Combining entransy theory with constructal theory, this mini-review paper summarizes the constructal optimization work of heat conduction, convective heat transfer, and mass transfer problems during the authors’ working time in the Naval University of Engineering. The entransy dissipation extremum principle (EDEP) is applied in constructal optimizations, and this paper is divided into three par...

Experiments were conducted to investigate flow boiling heat transfer to a dielectric fluid in a silicon chip-integrated microchannel heat sink. Twenty-four microchannels, each 389 m  389 m in crosssection, were fabricated into the 12.7 mm  12.7 mm silicon substrate. High-speed visualizations (at 12,500 frames per second) were performed simultaneously with heat transfer and pressure drop mea...

Heat transfer improvement in circular pipe by using nanofluid and twisted tape is presented in this review paper. Experimental and numerical studies are incorporated involving both the range of turbulent and laminar flow. Effect of type and volume fraction of nanofluid on performance of heat transfer was referred along with the length and twist ratio of the tape through the pipe on heat transfe...

Heat transfer during compression of air in a long, thin tube is studied by CFD. The tube represents one of the many in a honeycomb geometry inserted in a liquid piston air compressor to minimize temperature rise. A dimensionless number for the heat flow rate that includes the changing heat transfer area between the tube wall and air during compression is used. From the CFD results, alinear rela...

cooling towers are widely used in most industrial units to reject waste heat to the atmosphere. this paper deals with an experimental analysis of heat and mass transfer phenomena between water and air by direct contact in a cooling tower. the tower is filled with 6 type packing. in this study temperature and pressure drop and tower characteristics was used in determining experimentally the ther...

A heat pump system is constructed tO evaluate the performance and the heat transfer characteristics. Mixtures of R22/Rl42b are adopted in the heat pump. The heat transfer in the evaporator and the overall perfomance arc measured and analyzed in terms of the compositions and the flow rate of the refrigerants. The evaporator consists of counter~currem concentric circular tubes. Possibility of cap...

This paper experimentally and numerically investigated the heat transfer and friction characteristics of microfluidic heat sinks with variously-shaped micro-ribs, i.e., rectangular, triangular and semicircular ribs. The micro-ribs were fabricated on the sidewalls of microfluidic channels by a surface-micromachining micro-electro-mechanical system (MEMS) process and used as turbulators to improv...

Ab = heat-sink-base surface area Ac = cross-sectional area of the fin Cp = specific heat of the air EI = Elenbaas number g = gravity H = fin height h = heat transfer coefficient around fin ka = thermal conductivity of the air kh = thermal conductivity of the heat sink L = fin length N = total number of fins of the heat sink P = plate-air parameter Pe = perimeter of the fin pf = fin pitch qb = h...

introduction nowadays, due to higher environmental pollution and decreasing fossil fuels many countries make decisions to use renewable fuels and restrict using of fossil fuels. renewable fuels generally produce from biological sources. biodiesel is an alternative diesel fuel derived from the transesterification of vegetable oils, animal fats, or waste frying oils. considering the differences be...