2019, Vol. 17, No. 3

Selle kollektsiooni püsiv URIhttp://hdl.handle.net/10492/5399

Sirvi

Nüüd näidatakse 1 - 20 23

Effect of rotors on the parameters of hop drying in belt dryers
(2019) Rybka, A.; Heřmánek, P.; Honzík, I.
This article contains a design and verification for a technical solution aimed at optimising the hop drying process in belt dryer and at increasing the quality of the final product. Above the first belt of our belt dryer two evenly distributed double-arm rotors were installed and tested in operation to improve the permeability of the drying air through a flattened hop layer, as well as to improve the speed of drying. The measurements carried out in operation and comparing the drying process with the rotors switched on and off concluded that by inclusion of rotors the hop layer becomes more permeable, and when switched on, the rotors have a positive effect on faster reduction of the relative humidity and on increase of the drying air temperature. With rotors switched on, the percentage drop in the drying air relative humidity at the third inspection window of the first belt, compared to the first inspection window, was 41% on average (values obtained from data loggers and fixed sensors), the drying air temperature increased by 29%, and the hop moisture content decreased by 12%. Whereas with rotors switched off, the drop in the drying air relative humidity was only by 26% on average, the drying air temperature increased only by 14%, and the hop moisture content decreased by 12%. Based on long-term monitoring of fuel consumption during the whole harvesting season starting 2011 until 2017 inclusive, the average annual consumption of LFO (2011–2014) results in 494 L t -1 operating without rotors, and 431 L t -1 when operating with rotors (2015–2017). This implies that due to the implementation of rotors, the fuel saving being 13% is significant.
Conversion of an industrial cutaway peatland to a Betulacea family tree species plantation
(2019) Neimane, S.; Celma, S.; Butlers, A.; Lazdiņa, D.
To evaluate the potential of establishing a deciduous tree plantation on an industrial cutaway peatland over an 8 ha large experimental site was established in the central part of Latvia and silver birch (Betula pendula Roth) and black alder (Alnus glutionsa (L.) Gaertn.) tree species were planted. As it is a harsh and unfavorable environment wood ash, otherwise a waste product, was used as a fertiliser and liming material in three applications (5, 10 and 15 t ha-1 ). In comparison with control, fertilised soils had higher Ca, Mg, P amounts, whilst the most substantial difference was seen in the amount of K. Application of wood ash also considerably increased soil pH from 3.5 (Control) to 5.9 (15 t ha-1 ). Even though showing reduced growth in unfertilised soil both alder and birch seedling survival rate was higher than 80%. The highest survival rate for birch was under wood ash treatment, while alder under 10 t ha-1 wood ash fertiliser treatment showed the lowest survival rate i.e. 81%. In total, more than 60 naturally occurring vegetation species were observed in the first and the second year of sites establishment after fertilisation. Species as Betula pendula, Betula pubescens, Populus tremula, Pinus sylvestris, Salix spp. often occurred from natural vegetation regeneration. Already after one year of vegetation succession increase in tree and shrub species cover was observed, suggesting perhaps such areas can be naturally afforested thus creating a more heterogeneous forest stand. In such a way sustaining economic use of land resources after peat extraction while providing other ecosystem services.
Possibilities of monitoring cattle via GSM and A-GPS
(2019) Sirotek, A.; Hart, J.
Nowadays, people and things can be localized using GNSS (Global Navigation Satellite System) or GSM technology. Devices using Differential Global Positioning Systems may not be suitable for they computing and energy intensity. The GSM and A-GPS systems have certain limitations and disadvantages. They are different in accuracy, energy intensity and therefore they are suitable for different applications. Trackers can’t be effectively used to locate animals, monitor their movements, and observe their behaviour. They can also be used to search for stolen pets and farm animals. Unguarded herds of cattle are often the target of thieves. For reasons of crime, localization was tested by devices using GSM and A-GPS technology. Specifically, the quality of these localization methods has been tested. Has been addressed above all, accuracy, reliability, speed and consistency of individual methods. In addition, further measurements were made. Localization has been tested in different well-defined environments. This makes it possible to judge the quality of individual localization technology and to suggest the best use of individual technologies and their link.
Influence of nitrogen fertilization on lettuce yields (Lactuca sativa L.) using the15N isotope label
(2019) Amirouche, M.; Zella, L.; Smadhi, D.
Nitrogen fertilization plays an important role in the growth of market gardening and the improvement of yields. Its efficiency of use is imperative for the preservation of the agricultural environment. An experiment is carried out over three consecutive years (2014/2015), (2015/2016) and (2016/2017), in a sub humid climate. The methodology adopted focuses on the variation of optimal nitrogen doses and their effects on the evolution of lettuce cultivation (Lactuca sativa L.), which has a socio-economic impact. The approach takes into account the isotopic marking technique, 15N. The experimental device adopted is of the complete random block type, with four (04) levels: 0 (control), 60, 120 and 180 kg N ha-1 with four (04) repetitions. These levels are used to diagnose the effect of different doses on biomass (dry matter) and yield. It has been shown those doses between 0 and 120 kg N ha-1 increase significantly (p < 0.05), yields and dry matter with values of 18.32, 45.49 to 57.93 t ha-1 and 4.32, 5.52 to 9.77 t ha-1 , respectively. The rate of 120 kg N ha-1 , is shown statistically, as the efficient rate to cover the nitrogen needs of lettuce. This efficiency reaches 74.48%. Beyond that, nitrogen is not valorized by the crop. These results contribute to the realization of a technical reference system for lettuce cultivation, for an efficient use of nitrogen.
Surface water runoff of different tillage technologies for maize
(2019) Novák, P.; Kovaříček, P.; Hůla, J.; Buřič, M.
The present paper is focused on the evaluation of efficiency of soil-conservation technologies to reduce surface water runoff in Central Bohemia Region. In the last years, there has been an increase in maize planting on hillslope plots due to the construction of many biogas plants in conditions of Czech Republic. It enhances the risk of water erosion because the occurrence of sloping lands in the Czech Republic is high. To evaluate the technologies of stand establishment a field trial was laid out with four treatments of maize planting. The trial was laid out on a plot with light soil and slope of around 12%. It was a multi-year trial. To measure erosion parameters a rainfall simulator was used (measurement of surface runoff). The values obtained in two seasons show a positive effect of the soil surface cover by organic matter when reduced soil tillage was used. Soil loss also decreased at the same time compared to treatments with conventional soil tillage. It was found up to six-fold reduction in surface runoff by appropriate soil tillage technology during two seasons of measurement.
Effects of drip irrigation on the yield of strawberry plants grown under arable conditions
(2019) Nowakowski, T.; Chlebowski, J.; Grzybowska, A.
The study investigated the effects of drip irrigation on the yield of ‘Honeoye’ strawberry plants for commercial purposes grown under arable conditions throughout the harvest season. The plants were irrigated at irregular intervals depending on natural precipitation. Crop yields and fruit parameters (diameter, length, individual weight, count per plant) were compared on several harvest dates. Statistical analysis has shown that irrigation has a significant impact on yield and fruit parameters. The irrigated plants yielded more strawberries, which also had a larger diameter, length, and individual weight.
Computational fluids dynamics (CFD) in the spatial distribution of air velocity in prototype designed for animal experimentation in controlled environments
(2019) Vilela, M.O.; Gates, R.S.; Martins, M.A.; Barbari, M.; Conti, L.; Rossi, G.; Zolnier, S.; Teles Junior, C.G.S.; Zanetoni, H.H.R.; Andrade, R.R.; Tinôco, I.F.F.
Maintaining a comfortable and productive thermal environment is one of the major challenges of poultry farming in tropical and hot climates. The thermal environment encompasses a number of factors that interact with each other and reflect the actual thermal sensation of the animals. These factors characterize the microclimate inside the facilities and influence the behaviour, performance and well-being of the birds. Thus, the objective of this study is to propose and validate a computational model of fluid dynamics to evaluate the spatial distribution of air velocity and the performance of a system designed to control air velocity variation for use in experiments with birds in controlled environment. The performance of the experimental ventilation prototype was evaluated based on air velocity distribution profiles in cages. Each prototype consisted of two fans coupled to a PVC pipe 25 cm in diameter, one at each end of the pipe, with airflow directed along the entire feeder installed in front of the cages. The contour conditions considered for the simulation of airflow inside the cage were air temperature of 35 °C at the entrance and exit of the cage; air velocity equal to 2.3 m s -1 at the entrance of the cage; pressure of 0 Pa. The model proposed in this study was representative when compared to the experimental measurements, and it can be used in the study of air flow behaviour and distribution for the improvement of the prototype design for later studies.
Finding least fragmented holdings with factor analysis and a new methodology: a case study of kargılı land consolidation project from Turkey
(2019) Arslan, F.; Değirmenci, H.; Rasva, Marii; Jürgenson, Evelin; Estonian University of Life Sciences. Institute of Forestry and Rural Engineering. Chair of Geomatics
Land fragmentation (LF) is a problem restrain agricultural activities and decrease mechanization level, production. Land consolidation (LC) projects are done in the World as well as Turkey to solve LF issues. Researchers created indicators to measure land fragmentation which is important to see success level of LC projects. The use of these indicators is controversial or not accurate. The core aim of the present study is to find new land fragmentation index and to find least fragmented holding with factor analysis using the other indicators which are Simmons, Januszevski, number of parcels, Shmook and Igbozurike besides new land fragmentation index. Kargılı Village land consolidation project in Mersin, Turkey was chosen as a material. Cadastral data before land consolidation, was used to calculate value of indicators, where number of parcels was 932, total area was 1,741.9 ha, the average parcel size was 1.9 ha, number of holdings was 542 and the average parcel size was village had 932 parcels. Data processing were performed with ArcMAP 10.6.1 and SPSS. A total of 18 holdings were identified randomly as sample size which were sufficient to carry out factor analysis including principle component to rank holdings (P < 0.01).As a result, new land fragmentation index found correlated with others (P < 0.01) and ranking according to new indicator performed better than ranking considering all indicators. In this context, it is possible to use new land fragmentation indicator to determine priority areas for land consolidation.
Most appropriate measures for reducing ammonia emissions in Latvia’s pig and poultry housing
(2019) Priekulis, J.; Melece, L.; Laurs, A.
New goals of ammonia emissions reduction for each of EU Member State, including Latvia, were approved by the EU Directive 2016/2284/EU ‘on the reduction of national emissions of certain atmospheric pollutants’. Agriculture sector, particularly livestock farming, is the main source of these emissions. Besides, the implementation of modern or intensive animal rearing/breeding technologies causes the increase of emissions in Latvia. Therefore, more effective ammonia abatement measures or techniques should be chosen for implementation in Latvia to reach the objectives. The description and benefits of such measures are provided in the guidelines and recommendations developed and approved by the United Nations Economic Commission for Europe (UNECE) and the European Commission. However, all of these recommendations are not applicable in Latvia. Therefore, the aim of research was to find most appropriate ammonia emissions abatement measures for pig and poultry farming in Latvia. The study was focused on the intensive pig and poultry farming, particularly animal housing. Evaluation or assessment of most appropriate ammonia emissions’ reduction measures was conducted using an expert method. The results of the study indicate that it is possible to ensure reduction of ammonia emissions by comparatively simple and less expensive options that could be more or less easy implemented (e.g. ensuring cleanness in the livestock building, periodical removal of manure, covering of poultry litter or solid manure stockpiles with plastic sheeting, etc.). Even more effective reduction of ammonia emissions can be achieved by implementation of measures, which require significant investments, as well as additional operating costs.
Controlled traffic farming delivers better crop yield of winter bean as a result of improved root development
(2019) Kaczorowska–Dolowy, M.; Godwin, R.J.; Dickin, E.; White, D.R.; Misiewicz, P.A.
This paper reports on the continuation of a long–term experiment on the effects of alternative field traffic systems (STP–random traffic with standard tyre inflation pressure, LTP– random traffic with low tyre inflation pressure and CTF–controlled traffic farming) on soil conditions and crop development as influenced by different tillage depths (DEEP–250 mm, SHALLOW–100 mm and ZERO–tillage), in a randomised 3 x 3 factorial design in 4 replicates launched by Harper Adams University in Edgmond, UK, in 2011. The results from season 2017– 2018 revealed that CTF delivered 8% higher crop yield of winter field bean (Vicia faba) cv. Tundra comparing to STP (p = 0.005), i.e. 4.13 vs 3.82 tonnes ha-1 respectively (at 14% moisture content). The ZERO–tillage plots featured significantly lower plant establishment percentage comparing to shallow and deep tillage: 79% vs 83% and 83% respectively (p = 0.012). The research showed that roots traits differed significantly between contrasting traffic at depths greater than 50mm with p < 0.05 of: tap root biomass, number of lateral roots, biomass of lateral roots as well as total root biomass (tap+lateral roots), delivering significantly greater values of those before mentioned parameters on CTF comparing to STP. Tap root length significantly differed between traffic systems (p < 0.001) giving significantly greater results on CTF comparing to LTP and STP (17.7, 13.4 and 12.6 mm respectively). Significant differences in tap root diameter were found only at the depth of 100 mm (p < 0.001) where again CTF delivered significantly higher root diameter than the remaining 2 traffic systems. In the shallow layer of soil (0–50 mm) a significant difference was found only for tap root biomass, for interactions, where STP ZERO gave significantly higher results than STP SHALLOW and CTF SHALLOW (1.430, 0.733 and 0.716 g respectively).
Role of humic substances in agriculture and variability of their content in freshwater lake sapropel
(2019) Stankevica, K.; Vincevica-Gaile, Z.; Klavins, M.
The term ‘humic substances’ (HS) refers to a general category of naturally occurring, biogenic, heterogeneous organic substances. They create the most widespread natural organic matter found in sediments, soils and waters. Organic carbon in soil (up to 70%) and peat (up to 90%) usually occurs in the form of HS. HS influence the formation process of fossil fuels, as well as they are involved in the plant nutrition process, have an influence on availability and toxicity of metallic and other elements. Furthermore, HS play a significant role in the global carbon geochemical cycle. Properties and application efficiency of humus depend on the source of HS. Freshwater sapropel is a huge reservoir of HS with superior biological activity, although their total content is lower than in peat. The aim of this paper, firstly, was to present the information about the options of HS in agriculture and their main effects on plant growth. Secondly, determination and characterization of HS content in freshwater lake sapropel was performed as sapropel nowadays becomes a popular natural organic-mineral fertilizer and soil conditioner. Sapropel samples were derived from Lake Pilvelis, Lake Pilcines, Lake Vevers, Lake Liducis and Lake Padelis situated in Eastern Latvia. Investigation of HS content in sapropel is significant for the Baltic States and Northern Europe due to wide distribution and availability of sapropel in freshwater bodies. That promotes a search for new ways of extraction methods and bioeconomically effective utilization of this natural resource, obtainable in economically significant amounts, with high opportunities of its use especially in agriculture. Contemporary agriculture strongly desiderates in new products of high effectivity enhancing soil and crop productivity and quality hand in hand with sustainable development and careful attitude to the nature and surrounding environment, thus, one of the ways how it can be achieved is understanding how, where and how much HS preparations can be applied.
Effect of nitrogen fertilization management on mineral nitrogen content in soil and winter wheat productivity
(2019) Skudra, I.; Ruza, A.
In recent years farmers must use integrated crop growing principles. One of the most important principle isto balance usage of mineral elementsin crop cultivation, especially nitrogen management. Excessive and unbalanced usage of nitrogen fertilizer reduces nitrogen use efficiency and increases nitrate leaching in surface and groundwater. The dynamics of nitrogen forms in soil at different depths and different plant growth stages are studied to increase the productivity of winter wheat, promoting nitrogen uptake in plants and reducing nitrogen leaching during the vegetation period. Field experiments were carried out at the Research and Training Farm Vecauce of the Latvia University of Life Science and Technologies from 2012 till 2015. Researched factors were nitrogen (N) fertilizer rate: 0 – control, 85, 153, 187, and N rate determined by chlorophylmeter (Yara N-tester) 180 (2012/2013), 150 (2013/2014), 205 (2014/2015) N kg ha-1 , nitrogen and sulphur (S) fertilizer rate – N175+S21 kg ha-1 , and conditions of the growing seasons: 2012/2013, 2013/2014 and 2014/2015. The content of nitrate (NO3–N) nitrogen and ammonium (NH4–N) nitrogen was determined in the soil layers 0–20 cm, 20–40 cm and 40–60 cm at the growth stages (GS) 30–32, 49–51, 69 and 90–92. All trial years the amount of nitrate nitrogen and ammonium nitrogen in soil decreased during vegetation, but increased with increasing fertilization dose. Nitrate nitrogen content was significantly influenced by year in 0–40 cm soil layer (P < 0.01) and by nitrogen fertilizer in the 20–40 cm soil layer. Ammonium nitrogen content had significant influence only on nitrogen fertilizer at 20–40 cm soil layer (P < 0.05). Average grain yields did not show significant correlation with the nitrate nitrogen and ammonium nitrogen in different soil layers and plant growth stages, except nitrate nitrogen content in soil layer 40–60 cm at GS 30–32 and ammonium nitrogen content in soil layer 40–60 cm at GS 69 and GS 90–92.
Review: Soil compaction and controlled traffic farming in arable and grass cropping systems
(2019) Antille, D.L.; Peets, S.; Galambošová, J.; Botta, G.F.; Rataj, V.; Macak, M.; Tullberg, J.N.; Chamen, W.C.T.; White, D.R.; Misiewicz, P.A.; Hargreaves, P.R.; Bienvenido, J.F.; Godwin, R.J.
There is both circumstantial and direct evidence which demonstrates the significant productivity and sustainability benefits associated with adoption of controlled traffic farming (CTF). These benefits may be fully realised when CTF is jointly practiced with no-tillage and assisted by the range of precision agriculture (PA) technologies available. Important contributing factors are those associated with improved trafficability and timeliness of field operations. Adoption of CTF is therefore encouraged as a technically and economically viable option to improve productivity and resource-use efficiency in arable and grass cropping systems. Studies on the economics of CTF consistently show that it is a profitable technological innovation for both grassland and arable landuse. Despite these benefits, global adoption of CTF is still relatively low, with the exception of Australia where approximately 30% of the grain production systems are managed under CTF. The main barriers for adoption of CTF have been equipment incompatibilities and the need to modify machinery to suit a specific system design, often at the own farmers’ risk of loss of product warranty. Other barriers include reliance on contracting operations, land tenure systems, and road transport regulations. However, some of the barriers to adoption can be overcome with forward planning when conversion to CTF is built into the machinery replacement programme, and organisations such as ACTFA in Australia and CTF Europe Ltd. in Central and Northern Europe have developed suitable schemes to assist farmers in such a process.
Possibilities for the biological control of yellow rust (Puccinia striiformis f. sp. tritici) in winter wheat in Latvia in 2017–2018
(2019) Feodorova-Fedotova, L.; Bankina, B.; Strazdina, V.
Yellow rust, caused by Puccinia striiformis f. sp. tritici, is a significant wheat disease worldwide. In Latvia, the distribution of yellow rust has increased recently and new aggressive races have been identified. The aim of this research was to investigate the possibilities for the biological control of yellow rust in winter wheat. A field trial was established in a biological field of winter wheat in Latvia in 2017 and 2018. Biological products that contained Bacillus spp., Pseudomonas aurantiaca, Brevibacillus spp., Acinetobacter spp., and chitosan were used for treatments, and one variant was left untreated. The efficacy of products was evaluated by the AUDPC (area under the disease progress curve) comparison. Differences in the severity of yellow rust between the trial years were observed. In 2018, the severity of yellow rust was lower than in 2017. In untreated plots, on flag leaf, the severity varied from 10.9% to 32.5% in 2017 and from 1.4% to 6.5% in 2018. In 2017, the severity of yellow rust reached its maximum on 05.07. at wheat growth stage (GS) 79, and in 2018 – on 20.06. GS 79. Both in 2017 and 2018, no significant differences (p > 0.05) were found in AUDPC values among the variants. After two years of investigations, the results were not convincing; therefore, further research is needed.
A software to estimate heat stress impact on dairy cattle productive performance
(2019) Teles Junior, C.G.S.; Gates, R.S.; Barbari, M.; Conti, L.; Rossi, G.; Vilela, M.O.; Souza, C.F.F.; Tinôco, I.F.F.
The aim of this study is to develop a computational tool, based on the Temperature and Humidity Index value, to characterize the thermal environment in dairy cattle barns and to evaluate the impact of thermal stress on productive performance. The software for the thermal environment prediction, and determination of the influence of heat stress on dairy cow productivity (Ambi + Leite) was developed using the C# programming language in the Microsoft Visual C# 2010 Express Integrated Development Environment. The following scenario was considered for the program test: air temperature 32°C, relative air humidity 70% and milk production potential in thermoneutrality condition 20 kg cow-1 day-1 . The prediction of the thermal environment based on the simulated situations indicates that the animals are submitted to a moderate heat stress condition with THI equal to 82.81. In this condition a decrease of approximately 26% in milk production and a reduction of 4 kg cow-1 day-1 in food intake was calculated. In conclusion, the developed software can be a practical tool to assist the producer in making-decision processes.
Bioenergy in agricultural companies: financial performance assessment
(2019) Nurmet, Maire; Mõtte, Mati; Lemsalu, Katrin; Lehtsaar, Jüri; Estonian University of Life Sciences. Institute of Economics and Social Sciences
The target of increasing the use of renewable energy in rural areas has initiated the investments in bioenergy. The purpose of this paper is to assess the financial performance of Estonian agricultural companies that have invested in bioenergy solutions. An investment in bioenergy is attractive to the company if the results obtained by it enable benefits to the investors. In the context of the study of financial performance of agricultural companies that have undertaken bioenergy investments, the key performance indicators based on DuPont identity are analysed from the perspective of formulating and implementing a company’s financial decisions. The data of financial statements of the analysed companies are from Estonian Agricultural Registers and Information Board (ARIB) and Commercial Register. The study reports the financial performance results of Estonian agricultural companies using renewable resources and producing bioenergy: whether they achieved higher efficiency and profitability or change in financial structure. The Estonian agricultural companies that have invested in bioenergy solutions may need to control their financial performance by improving profitability and controlling financial leverage.
Single cell oil production from waste biomass: review of applicable agricultural by-products
(2019) Spalvins, K.; Blumberga, D.
Single cell oil (SCO) is an attractive alternative source of oils, since it can be used as feedstock in biofuel production and also have been recognized as viable option in production of essential fatty acids suitable for either human nutrition or as supplementary in animal feeds. However, the usability of SCO is limited due to the high price of raw materials used in the fermentation process. This problem can be tackled by using low-cost agro-industrial residues which are applicable for SCO production. Use of these by-products as the main carbon source in fermentations not only significantly reduces the overall production costs of SCO, but also enables treatment of generated waste streams, thus reducing the negative impact on environment. Since various biodegradable agro-industrial by-products can be used in microbial fermentations, this review aims to categorize and compare applicable agricultural residues by their availability, necessary pre-fermentation treatments, SCO yields and current usability in other competing sectors.
Alternative form to obtain the black globe temperature from environmental variables
(2019) Zanetoni, H.H.R.; Tinôco, I.F.F.; Barbari, M.; Conti, L.; Rossi, G.; Baêta, F.C.; Vilela, M.O.; Teles Junior, C.G.S.; Andrade, R.R.
Reaching thermal comfort conditions of animals is essential to improve well-being and to obtain good productive performance. For that reason, farmers require tools to monitor the microclimatic situation inside the barn. Black Globe-Humidity Index (BGHI) acts as a producer management tool, assisting in the management of the thermal environment and in decision making how protect animals from heat stress. The objective of this work was to develop a mathematical model to estimate the black globe temperature starting from air temperature, relative humidity and air velocity. To reach this goal, data of air temperature and humidity were collected, with the aid of recording sensors. The black globe temperature was measured with a black copper globe thermometer and the air velocity was monitored with a hot wire anemometer. Data were analysed using a regression model to predict the black globe temperature as a function of the other variables monitored. The model was evaluated, based on the significance of the regression and the regression parameters, and the coefficient of determination (R²). The model proved to be adequate for the estimation of the black globe temperature with R2 = 0.9166 and the regression and its parameters being significant (p < 0.05). The percentage error of the model was low (approximately 2.2%). In conclusion, a high relation between the data estimated by the model with the data obtained by the standard black globe thermometer was demonstrated.
Hydrothermal carbonization and torrefaction of cabbage waste
(2019) Tamelová, B.; Malaťák, J.; Velebil, J.
In recent years, waste biomass has been increasingly becoming an energy source. The utilization of biomass includes a number of potential treatments: thermochemical, physicochemical and biochemical. In the food industry, significant amounts of biodegradable wastes are produced which have to be quickly treated to not pose an environmental problem. In this work cabbage waste (Brassica oleracea var. capitata) was treated by hydrothermal carbonization and torrefaction. Hydrothermal carbonization experiments were carried out in a pressure reactor vessel Berghof BR-300 (inner volume 400 mL, temperature regulation by Berghof BTC 3000). The carbonization took place at target temperatures 180 °C and 225 °C. Torrefaction tests were carried out in a thermogravimetric programmable oven LECO TGA701 under nitrogen atmosphere at temperatures 225 °C, 250 °C and 275 °C. The residence time was 30 min for both processes. Proximate and elemental composition, as well as calorific value was analysed in all samples. To express the influence of the treatments on combustion behaviour, stoichiometric combustion calculations were performed. The analyses show a positive effect of both torrefaction and hydrothermal carbonization on fuel properties in the samples. Most obvious is the reduction in oxygen content which depends on the process temperature. After hydrothermal carbonization at 225 °C the oxygen content was lowered by 46.7%. The net calorific value increased proportionally with temperature in both processes. After hydrothermal carbonization at 225 °C the net calorific value increased on average by 3 MJ kg-1 to 20.89 MJ kg-1 . Both tested processes significantly increased the fuel value of this biodegradable waste.
Numerical modelling of process of cleaning potatoes in spiral separator
(2019) Bulgakov, V.; Nikolaenko, S.; Holovach, I.; Adamchuk, V.; Ruzhуlo, Z.; Olt, Jüri; Estonian University of Life Sciences. Institute of Technology
Cleaning potato tubers from soil and plant residues after their digging from the soil is a topical problem in the industrial production of potatoes. Taking into account the fact that the cleaning spirals are positioned with overlapping and rotate in the same sense, the potato tuber that has landed on the surface of the spiral separator in the trough between two adjacent spirals will perform translational motion towards the output ends of the spirals. As a result of solving the said system of equations, the graphical relations between the values of the normal reactions and friction forces generated during the translation of the potato tuber along the mentioned spirals, on the one hand, and the design and kinematic parameters, on the other hand, based on the requirement of not damaging tubers when performing the said work process of transportation and cleaning, have been obtained. The limitations for the normal reactions and friction forces at the points of contact between the tuber and the surface of the cleaning spiral are set in accordance with the requirement that they do not exceed the force of scraping (damaging) the tuber’s external surface permissible for potato tubers. That has provided an opportunity to obtain the rational values of the design and kinematic parameters of the separator’s operating spirals, in particular, the value of the angular velocity of the rotating cleaning spirals as well as their radius and helix lead.

Sirvi

Sirvi 2019, Vol. 17, No. 3 Kuupäev järgi

Tulemused lehekülje kohta

Sorteerimisvalikud