, 20%, and 30% castor biodiesel. The results are then compared to 100% diesel fuel combustion performances. By setting the boiler pressure, mass flow rate, and damper opening to 200 kPa, 1.25 kg hr−1, and 41/2, respectively, the experiment tests are carried out. The outcomes demonstrated that the antioxidant from moringa increased the stability of the castor biodiesel blend’s combustion, resulting in an increase in cetane number to 56.61, which was significantly higher than the minimum cetane number (37.55) required to have good ignition. Furthermore, the 30% castor biodiesel blend results in a boiler with a maximum thermal efficiency of 63.25%. Additionally, a 30% castor biodiesel blend can reduce CO2 and HC emissions by 27.53% and 15.2%, respectively. Since the boiler uses heavy fuels, the investigation found that gasoline can be substituted with a blend of castor biodiesel and moringa antioxidant fuel. This seems like a promising way to lower greenhouse gas emissions while simultaneously improving the boiler’s overall efficiency.


Introduction
Urbanization is associated with an increase in vehicle fleets, intensive industries, and the consumption of fossil fuels.This condition has a negative impact on the environment by increasing the pollutants in the surrounding.The main source of air pollution in most cities of the world is due to the combustion of fossil fuels, those are associated with industries and vehicles fleets exhaust gases.American, Asian and European 25 cities have a 52% share of air pollution in the world.In Asia, the most polluted countries are India, Pakistan, and China.In a similar way, the United States of America, Mexico, and Canada are the most polluted countries in North America.In those specified countries the harmful effect on the environment distressing the human health of the cities habitants significantly.Therefore, mitigation of the greenhouse gas effect by using alternative sustainable fuels are a priority of different countries in recent years [e.g.[1][2][3][4][5].
Conventional energy sources such as diesel and gasoline fuels have many negative impacts on the environment.Therefore, to reduce this environmental negative impact alternative energy sources are needed by the world communities.Biofuels are the sources of alternative fuels that partially replace fossil fuels in recent times to keep the sustainability of resources and the environment.They are an environmentally friendly and sustainable energy source with little environmental negative impact.The alternative biofuels can be produced from both edible vegetables, waste cooking oil, and nonedible feed stokes.The edible vegetables higher production cost and contaminating nature cause engine components failure empowering to tend biodiesel productions from non-edible sources [6][7][8][9].Industrial oil seed biofuel is one type of an alternative fuels that can be used by various engine types without modifications of the engine with better performances with reasonable comparisons to diesel fuels [10].Biofuels produced from non-food crops generating new markets for agricultural producers in developing countries.They are free from sulfur and nitrogen so they didn't affect the environment.The particulate matter produced in the combustion process has no effect on the environment, unlike fossil fuels.Low-Carbon Fuels are renewable fuels with a lower carbon content than fossil fuels, making them a sustainable alternative fuel for reducing greenhouse gas emissions.Moreover, biodiesel is a biodegradable and non-toxic organic fuel made primarily of methyl or ethyl esters generated from triglycerides.Because waste cook oil is generated and used entirely inside the city limits, it is an economically viable feedstock for producing biodiesel with the lowest carbon emission factor or carbon intensity of all biofuels on the market [9].
Natural fats and oils are potential feedstock sources for biofuel production.At the moment, the main feedstock sources for biodiesel production are edible and non-edible vegetable oils.The transesterification of triglycerides with methanol deployed to produce oils consist of fatty acid methyl esters [11].The fundamental problem of this oil is low cetane number, high viscosity, and low flow properties.Therefore, the improvement of the quality of feedstock properties leads to an increase in the price of biofuel.These processes take place in the presence of hydrogen at relatively high pressures and temperatures.Furthermore, the quality of the fuels is determined by the activity of the catalyst as well as the operating conditions.As a result, catalytic hydroprocessing of vegetable oils is a promising biofuel production method that could make use of existing petroleum refinery infrastructure.The removal of heteroatoms such as sulfur and nitrogen are a standard part of hydro treatment.To produce high-quality gasoline and diesel fuels, the hydrocracking process involves the saturation and breaking of C-C bonds [12][13][14][15][16][17][18].In comparison to biodiesel, the catalytic hydro-processing of vegetable oils process produces better fuel properties.Sovran et al reported a processing cost that is half the cost of the transesterification process.Under normal hydro-desulfurization, operating conditions, hydro-treatment of vegetable oils and their mixtures with heavy vacuum gas oil has been investigated for the production of biofuels using hydro-treatment catalysts based on NiAMo/Al2O3 and CoAMo/Al2O3 [19].Biofuels are also produced through catalytic deoxygenation reactions of palm fatty acid distillate.The primary barriers to biodiesel commercialization are its use in cold environments and long-term storage due to poor low-temperature fluidity and oxidation stability [20,21].Various scholars discussed the potential and challenges of producing biofuels from various feedstocks.Researchers were also interested in advances in processing technologies that used a variety of feedstocks [22,23].Therefore, the use of nanotechnology improves the performance of biofuels significantly [24].
Many scholars addressed the combustion performance of castor biodiesel blends to use them as alternative fuels.However, it is quite challenging to completely replace gasoline with biodiesel.Instead, they are doing numerous studies to increase the biodiesel blend's effectiveness.The primary goal of the current study is to experimentally investigate the baseline diesel fuel and biodiesel blends and the transient properties in the mini boiler (VITOLA 200) for enhancing the combustion efficiency of castor biodiesel.

Methods and materials
2.1.Experimental setup Flow-regulating devices, a rocket burner MHG RE 1.19HK (15 kW), and an oil tank were the three primary components of the experimental setup of a mini boiler (VITOLA 200) shown in figure 1.The needle valve and pressure regulators were used to regulate and control the fuels that were supplied from the oil tank.Furthermore, it was employed to control the fluid flow into and out of the boiler.Impurities in the oil were filtered out using an oil filter connected to the oil tank before feeding the diesel and biodiesel fuel to a rocket burner.The boiler safety group controls the combustion processes in the rocket burner.On the other hand, vapor and dry water were fed into and returned through an insulated pipe to the boiler.The flow rate of dry water is controlled by the drain valve.In conclusion, the fixed parameters like flow rate, pressure, and damper opening were adjusted on the dashboard of the boiler when we were performing experimental tests.On a 300-kW oilfired furnace boiler, the viability of using these castor oil biodiesel blends with various mixing ratios, B10, B20, and B30 was investigated.The boiler detail specification is presented in table 1.In every aspect, the Vitola 200 oil and gas-fired boilers provide cutting-edge, innovative solutions.Both energy consumption and emissions are reduced by the Vitola 200.Due to its minimal emissions, the rocket burner plays a major role in protecting the environment.Because of the improved design of the combustion chamber, nitrogen oxide emissions are greatly decreased.In the current experimental study, castor biodiesel blends are being employed in place of diesel oil to assess the overall performance of the boiler.Consequently, blends of castor biodiesel can be used in place of diesel oil without reducing boiler efficiency.

Materials
Castor seed types and physiochemical properties was presented in table 2. During the cleaning and preparation process, dust and contaminants from the castor seed, such as sand and dry leaves, were eliminated.After that, the castor seed cover was manually dehulled, and the dehulled seeds were grinded to reduce their size.It was then heated in the oven to eliminate the moisture content from the seeds.Similar to this, Moringa leaves were collected from Arba Minch University research center and were processed for use as an antioxidant to improve combustion stability.After the material was collected, biodiesel is produced and characterized and test on a mini-boiler.Castor seed has a high oil content, around 48%.As a result, castor seeds have a higher oil output potential than other non-edible oilseeds, making them a viable resource for biodiesel production.Due to its extremely high fatty acid and viscosity, raw castor oil is not suitable for direct use in engines and boilers.Therefore, the extraction process goes through several steps before being used directly in engines and boilers.

Oil and biodiesel extraction process
Solvent extraction is a type of oilseed extraction that employs organic solvents such as hexane, n-hexane, ethanol, isopropanol, ethyl acetate, and acetone.Hexane was used as the solvent during the solvent extraction process described in [25,26], which was used to extract the castor oil.A 1:6 (weight to volume ratio) mixture of seed and hexane was prepared before starting the Soxhlet apparatus.Then, hexane was added to a flask with a round bottom.The extractor's center was fitted with the thimble containing the sample.At 60 °C, the Soxhlet heating mantle was set.As soon as the hexane started to boil, the vapor rose up the vertical tube and into the condenser at the top.After that, the liquid condensate was poured into the central filter thimble, which was holding the solid sample to be extracted.Four hours were allowed for this treatment.Then, the oil and hexane were separated by moving the mixture from the round bottom flask to a flask with a rotary evaporator.Due to the solvent's lower boiling point under vacuum pressure, rotary evaporators are used to remove solvents from samples.The inner wall of the round flask can become covered in a sizable region of the uniformly thin liquid layer due to spinning.The sample was placed in the evaporation round bottom flask, which was then evenly warmed in a water bath.Under vacuum, the lower boiling-point liquid swiftly evaporated.After being removed from the round-bottom flask, it was dried in the oven, cooled in the desiccators, and weighed once again to find out how much oil was extracted.After being cooled by the high-efficiency reflex condenser, the solvent stream was recovered in the receiving flask.Therefore, the overall castor crude oil extraction process is expressed in figure 2 in detail.Kinematic viscosity and surface tension of the biodiesel blends are presented in table 3. Consequently, the kinematic viscosity increases with an increase in the blending ratio.However, the variation in surface tension is modest.By applying the capillary rise method, the surface tension is computed.Therefore, the surface tension equation is given by ( ), where h= capillary tube height, ρ = density, g = gravity and d = diameter of the capillary tube.Five steps should be followed when measuring surface tension: cleaning the capillary tube, adding the biodiesel blend to the beaker, inserting the capillary tube, aligning the pointer and capillary tube vertically, adjusting the metallic gripper's height, and positioning the pointer so that it just touches the surface of the biodiesel blend to begin the measurement.In conclusion, both kinematic viscosity and surface tension of the blends are within the boiler operation standard.Impurities like phosphatides, too many free fatty acids (FFAs), and coloring additives are all taken out of the castor oil during this refining process, which was expressed in figures 3 and 4. The castor oil is refined using a method called water degumming, which lowers the number of phosphatides in the castor oil.The process involves heating castor crude oil to about 70 °C and distilling it.The castor oil is then combined with water, well mixed, and left to stand for 30 min before being placed in a separating funnel.In order to ensure that the extracted refined oil could be used as a source of raw materials for the production of biodiesel, it was characterized.The qualities of the oil derived from castor seeds were determined through testing on several variables, including moisture content, density, viscosity, acid value, saponification value, and iodine value.
Depending on the feedstock and end products required, biodiesel can be produced in a variety of ways.Such as catalyst cracking, pyrolysis, fermentation, and transesterification.Therefore, the castor biodiesel shown in figure 3 was produced through a transesterification process involving methanol and potassium hydroxide.Transesterification is a chemical reaction that requires triglyceride and alcohol to form esters with glycerol as the backbone in the presence of a catalyst.According to information from the literature review, the total alcohol to oil molar ratio (MR) and the catalyst amount (Wt% of oil consumed) was selected as process variables, whereas reaction time, temperature, and agitator speed were selected as constant variables.Throughout the experiment, a mercury-type thermometer was utilized, and a 500 ml beaker was used as the reactor.A hot plate with a magnetic agitator was used to pre-heat the oil to 60 °C.Freshly made, the established quantity of the catalyst solution KOH dissolved in methanol at a molar ratio of the various ranges was added to the oil.After being combined, the alcohol and catalyst were added, and then the mixture was placed in a bath of cold water to dissolve the catalyst.The mixture was then heated to 60 °C for 90 min while being refluxed with concurrent 650 rpm stirring.Based on literature data published for homogeneous catalyzed reactions, the reaction temperature, duration, and agitation speed were fixed.The products were moved to a separating funnel to separate the two layers when the reaction was complete.The top layer (obtained biodiesel) was further purified

Biodiesel blending process
For direct, and indirect diesel engines and boilers, direct use of castor biodiesel has generally been regarded as poor and impractical.The high viscosity, acid composition, free fatty acid content, and gum formation as a result of oxidation and polymerization during storage and combustion, as well as carbon deposits and lubricating oil thickening, are all noticeable issues.According to experts [27], the two major issues associated with the direct use of castor biodiesel as fuels are oil deterioration and incomplete combustion.As a result, blending castor biodiesel with diesel is advantageous.Blending significantly reduces the viscosity and density of castor biodiesel, which improves combustion performance.Therefore, this study blends castor biodiesel with diesel in ratios of 10%, 20%, and 30% of biodiesel for detecting the best combustion performance.The ratios were adapted from Nadir Yilmaz et al with minor changes [28].On a mini boiler (VITOLA 200), the three blends' combustion performance and emission behavior were characterized.

Emission characterization method
The emission characteristics of castor biodiesel blends were determined using a Kane gas analyzer, and detailed specifications are shown in table 5.As a result, emission characteristics of castor biodiesel blend with diesel such as CO, CO 2 , NOx, HC, and SO 2 were detected using this instrument.However, the major exhaust gas boiler with heavy oils was CO and CO 2 .The boiler was started with biodiesel blends and allowed to warm up until steadystate conditions were reached.Then, fixing the boiler pressure, mass flow rate, and damper opening to 200kPa,

Combustion performance
Before conducting the experiments, the diesel fuel is burned to preheat the walls of the three sub-sections of the rocket burner until the wall temperature reached a near-steady state in order to provide a steady-state hightemperature environment to examine the combustion and emission characteristics of the flame.The preheating procedure was followed in a systematic manner.Following the pre-heating process, the combustion tuning for castor biodiesel blends B10, B20, and B30 was performed.Then, the minimum excess oxygen in the flue gas required for complete combustion was obtained from combustion tuning procedures used for stable  combustion experiments using pure diesel and castor oil/diesel blends as fuels.The primary goal of combustion tuning is to reduce the airflow rate to the amount of excess oxygen required for complete fuel combustion in the flue gas.Before data collection began, the operation had been stable for at least 20 min.The point at which CO emissions in the flue gas were at their lowest was identified as the minimum excess oxygen requirement.Figures 7(a)-(d) depicts the basic diesel fuel properties for a fixed flow rate, damper opening, and boiler working pressure for a mini boiler.The temperature variation of the boiler's inlet and outlet with time is shown in figure 7(a).As a result, the temperature rises gradually until it reaches 24 min' temperature before becoming stable and constant.Therefore, it can possibly achieve stable proper combustion with a maximum combustion decay rate of 20 min.Heat-exchanger inlet and outlet temperature variation with time are shown in figure 7(b).The outlet heat-exchanger's temperature is gradually increasing up to 20 min, while the inlet temperature is  nearly constant at 23 °C.The temperature variation of the combustion chamber inlet and exhaust with time is shown in figure 7(c).The exhaust temperature gradually rises to 125 °C, but the combustion chamber temperature rises exponentially to 750 °C in 8 min.The combustion chamber then becomes stable to 750 °C as time passes.As a result, the combustion chamber becomes stable and has proper combustion in less than 10 min.Figure 7(d) shows the variation of exhaust gases (carbon dioxide and carbon monoxide) over time.The variation of CO with time is nearly constant and less than 0.04 ppm, whereas the variation of CO 2 with time is exponential for a time less than 2 min and then becomes constant to 14 ppm.Finally, this characterization is used as a baseline for comparison with castor biodiesel blends.Figures 8(a)-(d) depicts the fuel properties of 10% biodiesel blended with 90% diesel (B10/D90) for a fixed flow rate, damper opening, and boiler working pressure for a mini boiler.Figure 8(a) illustrates the temperature variation of the boiler's inlet and outlet with time for B10/D90 fuels.Therefore, the boiler's temperature gradually rises until it reaches 75 °C before becoming stable and constant after 24 min.Hence, for B10/D90 fuel, the maximum combustion decay rate with stable and proper combustion for less than 20 min was achieved.Figure 8(b) shows the inlet and outlet temperature variation with the time of a heat exchanger using B10/D90 fuel.The outlet temperature of the heat exchanger gradually rises to 65 °C in less than 18 min for the fuel B10/ D90, while the inlet temperature remains nearly constant at 23 °C.The combustion chamber inlet and exhaust temperature variation with time is expressed in figure 8(c).The temperature of the heat-exchanger exhaust gradually rises to 125 °C, while the temperature of the combustion chamber rises exponentially to 750 °C in less than 6 min.After that, the combustion chamber becomes stable to 750 °C in less than 6 min.Therefore, in less than 6 min, the combustion chamber achieves stable and proper combustion.Figure 8(d) depicts the change in exhaust gases (carbon dioxide and carbon monoxide) over time.CO variation with time is nearly constant and less than 0.02 ppm, whereas CO 2 variation with time is exponential for less than 1.5 min before becoming constant at 13 ppm.This indicates that the emitted exhaust gas became constant in less than 1.5 min.As a result, the combustion is desperately stable.
The fuel properties of a 20% biodiesel blended with 80% diesel (B20/D80) for a fixed flow rate, damper opening, and boiler working pressure for a mini boiler are shown in figures 9(a)-(d).The temperature variation of the boiler's inlet and outlet with time for B20/D80 fuels is shown in figure 9(a).As a result, the temperature of the boiler gradually rises until it reaches 75 °C before becoming stable and constant after 20 min.As a result, for B20/D80 fuel, the maximum combustion decay rate with stable and proper combustion was achieved in less than 18 min.The inlet and outlet temperature variations with the time of a heat exchanger using B20/D80 fuel are shown in figure 9(b).For the fuel B20/D80, the outlet heat exchanger's temperature gradually rises to 62.5 °C in less than 16 min, while the inlet temperature remains nearly constant at 23 °C.The variation of the combustion chamber inlet and exhaust temperatures with time is depicted in figure 9(c).The temperature of the heat-exchanger exhaust gradually rises to 125 °C, while the temperature of the combustion chamber rises exponentially to 750 °C in less than 6 min.After that, the combustion chamber reaches 750 °C in less than 6 min.Figure 9(d) shows the evolution of exhaust gases (CO2 and CO) over time.The CO 2 variation with time is exponential for less than 1.5 min before becoming constant at 10.5 ppm.This implies that the exhaust gas emitted became constant in less than 3 min.As a result, combustion is stable.
Figures 10(a)-(d) shows the fuel properties of a 30% biodiesel blended with 70% diesel (B30/D70) for the fixed damper opening, boiler working pressure, and constant flow rate boiler for a mini boiler.The temperature variation of the boiler's inlet and outlet with time is depicted in figure 10(a).The boiler temperature gradually rises until it reaches 72 °C, at which point it becomes stable and constant after 15 min.As a result, with stable and proper combustion, the maximum combustion decay rate for B30/D70 fuel was achieved in less than 15 min.The heat-exchanger inlet and outlet temperature variations with time for a B30/D70 castor biofuel blend are shown in figure 10(b).The inlet temperature of the heat exchanger remains constant at 23 °C.However, the temperature of the outlet heat exchanger gradually rises to 62.5 °C. Figure 10(c) depicts the time-dependent variation of the combustion chamber inlet and exhaust temperatures.The heat-exchanger exhaust temperature gradually rises to 125 °C, while the combustion chamber temperature rises rapidly to 750 °C in less than 5 min.As a result, as the blending ratio of castor biodiesel increases, the combustion time gradually decreases.Figure 10(d) shows the time evolution of exhaust gases (CO2 and CO) for the B30/D70 castor biofuel blend.CO 2 variation with time is exponential for less than 1.5 min before becoming constant at 10.5 ppm.Therefore, in less than 1.5 min, the CO 2 gas emitted stabilized.As a result, the combustion process has become more stable.

Combustion efficiency characteristics
The average CO 2 and CO concentrations in all cases were less than 15 ppm, according to the experimental results, as shown in figures 7-10.Several scholars [e.g. 29, 30] presented similar findings.The minimum and maximum CO 2 concentrations in exhaust gas are 99.87% and 99.9%, respectively.This demonstrated that complete combustion had occurred for castor biofuels blending ratios.As the castor biofuel blending ratio increased from B10 to B30, the percentage of CO 2 concentration decreased slightly.On the other hand, the effect of NOx on boiler combustion was negligible.As a result, the NOx result was excluded from this finding.The thermal combustion efficiency of the boiler was obtained by using equation (1).

* Steam heat energy Heat supplied to boiler
The calorific value and mass flow rate of the fuel are used to calculate the amount of heat supplied by the boiler.Steam heat energy is calculated using the temperature of the steam output.As a result, the thermal efficiency of the boiler is determined by following the procedures outlined above.D100, B10/D90, B20/D80, and B30/D70 biofuel blends have calorific values of 11531, 11283, 11026, and 11013 kcal, respectively.The calorific value of diesel fuel is slightly reduced when it is blended with castor biofuel.As a result, the variation in thermal efficiency with time is very small, as shown in figure 11.However, as shown in figure 11, the mass flow rate of the fuel has a significant impact on thermal efficiency.On the other hand, the blending ratio has a direct proportionality effect on the boiler's fuel consumption.In general, the maximum thermal efficiency of a B30/ D70 biofuel blend is around 63.25%, while D100 has a maximum thermal efficiency of 64.85%.
Figure 12 shows the mass burning rate change with fan opening number.Fuel consumption became saturated in all four blending ratios when the fan opening was set to 6. Six is the optimal fan opening for fuel economy.The boiler's fuel consumption considerably increased as the biodiesel blending percentage rose above 10%.According to figure 12, 90% diesel and 10% biodiesel blend have roughly the same fuel usage with pure diesel.

Uncertainty analysis
The uncertainty analysis was performed in accordance with the procedure recommended in [31] to determine the reproducibility of the experimental data and various calculated parameters.The overall uncertainty of the parameters measured during the experiments (density, viscosity, saponification value, FFA, moisture value, iodine value, flashpoint, cloud point, pour point, and temperature) was found to be less than 2.24%, which is well below the acceptable limit of 5%.

Conclusions
Despite the fact that biodiesel is a better alternative to petroleum diesel in many ways, it is always threatened by high feedstock costs and a lack of economically and technically viable technology for its efficient production from any feedstock type.There are several techniques for transesterification of biodiesel production, each with its own set of feedstock properties and optimal operating conditions for efficient biodiesel production to enhance feasibility of castor biodiesel production.As a result, the conclusions drawn from the results and discussion are as follows.
(1) Homogenous acid-catalyzed transesterification requires less energy but operates at a higher temperature, and the castor biodiesel produced typically contains more free glycerol.
(2) The characterization of transient castor biodiesel behavior is critical for detecting fuel atomization properties for improved mixing and combustion efficiency.After about 12 min, the combustion process became stable.Therefore, the fuel consumption is significantly improved.And complete combustion is obtained.
(3) A 30% castor biofuel blend to diesel has a maximum thermal efficiency of around 63.25%, while 100% diesel has a maximum thermal efficiency of 64.85%.As a result, a 30% castor biodiesel blend is used in a mini boiler with little effect on performance and lower emissions.

Figure 5 .
Figure 5. Schematic diagram of castor oil extraction flow diagram.

Figure 6 .
Figure 6.Schematic diagram of biodiesel production flow diagram.

Figure 7 .
Figure 7. Baseline diesel fuel properties for fixed flow rate, damper opening, and boiler working pressure for mini boiler.(a) Boiler inlet and outlet temperature, (b) Heat exchanger inlet and outlet temperature, (c) Combustion chamber temperature and exhaust temperature, (d) Exhaust gas.

Figure 8 .
Figure 8. B10/D90 fuel properties for fixed flow rate, damper opening, and boiler working pressure for mini boiler.(a) Boiler inlet and outlet temperature, (b) Heat exchanger inlet and outlet temperature, (c) Combustion chamber temperature and exhaust temperature, (d) Exhaust gas.

Figure 9 .
Figure 9. B20/D80 fuel properties for fixed flow rate, damper opening, and boiler working pressure for mini boiler.(a) Boiler inlet and outlet temperature, (b) Heat exchanger inlet and outlet temperature, (c) Combustion chamber temperature and exhaust temperature, (d) Exhaust gas.

Figure 10 .
Figure 10.B30/D70 fuel properties for fixed flow rate, damper opening, and boiler working pressure for mini boiler.(a) Boiler inlet and outlet temperature, (b) Heat exchanger inlet and outlet temperature, (c) Combustion chamber temperature and exhaust temperature, (d) Exhaust gas.

Figure 11 .
Figure 11.Boiler thermal efficiency for fixed flow rate, damper opening, and boiler working pressure for mini boiler.

Figure 12 .
Figure 12.Fan opening No versus mass burning rate for various blending ratio.

Table 3 .
Viscosity and surface tension.

Table 4 .
Physical/chemical properties of castor biodiesel.

Table 5 .
Kane gas analyzer detail specification.