The world's population is projected to increase, impacting a 60% rise in food production demand by 2050, including the demand for maize. Currently, maize production is estimated to reach 1510 million tons in 2023, necessitating suitable methods for preserving maize kernels to maintain quality and reduce post-harvest agricultural losses. Although drying methods present a viable solution to address this issue, the majority of farmers in Indonesia still use conventional drying methods, such as open sun drying, which has several drawbacks. Hence, solar drying systems aim to overcome these limitations by harnessing renewable, clean, sustainable, and eco-friendly energy to support the sustainable development goals (SDGs). This research comprehensively reviews the progress of solar drying technology, providing insights into its working principles, innovative designs, and operational modes across various types of solar dryers. The 4E + Q analysis provides information regarding the performance of solar drying systems, including energy analysis to determine the quantity of energy utilized and exergy analysis to demonstrate irreversibility in thermodynamic processes. Additionally, this analysis highlights environmental impacts such as CO2 emissions and mitigation efforts, while considering economic aspects through lifecycle assessment and payback period methods. The quality assessment of dried maize kernels according to the standards set by the Indonesian National Standard (SNI) is conducted, including proximate analysis, aflatoxin levels, color measurements, and internal cracking analysis.

Post-harvest losses in cocoa plantations often occur in developing countries and can be significantly reduced by using various drying technology designs. This comprehensive review presents the development of drying cocoa beans, such as sun drying, convective solar drying, oven drying, freeze drying, heat pump drying, and hybrid solar drying, as well as an analysis of the quality of the cocoa drying. Based on the review that has been explained, hybrid solar drying is a perspective that needs to be developed for the future. Hybrid solar can be assisted with various drying models or can be known as mixed mode hybrid solar drying, the addition of heat can also be assisted with heat pump-biomass drying, assisted again with photovoltaic hybrid and auxiliary heater. Most likely in the future hybrid solar drying will be added to the drying place (chamber) to the collector or also to the drying system with a water vapor absorber (desiccant). The application of mirrors, the development of solar collectors to overcome the volume of hot air transfer, and the application of selective coatings on absorber sheets to increase solar energy collection can improve dryer performance. Air-based solar collectors are not the only method available. Water can be a heat exchanger that can be applied in solar collectors to replace air. In this technique, hot air for drying food products needs to flow through the water to the air heat exchanger, and a hot water tank is used as storage material.

This study investigates the impact of various drying temperatures on the performance evaluation of photovoltaic – direct solar dryers in the coffee bean drying process. The use of photovoltaic systems in solar drying provides opportunities for the future to support clean and eco-friendly renewable energy. Three drying temperature conditions were tested, namely 40°C, 45°C, and 50°C, with the optimum temperature obtained at 50°C. During the drying process, the weather appears to be very sunny and cloudless, resulting in an average solar intensity of 974.36 W/m2. Utilising this solar dryer, it takes 12–16 hours for the coffee bean drying process to achieve a moisture content below 12.5% by the SNI 01-2907-2008 standard, starting from an initial moisture content of 45%. The drying and solar collector efficiencies ranged between 0% to 54% and 67.33% to 88.24%, respectively. Energy consumption is directly proportional to drying efficiency, depicted as the energy utilisation ratio (EUR), with the highest EUR being 22.96%. Meanwhile, the exergy flow (inlet, outlet, and loss) is directly proportional to the solar intensity, forming an open downward parabolic curve, with the average exergy efficiencies obtained at temperatures of 40°C, 45°C, and 50°C being 53.95%, 54.72%, and 56.88%, respectively.

Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter Facebook Reddit LinkedIn Tools Icon Tools Reprints and Permissions Cite Icon Cite Search Site Citation Indro Sumantri, Yordianto Yordianto, Priscila Indah Ratnasari, Hadiyanto Hadiyanto, Suherman Suherman; Comparison of pretreatment process of sodium hydroxide and soaking in aqueous ammonia for delignification of rice husk. AIP Conf. Proc. 28 February 2023; 2667 (1): 040007. https://doi.org/10.1063/5.0114052 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAIP Publishing PortfolioAIP Conference Proceedings Search Advanced Search |Citation Search

Drying process has been employed since ancient times to preserve agricultural products by reducing the moisture content. Solar dryer is one of the most commonly used dryers due to its availability, reliability, and environmentally friendly nature. It is practical in rural areas since solar dryer can be fabricated with a simple design. Despite its potential, designing a long-term, feasible solar dryer is challenging without a good understanding of its performance parameters, such as energy, exergy, economic, environmental (4E) aspect, and its impact on product quality. Therefore, many attempts have been dedicated to conducting these analyses. Nonetheless, the information obtained is only one-dimensional, and they do not reflect the actual behaviour of a solar dryer. This paper aims to provide a comprehensive and critical review of the additional 3E parameters, namely energoeconomic, exergoeconomic, and enviroeconomic. Moreover, the effect of solar drying on product quality parameters (Q) will be discussed. Furthermore, a new idea to perform energy, exergy, environmental, economic, energoeconomic, exergoeconomic, and enviroeconomic (7E) and quality analysis (7E + Q) is proposed and outlined to improve the operability of the solar dryer. It is envisaged that 7E + Q analysis will pave the way for more effective and efficient solar dryers.

Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter Facebook Reddit LinkedIn Tools Icon Tools Reprints and Permissions Cite Icon Cite Search Site Citation Suherman Suherman, Riri Marza Rilna, Naufal Afriandi, Evan Eduard Susanto, Hadiyanto Hadiyanto; Drying of tomato slices using solar drying method. AIP Conf. Proc. 28 February 2023; 2667 (1): 020002. https://doi.org/10.1063/5.0112428 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAIP Publishing PortfolioAIP Conference Proceedings Search Advanced Search |Citation Search

Emissions of carbon monoxide (CO) and carbon dioxide (CO2) gases are the main problem that must be rectified as they are harmful and contribute to global warming through the greenhouse gas effect. In Indonesia, motor vehicles, especially four wheelers, are one of the biggest contributors with up to 71 million tons of CO2 emissions and energy consumption of 179 million barrel of oil equivalent. Bioethanol has octane rating >100, which is higher than that of gasoline; and emission contribution of only 0.02 kg/L, which is lower than that from gasoline (2.23 kg/L). Accordingly, a mixture of gasoline and bioethanol is the solution proposed in this study to solve the issues of CO and CO2 emissions. Gasoline and bioethanol mixture consists of six products, namely E-0, E-5, E-10, E-15, E-20, and E-25, which have different percentage values of bioethanol mixture (0%–25%). This study was conducted through engine testing with different rpm values (500–2500 rpm) to identify the concentration and mass of CO2 emissions, fuel efficiency, and cost efficiency. Based on the test results, this product succeeded in reducing CO emissions by up to 86% and CO2 emissions up to 30.6% from Pertalite (E-0) and increasing the fuel efficiency up to 51.76% for 1 L and cost efficiency up to 33.6% after considering the actual price of Pertalite. Therefore, the proposed product can be a solution to the existing problems.

This research aimed to evaluate the effectiveness of microalgae Dunaliella salina in the biodegradation process of oxidized oxium and HDPE plastics. Microalgae and microplastic interactions were evaluated in two 1 L glass bioreactors containing D. salina with oxium microplastics and oxidized HDPE at various concentrations (100 mg/500 mL, 200 mg/500 mL, and 300 mg/500 mL) for 15 d. The results showed a more significant decrease in alkene functional groups in oxium plastics than in HDPE. In addition, there was a change in the oxium functional group with the formation of carbonyl, ether, and primary alcohol. The growth rate of D. salina decreased significantly after interaction with oxidized HDPE microplastics compared to oxium interaction. We established that oxium plastics have a faster biodegradation ability owing to the addition of additives to the plastic. However, oxidation pre-treatment with H2O2 on HDPE plastic can also accelerate the plastic degradation process.

A tertiary recovery technique is needed to recover the remained oil in the oil field after primary and secondary recoveries, which can only recover approximately 30–50% of the total oil. This study investigated the synthesized polymeric surfactants from rice husk and polyethylene glycol (PEG) for the enhanced oil recovery (EOR) process as a tertiary recovery technique. The rice husk was used as sodium lignosulfonate (SLS) surfactant production feedstock. SLS-PEG polymer surfactant from rice husk has not been widely studied, especially for the EOR process. This study has comprehensively investigated the effect of PEG concentration on the polymeric surfactant properties. The surfactants were characterized using Fourier transform-Infrared (FT-IR) analysis. Several other tests were also conducted, including surfactant compatibility, viscosity, thermal stability, interfacial tension (IFT), and phase behavior. It was found that the PEG introduction to the SLS surfactant could increase the hydrophilic property of the polymeric surfactant due to the presence of the C−O−C group. In addition, the IFT value decreased with the increase in the PEG concentration due to the increase in the hydrophilic property. However, the IFT value decreased when the PEG concentration was too high. The lowest IFT value was obtained at the SLS to PEG ratio of 1:0.8. It produced the highest increase in the additional recovered oil after brine flooding. The results showed that the rice husk, which is agricultural waste, could be utilized as a feedstock for the surfactant production.

Recently, the increase in fuel oil demand was not supported by petroleum production due to the low productivity of old wells. Furthermore, an appropriate technology, such as Enhanced Oil Recovery (EOR) technology, is needed to maximize the productivity of the old well. Therefore, the purpose of this study was to synthesize a polymeric surfactant for the EOR process from sodium lignosulfonate (SLS) and polyethylene glycol (PEG) in various SLS to PEG ratios, namely 1:1 (PS1), 1:0.8 (PS2), and 1:0.5 (PS3). The surfactants were characterized using several methods, such as Fourier Transform-Infrared spectroscopy (FT-IR), compatibility, stability, viscosity, and phase behavior tests. The performance of the surfactants for the EOR process in different brine solution concentrations (16,000 ppm and 20,000 ppm) was also studied. The result showed that the introduction of the PEG molecule to the surfactant had been successfully conducted as FT-IR analysis confirmed. The surfactant's hydrophilicity increased with the introduction of PEG due to the increase of the ether group. A Winsor Type I or lower phase microemulsion was formed due to the high hydrophilicity. The highest oil yield (79 %) was obtained by PS1 surfactant, which has the highest PEG dosage, in a brine solution of 1,600 ppm. Therefore, it was concluded that the introduction of PEG could increase the hydrophilicity, viscosity, and EOR performance.

This study aimed to evaluate the effect of microplastics on Spirulina sp., the pigment phycocyanin in Spirulina sp., and the effect of Spirulina sp. on the degradation of PE and PP plastic. The interaction of Spirulina sp. with microplstic (PE and PP) was conducted by adding the microplastic (500 mg/500 mL, with a size of 0.5–1 mm2) to microalgae culture. The optical density was measured for 30 days to determine the growth of Spirulina sp. Harvesting was performed to obtain dry Spirulina sp biomass. Phycocyanin was obtained through extraction by mixing 0.1 g dry Spirulina sp. biomass with 25 ml of 1% CaCl2 in an ultrasonic water bath at 50 kHz, 300 W at 30 °C for 15 min. The results showed that the growth rate of Spirulina sp significantly decreased (p < 0.05) with treatment of PE (SP + PE) (0.0228/day) and PP (Sp + PP) (0.0221/day), compared to the control (Sp-Control) (0.0312/day). Scanning electron microscopy and Fourier transform infrared spectroscopy (FTIR) analyses of Spirulina sp. biomass with the addition of PE and PP revealed surface damage of Spirulina sp. cells and loss of carboxyl groups from proteins in Spirulina sp. at wavelengths of 1397–1450 cm−1. In addition, Spirulina sp. had decreased the intensity of amine and amide groups from proteins at wavelengths of 3280, 1637, and 1537 cm−1 in the microplastic treatment. The phycocyanin yield and protein content in Spirulina sp. control were 19.69% and 0.147%, respectively, which decreased by 10.7% and 0.121%, respectively, with PE treatment and by 8.7% and 0.108%, respectively, with PP treatment. Moreover, the investigation of PE and PP treated by Spirulina sp showed more significant changes of functional group indicated by the formation of hydroxyl (3286 cm−1), carbonyl (1700 cm−1), ester (1750 cm−1) and primary alcohol (1085 cm−1). The results of the EDX microplastic analysis showed a decrease in carbon in PE (1.62%) and PP (1.08%). These FTIR and EDX analysis also proved that microplastic has experienced degradation when treated by Spirulina sp cell culture.

ABSTRACT Ginger is widely used as a traditional medicine for several diseases and has gained more attention due to how healthy and safe it is. Freshly harvested gingers have high moisture content and may cause product deterioration if treated incorrectly. Most ginger farmers still implement the traditional drying method, which requires a long drying time and relies heavily on the weather. In this paper, hybrid solar drying method for ginger is introduced. The performance of hybrid solar dryer, thin-layer modeling, and the quality of dried ginger were investigated. Experimental results show that in four hours of drying, only drying at 60 °C can satisfy the maximum moisture content limit of ginger, which is 12 % wet basis. The decreasing value of drying rate over time indicates that drying of ginger mostly takes place in the falling rate period. Page model is found to be the best thin-layer model to describe the behavior of ginger drying. The values of effective diffusivity are in agreement with the generally accepted value. Although the dried gingers have a good quality according to the standards, the efficiency of hybrid solar dryer is lower compared to other drying methods. Therefore, it can be concluded that hybrid solar drying is applicable for ginger due to fast drying process and acceptable quality of dried ginger, although further improvements are required.

Penelitian ini bertujuan untuk menafsirkan kumpulan data kualitas air pada Sungai Pepe, Sungai Anyar, Sungai Jenes, Sungai Kedung Jumbleng, Sungai Gajah Putih, Sungai Brojo, dan Sungai Premulung di Kota Surakarta, Jawa Tengah. Data diperoleh dari hasil pemantauan kualitas air yang dilakukan oleh Dinas Lingkungan Hidup Kota Surakarta di 13 titik lokasi pengambilan sampel pada tahun 2020. Terdapat 12 parameter yang digunakan yaitu TSS, TDS, pH, BOD, COD, DO, P, NO3-N, NH3, NO2-N, Total Coliform, dan Fecal Coliform. Dengan algoritma k-means diperoleh dua klaster dengan parameter pembeda yaitu Total Coliform dan Fecal Coliform. Dengan kandungan 3.790.050 MPN/100ml Total Coliform dan 604.400 MPN/100ml Fecal Coliform, Sungai Jenes Hilir mempunyai kualitas air yang lebih buruk dibandingkan sungai lainnya dalam hal kandungan pencemar Total Coliform dan Fecal Coliform.

In this paper, a newly-designed solar dryer was used for drying of cassava slices. Cassava from local market were peeled, washed, and cut into slices with approximately 1-2 mm in thickness. Using the oven method, it is found that the initial moisture content of cassava slices used in this experiment was 54,25% w.b. Drying experiment was carried out from 09.00 A.M. to 05.00 P.M. Several analysis were conducted, namely the temperature, relative humidity, and solar radiation profiles analysis, the drying curve analysis, drying rate analysis, and the effectiveness factor analysis. It is found that the temperature and solar radiation values were maximum at 11.00 A.M., while at the same time the value of ambient relative humidity was minimum. Only cassava slices dried at the 1st tray (top tray, 13,1% w.b.) could satisfy the maximum moisture content of cassava slices governed by Indonesian Standardization Body, which is 14% w.b. Drying rate at the first tray was the fastest and drying of cassava slices happened at the falling rate period, indicated by the decreasing values of drying rate. The effectiveness factor varied between 0,68 - 2,59 which indicated that the solar dryer used in this experiment was more efficient than the open sun drying. The dryer efficiency from the three drying trays were ranged from 0,7% to 2,72%, which were lower than the values found in several literatures about solar dryer.

Sugar palm is an abundant palm in Indonesia and widely used for various foods, one of which is vermicelli. During vermicelli production, local farmers still implement open-sun drying, which reduces the quality of vermicelli, requires long periods of time, and cannot be performed during poor weather. Therefore, in this study, a new method of vermicelli drying is introduced using a hybrid solar dryer, which consists of a solar dryer and an additional heater powered by liquefied natural gas. Hybrid solar drying is conducted at 40, 60, 80, and 100 degrees C. With 2 hr of drying time, the final moisture contents of vermicelli dried using hybrid solar dryer have satisfy the standard limit, while the open-sun drying and natural solar drying do not, indicating that hybrid solar drying is faster and more effective. Vermicelli drying occurs at the falling-rate period and increasing drying temperature from 40 to 100 degrees C increases dryer efficiency, energy utilization ratio, and exergy efficiency, from 13.02 to 17.02%, from 0.18 to 0.32, and from 67.4 to 83.6%, respectively. Although the overall quality of dried vermicelli is acceptable, increasing drying temperature from 40 to 100 degrees C result in the damaged vermicelli surface as evident fromSEManalysis and degradation of vermicelli whiteness value from 87.2 to 82.5. Practical applications The drying process is playing an important role in heat sensitive products dehydration. The present study provides an investigation of potential use of solar energy for drying of vermicelli which combine with the natural gas heating process. The results show that hybrid drying system could enhance the product quality of vermicelli and also reduce the drying process. During drying, proximate components of vermicelli essentially do not change but it alters the color of product.

Lime is one of the most commonly consumed medicinal plants in Indonesia, which must be dried to preserve its quality, but mostly by using traditional, ineffective drying method. Therefore, this study aims to investigate lime drying process a hybrid solar drying method. The hybrid solar dryer consisted of a solar dryer and Liquefied Petroleum Gas as the supplementary heater. The drying process was conducted until there was no significant weight decrease, with the drying temperature of 40, 50, 60, 70, and 80 °C. Thin-layer modeling and quality analysis were also conducted. The experimental results indicated that 5 h was required to sufficiently dry the lime at 80 °C, while drying at 40 °C took 24 h to finish. The drying rate curve of lime suggested that lime drying mostly happened during the falling-rate period. Moreover, the average efficiency of the hybrid solar dryer ranged from 5.36% to 38.61%, which increased with temperature. From the 10 thin-layer drying models used, the Wang and Singh model was the most suitable to describe the drying behavior of lime. The effective diffusivity values of the limes and the activation energy value during hybrid solar drying were within their respective acceptable range for agricultural products. However, as the drying temperature was increased from 40 to 80 °C, the total phenolic content and vitamin C content decreased, from 87.3 to 27.8 mg GAE/100 g dry limes and 0.118 to 0.015 ppm, respectively. It can be concluded that hybrid solar dryer is able to sufficiently dry the lime, with acceptable drying time and dryer efficiency, although using high drying temperature will decrease the quality of dried lime. Further modifications and improvements to the hybrid solar dryer are required to maximize the quality of dried lime while still maintaining fast and effective drying process.

An experiment has been performed to study the performance of hybrid solar dryer for cassava starch. This paper introduces a drying method in which solar dryer is combined with Liquefied Petroleum Gas as an auxiliary heater to support the drying process. Drying experiment was carried out from 10.00 to 13.00 with the dryer temperature of 40, 50, and 60 degrees C. The profiles of temperature, relative humidity, and solar intensity were very dependent of weather condition, geographical condition and location, and measurement time. Only the final moisture content from drying at 60 degrees C that could satisfy the maximum limit of cassava starch's moisture content. It is found that higher temperature will lead to faster and more effective drying. The fastest moisture reduction occurred at the first tray, followed by the second and the third tray. The value of drying rate was high when the moisture content is still high, then gradually decreased as moisture content decreased. In this drying process, the constant rate period occurred very quickly, namely during the initial phase of the drying process. The drying process of cassava starch mostly happens in the falling rate period. The highest value of effectivity factor was recorded at 11.00, with the highest value of 6.4

Abstract In this study, we aimed to energetically and exergetically evaluate the usage of a hybrid solar dryer system for cassava drying via a series of drying experiments. The experiments were performed beginning at 10.00 A.M. (hereafter, in local time) until the moisture content of cassava starch became constant at a value less than 14% on a wet basis at drying temperatures of 40 °C to 60 °C and drying times of 180–240 min. The results demonstrated that the highest overall dryer energetic efficiency was 20.82%, which was achieved at a drying temperature at 60 °C, and that the maximum energetic efficiency of 27% was recorded at 11.00 A.M. The exergy flows fluctuated during the drying process and were dependent on the solar radiation and drying conditions; however, the exergetic efficiency of the dryer was 25.1%–73.8%. Comparison of the fitting models denoted that the Page model was the most suitable model for describing the experimental drying performances. The calculated effective diffusivity constant (Deff ) and the activation energy (Ea ) during the drying process from 50 °C to 60 °C were 3·× 10−10 m2/s and 15.3 kJ/mole, respectively.