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...

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...

In this work, analysis of transient three-dimensional heat transfer in a slab with internal heat generation and heated by a point moving heat source along its axis is carried out using integral transforms methods. The heat input into slab or workpiece by the moving heat source is considered in the model. From the results, it was established that the temperature of the material during the heat t...

the objective of the present study is the synthesis of mwcnt-tio2 hybrid nanostructures by solvothermal synthesis method with ticl4 as precursor. the heat transfer enhancement due to the use of mwcnt-tio2 nanofluid was investigated. as-prepared hybrid materials were characterized by x-ray diffraction (xrd) and scanning electron microscopy (sem). the results showed that mwcnts were uniformly dec...

In the current research project, the thermal performance of a series of newly designed mixers has been investigated. Each mixer has two concentric cylinders comprising two annular slot flow channels around a solid cylindrical rod at the center. In each mixer, the first cylinder around the central solid rod has either spherical or pyramidal protrusions throughout the outer surface. It has been o...

In the present study, the effective parameters of water-Al2O3 nanofluid flowing in flat tubes are investigated using the EFAST Sensitivity Analysis (SA) method. The SA is performed using GMDH type artificial neural networks (ANN) which are based on validated numerical data of two phase modeling of nanofluid flow in flat tubes. There are five design variables namely: tube flattening (H), flow ra...

This study discusses the application of Taguchi method in assessing minimum entropy generation and maximum heat transfer rate for natural convection in an enclosure embedded with isothermal cylinder. The simulations were planned based on Taguchi’s L25 orthogonal array with each trial performed under different conditions of position and aspect ratio (AR) of the cylinder. The thermal lattice Bolt...

A semi-analytical investigation has been carried out to analyze unsteady MHD second-grade flow under the Dual-Phase-Lag (DPL) heat and mass transfer model in a vertical microchannel filled with porous material. Diffusion thermo (Dufour) effects and homogenous chemical reaction are considered as well. The governing partial differential equations are solved by using the Laplace transform method w...

In this paper, fluid flow and heat transfer in the laboratory (small size) shell tube heat exchanger are analysed by computational fluid dynamic software. In this type of shell tube heat exchanger baffles with different angles of rotation: 00 (horizontal segmental baffle), 150 (from horizontal), 300, 450, 600, 750, 900 (vertical segmental baffle) is used. Effect of baffle orientation on shell t...

This study numerically investigated heat transfer and fluid flow characteristics in a novel cylindrical heat sink with helical minichannels for the laminar flow of fluid with temperature-dependent properties. A finite volume method was employed to obtain the solution of governing equations. The effects of helical angle, channel aspect ratio, and Reynolds number, which were regarded as main para...