The History of the Lands across the Atlantic 1440 1820 Research Paper

The History of the Lands across the Atlantic 1440 1820 - Research Paper Example The Portuguese chronicler, Azarura identifies that there were nearly 1,000 African slaves in Portugal by 1446. He was the head of the royal library. In his account of events in The Chronicle of the Discovery and Conquest of Guinea, he gave a vivid account of the separation of African slaves from their families during one of such journeys. He said of the Africans: â€Å"faces bathed in tears †¦ others stuck their faces with the palms of their hand, throwing themselves upon the ground† However, this kind of activity was not seen as cruelty. Rather, the Portuguese saw it as an opportunity to 'civilize' the Africans and introduce them to Christianity. The Portuguese government-sponsored explorations of new lands across Africa. This was done through a school of navigators that was funded by the Royal government of Portugal. Also, there were private interests because the Portuguese Crown promised the monopoly and control of new lands discovered by private sailors to the individ uals who found them. Some of the notables were Prince Henry the Navigator. The main commodities the Portuguese sailors sought was ivory, gold, spices, and slaves. Prince Henry, who was a notable royal and sailor explored the African coastline as far as Senegal and Sierra Leone by 1460. In 1469, Fernando Gomes discovered the island of Sao Tome which is 350 miles away from the African coast. In 1471, the Portuguese landed in Elmina, now part of Ghana. They moved further to the Benin Kingdom which is now a part of Nigeria.

Water Desalination using Vacuum Membrane Distillation Essay

Water Desalination using Vacuum Membrane Distillation - Essay Example Of course, it can also be used for water desalination [5]. Vapor migrates from the membrane surface to the permeate side. How this process occurs varies with the different configurations, depending on the feed solution which is treated [3, 11, 16]. All the configurations have advantages and disadvantages, depending on their applications. In Direct Contact Membrane Distillation, for instance, the membrane is in direct contact with the water only during liquid phases. According to classical heat transfer theory, a thermal boundary is formed when liquid is in direct contact with a solid surface when their temperatures differ. This thermal boundary stays next to the solid surface, where the liquid exhibits its temperature fluctuations. The process of heat and mass transfer illustrates the membrane distillation process, wherein a microporous membrane separates two fluids of differing temperatures (membrane thickness of). The feed temperature decreases from at its bulk to at the membrane’s surface. Accordingly, the permeate temperature increases from at its bulk to at the membrane’s surface. Two thermal boundary layers appear at the feed side (with the thickness of) and the permeate side (with the thickness of) of the membrane respectively, as shown in Fig. 3. where is the mass transfer flux through the membrane and is the latent heat of the volatile component. Here, is only a small part of the energy transferred through the membrane in the form of latent heat. The temperature difference between the two sides of the membrane also conducts heat through the membrane and the gas that fills the pores with flux, written as The equation illustrates the temperature difference between the two sides of the hydrophobic membrane. Accounting for the vapor pressure difference is illustrated by, which is the driving force for mass transfer through the membrane. Three mechanisms regulate the mass transfer through the membrane: The mass transfer mechanism