Effect of Particle Size and Transparent Solar Dryer Cover on the Proximate Analysis of Dried Onion

In this work, we investigate effect of particle size and transparent solar dryer cover on the proximate analysis of dried onion. A solar drying unit was developed and constructed for drying the of red onion slices in order to determine the proximate composition of fresh and dried red onion using multi-crop direct solar dryer. Also, the evaluation and effect of particles size and multi-crop transparent solar dryer cover on the proximate analysis of red onion during drying. Consequently, the higher efficiency of the solar collector was obtained at the higher airflow rate. The moisture content of dried onion slices was strongly affected by the thickness of the onion slices and the density of the polyethylene. The final moisture content of dried onion slices ranged from 10.85% to 13.01%, 4.95% to 6.01% ash, 4.69% to 5.26% fibre, 11.17% to 13.09% fat, 6.70% to 5.60% protein and 68.64% to 68.03% carbohydrate for particle sizes of 3 mm, 5 mm and 7 mm dry-basis depending on drying temperature cycle for low density polyethylene cover. While the final moisture content of dried onion slices ranged from 9.85% to 12.01%, 5.96% to 6.01% ash, 3.69% to 4.26% fibre, 13.17% to 12.09% fat, 5.70% to 6.60% protein and 61.64% to 58.03% carbohydrate for particle sizes of 3 mm, 5mm and 7mm dry-basis depending on drying temperature cycle for high density polyethylene cover.

Optimization of operating parameters a heat-recovery exchanger of a boiler plant based on the exergy approach

The results of operating parameters optimization of the air-heating heat-recovery exchanger of complex heat recovery system of a gas-fired boiler designed for heating water and blown air are presented. Air heating in this heat-recovery exchanger is realized by deep cooling of the waste exhaust gases, that is, with a change in their moisture content during the heat recovery process. The possibilities of using a complex technique based on the structural-variant method and exergy analysis methods for the optimization of the heat-recovery exchanger are analyzed. The developed structural scheme of the boiler plant with identification of input and output exergy streams for all elements of the installation is presented. The change of exergy losses in this heat-recovery exchanger has a rather strong effect on the change of the whole heat recovery system efficiency is established. Thus, the optimization of heat-recovery exchanger operating parameters of is a necessary condition for increasing the efficiency of heat recovery in general. The choice of multiplicative exergy efficiency criteria used as target functions of operating parameters optimization of the investigated air-heating heat exchanger is substantiated. The obtained dependences of exergy efficiency criteria on the operating parameters of the heat-recovery exchanger, such as the ratio of the Reynolds numbers of exhaust gases and air and the ratio of the initial and final moisture content of exhaust gases, are analyzed. It is established that the minimum values of the efficiency criteria, which corresponds to the maximum exergy efficiency, is observed in the range of values of the ratio of the initial and final moisture content of exhaust gases in the range from 2.4 to 3.0. It is shown that at a value of the specified ratio of 2.7, the exergy efficiency of the investigated heat-recovery exchanger does not depend on the ratio of the Reynolds numbers of exhaust gases and air. It is established that of initial and final moisture content ratio of exhaust gases, equal to 2.7, and the Reynolds numbers ratio of exhaust gases and air, equal to 0.8 and 1.2, depending on the values of initial and final moisture content ratio of exhaust gases, can be taken as the optimal values of the operating parameters. Key words: heat-recovery exchangers, exergy efficiency, complex techniques

Mathematical Modelling of Conveyor-Belt Dryers with Tangential Flow for Food Drying up to Final Moisture Content below the Critical Value

This work presents the mathematical modeling of the conveyor-belt dryer with tangential flow operating in co-current, which has the advantage of improving the preservation of the organoleptic and nutritional qualities of the dried food. On the one hand, it is a more cumbersome dryer than the perforated cross flow belt dryer but, on the other hand, it has a low air temperature in the final section where the product has a low moisture content and, therefore, it is more heat sensitive. The results of the mathematical modeling allowed a series of guidelines to be developed for a rational design of the conveyor-belt dryer with tangential flow for the specific case of the moisture content of the final product XF lower than the critical one XC (XF < XC). In fact, this work follows a precedent in which a mathematical model was developed through the differentiation of the drying rate equation along the dryer belt with the hypothesis that the final moisture content XF of the product was higher than the critical one XC. The relationships between the extensive quantities (air flow rate and product flow rate), the intensive quantities (temperatures, moisture content and enthalpies) and the dimensional ones (length and width of the belt) were then obtained. Finally, based on these relationships, the rules for an optimized design for XF < XC were obtained.

IMPROVEMENT OF PROCESSING TECHNOLOGY BREWER'S GRAINS TO DRY FORAGE ADDITIVE

Традиционные способы удаления влаги из пивной дробины – ее механическое обезвоживание и сушка, которая является энергоемким технологическим процессом, поскольку для удаления значительного количества связанной влаги из крупных частиц сырой пивной дробины требуется продолжительное воздействие на материал. Для исследования возможности сокращения продолжительности сушки нами выдвинуто предположение, что разрушение клеток пивной дробины, способствующее переходу части связанной влаги в свободную, должно отразиться на кинетике сушки материала. Перед проведением сушки сырую пивную дробину помещали на сито до полного стока с нее жидкости. Из полученного таким образом материала сформировали три образца: образец 1 (исходный); образец 2 – дробленая пивная дробина; образец 3 – дробленая и отжатая на ручном прессе пивная дробина. Сушку трех образцов проводили при температурном режиме 60°С в сушильном шкафу Memmert UFE 400. Убыль массы навески фиксировали на весах через каждые 5 мин в течение всего эксперимента. Содержание сухого вещества, определенное по ГОСТ 31640–2012, составило, %: для образцов 1 и 2 – 19,2; для образца 3 – 22. По результатам эксперимента построены кривые скорости сушки, на основе анализа которых установлено, что операция дробления перед сушкой позволяет разрушить клеточную структуру пивной дробины и перевести часть связанной влаги в свободную. Конечная влажность образцов пивной дробины составила, %: образец 1 – 112,453; 2 – 10,842; 3 – 9,585. На основе полученных экспериментальных данных было предложено при производстве сухой кормовой добавки из вторичного продукта пивоваренного производства после его отжима перед сушкой ввести стадию измельчения пивной дробины до размера частиц 3–5 мм. Это позволяет увеличить поверхность массообмена между сушильным агентом и твердой фракцией, что повышает скорость сушки и снижает ее продолжительность, а также получить высушенную твердую фракцию пивной дробины с влажностью 9–10%. Снижение конечной влажности сухой кормовой добавки может способствовать увеличению срока ее хранения. Traditional methods of removing moisture from raw brewer's grains are mechanical dewatering and drying. Drying is an energy-intensive technological process, since it requires prolonged exposure to the material to remove a significant amount of bound moisture from the large particles of raw brewer's grains. To study the possibility of reducing the drying time, we put forward the assumption that the destruction of the brewer's grains cells, which contributes to the transition of part of the bound moisture to the free one, should affect the kinetics of drying the material. Before drying, the raw brewer's grains were placed on a sieve until the liquid was completely drained from it. Three samples were formed from the material obtained in this way: sample 1 – initial; sample 2 – crushed brewer's grains; sample 3 – crushed and pressed on a manual press brewer's grains. Three samples were dried at a temperature of 60°C in a Memmert UFE 400 drying cabinet. The weight loss of the sample was recorded on the scale every 5 minutes throughout the experiment. The dry matter content determined according to GOST 31640–2012 was, %: for samples 1 and 2 – 19,2; for sample 3 – 22. According to the results of the experiment, the drying rate curves are constructed. Based on their analysis, it was found that the crushing operation before drying allows you to destroy the cellular structure of the brewer's grains and transfer part of the bound moisture to the free. The final moisture content of the beer pellet samples was, %: sample 1 – 112,453; 2 – 10,842; 3 – 9,585. On the basis of the experimental data obtained, it was proposed in the production of dry feed additives from the secondary product of brewing production to introduce after its extraction before drying a stage of crushing the brewer's grains to a particle size of 3–5 mm. This allows you to increase the mass transfer surface between the drying agent and the solid fraction, which increases the drying speed and reduces its duration, as well as to obtain a dried solid fraction of brewer's grains with a humidity of 9–10%. Reducing the final moisture content of a dry forage additive can increase its shelf life.

Natural Drying and Chemical Characteristics of Hybrid Poplar Firewood Produced from Agricultural Bioenergy Buffers in Southern Québec, Canada

Implementing bioenergy buffers on farmland using fast-growing tree species could reduce firewood harvest pressure in woodlots and increase forest connectivity, while improving carbon sequestration, phytoremediation, stream habitats, soil stabilization and hydrological regulation. The objective of the study was to evaluate the natural drying and chemical characteristics of hybrid poplar firewood produced from bioenergy buffers, and to compare these characteristics with those of native species harvested in adjacent woodlots. In Trial A, 110 cm-long unsplit logs (a feedstock for biomass furnaces) were produced to evaluate the effect of log diameter class on firewood quality. In this trial, hybrid poplar firewood characteristics were also compared with Populus tremuloides, Acer rubrum and Fraxinus americana. In Trial B, the effect of hybrid poplar genotype and cover treatment was evaluated on the moisture content of short split logs (40 cm long). Firewood of satisfactory quality was produced on a yearly cycle for short split logs, and on a biannual cycle for long unsplit logs. Covering short split log cords with metal sheeting lowered the final moisture content (from 20.7% to 17.3%) and reduced its variability, while genotype did not significantly affect final moisture content. In Trial A, larger-diameter logs from hybrid poplar had lower element concentrations, but slightly higher moisture content after two years. A two-fold variation in N concentration was observed between diameter classes, suggesting that burning larger poplar logs would minimize atmospheric N pollution. Heating value, carbon and calcium concentrations increased following the seasoning of hybrid poplar firewood. After the first seasoning year outdoors, hybrid poplar had the highest moisture content (33.1%) compared to native species (24.1–29.5%). However, after the second seasoning year in an unheated warehouse, the opposite was observed (14.3% for hybrid poplar vs. 15.0–21.5% for native species). Heating value, carbon and nitrogen concentrations were similar between tree species, while high phosphorus and base cation concentrations characterized hybrid poplar, suggesting higher ash production. Poplar bioenergy buffers could provide a complementary source of firewood for heating in the fall and in the spring, when the heat demand is lower than during cold winter months.

Conveyor-Belt Dryers with Tangential Flow for Food Drying: Development of Drying ODEs Useful to Design and Process Adjustment

The mathematical investigation presented in this paper concerns the conveyor-belt dryer with tangential flow operating in co-current. This dryer is bigger than the continuous through-circulation conveyor dryer but has the advantage of better preserving the organoleptic and nutritional qualities of the dried product. In a previous work a mathematical modeling of the conveyor-belt dryer with tangential flow was carried out to offer guidelines for its optimized design. The last of those design guidelines indicated the need for an optimized adjustment of the dryer to ensure the constant maintenance of the final moisture content of the product. The fast and very precise measurement of the moisture content as the first step in the feedback chain was therefore necessary. Considering the difficulty of this type of measurement, two specific ordinary differential equations (ODEs) were obtained with the mathematical investigation of this work. Their solution became a relationship between the final moisture content of the product, the outlet air temperature, and other quantities that could be easily implemented in an automatic dryer control system. Therefore, the fast and accurate and much less expensive measurement of the temperature of the air leaving the dryer, owing to the relationship found, replaces the measurement of moisture content for the adjustment system. The experimental verification of the relationship highlighted the need to introduce a modification by which the relationship was finally validated.

Effect of drying temperature on physical properties of fermented dried locust bean flour

Drying plays a major role in food processing as it reduces the activities of micro-organisms and hence preserve food from deterioration. It has been reported that drying imposes new changes to the physical properties of the product which may in turn affect its handling, packaging and usability. The present research work, therefore aimed to evaluate the effect different drying temperature on physical properties of fermented dried locust bean flour. The local fermented locust bean was dried at different temperature of 50, 60, 70, 80 and 90°C at airflow rate of 1.8 kg/min. then milled and Investigated on final moisture content, bulk density, water retention ratio, flour wetting time, and swelling capacity of the fermented dried locust bean flour. The effect of drying temperature was found to be significant (p ≤ 0.05) on all the physical properties investigated except bulky density (0.638 g/ml). As the drying temperature increased from 50 to 90°C, final moisture content decreased significantly from 5.62 to 3.52%. Whereas, water retention ratio, wetting time, swelling capacity, porosity ratio and water retention ratio increase from 1.96 to 2.5 m/g, 153 to 299 s, 2.26 to 2.44, 0.81 to 0.91 and 1.96 to 2.5 m/g respectively. These findings could prove useful in the modeling of locust bean drying and to flour millers and pelletizer who may want to use locust bean flour as a sole or composite flour for different production and application. Keywords: Fermented locust bean flour, physical properties, modeling, pelletizer, miller, drying temperature, final moisture content.

Effect of solar drying on proximate composition of two varieties of ginger rhizomes for blanched and unblanched treatments

Ginger (Zingiber officinale Roscoe) of two verities UG I ('Tafin-Giwa', a yellowish variety with plump rhizomes) and UG II ('Yatsun-Biri', a black or dark variety with small compact rhizomes), were analysed to identify its proximate composition. The effects of drying as a processing technique on ginger were investigated with respect to the proximate composition of the produce. The UG I and UG II were collected, sorted (whole, peeled and unpeeled) and (slice, peeled and unpeeled), and were subjected to Unblanched and Blanched (50℃ at 3,6 and 9 min respectively) treatments and dried using solar dryer for a period of one month. The initial moisture content of UG I and UG II were 71.12% and 72.47% respectively, the final moisture content were reduced to 7.02% SUP (Unblanched) and 5.52% SUP (Blanched at 9 min) for UG I, while that of UG II were 4.82% SP (Unblanched) and 5.85% WUP (Blanched at 3 min). For Carbohydrate content, 61.38% was noted to be the lowest level at Unblanched (Whole peeled), and 68.37% indicates higher CHO content at Blanched 50℃ at 9 min (Split Unpeeled) treatments for UG I samples. Similarly, for UG II, CHO's presence was low at 56.01% for Unblanched (Whole peeled) and high at 76.32% for Blanched on the temperature of 50°C at 9 min (Whole peeled) treatment. Ash content was observed to be low at 4.68% for Blanched 50℃ at 3 min (Split Unpeeled) and high at 6.47% for Unblanched (Whole peeled) treatment for UG I samples, and 3.82% low for Blanched on the temperature of 50°C at 9 min (Split peeled) with higher ash content of 7.69% Unblanched (Split Unpeeled) treatment for UG II samples.

Unjuk Kerja Pengering Tenaga Surya Tipe Efek Rumah Kaca Untuk Pengeringan Cabai Dengan Perlakuan Low Temperature Long Time Blanching

Abstrak. Penelitian ini bertujuan untuk menguji unjuk kerja pengering tenaga surya tipe efek rumah kaca pada pengeringan cabai dengan perlakuan low temperature long time (LTLT) blanching. Selain itu, pada penelitian ini juga dilakukan kajian mengenai karakteristik pengeringan cabai yang dipengaruhi oleh perlakuan LTLT blanching, terutama pada kadar air, laju pengeringan, kecepatan pengeringan, dan kualitas warna. Pengujian dilakukan dengan cara mengeringkan cabai merah dengan pretreatment LTLT blanching yang dikombinasikan dengan perlakuan merotasikan rak pengering (R) dan tanpa merotasikan rak pengering (TR). Sebagai kontrol adalah cabai yang dikeringkan tanpa blanching dan tanpa merotasikan rak pengering (K). Hasil penelitian menunjukkan bahwa perlakuan LTLT blanching yang dikombinasikan dengan merotasikan rak pengering (R) merupakan perlakuan yang terbaik, dengan kadar air akhir cabai kering sebesar 9,82% dan sesuai dengan standar SNI. Waktu pengeringan yang dibutuhkan adalah selama 5 hari. Warna cabai kering yang dihasilkan adalah yang terbaik dari dua perlakuan lainnya, dengan nilai L*, a*, dan b* untuk setelah proses LTLT blanching (sebelum proses pengeringan) dan setelah pengeringan berakhir (cabai kering) berturut-turut adalah 36,02, 38,22, 13,62, dan 32,44, 33,89, dan 10,19. Energi yang terpakai untuk pengeringan cabai adalah sebesar 596181 kJ. Perlakuan R ini juga menghasilkan efisiensi pengeringan terbaik, yaitu sebesar 34,01%.Performance of Green House Effect Type Solar Dryer in the Chillies Drying with Low Temperature Long Time Blanching TreatmentAbstract. This study aims to examine the performance of the greenhouse effect type solar dryer on drying chillies with low temperature long time (LTLT) blanching treatment. In addition, a study was also conducted on the characteristics of drying chillies and the final product affected by LTLT blanching treatment, especially in terms of moisture content, drying rate, drying speed, and color. Testing was performed by drying red chilli with LTLT blanching treatment, which was combined with the treatment of rotating dryer rack (R) and without rotating dryer rack (TR). As a control, chillies were dried without blanching treatment and without rotating dryer rack (K). The results show that the LTLT blanching treatment combined with rotating the drying rack (R) is the best treatment, with a final moisture content of 9.82% which is in accordance with SNI standards. The drying time needed is 5 days. The dried chilli color produced is the best of the other treatments, with values of L*, a*, and b* for after the LTLT blanching process and after drying ended, respectively 36.02, 38.22, 13.62, and 32.44, 33.89, 10.19. The energy used for drying chillies is 596181 kJ. This R treatment also produces the best drying efficiency, which is 34.01%.

Conveyor-Belt Dryers with Tangential Flow for Food Drying: Mathematical Modeling and Design Guidelines for Final Moisture Content Higher Than the Critical Value

The mathematical modeling presented in this work concerns the conveyor-belt dryer with the tangential flow of air with respect to food. This dryer, if operating in co-current, has the advantage of well preserving the organoleptic and nutritional qualities of the dried product. In fact, it has a low air temperature in the final stretch where the product has low moisture content and is therefore more temperature sensitive. It is a bulkier dryer than the continuous through-circulation conveyor dryer with a perforated belt. The latter is therefore more frequently used and has received greater study attention from researchers and designers of the industry. With the aim to propose guidelines for a rational design of the conveyor-belt dryer with tangential flow, a mathematical model was developed here through the differentiation of the drying rate equation followed by its integration performed along the dryer belt. Consequently, and with the assumption that the final moisture content XF of the product is higher than the critical moisture content XC, the relationships between the intensive quantities (temperatures, humidity and enthalpies), the extensive quantities (air and product flow rates) and the dimensional ones (length and width of the belt), were obtained. Finally, on the basis of these relationships, the rules for an optimized design for XF > XC were obtained and experimentally evaluated.