نوع مقاله : مقاله پژوهشی

نویسندگان

1 استادیار گروه مهندسی مکانیک بیوسیستم، دانشگاه اراک، اراک، ایران

2 استادیار پژوهشی، مؤسسه تحقیقات جنگلها و مراتع کشور، سازمان تحقیقات، آموزش و ترویج کشاورزی، تهران، ایران

چکیده

برای کاهش مصرف مواد و انرژی و ارتقای استفاده از منابع تجدیدپذیر مانند سوخت های زیستی، نیاز به اندازه گیری جریان مواد و انرژی اهمیت بیشتری پیدا می کند. تحلیل جریان اکسرژی به عنوان یک ابزار ارزیابی زیست محیطی برای محاسبه پسماندها، تعیین بازده اکسرژی، ارزیابی جایگزین ها و منابع انرژی مختلف، در تعیین سیاست های اقتصادی و زیست محیطی بسیار موثر است. این پژوهش فرآیند ترانس استریفیکاسیون پسماند روغن خوراکی را برای تولید بیودیزل با تمرکز بر کاهش مصرف مواد و انرژی و ارتقای بازده انرژی و اکسرژی بررسی می کند. اجرای واکنش ترانس استریفیکاسیون در شرایط مختلف جرم و انرژی انجام شد و تجزیه و تحلیل ترمودینامیکی برای اندازه گیری ورودی و خروجی اکسرژی فرایند تولید مورد استفاده قرار گرفت. ارزیابی تأثیر متغیرهای آزمایشی از جمله نسبت مولی متانول به روغن، غلظت هیدروکسید پتاسیم و دمای واکنش بر بازده اکسرژی و اتلاف اکسرژی در ترانس استریفیکاسیون صورت گرفت. بیشترین بازده اکسرژی (7/91 درصد) و حداقل اتلاف اکسرژی (MJ 32/4 به ازای یک کیلوگرم تولید بیودیزل) با نسبت مولی متانول به روغن 8:1، غلظت هیدروکسید پتاسیم 1 درصد وزنی و دمای واکنش ℃55  حاصل شد. تحلیل اکسرژی واکنش ترانس استریفیکاسیون نشان داد که استفاده بیش از حد بهینه متانول و کاتالیست در فرآیند تولید بیودیزل باعث افزایش اتلاف اکسرژی به دلیل تولید و هدررفت مواد پسماند شده که این امر باعث کاهش بازده اکسرژی شده است.

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

Analyzing the efficiency of biodiesel production through exergy analysis of transesterification

نویسندگان [English]

  • Mahmoud Karimi 1
  • Reza Mohammadigol 1
  • roohollah rahimi 2

1 Assistant Professor, Department of Biosystem Mechanics Engineering, Arak University, Arak, Iran

2 Assistant Professor, Research Institute of Forests and Rangelands, Agricultural Research, Education and Extension Organization (AREEO), Tehran, Iran

چکیده [English]

Introduction: Biodiesel is viewed as a promising alternative to fossil fuels due to its favorable chemical properties and environmental benefits. Research has shifted towards producing biodiesel from non-edible oils and waste cooking oils to avoid food scarcity issues. The high cost of production is a major challenge, with raw materials accounting for 75% of the total cost. Sustainability depends on low-cost feedstocks like waste cooking oil. Exergy analysis is a useful tool for optimizing biodiesel production by reducing energy and resource consumption and increasing production yield. The study focuses on the exergy flow of transesterification of waste cooking canola oil, with parameters like methanol:oil ratio, catalyst concentration, and temperature being evaluated.
Materials and Methods: Waste cooking oil (WCO) was used in the present study, with physicochemical properties including density, viscosity, free fatty acid content, and acid value measured. Biodiesel production using a two-step catalyzed method was carried out, with the first step being esterification to remove high water and FFA content in the waste cooking oil. The second step involved transesterification using different methanol:oil ratios, catalyst concentrations, and reaction temperatures. The FAME content of the samples was analyzed using gas chromatography and an equation was provided to calculate the FAME content of the biodiesel samples. In the process of transesterification of WCO, four balance equations were used to analyze exergy. Mass, energy, and entropy input and output must be balanced, with a portion of exergy input being destroyed. The mass exergy component is divided into physical, chemical, potential, and kinetic exergy. The overall exergy of a mixture of substances was calculated by considering physical and chemical exergy. Mixing in the transesterification process is irreversible, with potential work being wasted. Exergy transfer by heat flow and workflow was calculated using specific equations. An exergy conversion coefficient was used to estimate the chemical exergy content of fuels. Dead state conditions were considered for calculating exergy efficiency in the transesterification process.
Results and Discussion: The GC analysis of transesterification conversion products from a standard sample showed that the main components in WCO-derived biodiesel were methyl salicylate, methyl palmitate, methyl stearate, methyl oleate, methyl linoleate, and methyl oleate. The efficiency of the transesterification process under specific conditions was determined to be 90.23% with an exergy efficiency of 91.73%. Exergy analysis revealed that the exergy embodied in biodiesel was higher than that in WCO, but a portion of WCO's exergy was consumed in the production of biodiesel. The study also highlighted ways to reduce energy loss and material waste in the transesterification process, emphasizing the importance of recycling and reusing waste materials to improve overall resource efficiency. The experiment variables of methanol:oil molar ratio, KOH concentration, and reaction temperature were investigated in the transesterification process for biodiesel production. A higher methanol:oil molar ratio of 6:1 was recommended for maximum yield when using pure oil with low FFA and water content. Increasing the ratio from 4:1 to 8:1 resulted in higher biodiesel yield and exergy efficiency. However, further increasing the ratio to 12:1 led to decreased efficiency. The KOH concentration and reaction temperature also had significant impacts on biodiesel yield and exergy efficiency. Higher catalyst concentration and reaction temperature increased exergy destruction, while a temperature increase from 45℃ to 55℃ improved efficiency and yield. The study suggested that careful optimization of these variables is essential for maximizing biodiesel production and minimizing exergy losses.
Conclusion: Exergy analysis is a valuable tool for assessing the environmental impacts of products, processes, or activities by quantifying energy and material usage and waste generation within a comprehensive framework. It also allows for estimating the resource requirements for processes such as transesterification in the production of renewable resources like biodiesel. In this study, the exergy flow in the transesterification of waste cooking oil was evaluated, with a focus on the impact of variables such as methanol:oil ratio, potassium hydroxide concentration, and reaction temperature on biodiesel yield, exergy efficiency, and exergy destruction. Experimental data was collected and used for exergy calculations, revealing that maximum biodiesel yield and exergy efficiency were achieved at specific conditions. Excess methanol or potassium hydroxide led to decreased efficiency and increased exergy loss in the process. Lower temperatures also resulted in higher exergy loss due to reduced conversion efficiency. Understanding the effects of these variables can help improve exergy efficiency and economic performance in commercial biodiesel production. Exergy analysis can also be used to evaluate environmental performance and aid in the development of environmental policies and resource management strategies.

کلیدواژه‌ها [English]

  • Exergy
  • Biodiesel
  • Transesterification
  • Waste
  • Vegetable oil
  • Thermodynamic analysis
1Ayres, R.U. and Ayres, W. 1999. Accounting for resources 2: the life cycle of materials. UK and Lyme MA: Edward Elgar, Cheltenham.
2Bahadur, S., Goyal, P., Sudhakar, K. and Prakash Bijarniya, J. 2015. A comparative study of ultrasonic and conventional methods of biodiesel production from mahua oil. Biofuels, 6(1 2): 107 113.
3Blanco Marigorta, A., Suárez Medina, J. and Vera Castellano, A. 2013. Exergetic analysis of a biodiesel production process from Jatropha curcas. Applied Energy, 101: 218 225.
4
Brockway, P.E., Steinberger, J.K., Barrett, J.R. and Foxon, T.J. 2015. Understanding China’s past and future energy demand: An exergy efficiency and decomposition analysis. Applied Energy, 155: 892 903.
5Caliskan, H., Tat, M.E. and Hepbasli, A. 2010. A review on exergetic analysis and assessment of various types of engines. International Journal of Exergy, 7(3): 287 310.
6Chen, Y., Xiao, B., Chang, J., Fu, Y., Lv, P. and Wang, X. 2009. Synthesis of biodiesel from waste cooking oil using immobilized lipase in fixed bed reactor. Energy Conversion and Management, 50(3): 668 673. 7 Chisti, Y. and Yan, J. 2011. Energy from algae: Current status and future trends: Algal biofuels A status report. Applied Energy, 88(10): 3277 3279.
8Demirel, Y., Matzen, M., Winters, C. and Gao, X. 2015. Capturing and using CO2 as feedstock with chemical looping and hydrothermal technologies. International Journal of Energy Research, 39(8): 1011
1047.
9Dilmac, O.F. and Ozkan, S.K. 2008. Energy and exergy analyses of a steam reforming process for hydrogen production. International Journal of Exergy, 5(2): 241 248.
10
Felizardo, P. 2006. Production of biodiesel from waste frying oils. Waste Management, 26(5): 487 494.
11Font de Mora, E., Torres, C. and Valero, A. 2012. Assessment of biodiesel energy sustainability using the exergy return on investment concept. Energy, 45(1): 474 480.
12Ganapathy, T., Murugesan, K. and Gakkhar, R.P. 2009. Performance optimization of Jatropha biodiesel engine model using Taguchi approach. Applied Energy, 86(11): 2476 2486.
13Hoang, N. and Alauddin, M. 2011. Analysis of agricultural sustainability: A review of exergy methodologies and their application in OECD countries. International Journal of Energy Research, 35(6): 459 476.
14Jafarmadar, S., Tasoujiazar, R. and Jalilpour, B. 2014. Exergy analysis in a low heat rejection IDI diesel engine by three dimensional modeling. International Journal of Energy Research, 38(6): 791 803.
15Jaimes, W., Acevedo, P. and Kafarov, V. 2010. Exergy analysis of palm oil biodiesel production. Chem Eng, 21: 1345 1350. 16 Karatay, S.E. and DÃnmez, G. 2010. Microbial oil production from thermophile cyanobacteria for biodiesel production. Applied Energy, 88(11): 3632 3635.
17Karimi, M. 2016. Immobilization of lipase onto mesoporous magnetic nanoparticles for enzymatic synthesis of biodiesel. Biocatalysis and Agricultural Biotechnology, 8: 182 188.
18.. Karimi, M. 2017. Exergy--based optimization of direct conversion of microalgae biomass to biodiesel. Journal of Cleaner Production.
19.. Karimi, M., Keyhani, A., Akram, A., Rahman, M., Jenkins, B. and Stroeve, P. 2013. Hybrid response surface methodology--genetic algorithm optimization of ultrasound--assisted transesterification of waste oil catalysed by immobilized lipase on mesoporous silica/iron oxide magnetic core--shell nanoparticles. Environmental Technology, 34(13): 2201--2211. 2020.. Karimi, M., Jenkins, B. and Stroeve, P. 2014. Ultrasound irradiation in the production of ethanol from biomass. Renewable and Sustainable Energy Reviews, 40: 400--421.
21.. Karimi, M., Jenkins, B. and Pieter, S. 2016. Multi--objective optimization of transesterification in biodiesel production catalyzed by immobilized lipase. Biofuels, Bioproducts and Biorefining. 22. Kheiralipour K. 2022. Sustainable Production: Definitions, Aspects, Elements. Nova Science Publishers, New York, USA. 2323.. Kheiralipour, K. 2020. Environmental Life Cycle Assessment. Ilam University Publication, Ilam, Iran.
24.. Kheiralipour, K., Khoobbakht, M. and Karimi, M. 2024. Effect of biodiesel on environmental impacts of diesel mechanical power generation by life cycle assessment. Energy 289: 129948. 2525.. Khoobbakht, G., Akram, A., Karimi, M. and Najafi, G. 2016. Exergy and energy analysis of combustion of blended levels of biodiesel, ethanol and diesel fuel in a DI diesel engine. Applied Thermal Engineering, 99: 720--729.4. 2626.. Khoobbakht, G., Najafi, G., Karimi, M. and Akram, A. 2016. Optimization of operating factors and blended levels of diesel, biodiesel and ethanol fuels to minimize exhaust emissions of diesel engine using response surface methodology. Applied Thermal Engineering, 99: 1006--1017. 2727.. Khoobbakht, G., Kheiralipour, K. and Karimi, M. 2021. Optimization of Chlamydomonas alga biodiesel percentage for reducing exhaust emission of diesel engine. Process Safety and Environmental Protection, 152: 25--36.
28.. Khoobbakht, G., Kheiralipour, K., Rasouli, H., Rafiee, M., Hadipour, M. and Karimi, M. 2020. Experimental exergy analysis of transesterification in biodiesel production. Energy, 196: 117092.
29.. Khoobbakht, G., Kheiralipour, K., Yuan, W., Seifi, M.R. and Karimi, M. 2020. Desirability function approach for optimization of enzymatic transesterification catalyzed by lipase immobilized on mesoporous magnetic nanoparticles. Renewable Energy, 158: 253--262. 3030.. Khoobbakht, G., Kheiralipour, K., Karimi, M. 2022. The effects of biodiesel and bioethanol on the performance and emission characteristics of diesel engines. International Journal of Renewable Energy Resources, 12 (1): 1--23. 3131.. Khoobbakht, G.M., Karimi, M., Kheiralipour, K. 2019. Effects of biodiesel--ethanol--diesel blends on the performance indicators of a diesel engine: A study by response surface modeling. Applied Thermal Engineering. 148(5):1385--1394. 3232.. Khoobbakht, M., Soleymani, M. Kheiralipour, K. and Karimi, M. 2024. Predicting performance characteristics of an engine fueled by algal biodiesel--diesel using response surface methodology. Renewable Energy Research and Applications, 5(2): 269--279.
33.. Kusumaningtyas, R.D., Purwono, S. Rochmadi, R. and Budiman, A. 2014. Graphical exergy analysis of reactive distillation column for biodiesel production. International Journal of Exergy, 15(4): 447--467.
34.. Montefrio, M.J., Xinwen, T. and Obbard, J.P. 2009. Recovery and pre--treatment of fats, oil and grease from grease interceptors for biodiesel production. Applied Energy, 87(10): 3155--3161.
35.. Morosuk, T., Tsatsaronis, G. and Koroneos, C. 2016. Environmental impact reduction using exergy--based methods. Journal of Cleaner Production, 118: 118--123.
36.. Ofari––Boateng, C., Keat, T.L. and JitKang, L. 2012. Sustainability assessment of microalgal biodiesel production processes: an exergetic analysis approach with Aspen Plus. International Journal of Exergy, 10(4): 400--416.
37.. Ofori--Boateng, C., Keat, T.L. and JitKang, L. 2010.Feasibility study of microalgal and jatropha biodiesel production plants: Exergy analysis approach. Applied Thermal Engineering, 36(0): 141--151.
38.. Peralta--Ruiz, Y., González--Delgado, A.--D. and Kafarov, V. 2013. Evaluation of alternatives for microalgae oil extraction based on exergy analysis. Applied Energy, 101: 226--236.
39.. Pierre, P. 1998. A to Z of Thermodynamics. Oxford Oxford University Press.
40.. Ranjan, A. and Moholkar, V.S. 2012. Biobutanol: science, engineering, and economics. International Journal of Energy Research, 36(3): 277--323.
41.. Said, Z., Saidur, R. and Rahim, N.A. 2016. Energy and exergy analysis of a flat plate solar collector using different sizes of aluminium oxide based nanofluid. Journal of Cleaner Production, 133: 518--530.
42
42.. Sakthivel, G. 2013. A hybrid multi––criteria decision support system for selection of optimum fuel blend. International Journal of Exergy, 12(4): 463--490.
43.. Sato, N. 2004. Chemical energy and exergy: an introduction to chemical thermodynamics for engineers. Elsevier.
44.. Shukla, K., Rangnekar, S. and Sudhakar, K. 2015. A comparative study of exergetic performance of amorphous and polycrystalline solar PV modules. International Journal of Exergy, 17(4): 433--455.
45.. Sudhakar, K., Rajesh, M. and Premalatha, M. 2012. Carbon mitigation potential of Jatropha Biodiesel in Indian context. Energy Procedia, 14: 1421--1426.
46.. Szargut, J. 1989. Chemical exergies of the elements. Applied Energy, 32(4): 269--286.
47. Szargut, J., Morris, D.R. and Steward, F.R. 1988. Exergy analysis of thermal, chemical, and metallurgical processes. New York: Hemisphere Publishing Corporation.
48. Talens, L., Villalba, G. and Gabarrell, X. 2007. Exergy analysis applied to biodiesel production. Resources, Conservation and Recycling, 51(2): 397--407.
49.. Tomasevic, A.V. and Siler--Marinkovic, S.S. 2003. Methanolysis of used frying oil. Fuel Processing Technology, 81(1): 1--6. 50. Torkian, Boldaji, M., Ebrahimzadeh, R., Kheiralipour, K., Borghei, A. M. 2011. Effect of some BED blends on the equivalence ratio, exhaust oxygen fraction and water and oil temperature of a diesel engine. Biomass and Bioenergy, 35: 4099-4106.
51.. Vatani, A., Mehrpooya, M. and Palizdar, A. 2014. Energy and exergy analyses of five conventional liquefied natural gas processes. International Journal of Energy Research, 38(14): 1843--1863.
52. Velásquez--Arredondo, H., Junior, S.D.O. and Benjumea, P. 2012. Exergy efficiency analysis of chemical and biochemical stages involved in liquid biofuels production processes. Energy, 41(1): 138--145.
53. Wang, Y., Ou, P.L.S. and Zhang, Z. 2007. Preparation of biodiesel from waste cooking oil via two--step catalyzed process. Energy Conversion and Management, 48(1): 184--188.
54. Xue, F. 2008. Studies on lipid production by Rhodotorula glutinis fermentation using monosodium glutamate wastewater as culture medium. Bioresource technology, 99(13): 5923--5927.
55.. Zhang, Y., Dube, M., McLean, D. and Kates, M. 2003. Biodiesel production from waste cooking oil: 2. Economic assessment and sensitivity analysis. Bioresource technology, 90(3): 229--240.
56.. Zhang, Y., McLean, M.A. and Kates, M. 2003. Biodiesel production from waste cooking oil: 1. Process design and technological assessment. Bioresource Technology, 89(1): 1--16.