Tag Archives: air

737–744 P. Kic
Effect of different air velocities on convective thin-layer drying of alfalfa for livestock feeding
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Effect of different air velocities on convective thin-layer drying of alfalfa for livestock feeding

P. Kic

Czech University of Life Sciences Prague, Faculty of Engineering, Kamycka 129, CZ165 21 Prague 6, Czech Republic
Correspondence: kic@tf.czu.cz

Abstract:

Alfalfa (Medicago sativa) is widely used as forage which has very high feeding value. The aim of this paper is to inform about the experimental and theoretical investigations of alfalfa drying in thin layer. Special device for convection drying with air flow passing through material from bottom through supporting trays with sieve by constant temperature was used for drying when air velocity was 0.7 m s-1, 1 m s-1, 1.2 m s-1 and 2.0 m s-1. The results were compared with natural convection drying by the same temperature, but with the 0 m s-1 air velocity. The increased air velocity for convection influenced drying process positively. The results show that the differences between the drying with air velocities 1.2 m s-1 and 2 m s-1 are very small, therefore 1.2 m s-1 could be realised as an optimum. The evaluation of measurement results was focused on curves of drying rate, changes in water content and changes of moisture depending on the time and their mutual relations. Experimental data create the background for calculation of main parameters useful for description and modelling of the drying process, which can be helpful e.g. for decision of optimum drying time. Drying alfalfa for hay by forced convection shortened the drying time as compared with natural convection two and a half times. Drying alfalfa for haylage by forced convection shortened the drying time as compared with natural convection even four times.

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75–81 P. Kic
Dust pollution in the sport facilities
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Dust pollution in the sport facilities

P. Kic

Czech University of Life Sciences Prague, Faculty of Engineering, Department of
Technological Equipment of Buildings, Kamycka 129, CZ 16521 Prague,
CzechRepublic; e–mail: kic@tf.czu.cz

Abstract:

The aim of this paper is to present the results of microclimatic research focused on the dust pollution in several buildings and different rooms used for sport activities at the University. The attention is paid mainly to the problems of dimensions of space, capacity and activity of sportsmen, and influence of space ventilation. In the frame of this research the concentration of air dust was measured by the exact instrument DustTRAK II Model 8530 aerosol monitor. Using the special impactors the PM1, PM2.5, PM4, PM10 size fractions were also measured. Obtained results of measurements were evaluated and concentrations of different size of dust particles were analysed. Results of different indoor conditions were generalized. Based on the results of measurements practical recommendations for the design, use and ventilation of these types of buildings were summarised in the conclusions.

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215-222 A. Aboltins, and P. Kic
Forced convection in drying of poultry manure
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Forced convection in drying of poultry manure

A. Aboltins¹,* and P. Kic²

¹Latvia University of Agriculture, Institute of Agricultural Machinery, Cakstes blvd. 5, Jelgava, LV–3001, Latvia; *Correspondence: aivars.aboltins@inbox.lv
²Czech University of Life Sciences Prague, Faculty of Engineering, Kamycka 129, 165 21, Prague 6, Czech Republic

Abstract:

Pollution of environment by animal waste can be problem of intensive animal production in many countries with high density of animal farms. The aim of this paper is to inform about the experimental and theoretical investigations of moisture content reduction from poultry manure by forced convection. The experimental data created the background for calculation and modelling, which resulted in definition of the theoretical drying coefficient, useful for description and modelling of the drying process. The theoretical model has been verified and compared with experimental results obtained from the measurement. The laboratory equipment was used for test the forced convective drying of poultry manure due to vertical air streams going from bottom through supporting trays with holes and therefore through the manure up. Changed opened area of trays with different density has been used for definition of main parameters, which can serve especially in designing and construction of the new equipment for housing of poultry or improvement of the use of drying tunnel or in similar applications. The experimental data show that the air flow significantly increase the amount of moisture carried away from the material. Holes´ size does not significantly affect water runoff by convection without additional air flow.

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759-764 P. Kic
Dust pollution in University offices
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Dust pollution in University offices

P. Kic

Czech University of Life Sciences Prague, Faculty of Engineering, Kamycka 129, CZ-16521 Prague 6, Czech Republic;
e-mail: kic@tf.czu.cz

Abstract:

The aim of this paper is to present results of microclimatic research focused mainly on dust pollution in several offices of Departments in the Faculty of Engineering at Czech University of Life Sciences Prague. The attention is paid to the dimensions of the room, floor covering, furniture, equipment, ventilation, frequency of the use and period of the year. In the frame of this research the concentration of air dust was measured by special exact instrument Dust-Track aerosol monitor. After the installation of different impactors the PM¹, PM².⁵, PM⁴, PM¹0 size fractions were also measured. The obtained results of measurements were evaluated by the statistical instruments and concentrations of different size of dust particles were analyzed. Results of different indoor conditions were generalized. Based on the results of measurements practical recommendations for the design, use, cleaning and ventilation of these types of rooms and buildings were summarised in the conclusions.

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5-11 A. Aboltins, J. Palabinskis and G. Ruškis
The Investigations of Heating Process in Solar Air Heating Collector
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The Investigations of Heating Process in Solar Air Heating Collector

A. Aboltins¹, J. Palabinskis¹ and G. Ruškis²

¹Institute of Agricultural Machinery, Latvia University of Agriculture,
Cakstes 5, LV3001, Jelgava, Latvia; e-mail: aivars.Aboltins@inbox.lv
²Institute of Agricultural Machinery, Latvia University of Agriculture,
Cakstes 5, LV3001, Jelgava, Latvia; e-mail: Janis.Palabinskis@llu.lv

Abstract:

The aim of the research is to find the optimal technical solutions, utilized materials as absorbers, operation parameters and power possibilities for a solar collector. Different absorbers of sun radiation, the absorbers’ ability and efficiency in air heating solar collector are compared. 0.1 x 0.5 x 1.0 meters long equipment for experimental research into the materials of solar air heating collector was built. The experimental data were measured and recorded in the electronic equipment REG. The investigations are devoted to the sun following collectors, which guarantee perpendicular location for all experimental time of the plane of absorber to the flow of the sun radiation. The collector covered material was a polystyrol plate and absorbers were: a) black colored steel tinplate and b) slices of black colored beer cans. The use experimental data received expressions of heating degree of air in collector depending on sun radiation and distance from absorber (steel tinplate) at 35 cm and 60 cm from inlet. In favorable weather conditions the heating degree of the ambient air with absorber black colored slices of beer cans reaches more than T = 10o C at the air velocity 0.9 m s-1.

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255-261 J. Palabinskis, A. Aboltins, A. Lauva and N. Karpova-Sadigova
The comparative material investigations of solar collector
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The comparative material investigations of solar collector

J. Palabinskis, A. Aboltins, A. Lauva and N. Karpova-Sadigova

Latvia University of Agriculture, Liela iela 2, Jelgava, LV – 3001, Latvia;e-mails: Janis.Palabinskis@llu.lv; Aivars.Aboltins@inbox.lv; Aigars.Lauva@inbox.lv;Nadezda.Karpova@llu.lv

Abstract:

The prices of energy resources used for grain drying are increasing year by year. In order to reduce costs, research into methods of saving energy in grain drying is in progress in the Research Laboratory of Grain Drying and Storing of the Faculty of Engineering, the LUA. Equipment for experimental research into the materials of solar collectors was built in the research laboratory for research purposes in 2005. The construction of the equipment allows for simultaneous comparative studies of two materials. The experimental data are metered and recorded in the electronic equipment REG. Cell polycarbonate PC (bronze, henceforth referred to as polycarbonate) with absorbers steel-tinplate and black-coloured wood was researched in comparison to the polyvinylchloride film (henceforth referred to as a film). The researches were made with different air velocities. The air heating degree ∆T in the solar collector is dependent on solar radiation I and air velocity v in the solar collector. In the experimental equipment, which is 1.5 meters in length, the air was heated to ∆T = 6°C at the velocity v = 0.5 m s-1.For theoretical investigation of the air heating power in solar systems the mathematicalmodel is applied; the solution can be used for estimation of different materials /absorbents/ and their heat source.

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