2018

Selle valdkonna püsiv URIhttp://hdl.handle.net/10492/5371

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Theory of retaining potato bodies during operation of spiral separator
(2018) Bulgakov, V.; Nikolaenko, S.; Adamchuk, V.; Ruzhуlo, Z.; Olt, Jüri; Estonian University of Life Sciences. Institute of Technology
The increase of the efficiency and quality of performance of the work process of potato heap separation can be achieved by means of improving the design of the vibrational spiral separator and substantiating theoretically its rational parameters under the condition of eliminating damage to the potato tubers. An equivalent schematic model of the interaction between the potato tuber and the surface of the cantilever spiral springs has been devised. On the basis of the model, the kinematic characteristics of the tuber’s flight and its impact contact with the elastic surface of the over mounted rebounding conveyor have been investigated. A new analytical mathematical model of the potato tuber’s flight from the surface of the spiral separator and its subsequent encounter with the rebounding conveyor mounted above the spiral springs has been developed. New analytical dependences have been obtained for finding out the distance and height of the potato tuber’s flight to the point of impact contact as well as the trajectory equation fo r the travel to the said contact, which makes it possible to obtain the kinematic constraints imposed on the allowed rate of travel under the condition of not damaging the tuber. On the basis of the obtained analytical dependences, the kinematic parameters of the improved design of the spiral potato harvester separator in its interaction with a potato tuber under the condition of not damaging the latter have been investigated .
Volatile combustible release in biofuels
(2018) Vitázek, I.; Majdan, R.; Mojžiš, M.
Plant biomass consists of varied materials. Biomass is used for different purposes, but it is most frequently burnt in modern combustion devices for heat production. The quality of solid biofuels depends on the total content of combustibles while the volatile combustible content affects the combustion process. The aim of the paper is to determine the exact content of the biofuel components by the means of the gravimetric method – namely volatile combustible, ash and moisture content – and to evaluate the process of volatile combustible release as a function of temperature during the experiment. The device Nabertherm L9/11/SW/P330 type with accessory was used to carry out the experiments. Various biofuel samples were examined, namely wood (9 kinds), wood cuttings and wood chips (2 kinds), pellets (4 kinds), sawdust (1 kind), compared to less traditional fuels (DDGS and RME – 2 kinds) and wood coal (1 kind). The tables and graphs present the experimental results, which allow evaluation of the components content in different biofuels and provide characteristics of the process of volatile combustible release in analysed fuels. Spruce wood without bark showed the highest content of combustible (99.89%). Sawdust of fruit trees contains the highest proportion of volatile combustible (93.978%) and releases the combustible at the highest rate (15.25 mg h-1).
Sunlight potential for microalgae cultivation in the mid-latitude region – the Baltic states
(2018) Stunda-Zujeva, A.; Zuteris, M.; Rugele, K.
Products, e.g. food and feed from microalgae are a promising part of bioeconomy. One of the most investigated and highly demanded microalgae is Spirulina . Light is one of limi ting factors for biomass cultivation by photosynthesis. Sunlight is cheap and climate friendly light source. The aim of this study was to evaluate available sunlight potential in the mid - latitude region - the Baltic states (Europe, 55 – 60 °N ) for microalgae, e.g. Spirulina growth. The data of Climate atlas based on satellites of EUMETSAT and data from an observation station in Riga were analyzed. The latitude and climate (cloudiness) were main parameters affecting the total solar radiation re ceived by Earth’s surface. The sunlight potential in the Baltic states was higher than in most of Europe in similar latitude. Multi - year mean daylight intensity in the Baltic states was slightly less than in Southern France or Bulgaria, (26 klux and 30 klu x , respectively, in summer) where Spirulina is commercially produced. Hourly solar radiation varied a lot in the Baltic states – from 880 W m - 2 to 200 W m - 2 , sunny and overcasted noon of summer day , respectively; average value (8 a.m. – 4p.m.) was 450 W m - 2 . Summer days are longer than 12 h, reaching 18 h in midsummer. The sunlight potential is suitable for microalgae, e.g. Spirulina cultivation in this period. From November till February days are shorter than 10 h and solar radiation is less than 300 W m - 2 e ven in noon of sunny days.
Investigation into the performance characteristics of electric automobiles by means of a data logger
(2018) Berjoza, D.; Pīrs, V.; Jurgena, I.
Fossil fuel deposits are constrained in the world. Various alternative energy sources are introduced in vehicles to limit the depletion of fossil fuel reserves and to reduce environmental pollution. One of the alternative energy sources is electricity. Th e use of electric automobiles has begun in the Baltic States too, yet accurate performance parameters of the automobiles, which could sometimes differ from the technical characteristics specified, are not always known. Road testing an electric automobile w as performed using a data logger that recorded the battery’s voltage, current, temperature and the automobile’s speed. These parameters allowed computing changes in the electric automobile’s power output under various driving regimes, e.g. acceleration or braking. Road testing the electric automobile was done under two driving regimes – urban and non - urban – on a certain route. The experiment represented a full cycle road test, with the batteries fully charged, that lasted until the batteries were discharge d to a minimum level, which was limited by the battery management system (BMS). The experiment identified the maximum current as well as the effectiveness of the regenerative braking system.
Extended use of Sphagnum peat as a biosorbent for Zn(II): repetiti ous sorption-desorption process
(2018) Denisova, V.; Tihomirova, K.; Mezule, L.
In this study, continuous biosorption - desorption cycles in a fixed - bed column were performed to evaluate the extended use of sphagnum peat as biosorbent material to remove Zn(II) ions from aqueous solutions. Biosorption - desorption studies revealed that the sphagnum peat as biosorbent could be regenerated using 0.1M HCl as eluting agent with more than 70% recovery in four successive biosorption - desorption cycles. The results showed that the sphagnum peat should be used as an alternative, effective and low - cost biosorbent for Zn(II) ions removal from polluted aqueous solution.
Typological analysis of the sustainability of dairy cattle farming in the Chelif valley (Algeria)
(2018) Ouakli, K .; Benidir, M .; Ikhlef, S .; Ikhlef, H .
To identify production systems that could increase local milk production in a sustainable manner, a study was conducted on 135 dairy farms in the three main plains of the Chelif Valley, Algeria. These have been evaluated for environmental, social and econo mic sustainability based on the IDEA (Farm Sustainability Indicators) method. The Principal Component Analysis identified 4 different types dairy production systems, namely Type 1: Medium - size dairy farms with cereal crop production; Type 2: Small - size dai ry farms; Type 3: Medium - size dairy farms diversified crop production, and Type 4: Large - size dairy farms with diversified crop production. Comparative analysis of ecological sustainability showed better results for medium - size dairy farms with cereal crop production (52.3 ± 10.17 / 100 points) and for large - size dairy farms with diversified crop production (51.6 ± 10.38 / 100 points), while the economic sustainability was better for medium - size dairy farms with diversified crop production (51.6 ± 19.20 / 1 00 points). On the other hand, social security was the weak point for all farm types. On the regional level, it appeared that agri - environmental scores were better in Middle and Low Chelif valley while the best economic performances were recorded in High C helif valley. On the regional level, it appears that the scores of agri - environmental scales are better in the middle and low Chelif while the economic performances are comparable between the three localities.
Humus content in a podzolized chernozem after a long-term application of fertilizers in a field crop rotation
(2018) Hospodarenko, H.; Prokopchuk, I.; Prokopchuk, S.; Trus, А .
The article presents the results of the research into influence of a long - term (50 years) application of different fertilizer rates and fertilizer systems in the field crop rotation on the humus composition and optical parameters of humic acids of a heavy - loamy podzolized chernozem of the Right Bank Forest - Steppe of Ukra ine. It was found that application of fertilizers significantly affects the dominance of humic acids over fulvic acids in the composition of soil, which indicates humate type of soil. Chroma index of humic acids is within 3.56 – 3.75 depending on a fertilize r. Indicators of the optical properties of humic acids of a podzolized chernozem have a high degree of humification.
Flash points of gasoline from Kukersite oil shale : Prediction from vapor pressure
(2018) Rannaveski, Rivo; Listak, Madis
The flash point of liquid fuels, especially of light distillates such as gasoline or naphtha, is an important parameter for the handling of such materials. In this work, flash points and volatility characteristics (vapor pressure, boiling point) of a numbe r of shale gasoline samples with different volatilities were measured. The shale gasoline fractions were produced from Kukersite oil shale using solid heat carrier retorting technology. Several existing correlations for calculating flash points of hydrocar bons and petroleum fractions are evaluated, and the absolute average deviations were found to be between 1.1 to 20.9 °C . New, easy - to - use correlations are proposed for estimating flash points for oil shale based gasolines from volatility characteristic tha t are readily available. The correlation proposed in this work are based on the vapor pressure at 20 or 37.8 °C (100 °F ), Reid vapor pressure (37.8 °C ) or boiling point. The average absolute deviations for these correlations were 0.82 to 0.93 °C , meaning t hey are comparable to or better than existing methods developed for petroleum oils, which mostly use boiling point as the input parameter, when applied to gasoline from Kukersite oil shale.
Properties of local produced animal-fat based biodiesel and its blend with fossil fuel
(2018) Sirviö, K.; Heikkilä, S.; Help, R.; Niemi, S.; Hiltunen, E.
In the near future, more emphasis must be put on reducing greenhouse gas (GHG) emissions in road transportation, house heating, agricultural activities, marine transport etc. This study concentrated on the use of alternative fuels in engine - driven applicat ions of non - road machineries and decentralized energy production . Today, the engines are mainly designed for crude oil derived fuels and liquid renewable fuels are blended with crude oil based fuels to fulfill the requirements of renewable energy usage. Du e to the environmental reasons on one hand and to the agricultural needs, on the other hand , different blends of bio - and fossil fuels are becoming more popular. In Europe, the maximum FAME content in diesel fuel is 7 vol% according to the EN 590:2013 but higher percentages are also available and targeted around the world. For example in the United States, the 20% blend fraction is becoming more common. For these reasons, B20 fuels were chosen to be investigated in this study. Special emphasis was put on im proving blending issues since fuel blending may cause some operating risks. The main aim was to research widely the properties of animal - fat based methyl ester (AFME) and B20 fuel blend produced from it. AFME is a waste based fuel and produced in Ostroboth nia region, Finland. The aim was to find out in which engine applications the fuels are feasible and investigate if the fuels fit in the quality of automotive fuel Standards. According to the results, AFME is a feasible option to increase self - sufficient e ne rgy production in Ostrobothnia.
Air-conditioning in the cabins of passenger cars
(2018) Kumar, S.; Cerny, J.; Kic, P.
The objective of this paper is to analyse the current state of the constructional design and operational conditions of air - conditioning device in passenger cars. The research was focused on the function of air - conditioning equipment of passenger cars Skoda and KIA in various modes of operation during the winter, spring and summer season at different levels of air conditioning (without air - conditioning, minimum, medium and maximum level). Air temperature, air humidity, globe temperature, CO 2 concentration, dust concentration and noise inside the cabin w ere measured. Solar radiation plays a big role to rise up temperature inside the cabin. It resulted in the higher values of globe temperature than temperature of the air. The results of the measurements showed that CO 2 values were significantly lower than 2,500 ppm at minimum air - conditioning, lower than 600 ppm at medium and lower than 500 ppm at maximum level of air - conditioning. For all vehicles, dust concentration was greater when it measured with the air conditioning switched off than with the air con ditioning system turned on. The measurements confirmed that the total dust concentration was not more than 47 μg m - 3 , PM 10 lower than 28 μg m - 3 and PM 1 lower than 27 μg m - 3 . The noise levels ranged from 49.1 to 68.7 dB(A). The air - conditioning had very positive impact on the inside comfort in car cabins from all points of view during all periods of the year.
Solution for remote real-time visual expertise of agricultural objects
(2018) Komasilovs, V.; Zacepins, A.; Kviesis, A.; Nasirahmadi, A.; Sturm, B.
In recent years automated image and video analyses of plants and animals have become important techniques in Pre cision Agriculture for the detection of anomalies in development. Unlikely, machine learning (i.e., artificial neural networks, support vector machine, and other relevant techniques) are not always able to support decision making. Nevertheless, experts can use these techniques for developing more precise solutions and analysis approaches. It is labour - intensive and time - consuming for the experts to continuously visit the production sites to make direct on - site observations. Therefore, videos from the site n eed to be made available for remote viewing and analysis. In some cases it is also essential to monitor different parts of objects in agriculture and animal farming (e.g., bottom of the plants, stomach of the animal, etc.) which are difficult to access in standard recording procedures. One possible solution for the farmer is the use of a portable camera with real - streaming option r ather than a stationary camera. The aim of this paper is the proposition of a solution for real - time video streaming of agricultural objects (plants and/or animals) for remote expert evaluation and diagnosis. The proposed system is based on a Raspberry Pi 3, which is used to transfer the video from the attached camera to the YouTube streaming service. Users will be able to watch the video stream from the YouTube service on any device that has a web browser. Several cameras (USB, and Raspberry Pi camera) and video resolutions (from 480p till 1 , 080p) are compared and analysed, to find the best option, taking into account video quality, frame rates, and latency. Energy consumption of the whole system is evaluated and for the chosen solution it is 645 mA.
Effect of nitrogen fertilization on sorghum for biomass production
(2018) Pannacci, E.; Bartolini, S.
Two field experiments were carried out in 2005 and 2006 in central Italy in order to evaluate the effects of different nitrogen (N) application rates (0, 50 100 and 150 kg ha-1 ) on flowering date, plant height, biomass production and partitioning (leaves, panicles and stems) and biomass quality of a sorghum hybrid (H133). Sorghum showed a high potential in terms of biomass production without N fertilization (18.5 t ha-1 of d.m. in 2005 and 26.6 t ha-1 of d.m. in 2006). The rate that maximized the biomass production was 100 kg ha-1 of N, increasing the biomass dry weight by 23.8% in 2005 and 18.8% in 2006, with respect to unfertilized sorghum; higher N rates are not advisable in order to avoid increasing fertilization costs and environmental impact without benefit of greater biomass production. The two highest N rates when combined with low water availability appeared to increase the rate of plant development, causing earlier flowering and increasing the percentage of panicles in total biomass. Higher heating value (HHV), lower heating value (LHV) and ash concentration of biomass varied among N rates, with values of HHV and LHV lower for unfertilized sorghum (17.6 and 16.7 MJ kg-1 d.m., respectively) than when N was applied (from 19.0 to 19.7 and from 18.1 to 18.8 MJ kg-1 d.m., respectively); on the contrary, ash concentration was greater for unfertilized sorghum (7.5% d.m.) than for fertilized sorghum (from 5.8 to 6.7% d.m.). This research showed the high potential of sorghum in terms of biomass production also when cultivated with limited irrigation and fertilization inputs. The biomass dry yield obtained by one hectare of sorghum crop without N nitrogen fertilization (i.e. 22.6 t ha-1 of d.m., average of 2005 and 2006 values) produces the same energy, by thermal utilisation, of 9.3 toe, that is equivalent to energy produced by 10,385 L of diesel fuel or 11,097 m3 of methane fuel. This aspect increases the certainty of the energetic and environmental sustainability of sorghum crop.
Evaluation of reed biomass use for manufacturing products, taking into account environmental protection requirements
(2018) Muizniece, I.; Kazulis, V.; Zihare, L.; Lupkina, L.; Ivanovs, K.; Blumberga, D.
In many countries reed is considered as invasive or unnecessary plant, because it is spreading rapidly, causing decrease in biodiversity and creating unacceptable living conditio ns for many bird species in their natural habitats. Due to environmental considerations it is necessary to cut reed, to decrease their over exceeding growth. Reed burning or leaving for decomposition on fields, that has been practiced until now, creates ad ditional carbon dioxide air pollution. Therefore, the question on what to do with cut reed has become vital from environmental protection perspective. In addition, this question applies to bioeconomy principles in compliance with their use in national econ omy, which makes it clear, that solutions for the use of reed biomass for production have to be found. But any production process can leave a negative effect on surrounding environment. Further to product production, economic motivation, possible market an d availability of resources are primarily essential to see whether it is worth to produce the product at all. Therefore, reed biomass use possibilities in production have to be analysed as a complex question, taking into account environmental and climate, economic and technological aspects. In this study, solutions to perspective reed biomass use are evaluated, considering environmental protection requirements. For this task, multi - criteria analysis method TOPSIS is used, which includes 11 environmental and climate, economic and technological criteria. Evaluation includes both – already existing and new products that are divided in 3 sectors: power industry, construction and other products. Results of the research clearly state, which of reed biomass made pr oducts are perspective, taking into account not only traditional economic and technological aspects, but also envi ronmental and climate aspects.
Application of conversion model for designing hydrodynamic pumps in turbine mode
(2018) Polák, M.
The use of the smallest water resources has been coming again to the centre of interest in recent years. A water engine – turbine, is the heart of these power plants. This is usually the highest expense for the investor, in terms of cost. The effort is therefore to seek investment less demanding alternatives. One of them is the use of hydrodynamic pumps in reverse turbine operation. This paper provides a methodology for conversion of parameters of the smallest power pumps (micro hydro sites) to turbine operation. The conversion model is based on the results of experimental research at the author's workplace and is suitable for pumps with low specific speeds and outputs. The pump design process for turbine mode is complemented by a practical example for a specific deployment site. This example also serves to verify the accuracy of the conversion model.
Effect of drying technologies on bioactive compounds maintenance in pumpkin by-products
(2018) Kļava, D.; Kampuse, S.; Tomsone, L.; Kince, T.; Ozola, L.
During the pumpkin processing large amounts of waste material as a combination of pumpkin peel, seeds and the flesh between seeds has produced. Therefore it is important to investigate the possibilities for using the pumpkin residues. The aim of this resea rch was to investigate the effect of different drying technologies on maintenance of bioactive compounds in pumpkin by - products. Two pumpkin residue products of Hubard group pumpkins were used to obtain pumpkin powder: residue products formed in the proces s of extracting industrial pumpkin purée by heating it in a heat exchanger and treating through a sieve of pulpier; residues resulting from pumpkin juice extraction process mechanically pressed from fresh, chopped pumpkins. In order to be able to choose th e most suitable drying technology pumpkin by - products were dried in the microwave - vacuum, convective (at 40, 50, 70 and 80 °C ) and freeze - drying type dryers. For all samples total carotenes, the ascorbic acid, total phenols content (TPC) and antiradical ac tivity (DPPH ̇, ABTS ̇+ ) were determined by using standard methods. The highest total carotenes content was retained in freeze - dried pumpkin powders. The most suitable drying method for obtaining pumpkin powder with the highest ascorbic acid, total phenolic content and antiradical activity is drying in convective type drying at 80 °C temperature.
The potential use of invasive plant species as solid biofuel by using binders
(2018) Zihare, L.; Soloha, R.; Blumberga, D.
The aim of the current research is to find sustainable pellet resources that are not made from forestry, agricultural materials, or food products. Evaluation has been carried out by experimentally determining the biofuel parameters of two invasive plant sp ecies. In comparison to the process of finding a new application, their use in the production of solid biofuel pellets would not require additional investment for the construction of a new pellet production plant. The article’s hypothesis suggests that bio fuel parameters for invasive plant species are sufficient for the production of solid biofuel and that their properties can be improved by binders that are available wor ldwide in the form of residues. The experiment was carried out for two invasive plant s pecies that are widespread in Latvia – Heracleum sosnowskyi Manden and Solidago canadensis L . The binders used include potato peel waste and spent coffee grounds. All of the tests have been carried out according to ISO standards on biofuel testing. Results show that H sosnowskyi is more suitable for solid biofuel than S canadensis as it has a higher calorific value and an ash content that is two times lower – 3wt%. Coffee grounds are a suitable binder b ecause they increase calorific value. The type and amount of binders partly confirms the hypothesis, since both binders reduced the amount of ash in pellets. Further research is needed to carry out pellet durability tests. It is also necessary to carry out an economic analysis in order to evaluate how beneficial it may be to use H sosnowskyi as a solid fuel in existing pellet production plants, thereby avoiding large initial investments and not encouraging the cultiva tion of invasive plant species.
Efficiency of the use of field beans in fattening lambs
(2018) Kairisa, D.; Aplocina, E.
The breeding and feeding of self produced pulses to livestock is one of the important directions of research for reducing the production costs of livestock products. Experiment on the effective using of the field beans to lambs for fattening was arranged in three replications using the Latvian Da rk - headed breed male lambs. The mixture of concentrated feed consisted of 50% of bean and 50% of oat. Lambs were weighed at the starting and ending of the trial. Carcass quality was assessed according to the European standard for the classification of carc asses of sheep. The fattening period lasted from 37 to 94 days, on average 63 ± 3.6 days. The average live weight gain per day was 247.4 ± 13.85 g, and live weight increased on average by 15.3 ± 0.94 kg. Significantly higher ( P < 0.05) growth rate during fattening period reached lambs of 3rd group, where lambs started fattening above 27 kg of live weight, reaching a 276.8 ± 26.26 g daily live weight gain. The quality of the obtained carcasses was an average, and score for musculatu re was from R to O class, but the average score for fat deposition was from 3 to 4 points. The mixture of field beans and oats provided 19.3% of crude protein and 12.1 MJ of metabolizable energy per 1kg of dry matter, and its unlimited feeding provided med ium lamb's growth rate. The level of feed conversion was 7.56 kg of dry matter .
Determination of the tension limit forces of a barley malt and a malt crush in correlation with a load size
(2018) Hromasova, M.; Vagova, A.; Linda, M.; Vaculik, P.
This article deals with determination of selected parameters of barley malt (whole grain and crushed grain). The barley malt is besides water, hops and brewer's yeast, one of the basic ingredients necessary for the production of traditional Czech pilsner type of beer. The aim of this research is to determine limit force and internal friction angle with depending on the size of the load. The assessed malt crush was produced using a 2-roller malt mill. The 2-roller malt mill is based on the principle of grinding the material in a milling gap between two milling rollers, which is a very commonly used production of the malt crush. By determining the tension limits of the barley malt and the malt crush in correlation with the load, we can obtain very important parameters that inform us of the bulk material behavior, particularly with respect to the storage method (storage shape, height of the stored material layer, and the removal method from the storage, etc.), and to the transport (route gradient, transport speed, etc.). The determination of the tension limits has a direct link with cohesion of the bulk material and thereby contributes to establishing of the basic parameters of the bulk material, such as - the friction angle. The measurement for the angle of internal friction determination were performed on a prototype device. The principle of measurement on a mobile prototype devices is, the upper square chamber slides down the lower square chamber. Barley malt (whole grain and crushed grain) were loaded from 100 g to 5,000 g. The results of measuring were statistically analyzed with software Statistica 12.
Comparison of predicted and real parameters of PV systems in the Czech Republic and Spain
(2018) Olšan, T.; Soucase, B. M.; Libra, M.
This paper compares predicted performance by a simulation software for a given new constructed PV system of crystalline silicon technology located in Prague with 10 kWp peak power and a similar system in Spain. Simulation software used for the sake of this paper was publicly available PVGIS from the website of its creators, parameters were set to be the same like in the real PV system. The difference between the predicted and the real data was calculated and then discussed in the result section of this pape r. Suggestion how to increase the accuracy of the prediction by the simulation software is in the discussion part of this paper.
Odour reduction of manure through addition of boracic charcoal
(2018) Hampejs, G.; Jäger, A.; Steiner, S.; Steiner, K.
Odours released during the land application of manure results from different gases released from the liquid phase. These gases do create objectionable odours in the vicinity of the land - applied manure. In order to reduce the intensity of odour durin g manure application, we investigated the effectiveness of combining Borkohle with manure during land application. Boracic acid is widely used as a flame retardant in cellulose insulation. During demolition of existing buildings, this insulation is sorted into its own residual waste fraction. The cellulose fibres are extracted and pelletized on site. Subsequently, the pellets are charred in a pyrolysis furnace. The resulting Borkohle – charcoal containing boron in various compounds - can be used as a soil e nhancer and provides the trace element Boron to the fields. Furthermore, Borkohle provides long - term storage of carbon in the soil. Initial trials of combining boracic charcoal with manure additionally showed that odour emissions seemed to be significantly lower when manure was combined with Borkohle. This work presents methods to quantify the odour reductions resulting from the addition of Borkohle to manure as well as first results. Parameters like the influence of the amount of charcoal added and exposur e time have been investigated. Charcoal was added at concentrations between 5 and 250 g L - 1 . While applying typical amounts of charcoal, a reduction of odour concentration of up to 85% was observed . A positive correlation between odour reduction and the amount of charcoal added was observed. Charcoal has a negligible effect when exposure times are less than 30 minutes.

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