Abstract In the present study, hydrodynamics and gas to particle heat transfer in pseudo two dimensional spouted beds (2DSB) with and without draft plates were investigated using the Eulerian-Eulerian approach. The main objective of the study was to provide an understanding of effects of the presence of draft plates on the hydrodynamics and heat transfer behavior of solid particles in the spouted beds. To validate the model, the predicted mean particle vertical velocity at the bed axis, the lateral profiles of vertical particle velocity at different bed heights for both systems, and the particle velocity vector fields in the beds were compared with the experimental measurements. A close agreement between the CFD results and the experimental data was found for both systems. The simulation results showed that the particle volume fraction in the spout and fountain regions of the spouted bed with draft plates is considerably lower than that in a conventional spouted bed (without draft plates). Simulation results also showed significant differences between the temperature distributions of gas and solid phases in spouted beds with and without draft plates.

RESUMO A alcaparra (Capparis spinosa) é utilizada como planta multifuncional e adaptável que fornece uma oportunidade valiosa de melhoramento de vegetais em áreas climáticas adversas. Essa planta, como as outras, é afetada pelos estresses hídrico e do cloreto de sódio, que são os estresses abióticos mais comuns no mundo. Este estudo foi realizado para determinar a interação entre a seca e as diferentes proporções de cloreto de cálcio e cloreto de sódio na alcaparra. O estresse hídrico estava em dois níveis (100 e 75% da capacidade de campo) e foi aplicado com base no método de pesagem diária de recipientes. Os tratamentos salinos estavam com quatro proporções diferentes de cloreto de cálcio: cloreto de sódio (1:0, 1:1, 1:3 e 1:5). Os tratamentos começaram quando as plantas foram semeadas nos recipientes. Os resultados indicaram que maiores proporções de cloreto de cálcio do que de cloreto de sódio, que causaram estresse por salinidade, possuem efeito destrutivo nas relações de água e teor de alcaparra. Este estresse afetou o crescimento e as características relacionadas à função morfológica e fisiológica de forma negativa. O crescimento e outras características tiveram redução sob condições de déficit hídrico. Parece que a interação entre a salinidade e a seca teve o efeito mais destrutivo nessa planta, diminuindo sua qualidade e a quantidade de suas características.

ABSTRACT Caper (Capparis spinosa) is used as multipurpose and adaptable plant which provides a valuable opportunity to enhance greenery in harsh climatic areas. This plant like the others is affected by drought and sodium chloride stresses as the most common abiotic stresses worldwide. This study was carried out to determine the interaction between drought and different ratios of sodium and calcium chloride on caper. Droughts stress were two levels of 100 and 75% of field capacity and were applied based on the daily weighting method of pots. Salt treatments were four different ratios of calcium chloride: sodium chloride (1:0, 1:1, 1:3, 1:5]. Treatments started when the plants were sown in the pots. Results indicated that higher ratios of calcium chloride than sodium chloride which caused salinity stress have destructive effect on water relationships and contents of the caper. This stress affected growth, morphological, and physiological function related traits in a negative way. Growth and other traits decreased under water deficit conditions. It seems that interaction between salinity and drought had the most destructive effect on this plant and decreasing its quality and quantity of its traits.

CFD modeling for an internal loop airlift reactor is developed for different superficial gas velocities, ranging from 0.015 to 0.073 m/s. Based on the presence of gas bubbles in the downcomer, three regimes can be generally classified as: no gas bubbles (I), stagnation of gas bubbles (II), and recirculation of gas bubbles into the riser (III). The aim of the study is to carefully investigate the regime transition from II to III by considering the gas distribution. In regime II, the CFD simulation results show that the gas holdup difference between the riser and the downcomer remains constant. Due to the transition from regime II to III, the gas holdup difference sharply increases and the ratio of gas holdup in the downcomer and riser changes between the two regimes. At a superficial gas velocity slightly lower than that of the transitional regime, a small amount of gas is dragged to the riser, while the behavior of the regime is similar to regime II. The computational results show that CFD can be used as an effective tool to provide information on the details of the transition regime in internal loop airlift reactors.