The passive method by using a vortex generator (VG) is an effective method for the improvement of convective heat transfer. This study is focused on usage of concave rectangular winglet vortex generator (CRW VG) for improving convective heat transfer in a fin-and-tube heat exchanger using numerical simulation. Concave rectangular winglet pairs (CRWP) and rectangular winglet pairs (RWP) VGs were mounted inside the gap between fins (gas side) with variations of the number of VG pairs of rows. Inlet air velocity variations expressed by the Reynolds numbers were ranged from 364 to 689. Augmentation of heat transfer is indicated by the ratio value of heat transfer convection coefficient between cases using VG and that without using VG (baseline). The results show that the convection heat transfer coefficient for cases using CRWP VG is higher than that using RWP VG. Convection heat transfer coefficient increases up to 102% by mounting CRWP VG at Re = 364. However, the increase in convection coefficient is accompanied by a rise in pressure drop to 216.8%.
<p><em>Mathematics subject matter of fractions with the Discovery Learning learning model. The research conducted was Classroom Action Research with 2 cycles, with each cycle consisting of 2 meetings. Each cycle includes the stages of planning, implementation, observation and reflection. Each meeting was conducted pre-test and post-test to determine the progress of students. In Cycle I, students who completed the post test were 68.18%. In Cycle II, the students who completed the post test were 90.91%. From the implementation of these 2 cycles, it is shown that the Discovery Learning model can improve the learning outcomes of students in Mathematics in Class V fractions.</em></p>
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