STUDY OF THE COAGULATION OF AEROSOL PARTICLES IN THE SCRUBBER ULTRASOUND CHAMBER

В данной работе представлены результаты исследования процесса коагуляции частиц аэрозоля моноаммонийфосфата в модельной ультразвуковой (УЗ) камере скруббера. Изучено поведение аэрозольных частиц внутри камеры на расстоянии 100 мм и 400 мм от ультразвукового излучателя с частотой излучения 22 кГц. Представленные результаты показывают практически отсутствие коагуляции частиц при интенсивности звукового давления 140 dB и процесс активной коагуляции при интенсивности звукового давления 150 dB для выбранного образца. Начальная массовая концентрация фосфата аммония в камере составляла 1 г/м3. Измерения дисперсного состава аэрозоля внутри камеры показали, что более интенсивно коагуляция проходила в области 400 мм. Через 30 минут воздействия значение среднего объемно-поверхностного диаметра частиц аэрозоля в камере изменилось на 238,4 %. This paper presents the results of the study of the coagulation of the monoammonium phosphate aerosol particles in the model ultrasonic scrubber chamber. The behavior of aerosol particles inside the chamber is studied at the distance of 100 mm and 400 mm from the ultrasonic emitter with 22 kHz of the radiation frequency. The presented results show almost complete absence of particle coagulation at the sound pressure intensity of 140 DB and the active coagulation process at the intensity of 150 dB for the selected sample. The initial mass concentration of ammonium phosphate in the chamber was 1 g / m3. Measuring the dispersed composition of the aerosol showed that coagulation proceeds more intensively in the region of 400 mm. After 30 minutes of exposure the value of the average surfactant diameter of the aerosol particles in the chamber has changed by 238.4%.

The Effect of Plant Density, Zinc Added to Phosphorus Fertilizer Sources and Location on Selected Yield Parameters of Soybean

Background: Soybean [Glycine max (L.) Merrill] is an annual herbaceous leguminous grain crop which is cultivated mainly for its oil and protein. The objective of the study was to determine the effects of plant density and zinc added to phosphorus fertilizer sources on soybean yield performance under different environmental conditions. Methods: A field trial was executed in two sites during the 2018/19 and 2019/20 summer planting seasons. The experimental design involved a 2 × 2 × 5 factorial fitted into a randomized complete block design (RCBD) with four replications. The experiment consisted of two plant densities, a lower plant density of 66 666 plants/ha and a higher plant density of 111 111 plants/ha. The five different types of fertilizer treatments were single superphosphate, monoammonium phosphate, zinc sulphate added to single superphosphate, zinc sulphate added to monoammonium phosphate and control. Result: The results showed that plant density has a significant effect (P less than 0.05) on soybean number of pods per plant and the field biomass yield. Soybean planted under lower plant density conditions produced a significantly larger number of pods per plant during both planting seasons, whereas higher plant density conditions resulted in a higher soybean field biomass yield during the 2018/19 planting season. It was observed that soybean treated with monoammonium phosphate had higher seed mass.

Fertilization management strategies for ‘Agata’ potato production

ABSTRACT Fluctuations in potato prices and invariably rising production costs need sustainable fertilization strategies. For this purpose, two experiments were conducted in the southwestern region of São Paulo state to evaluate fertilization management strategies for the ‘Agata’ potato cultivar. The treatments consisted of the producer’s standard fertilization (1700 kg ha-1 NPK 4-30-10 at planting + 100 kg ha-1 urea and 150 kg ha-1 KCl at hilling) and combinations of two P rates at planting (standard rate and half of the rate), as monoammonium phosphate (MAP) with two forms of KCl application (total rate in the post-planting phase or half of the rate in the post-planting phase and half at hilling). The application of half the P rate (255 kg ha-1 P2O5) as the MAP at planting and the transfer of K from planting to applications in the post-planting phase or in the post-planting phase and at hilling, despite having provided a lower leaf P concentration, maintained the total tuber yield with higher operational yield of planting fertilization. It also increased the yield of tubers with a diameter >4.5 cm under conditions of lower water availability in the vegetative stages of the crop and soil with medium availability of P and K. Such a fertilization strategy is valuable for cost reductions and possible environmental liabilities.

Long-term fate of fertilizer sulfate- and elemental S in co-granulated fertilizers

In previous studies, we assessed sulfur (S) uptake by crops from elemental S (ES) and sulfate-S (SO4-S) in S-fortified monoammonium phosphate fertilizers over two years. The recovery by the crop ranged from 16 to 28% for ES and from 9 to 86% for SO4-S. Here, we used a model which takes into account organic S cycling, SO4-S leaching and ES oxidation to explain the observed recoveries. Higher recoveries of ES than SO4-S in two of the four sites could be explained by partial leaching of SO4-S and relatively fast oxidation of ES, due to a warm climate and high S-oxidizing soils. The same model was used for longer-term (5-year) predictions, and a sensitivity analysis was carried out. The size of the labile soil S pool and total S uptake strongly affected the recovery of both SO4-S and ES. Predicted recoveries after 5 years were over threefold higher for a small than for a large labile organic S pool and for a high-uptake than for a low-uptake scenario. Leaching mainly affected SO4-S, with predicted recoveries halved under a high-leaching scenario. Slow oxidation resulted in recoveries in the first year being fourfold lower for ES than for SO4-S or even lower in case of a long lag-time. However, it is predicted that total recoveries of ES will eventually reach those of SO4-S or exceed them if there is SO4-S leaching. Our model demonstrates that long-term trials are needed to evaluate the true effectiveness of a slow-release fertilizer source such as ES.

Experimental Studies of the Electrical Breakdown of Fire Extinguishing Powders

The method for determining the breakdown voltage in the air suspension of fire extinguishing powder, simplified and more appropriate to the actual conditions of such powders use is proposed and tested. Experimental studies of the electrical breakdown of fire extinguishing powders in an alternating electrical field — homogeneous and non-homogeneous are presented. Double effect of fire extinguishing powders on the breakdown in a homogeneous electrical field in comparison with air is established. The first option: powders to a small extent complicate the breakdown (increase the breakdown voltage), which is due to the high electrical strength of solid dielectrics. The second option: powders slightly facilitate the breakdown. Presumably, this is due to the abnormally high polarizability of one of the components — monoammonium phosphate (ferroelectric). Due to the avalanche-like polarization caused by the ferroelectric, the uniformity of the field is disturbed, which reduces its electrical strength. In an inhomogeneous electric field, the breakdown voltage was about one third lower than in a homogeneous one, and exactly corresponds to the breakdown voltage of the air. In a homogeneous field between the electrodes the «bridges» of powder particles containing monoammonium phosphate appeared and continued to hang even after the breakdown. An unexpected phenomenon was revealed: a relatively weak dependence of the breakdown voltage on the presence of moisture in the extinguishing powder. It is advisable to continue research in this area. The main conclusion: fire extinguishing non-conductive powder does not participate in the electrical breakdown that goes through the air between the powder particles. In view of this, the voltage of 1 kV seems an anachronistic one, at which the use of powder fire extinguishers is allowed, while for carbon dioxide fire extinguishers this figure is 10 times higher (though the electrical strength of carbon dioxide is 0.9 of the air electrical strength). Since the air electrical strength depends on the external conditions (temperature, pressure, humidity, distance between the electrodes), it is proposed to enter relative values for the assessment of the extinguishing powder electrical strength, for example, the ratio of the breakdown voltage to the breakdown voltage in the air.