Numerical Modeling of Fluid Flow and Thermal Transport in Gravity - Dominated 3D Microchannels

The success recorded by the usage of microchannel in high flux cooling application, has led to several studies aimed at advancement in microchannel fluid flow and heat transfer technology. A recent study area with promising breakthrough is the effects of g ravity on microscale flow. Numerical simulations were conducted to study single phase flow and heat transfer in 3D microchannels. A priori, the 3D models were validated with experimental results and showed agreement. Two different aspects were simulated: f irstly a microchannel with hydraulic diameter of Dh =199 휇푚 for gravity effects on heat transfer. Secondly, gravity effects on friction factor with hydraulic diameter Dh = 1587 휇푚 . The 3D model confirmed the existence of gravity effects and scaled with significant factors previous 2D model predictions. This result realistically presents the potential of microchannel angular orientation as a passive tool for flow optimization and heat enhancement in portable electronics devices and compact - sized biomedic al devices

Development of an Efficient Chamber for Green-Drying Moringa Oleifera Leaves

The Moringa oleifera (M. oleifera) leaves are very nutritious leaves, rich in protein, vitamins and minerals. The leaves are also used for varied applications such as nutritional and medicinal purposes. This potential presents M. oleifera as a leaf with economic cum health prospects especially to agrarian communities. To sustain these potential benefits of M. oleifera, a means of processing them has to be developed and this process must not in any way reduce the nutritional value of the leaves. Drying under room condition is a usual process practice for M. oleifera, this is quite remote and would not encourage large scale production which could determine the economic feasibility. However, several efforts have been reported for processing M. oleifera, yet the balance between drying and retention of nutritional content is yet to be established for mechanized drying process. Therefore, there is the need to develop a mechanized chamber for green-drying M. oleifera. In this work, development of an efficient drying chamber was addressed using indigenous materials. The machine was designed, constructed and tested using fresh M. oleifera leaves. The machine is electrically-controlled via a switch and a thermocouple that will cut off the heater chamber when the required temperature is reached. To test the effectiveness of the dryer, M. oleifera leaves were dried using the designed dryer and the same quality dried using the room method. The method was able to dry M. oleifera leaves about three (3) hours compared to four (4) to seven (7) hours using the room method. The two samples were then sent to a laboratory for analysis. For nutrients like crude fibre of the sample dried using the new design yielded 7.4% crude fibre which is very close to 7.5% nutritional crude fibre content with room drying method. The drying chamber presented in this study showed efficient greendrying performance of M. oleifera with high nutritional content retention. The drying chamber presented in this work has the potential to benefit medium-scale production of M. oleiferawith nutritional components.Keywords: Nutritional leaves, drying, processing, chamber, minerals, medium-scale productio