THERMODYNAMIC ANALYSIS OF SOLAR ENERGY INTEGRATED MENTHA OIL DISTILLATION SYSTEM

Abstract

Herbal medicines are used by most of the people around the world to address their health requirements. Therefore, medicinal and aromatic plants are essential since herbal medicines (essential oils) are made from their product. These oils are utilized in food as a flavoring agent, in cosmetic items as a scent, and in medicine for functional purposes. Various traditional and advanced extraction techniques are used for extraction of essential oil from aromatic and medicinal plants. Traditional methods are undesirable in terms of environmental perspective since they produce aerosols and greenhouse gases. These methods required high energy consumption and longer distillation extraction time, resulting in low efficiency and high cost. Therefore, solar energy assisted extraction is an advanced extraction method and an alternative approach to addressing the drawbacks of conventional oil extraction techniques because it is a never-ending source of clean energy. In the present study, two different oil extraction systems (a) Conventional steam distillation (CSD) system (biomass based) (b) Solar steam distillation system (SSDS) have been analysed. Conventional steam distillation system has been analysed in terms of performance, energy balance, mass balance, environmental and economic assessment under different batch size of peppermint. Solar steam distillation system has been analysed based on energy, exergy, economic, exergoeconomic, environmental, and enviroeconomic point of view under different variable parameters such as solar radiation, relative humidity, ambient temperature and batch size of peppermint and eucalyptus. System is analysed for various batch sizes of two different medicinal plants (Peppermint and Eucalyptus) and compared. Moreover, the effect of lifespan of system on cost of essential oil per liter (CPL) and exergoeconomic parameters has been analysed in present study. Performance of The CSD system was assessed in terms of thermal efficiency, productivity, essential oil yield, and extraction efficiency. Maximum hourly system productivity, cumulative productivity, maximum extraction efficiency, maximum essential oil yield and maximum hourly thermal efficiency were obtained for 1900 kg. The average increase in total productivity, extraction efficiency, and essential oil yield was 49.25%, 1%, and 26%, increasing in batch size from 1500 kg to 1900 kg. Process parameters of conventional distillation systems were optimized using RSM. Optimal process parameters are identified as 300 minutes of vi extraction time and 1807.5 kg of batch size. The study explored the effect of peppermint batch sizes on energy measures, net CO2 mitigation, and net carbon credit earned. Life cycle energy production factor (EPFs) and life cycle conversion efficiency (LCCE) for 18 years of life span were estimated to be 29.2, 33.1, 38.9, 12.6%, 14.8%, and 17.9% for 1500, 1700, and 1900 kg batch sizes, respectively. Maximum energy and fuel consumption were 4,966 MJ and 193 kg for 1500 kg, respectively. ROI, IRR and PBP were 73.9%, 85.7% and 1.26 years, respectively. The distillation system has a total embodied energy of 166,237 kWh. Lifetime CO2 mitigation and net carbon credit earned are estimated to be 426.6, 438.5 and 568.8 tones and ₹1,95,239 (US$2,383.9), ₹2,63,049 (US$3,211.9) and ₹3,61,518 (US$4,414.3) for 1500, 1700, and 1900 kg batch size, respectively, if traded at the rate of 14.85 US$/ton. The developed thermal model and characteristics equations have been used to analyse the solar steam distillation system. Optical losses in reflector as well as thermal losses in distillery, steam line, and condenser are calculated. Maximum and minimum system efficiency is calculated as 48.68% and 43.25 % for 2 kg of peppermint and 6 kg of eucalyptus, respectively, whereas highest and lowest exergy efficiency of system are 27.96 % and 22.50 % for 6 kg and 4 kg of eucalyptus leaves, respectively. Estimated return on investment (ROI), internal rate of return (IRR) and payback period (PBP) of SSDS producing 72 liters of peppermint oil per year were 14.03%, 18.77% and 5.67 years, respectively over the projected economic life span of 25 years. Cost per litre (CPL) values of produced peppermint oil at the same interest rate (5%) were 2.10, 1.89 and 1.75 US$/L for 20, 25, and 30 years of lifespan, respectively while for eucalyptus oil, the corresponding values were 2.53, 2.27 and 2.10 US$/L, respectively. Exergoeconomic parameter for peppermint oil is enhanced by 11.43 and 19.94% with increase in lifespan of system by 5 and 10 years, respectively at same interest rate of 5% while the corresponding values for eucalyptus oil are increased by 11.30 and 19.90%, respectively. CO2 mitigated over the lifespan from SSDS for peppermint oil and eucalyptus oil based on energy approach is found as 2.37, 4.74, 7.11 tons CO2 and 1.97, 3.95, 5.9 tons CO2 for 2, 4 and 6 kg batch size, respectively. Whereas, the corresponding values based on exergy approach are 0.15, 0.11, 0.14 tons CO2 and 0.12, 0.09, 0.12 tons CO2, respectively. Thermal efficiency, EPF and LCCE of SSDS were reduced by 11.17, 16.8 and 17.76%, respectively for eucalyptus oil extraction than peppermint oil for constant batch size (i.e. 6 kg). Enviroeconomic parameter of SSDS for peppermint oil extraction is more than that of eucalyptus oil. This research will be helpful for vii researchers and investors to find out various energy-saving potentials at different parts of system and to establish a cost-effective, environment-friendly solar distillation system for essential oil extraction from aromatic and medicinal plants. The overall research work has undergone extensive analysis to produce responsible, system-effective results that are nourished by a detailed discussion of the results and conclusions, as well as future recommendations that may enlighten the researchers and inspire them to pursue additional potential developments in this field for the benefit of society, the environment, and the ecologically sustainable growth of peoples.