Financial, energy, performance and emission analysis of a repurpose used cooking oil (RUCO) diesel fuel blends

In this study, exergy, energy, performance and emission analysis were investigated 7 for the repurpose used cooking oil (RUCO), Jatropha curcas (JC), Pongamia Pinnata (PP) and 8 petroleum diesel fuel (PDF) fueled compression ignition engine under various engine loads. 9 In this study, 20% of each biodiesel was tested in single cylinder, four stroke, diesel engine, 10 given that open literature shows the potential use of biodiesel of up to 20% in a diesel engine 11 without modification. The diesel engine was used to investigate their performance, 12 combustion and emission characteristics of diesel-repurpose used cooking oil, Jatropha 13 curcas, and Pongamia Pinnata fuel samples at different compression ratios and load 14 condition. The results showed that thermal efficiency is higher with the PDF compared to 15 DRUCO20, DJC20, DPP20 biodiesel blends. The exhaust gas temperature decreased and 16 specific fuel consumption of the engine were increased by adding RUCO, Jatropha curcas, 17 Pongamia Pinnata to petroleum diesel fuel. Engine ecological analysis showed that blended 18 fuel reduces the average hydrocarbons (HC), carbon monoxide (CO) and NO X than petroleum 19 diesel fuel. While DRUCO20 showed better performance and reduction in ecological analysis 20 but higher ecological of CO 2 is comparable with DCJ20 and DPP20.


Introduction 54
Rapid depletion of fossil fuels due to enormous growth of transport sector and release of 55 hazardous emissions from engine tail pipe have gained the attention of many fuel-based 56 industries globally towards novel and renewable based fuels for IC engine applications. Also, 57 the need for reduction of carbon foot print by global emission standards enforced the 58 researchers to search for environmentally friendly fuels without compromising the engine 59 performance. Among the IC engines, diesel engines are considered to be the most favourable 60 one, due to its widespread range of utilizations in various industries such as buildings, 61 transport, agricultural fields and power production (Lloyd and Cackette 2001). The reason for 62 this can be accredited to its high thermal efficiency and greater power production. This 63 resulted in rapid increase of consumption of diesel fuel. But the diesel fuel is one among the 64 non-replenishable and moreover it discharges harmful emissions viz., atmospheric particle 65 pollution, carbon dioxide (CO2), oxides of nitrogen (NOX) and sulphur (SOX) (Agarwal et al. 66 2006). 67 In order to overcome these drawbacks many alternate fuels were examined by various 68 researchers viz., derivates of alcohol, dimethyl ether and biodiesel fuels. Among these 69 alternatives, it has been found that biodiesel fuels are promising one as they release less 70 greenhouse gases, possess high cetane number, replenishable and biodegradable. Further, the 71 6 in India (BDAI) for gathering waste cooking oil from the restaurants and food handling units 128 and transform it into bio-fuel (FSSAI 2018). 129 Hence in the current work, RUCO biodiesel is compared with pure diesel and other 130 biodiesel blends generated from Jatropha (Jatropha Curcas) and Karanja (Pongamia Pinnata) 131 oil by conducting a thorough investigation of performance, combustion, emission and exergy 132 analysis in a single cylinder, 4-stroke CI engine at varying compression ratios (16.5, 17.5 and 133 18.5). All the biodiesel blends were produced at 20% concentration by volume to the diesel. 134 As far as author's attention, lesser study has carried out such a comprehensive investigation 135 on these biodiesel blends and hence the results of our study will be of greater interest to the 136 researchers in this field. 137

Test Fuels and their Properties 139
The standard fuels used in this investigational work are repurpose used cooking oil (RUCO), 140 Jatropha curcas (JC), Pongamia Pinnata (PP) biodiesel and petroleum diesel fuel (PDF) 141 fueled. The fuels are collected from local market respectively. The RUCO alternative fuel is 142 produced by transesterification of cooking oil and the complete process is conducted in the IC 143 engine laboratory at Maulana Azad National Institute of Technology, Bhopal. Earlier study 144 done by the scholars stated that RUCO substitute fuel has up to 20% with diesel base fuel 145 shown better engine characteristics. Hence, in the present investigation RUCO, JC, PP blend 146 proportion is fixed at 20% by basis of volume with PDF has been used. In following blends, 147 the repurpose used cooking oil, JC and PP alternative proportion is raised by 20%, thus 148 making blends with 80% PDF. These blends are termed as RUCO20 (Containing 80% PDF 149 and 20% repurpose used cooking oil alternative), JC20 (Containing 80% PDF and 20% 7 alternative). The characteristics of the PDF and blends samples are indicated in Table 1. The  152 PDF, RUCO20, DJC20 and DPP20 blends are shown in Fig.1 158

Cost Analysis 159
Although biodiesel has many advantages, the main concern pertains to the usage of biodiesel 160 is its primary cost, which relies on economics of petroleum product, feedstock and transport. 161 The total production price for RUCO, JC and PP substitutes rely on the yield of seed, oil 162 content, and quality. It is obvious from the examination that the price of 1 litre biodiesel is 163 more than that of the conventional diesel by 3 to 5 %. Estimated cost analysis of RUCO, JC 164 and PP alternative as represented in Table 2, Table 3 & Table 4. 165

173
To read the engine load value, a Kistler equipment, which magnetically measures the load, is 174 used. With gathering the relevant data from the tests, the SFC, and BTE are calculated using 175

1000
(1) 177 =̇. software. In the study, software analysis to draw the combustion data is used, and each curve 185 given in the combustion graphs represents the mean of more than 1000 cycles for this study. 186 After recording the in-cylinder pressure values, the heat discharge rate curves are calculated 187 from the Eq. (4) in harmony with the first law of thermodynamics. 188 The symbols in equation (1) is explained in the nomenclature part of the paper. Here, the 190 authors accept that there is no gas leakage from the valves or segments during the 191 experiments, and the gas in the cylinder is accepted as ideal. The investigational setup is as 192 indicated in Fig.2. The investigational setup specifications are given in Table 5.  An uncertainty analysis is of great importance for the experimental studies because its result 199 gives an idea about the accuracy and repeatability of the presented results to the readers. 200 Therefore, a total uncertainty value of the results is calculated using the following equation 201 according to the data given in Table 6. The explanation of the symbols is given in the 202 nomenclature part of the paper. 203

Exergy analysis considerations 208
Exergy investigation has been carried out from I & II law of thermodynamics. In this 209 investigation total energy can be utilized in various ways. The work from engine consumes 210 the whole power of fuel, which takes away the heat by the tail pipe emissions. Heat transfer 211 losses by cooling medium and unaccounted losses are also considered. Energy losses in the 212 engine is calculated by using subsequent equations (Eq. 6 to 10). The total energy efficacy of 213 the system enhanced by improving the energy distribution. The following assumptions are 214 made: 215 • Steady state engine run throughout the examination. 216 • Total engine is considered as control volume. 217 • The ideal gas is formed in the combustion chamber. 218 • Neglect the influence of changes in potential and kinetic energy. 219 Fuel provided to the engine is as given in Eq, (6) 220 Where mf is the rate of fuel provided in kg/Sec, LCV indicates lower heating value 222 Brake power is stated by Eq. (7). 223 Where, N is the crankshaft rpm and T is the torque induced (kN-m) 225 Cooling water heat loss is given by Eq. (8) 226 Where mwe is the water mass flow rate in the engine in kg/Sec, Cpw specific heat of water 228 in kJ/Kg. K, T1 is the water temperature at inlet, whereas and T2 is the exit water temperature 229 from engine ( o C). Heat taken away by the tailpipe gases is expressed by Eq. (9) 231 Where meg is the rate of discharge gases from engine tail pipe in kg/Sec, Cpe is the specific 233 heat of the discharge gas (kJ/Kg. K), T5 is the temperature of discharge gas at calorimeter (K) 234 Ta is the atmosphere temperature (K). Not accounted energy losses can be examined by Eq. 235 (9) by considering subsequent facts: The engine power developed employed to run pump, 236 water circulation, pump lubrication. 237 Where Qunaccounted is the unaccounted energy losses (kJ) while Qs, Qbp, Qcw, and Qeg are heat 239 supplied, brake power, cooling water and heat taken away by tailpipe gas respectively. 240 Energy analysis is indicated in Fig.3 (a, b and c). the BTE for all the tested fuels are relatively the same. In general, the BTE enhanced with the 253 rise of engine loads for all the fuels. At high loads, the gaseous fuel air mixture is rich due to 254 high pilot quantity, thus the rise of combustion rates and BTE. It is important to note that 255 D100 shows the highest value of BTE compared to DRUCO20, DJC20, DPP20 as depicted in 256 gave the lowest SFC among the tested fuels. This is because the pure diesel has the highest 277 lower heating value (42.5 MJ/kg) compared to the biodiesel blends as can be seen in Table 1  Enhancing the CR does not seem to improve the value of SFC significantly as shown in Fig.  281 5. However, it is noteworthy to observe that at the highest compression ratio (18.5), DPP20 282 gives the highest SFC compared to pure diesel and other biodiesel amalgamations tall engine 283 loads. Note that the SFC and BTE have inverse relationship (Veza et al. 2021), and this 284 inverse tendency is obvious from Figs. 4 and 5. In Fig 4, it is shown that DPP20 gives the 285 lowest value of BTE, while in Fig. 5, it is depicted that the DPP20 gives the highest of SFC, 286 confirming the inverse trend between SFC and BTE. Therefore, lower the SFC, greater the 287 BTE. Also, as DRUCO20 gives the second highest BTE as discussed previously (Fig. 4) load for D100, DRUCO20, DJC20 and DPP20 at 16.5, 17.5 and 18.5 CRs. As the engine 302 loads increases, the tailpipe gas temperature rises for all the tested fuels. Nearly the same 303 trends were also observed for the 3 CRs. Furthermore, except for the 20% engine load, a 304 minimum EGT of approximately 200°Cfor the most operating conditions were achieved. The 305 burning of biodiesel blends was seen to enhance the EGT than that of pure diesel but the 306 variances among the tested fuels were insignificant for each CR. With the rise in CR, EGT 307 reduced slightly. As the CR inclined, the temperature at the start of compression stroke would 308 lessen owing to the reduction in burnt gases mass. Therefore, the EGT will drop at high CRs 309 and as a result lower temperature is found at the start of the compression stroke.

Ecological analysis 315
Ecological analysis of CO 316 CO emissions from diesel combustion are greatly rely on the A/F ratio. Insufficient O2 is the 317 major reason for the CO formation. Fig. 7 shows that the CO emissions were relatively the 318 same for the all-test conditions. At the maximum load, highest CO emissions are seen for all 319 the fuels. The insignificant changes in CO emissions among DRUCO20, DJC20 and DPP20 320 were down to their comparable levels of O2 content. Moreover, it is also noticed from Fig. 7  321 that biodiesel blends produced relatively smaller CO emissions than that of pure diesel. The 322 highest reductions in CO emissions were found to be at 60% engine load for DRUCO20, 323 whereas the highest value of CO exhaust was given by pure diesel at maximum loads for all 3 324 CRs.

Ecological analysis of NOX 344
NOX emission in a CI engine sowing to its high in-cylinder temperature. It is known that 345 the NOX formation relies on the combustion temperature where the NOX formation rates rises 346 exponentially once combustion temperature reaches above 1800 K. It is identified from Fig.  347 9that NOX emissions enhances with rise in engine loads for all the tested fuels. The figure  348 also shows that biodiesel blends emit slightly higher NOX emissions than pure diesel for all 349

Load (%)
D100 DRUCO20 DJC20 DPP20 test conditions. The increased level of NOX emissions in DRU20, DJC20 and DPP20 is 350 attributed to the additional oxygen content in biodiesel which enhance the combustion in the 351 chamber, thus increasing the in-cylinder temperature. As a consequence, high NOX emissions 352 for biodiesel combinations are noticed than those of diesel fuel. These findings are in 353 reasonable harmony with those attained (Nabi andRasul2018, Nanthagopal et al. 2019). Note 354 that at 20% of engine loads at CR16.5, CR17.5 and CR 18.5, the NOX emissions for all the 355 tested fuels are significantly low because of lesser in-cylinder temperature at lower engine 356 load. As the load enhances, the A/F ratio caused a significant rise in the gas temperature 357 inside the combustion chamber, thus significantly increasing the NOX formation, which is 358 known considerably sensitive to the rise in the combustion temperature. Therefore, the 359 highest amount of NOX emissions was generated at the maximum engine load. emissions raised with mounting engine loads for all the tested fuels as depicted in Fig. 10. 370 The figure also shows that biodiesel blends produced relatively higher CO2 emissions than 371 pure diesel for all test conditions. At CR16.5 and 17.5, DJC20 gives the highest CO2 372 emissions of all the tested fuels except for 20% load at CR16.5 where pure diesel gives the 373 highest values. At 18.5, the highest level was given by DRUCO20 with approximately 3% 374 concentration of CO2. This is because the molecular oxygen found in biodiesel promotes 375 more complete combustion, thus increasing the conversion of CO into CO2. It interesting to 376 note that although DRU20, DJC20, DPP20 emits more CO2 than pure diesel (D100), the 377 biodiesel blends are expected to have net negative CO2 emission owing to its renewable 378 nature. The CO2 released from the CI engine is absorbed by the trees of biodiesel feedstocks. The BTE of all the investigated fuels did not significantly increased with a rise in CR, but it 401 improved with enhancement in engine loads for all 3 CRs with D100 showing the higher 402 value compared to DRUCO20, DJC20 and DPP20 throughout under all load conditions. Of 403 all the biodiesel blends, DRUCO20 shown the highest BTE with its value being close to 404 D100. In terms of SFC, rising the CR did not substantially improve fuel consumption. At 405 18.5 CR, the DPP20 gave the highest SFC value for all engine loads. The second lowest 406 BSFC among all the tested fuels was given by DRUCO20. The SFC shown an inverse 407 relationship with BTE. 408 The biodiesel blends were found to enhance the EGT than the pure diesel in spite of the 409 variances among the tested fuels were insignificant for each CR. Except for the 20% engine 410 load, at all test conditions a minimum EGT of 200°C was identified. 411 The CO emissions at different test conditions were compared. At 100% load, the higher CO 412 emissions were recorded for all test conditions. Biodiesel blends emitted relatively lesser 413 level of CO emissions than those of pure diesel. The most significant lessening was achieved 414 by DRUCO20 at 60% engine load, while the highest rise of CO was given by D100 at full 415 loads for all the three CRs. 416 Alike CO emissions, the HC emissions for all biodiesel blends were also lesser than D100. 417 Under all test environments, the peak lower HC emissions was attained by DJC20 at 50% 418 load, while the peak higher HC discharge was given by D100 at 100% load state. 419 The NOx emissions were noticed to rise with enhancing engine loads for all the test fuels. 420 Compared to pure diesel, biodiesel blends emit slightly higher NOx discharge for all test 421 conditions. The higher level of NOX emissions in DRU20, DJC20, DPP20 are owing to the 422 additional oxygen content in biodiesel which enhance the combustion in the cylinder, thus 423 elevating the in-cylinder temperature and NOX exhaust. 424 As regards CO2, biodiesel blends produced higher amount of CO2 than D100. At CR16.5 and 425 17.5, DJC20 gave the highest CO2levelexcept for the 20% load condition at CR16.5 where 426 D100showed the highest values. At 18.5, the highest level was given by DRUCO20 with 427 approximately 3% concentration of CO2. Overall, the inherent molecular oxygen found in 428 biodiesel facilitates complete combustion, thus improving the CO conversion into CO2.    EGT analysis for all test conditions CO2 ecological analysis against various engine loads for CR16.5, CR17.5 and CR18.5