Effect of phase transitions on operation of air-to-air heat exchangers with drop irrigation

The article presents the results of experimental studies of the thermal and humidity parameters of air flows of a regenerative air-to-air heat exchanger with drop irrigation and an intermediate heat carrier when operating in winter conditions with negative outside temperatures. The dependences of temperature and humidity efficiency of the heat exchanger on saline solution flow rate were determined, while the maximum temperature efficiency in the heating column was more than 70%. It is shown that under all investigated regimes in the heating column, moisture evaporated from the saline solution, and the air entering the room became more humid, which is a positive factor that increases the comfort of premises at negative outside temperatures.

Removal of isopropyl alcohol by electrical discharge from an aqueous solution with microbubbles

The removal of isopropyl alcohol impurities with an initial volume concentration of 20 % in a cell with a working area volume of 831 cm 3 in a water flow with fine air bubbles with a solution flow rate of 2 m 3/h by a quasi-volume electric discharge obtained using a multi-electrode system of sectioned needle electrodes has been experimentally investigated. At an alternating voltage of an industrial frequency of 50 Hz, the creation of a finely dispersed phase with air bubbles in an electric discharge cell increases the efficiency of isopropyl alcohol removal from the water flow by 6 %.

Experimental study on dehumidification performance of liquid desiccant system with aqueous HCO2K solution

The liquid desiccant systems are one of the promising technologies in dehumidification applications. The experimental study on dehumidification performance of a counter flow structured packing liquid desiccant system is done with Aqueous HCO2K as working fluid. The HCO2K solution at different mass flow rate of air and solution is tested. The airflow rate is varied from 0.187 kg/s to 0.272 kg/s and the solution flow rate is varied from 0.053 to 0.115 kg/s. The output parameters, specific moisture change, moisture removal rate, dehumidification effectiveness and latent heat removal capacity varied in following ranges 3-4.2 g/kg of dry air, 2.4-3.1 kg/h, 0.12-0.21 and 1.7-2.1 kW respectively. Particularly when air flow rate increases from 0.187 kg/s to 0.272 kg/s the moisture removal performance improves about 11% whereas when the solution flow rate increases from 0.055 to 0.115 kg/s, improvement in moisture removal performance about 20%. The results imply that increase in solution flow rate always have the positive impact on dehumidification performance. The increase in airflow rate has the negative impact on specific moisture removal and effectiveness, but the impact is positive in case of the moisture removal rate and latent heat removal capacity. The Overall results show a promising dehumidification performance and further improvement is possible by incorporating a cooling system.

Effect of Nutrient Solution Flow Rate on Hydroponic Plant Growth and Root Morphology

Crop production under hydroponic environments has many advantages, yet the effects of solution flow rate on plant growth remain unclear. We conducted a hydroponic cultivation study using different flow rates under light-emitting diode lighting to investigate plant growth, nutrient uptake, and root morphology under different flow rates. Swiss chard plants were grown hydroponically under four nutrient solution flow rates (2 L/min, 4 L/min, 6 L/min, and 8 L/min). After 21 days, harvested plants were analyzed for root and shoot fresh weight, root and shoot dry weight, root morphology, and root cellulose and hemicellulose content. We found that suitable flow rates, acting as a eustress, gave the roots appropriate mechanical stimulation to promote root growth, absorb more nutrients, and increase overall plant growth. Conversely, excess flow rates acted as a distress that caused the roots to become compact and inhibited root surface area and root growth. Excess flow rate thereby resulted in a lower root surface area that translated to reduced nutrient ion absorption and poorer plant growth compared with plans cultured under a suitable flow rate. Our results indicate that regulating flow rate can regulate plant thigmomorphogenesis and nutrient uptake, ultimately affecting hydroponic crop quality.

Removal of Congo Red from Aqueous Solution by Circulating Fluidized Bed(CFB)

In this study circulating fluidized bed was adopted to remove of Congo Red from wastewater using Eichhornia crassipes as a adsorbent. Solution flow rate(6,12 and 18)l/hr, bed height(2,4 and 6) cm and Congo Red initaial concentration (10,25 and 50)mg/l were examined in experiments to show their effects on breakthrough curves and time required to reach the adsorbent to fully saturated curve. The mass transfer coefficient "KL"decreased with decreasing the liquid flow rate. The minimum fluidization velocities of bed found equal to 1.6, 2, 2.5 mm/s for heights of 2, 4,6 cm respectively. The increasing of the bed height will increase the contact time of the solute in the bed, and these improve the solute removal efficiency. the increasing in flow rate and initial concentration will increase the mass transfer rate.

Photocatalytic Degradation of Malachite Green Dye from Aqueous Solution Using Environmentally Compatible Ag/ZnO Polymeric Nanofibers

An efficient, environmentally compatible and highly porous, silver surface-modified photocatalytic zinc oxide/cellulose acetate/ polypyrrole ZnO/CA/Ppy hybrid nanofibers matrix was fabricated using an electrospinning technique. Electrospinning parameters such as solution flow rate, applied voltage and the distance between needles to collector were optimized. The optimum homogenous and uniform ZnO/CA/Ppy polymeric composite nanofiber was fabricated through the dispersion of 0.05% wt ZnO into the dissolved hybrid polymeric solution with an average nanofiber diameter ranged between 125 and 170 nm. The fabricated ZnO-polymeric nanofiber was further surface-immobilized with silver nanoparticles to enhance its photocatalytic activity through the reduction of the nanofiber bandgap. A comparative study between ZnO polymeric nanofiber before and after silver immobilization was investigated using X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) and thermal gravimetric analysis (TGA). The photocatalytic degradation efficiency of the two different prepared nanofibers before and after nanosilver immobilization for malachite green (MG) dye was compared against various experimental parameters. The optimum degradation efficiency of nanosilver surface-modified ZnO-polymeric nanofibers was recorded as 93.5% for malachite green dye after 1 h compared with 63% for ZnO-polymeric nanofibers.

DRYING OF THE NEW WATER-SOLUBLE POLYMER COMPLEX OF ALBENDAZOL WITH PECTIN

The drying process of the aqueous solution of the complex of Albendazole with pectin (Alpec) in a vacuum oven and by spray drying was studied. It was found that the drying in a nozzle-type spray dryer is preferable in yield and subsequent solubility of the final product. As a result of the studying of the parameters affecting to the drying process, the optimal mode of the dryer was established, which provides the high yield of the dry product: the temperature of the coolant at the inlet is 130–140 °С, the output is 60–70 °С, the solution flow rate is 2.5 l/h·min. The yield of the dry product is 85%. The comparative IR spectra of Alpec powder after spray drying, after drying in air, the starting Albendazole and pectin unambiguously indicate that the structure of the complex of Albendazole with pectin (Alpec) is identical after different types of drying. The biological activity of Alpec dry substance after spray drying compared with Albendazole was studied. The increased biological activity of Alpec compared with Albendazole was established, which can, probably, be explained by the good water solubility of Alpec in contrast to Albendazole and, as a consequence, the increase of bioavailability of the drug. It was found that the average lethal dose of Alpec (LD50) is 680 (601.8–768.4) mg·kg-1 (LD50 Albendazole - 400.2–450.4 mg·kg-1), i.e. the drug "Alpec" in terms of acute toxicity during intragastric use is classified as moderately hazardous substances. On the base of the results obtained, the technology of the obtaining of the anthelmintic drug alpec substance in the form of a water-soluble dry powder has been developed.

Effect of Tin Oxide Coatings by Spray Pyrolysis Process on Mechanical Properties of Aluminium, Brass and Mild Steel

Mechanical properties of materials are enhanced by different methods to increase the usage of the materials. In this research spray pyrolysis method is employed to increase the mechanical characteristics of three different materials. The tin oxide is chosen as coated material and aluminium, brass, mild steel are selected as substrate materials. The 500nm thin film is developed over the substrate materials by spray pyrolysis. The substrate temperature are chosen as 300? C for aluminium, 400? C for brass and mildsteel. Nozzle to substrate distance is 0.4 m, substrate temperature is 300? C for aluminium and 400? C for solution concentration as 0.2 mole and solution flow rate is 1ml/min are selected for constant deposition parameters. The hardness and tensile strength result clearly shows that strength is increased by adding the coating over the surface. The material is heated above crystallization temperature and SnO2 increases the tensile and hardness strength of the materials. The triangular metrological microscope is used to examine the microstructure of non coated and coated substrate materials. The microstructural analysis is showed that the uncoated surface of the substrate material is full of rough and pores. And displays that the tin oxide coated surface of the substrates after the initial deposition disclosed a surface with a agglomeration of tin oxide in homogeneous and uniform than the uncoated substrates.