Numerical Predication of Solidification Phenomena of Phase Change Material in Concentric Annulus Pipe

Two-dimensional numerical simulation is performed aiming to understand the role of buoyancy force convection during restricted solidification of phase change materials (PCMs) inside a shell and tube heat exchanger according to annulus cross section. Where the transient history of PCM solidification evolution was studied. The governing equations of mass, momentum and energy are solved to study the solidification behavior inside the annulus geometry. The fluid flow in the mushy zone was accounted for using the Darcy drag source term in momentum, and the liquid percentage in each cell was updated using the enthalpy-porosity method. Thermal conditions of the outer cylinder insulated (adiabatic) and the inner cylinder at constant temperature (isothermal). The results are presents as a temperature contour and liquid fraction distribution in the domain. The predicted result shows the capturing phenomenon: primary heat conduction in all regions, then heat convection and conduction become dominant in the top and bottom regions, respectively. The max. and min. temperature changes near the outer pipe surface during 16 hrs. are 56.25% and 42.5%, respectively.

DESAIN PASSIVE COOLING MENGGUNAKAN PERFORATED ALUMINUM PLATE PADA FOTOVOLTAIK MONOKRISTALLIN

Konversi energi Matahari menjadi energi listrik menggunakam Photovoltaic Monocrystallin modul merupakan pembangkit listrik alternatip yang bebas polusi dan ramah lingkungan. Indonesia merupakan daerah subtropis yang kaya akan cahaya Matahari, merupakan bahan baku utama PV. Proses konversi energi pada PV sangat dipengaruhi oleh peningkatan temperatur yang melebihi ambang batas, akan menyebabkan penurunan efisiensi PV. Peningkatan efisiensi PV ini sudah banyak dilakukan peneliti dari berbagai negara, penelitian yang terdahulu lebih banyak menggunakan methoda force convection ( konveksi paksa ) atau active cooling dengan menambahkan cooling fan, spray water, heat sink yang membutuhkan energi tambahan, permasalahan yang timbul bagaimana meningkatkan efisiensi fotovoltaik tanpa menambahkan energi tambahan?. Pada penelitian ini peningkatan efisiensi PV menggunakan metoda free convection atau passive cooling, mendesain perforated aluminum plate yang dipasang disebelah bawah panel PV dengan mendesain hole yang bervariasi dari diameter 15mm dan berjarak 20 mm. Ide penelitian ini merupakan sesuatu yang baru dan mempunyai suatu kontribusi terhadap ilmu pengetahuan, sehingga sangat perlu untuk dilakukan penelitian ini dalam mengembangkan teknologi baru dan terbarukan.

A Stability of Force Convection Boundary Layer Laminar flow in Diverging Chennal

The objective of this paper works is to study, a stability analysis of two dimensional boundary layer forced convection over a fixed vertical plate vary in viscosity and prandtl number with time dependent . The governing equations are transformed to non linear coupled partial differential equations with boundary conditions have been solved numerically by finite difference scheme in combination with quasi-linearization technique with suitable step size along the stream- wise direction. Results are showed different values of mass transfer parameter (A) . It was found that the solutions is stable when increases the suction/injection parameter A.

Numerical Research of Flow Heat Transfer through Micro Channel of Mems Device

Micro-channel has been increasingly applied in MEMS devices and electronics devices due to its higher efficiently heat dissipation rate, more compact size and lower cost. The present work demonstrates that the theoretical analysis of single phase micro channel has been investigated. To predict the behavior of micro-channel, the non-linear thermal hydraulic equations are developed namely mass, momentum and energy conservation, these equations are solved to predict the thermal physical properties and hydrodynamic behavior of the fluid in micro-channel. The configuration geometry of the problem has been made in design modular of commercial software ANSYS 15.0 Workbench and meshing of it has been done in ANSYS 15.0 Workbench fluent. Water is used as the working fluid in the micro-channel and the problem has been solved in ANSYS 15.0. To analyze the thermal behavior of micro-channel in force convection for various input power. Numerical simulation is carried out to calculate the wall temperature of the micro-channel, heat transfer coefficient (HTC) values etc. Next more simulation have been performed to investigate the parametric effect on the circular micro channel in terms of different diameter and length, and optimize the geometric parameters and coolant flow rate to maintain the critical temperature of the MEMS device (geometry and thermodynamic performance of micro-channel).

Evaporation Rate of Colloidal Droplets of Jet Fuel and Carbon-Based Nanoparticles: Effect of Thermal Conductivity

Adding nanoparticles to liquid fuel is known to promote its combustion characteristics through improving several thermo-physical properties. This study investigates the effects of adding carbon nanoparticles on thermal conductivity and evaporation rate of liquid jet fuel. Multi-walled carbon nanotubes, activated carbon nanoparticles, and graphene nanoplatelets were added to jet fuel at different concentrations to prepare colloidal suspensions. Thermal conductivity is determined by passing known amounts of heat through a very thin layer of fuel and measuring temperature difference across its thickness. A fiber-supported droplet technique is also used to evaluate evaporation rate due to force convection of a hot inert gas. It is observed that both thermal conductivity and evaporation rate increase as a result of nanoparticle addition. Since there is no radiation heat transfer mechanism, the increase in evaporation rate is concluded to be only due to enhanced thermal conductivity.