A Theoretical and Experimental Study for A humidification-Dehumidification (HDD) Solar Desalination Unit
A humidification-dehumidification (HD) solar desalination unit was designed. It seems to be suitable to provide drinking water for population or remote arid areas. Solar water and solar air collectors were designed to provide the hot water and air to the desalination chamber. The desalination chamber was divided into humidifier and dehumidifier towers. The circulation of air in the two towers was maintained by the forced convection. Theoretical and experimental works were done at different environmental conditions. A mathematical model was formulated, in which the thermodynamic relations were used to study the flow, heat and mass transfer inside the humidifier and dehumidifier. Such a technique was performed in order to increase the unit performance. Heat and mass balance was done and a set of governing equations was solved using the finite difference technique. The solar intensity was measured along the working day during the summer and winter months and a comparison between the theoretical and experimental results were performed. The average accumulative productivity of the system in November, December and January was ranged between 2 to 3.5 kg / m day while the average summer productivity was found between 6 to 8 kg/m day in June and 7.26 to 11 22
EXPERIMENTAL STUDY ON DESALINATION SYSTEM USING HUMIDIFICATION- DEHUMIDIFICATION PROCESS WITH BAFFLES IN THE DEHUMIDIFIER
The humidification-dehumidification desalination process is a promising technique to desalinate seawater. To improve the output of a desalination unit the baffle plates are placed in the dehumidifier. The effect of variables on freshwater production was studied experimentally. Two packing materials are used and compared with previous researchers. Operating variables include the air and water temperature at the entry to the humidifier, the humidifier water flow rate, airflow rate and the cooling water flow rate into the dehumidifier. The experimental setup, which includes a geyser for water heating, air heater, humidifier and a baffle plates in the dehumidifier. The results show that by enhancing the temperature up to 60 oC of inlet water supplied to the humidifier,0.785 kg/hr-m freshwater was produced. Also, increase in the water flow rate in the humidifier, and the flow rate of cooling water in the dehumidifier, which in turn increases the output of the desalination system with increased production of distilled water. The inlet temperature of cooling water reduced from 30 oC to 20 oC enhances the production of distilled water significantly. The productivity increases by 60 % with baffle plates inside dehumidifier as compared to without baffles.
A preliminary account of a new tyrannosauroid theropod from the Wessex Formation (Early Cretaceous) of southern England
Abstract A new genus and species of coelurosaurian theropod dinosaur from the Wessex Formation (Early Cretaceous, Barremian) of the Isle of Wight, England, is described and named. Distinctive characters of the premaxilla, its dentition, maxilla and nasals allow it to be diagnosed. The teeth in the premaxilla are D-shaped in cross-section and the nasals are fused. The hands are elongate and slender and the hindlimbs are gracile. Lack of element fusion elsewhere in the skeleton suggests that it is a subadult. Numerous character states are shared with tyrannosaurids but the new taxon appears to be excluded from the group that comprises aublysodontine and tyrannosaurine tyrannosaurids. We conclude that the taxon is a basal tyrannosauroid and as such it is one of the earliest and (with the exception of some teeth and an isolated ilium from Portugal) the first from Europe. Implications for tyrannosauroid biogeography and evolution are discussed. The animal was part of an unusual taphonomic assemblage in which some elements were partially articulated while others were scattered or broken.