Agroinžinerija ir energetika / Agroengineering and Energetics 2020, nr. 25

As societal needs grow, more and more attention is paid to green products, which can reduce environmental problems related to nature pollution, climate change, greenhouse gas emissions. One of the solutions to reducing plastic is to produce bioplastics. It is likely that the most suitable raw material for this would be agricultural plant biomass containing cellulose. Aim of the work: to evaluate chemical composition and structure of agricultural plants and to determine suitability of plant biomass for production of cellulosic bioplastics. Four types of herbaceous plants were selected: miscanthus (lot. Miscanthus gigantheus), sida (lot. sida hermaphrodita), artemisia dubia and spring wheat (lot. triticum). Determining the amount of cellulose that is suitable for the production of bioproducts had the most effect artimisia dubia 54,43 ± 2,17 %. However, the highest fiber yields are obtained from miscanthus – 7,15 ± 0,22 t ha-1. Therefore, growing this herbaceous plant for bioproducts and obtaining fiber would be beneficial.

Mulch is used in agriculture for various purposes, so the study of its benefits in various agricultural systems is relevant. Mulch has been found to be beneficial in the ecological horticultural system for soil, water conservation and improved fertility. The research was carried out in onion seedling crop using different types (chopped straw, dry grass, green grass) and different thickness (5 and 10 cm) of organic mulch. The influence of organic mulch on soil moisture and temperature, crop weediness and onion yield was evaluated. The highest soil temperature (18.62°C) and the highest soil moisture (33.7%) are observed by mulching the onion crop with green grass mulch. The highest onion yield (27.7 t/ha) was determined using green grass mulch, an increase of 59.6 % yield was observed in comparison with unmulsified onion crop.

The essence of the study is to find the best option between the welds. In order to discover the best welding method with the smallest displacement. The work compares the welds of three different ways of welding, as well as the displacements obtained during welding.

In order to ensure animal well-being, one of the most important factors is microclimate of a cattleshed, which consists of air temperature, relative air humidity, dustiness, lightning etc. Air temperature is considered to be the most important factor. Optimal air temperature in a cattleshed usually ranges from -7°C to 22°C. Optimal relative air humidity ranges from 40% to 88%. Relative air humidity depends on the intensity of ventilation and the air temperature in a cattleshed. The study was conducted in a beef cattleshed from March 2019 to February 2020. In this period air temperature in the cattleshed fluctuated from -6,36°C to 34,53°C. It was not uncommon for the relative air humidity to reach 100% thus exceeding norm values. The lowest value of relative air humidity was observed in April 2019 when it was as low as 24,3%. Data that was gathered during this study is compared to other academical sources.

The paper presents the results of experimental tests on non-pressure solar collector, dynamics of temperatures changes when sunlight changes. During a research the sunlight values were changing from 600 W/m2 to 800 W/m2 for a mono-block of 12 vacuum tubes solar collector, which has 140 liters capacity. The results of tests and calculations showed the loss of comparative heat, which reached 1,36 W/K of storage tank. When sunlight was changing from 600 W/m2 to 800 W/m2 the heat accumulated 23 % and more in 7 hours.

This paper describes a research of driving speed, distribution ratio of load mass and length of coupling device influence to car trailer yaw glows. Three different driving speeds were selected: 40, 60 and 80 km/h, load mass distribution ratios were changed at range 0–100%. Three different lengths of coupling device were selected for this research – 1850 mm, 2450 mm, 3500 mm. Tests have shown that as the driving speed increases, the yaws amplitude and frequency increases as well. Analyzing the influence of coupling length, it was found that increasing the coupling length the amplitude of the swing increases too, but their frequency decreases. Comparing different load mass distribution ratios, it was found that the lowest yaws are obtained when the entire load is loaded at the front of a trailer. However it is still recommended that the load mass is evenly distributed on the trailer due to a better car-trailer handling.

The paper presents the results of aerodynamic research, which investigated the influence of the front bumper spoiler and its parameters on the dynamic and economic parameters of the car, such as aerodynamic lift and drag coefficients, fuel consumption change, increase or decrease of maximum speed. The research was carried out by modeling a simplified Audi A4 B7 sedan car model in SolidWorks with the Flow Simulation plug-in that changes the airflow speed from 50 to 130 km / h. The model also features an adjustable front bumper spoiler with adjustable tilt angles of 30°, 45° and 90°. At each angle, the spoiler height is varied from 30 mm to 150 mm. The purpose of the study was to determine the benefits or disadvantages of a front bumper spoiler for a standard car. The graphs of the studies show that the proper use of the front bumper spoiler can reduce fuel consumption to 0.1 l and reduce the lifting factor by choosing the right parameters. It is also possible to increase fuel consumption and increase the lifting factor due to selected incorrect parameters.

Light emitting diodes application for flower greenhouses and efficiency of lighting is evaluated in this paper. It was found, that using MR lighting, plants were shortest. MRTR lighting effected largest surface area of flowers and highest yield of dry mass. The highest energy efficiency of growing dry mass (3.62 g/kWh) were shown by lighting with MRTR diodes

The main subject investigated in the current study is of an innovative LAK-VAWT triple slit wing and Axial generator 10kW small vertical axis wind turbine. The VAWT study was carried out under the condition of low roughness field. The average efficiency of the slit wing identified in the study was 0.5 and the maximum efficiency was 0.62. The highest Cp is achieved in the wind speed range of 7 to 10 m/s for a TSR index of 1.6. It has been found that without taking into account the difference between the height of the VAWT rotor center and the anemometer height difference, the efficiency coefficient at 6 m is overestimated to 15%.

The paper presents the results of experimental and theoretical research on the influence of common rail electromagnetic injector control valve stroke on the amount of fuel injected. The stroke of the injector control valve was increased and decreased by 0.010 mm. The numerical model of the injector in AVL Boost Hydsim enviroment was created for theoretical research. Studies have shown that increasing the stroke of the control valve increases the amount of fuel injected and decreasing the stroke of the control valve decreases the injection quantity. The lower the cyclic fuel quantity, the greater the influence of change in the control valve stroke. Theoretical studies have identified the same trends in the effect of the change in control valve stroke on the amount of fuel injected as in experimental studies. The numerical model in AVL Boost Hydsim environment can be used to predict changes in the injection process.