Design and hydrodynamic performance testing of a new pressure sand filter diffuser plate using numerical simulation

Sand filters are widely used for treating irrigation water. Their technical development maximises their operational efficiency. Using numerical simulation techniques, such as computational fluid dynamics (CFD) can provide a better understanding of the processes associated with fluid flow. This study aimed to design, build and evaluate the hydrodynamic performance of a sand filter diffuser plate using numerical simulations. The objective was to maximise hydrodynamic efficiency during the filtration process and consequently minimising the effects of flow on the sand bed surface. The numerical simulations and laboratory tests were divided into two parts. Firstly, the hydrodynamic flow profile in three different sand filter diffuser plates was established using three commercial filters available in Brazil. Secondly a new model of sand filter diffuser plate was designed and evaluated. The simulations predicted the flow pattern of sand filters for the test conditions. For the three commercial diffuser plates and flow velocities evaluated, a tendency to generate a vortex and a tangential flow on the sand bed surface was observed. This resulted in sand movement inside the equipment with the formation of accumulation points and creation of preferred paths for water and suspended solids. The new model showed reduced internal flow kinetic energy and vortex formation. Consequently there was increased flow uniformity in the sand bed surface with reduced deformation of the bed1835869FAPESP – Fundação de Amparo à Pesquisa Do Estado De São PauloNão te

Economic analysis of irrigated melon cultivated in greenhouse with and without soil plastic mulching

ABSTRACT The objective of this study was to analyze technically and economically the irrigated ‘Gália’ melon (Hybrid Nectar), cultivated in greenhouse with and without using plastic mulch covering on the soil. Simultaneously, two experiments were conducted using a completely randomized design (CRD), in which melon plants were submitted to five water availability levels, defined by 50, 75, 100, 125, and 150% of crop evapotranspiration, with four replicates. The difference between experiments were only about the soil covering with plastic mulch: with (CC) or without (SC) plastic mulch. The economically optimal irrigation depths were 208.83 and 186.88 mm, resulting in yields of 50.85 and 44.51 t ha-1 for the experiments with and without mulching, respectively. The results showing the economically optimal irrigation depths were very close to those that produced the highest yield

Efeitos da fertirrigação sobre a produção de palmito da pupunheira Fertirrigation in peach palm: effects on heart-of-palm yield

Com o objetivo de avaliar o efeito da aplicação de lâminas de irrigação e níveis de adubação nitrogenada na produção de palmito de pupunheira (Bactris gasipaes Kunth), foi conduzido um experimento a campo, durante 22 meses, em Piracicaba (SP). Empregou-se o delineamento em blocos casualizados, com tratamentos distribuídos em esquema fatorial 3 (nitrogênio) x 4 (lâminas). Os níveis de nitrogênio corresponderam a 0; 200 e 400 kg ha-1 ano-1 de N, aplicados por meio de fertirrigações semanais. As lâminas de irrigação foram equivalentes a 0; 50; 100 e 120% da evapotranspiração de referência (Eto), determinada em função de tanque classe A. A produção de palmito por planta foi avaliada dos 30 aos 34 meses após o plantio. Houve efeito significativo dos tratamentos (irrigação e adubação) para todas as variáveis relacionadas à produção. Os tratamentos com menores lâminas e doses de nitrogênio apresentaram as menores produções. Levando-se em conta o crescimento da planta e a produção de palmito, os resultados indicam que irrigação com 100% da ETo e fertirrigação com 200 kg ha-1 ano-1 de N são as recomendadas para a pupunheira cultivada em condições de solo, clima e manejo cultural semelhantes às deste estudo.<br>Peach palm (Bactris gasipaes Kunth) yield responses were evaluated, using four irrigation levels and three nitrogen doses, in a field experiment carried out, during a 22-month period, in Piracicaba, São Paulo State, Brazil. A randomized block trial in a factorial design was utilized. Nitrogen doses corresponded to 0; 200 and 400 kg ha-1 year-1 of N, whereas irrigation levels were equivalent to 0; 50; 100 and 120% of the daily reference evapotranspiration (ETo), determined by a class A evaporation pan. Weekly fertirrigations were applied using a diaphragm injection pump. Heart-of-palm yield was evaluated from 30 to 34 months. There were significant treatment (irrigation and fertilization) effects for all yield related variables. The treatments with low irrigation levels and nitrogen doses presented the smallest yields. Taking into consideration plant growth and heart-of-palm yield, the results indicate that irrigation with 100% of ETo and fertirrigation with 200 kg of N ha-1 year-1 are recommended when cultivating peach palm plants in conditions similar to the ones presented in this study