Geometrical investigation of microchannel with two trapezoidal blocks subjected to laminar convective flows with and without boiling

Microchannels are important devices to improve the heat exchange in several engineering applications as heat, ventilation and air conditioning, microelectronic cooling, power generation systems and others. The present work performs a numerical study of a microchannel with two trapezoidal blocks subjected to laminar flows, aiming to analyze the influence of the boiling process on the geometric configuration of the microchannel. Constructal Design and Exhaustive Search are used for the geometrical evaluation of the blocks. The Mixture multi-phase model and the Lee phase change model were both employed for the numerical simulation of the boiling process. In this study, the influence of the height and higher width of the first block (H11/L11) over the heat transfer rate and pressure drop for different magnitudes of the ratio between the lower width and higher width (L12/L11) was investigated. It is considered water in monophase cases and water/vapor mixture for multiphase flow. Two different Reynolds numbers (ReH = 0.1 and 10.0) were investigated. Results indicated that, for the present thermal conditions, the consideration of boiling flows were not significant for prediction of optimal configurations. Results also showed that in the cases where the boiling process was enabled, the multi-objective performance was higher than in the cases without boiling, especially for ReH = 0.1.

British penetration into and subjugation of Isokoland in South Central Nigeria, 1896–1911: A narrative

The Isoko, like other peoples of Nigeria, played significant roles in the historical process and evolution of Nigeria and should be acknowledged as such. The paper teases out much more clearly—and, more importantly, the multiple stages of the British expansion into Isoko. That is, how does that multi-stage, multi-phase process affect how we think more broadly about British colonial expansion in Africa in the 19th century? The paper deposes that the Isoko as a people did not accept British rule until the “punitive expedition” to the area in 1911 brought the whole of the Isoko country under British control. This is done within the context of the military conquest and subjugation of the people, colonial prejudices, and the resulting social economic, and political changes. The paper deploying both primary and secondary data highlights the role played by the Isoko in resisting British penetration into and subjugation of their country between 1896 and 1911. The year 1896 marked the beginning of British formal contact with the Isoko when the first treaty was signed with Owe (Owhe), while 1911 was when the Isoko were conquered by the British and brought under British control.