In the present study, the condensation and evaporation heat transfer performance of a zeotropic refrigerant mixture (HFC32/HFC125/HFC134a) inside horizontal tubes with smooth, grooved or cross·grooved inner surfaces was investigated experimentally. The cross-gTOoved tube showed the highest heat transfer coefficient for both condensation and evaporation with the zeotropic mixture. Its heat trans...

The aim of this paper is the theoretical estimations for boundary layer thickness and heat transfer coefficient which is analysed using CFD with certain parametric functions and partial differential equations as well. Along with it the feasibility of the convective heat transfer coefficient for the calculations examined during their rendering certainty with CFD methods. The equations have been ...

Computational study was carried out to determine average heat transfer coefficients and friction factors for turbulent flow through rectangular ducts with ribs. A commercial finite volume package ANSYS FLUENT 12.1 is used to analyze and visualize the nature of the flow across the ribbed duct The fluid in the duct was air, and the average heat transfer coefficients were determined by measuring t...

To learn about cooling of gas quenched batches, this paper reports on numerical predictions of local and average convective heat transfer coefficients, and overall pressure drops, on batches of five axially aligned, constant temperature, short cylindrical disks 25 cm diameter, 5 cm thickness with and without a concentric hole, with interdisk spacings of 5–20 cm, in axial turbulent flows of 20 b...

Forced convective condensation in vertical channel is investigated numerically. The condensation boundary layers that occur due to temperature difference between the walls and saturation temperature of steam is simulated by the volume of fluid (VOF) method. The effect of variations in the hydraulic diameter, steam velocity, Re number and temperature difference between the wall and saturation te...

There are a number of systems in which supercritical cryogenic fluids are used as coolants or propellant fluids. In some modern military aircraft, the fuel is pressurized above its critical point and used as a coolant to remove heat from the aircraft engine. Accurate prediction of heat transfer coefficients to turbulent flows of supercritical fluids is essential in design of such systems. One o...

Three – Phase Sparged Reactors are widely used in Chemical, Bio-Chemical and Petrochemical Industrial processes. The advantages of these reactors include high mass and heat transfer rates,isothermal conditions and on-line catalyst addition and withdrawl. The high heat transfer rates of Three-Phase Sparged Reactors are particularly attractive for highly exothermic reactions where substantial red...

Detailed knowledge of local external heat transfer around a turbine airfoil is critical for an accurate prediction of metal temperature and component life. This paper discusses the results of measurements of the local gas side heat transfer coefficient distribution which were performed in an annular gas turbine vane hot-cascade test facility and provides comparisons with analytical predictions....

Infrared thermography was used to measure heat transfer by radiation and the surface temperature of starlings (Sturnus vulgaris) (N=4) flying in a wind tunnel at 6-14 m s-1 and at 15-25 degrees C. Heat transfer by forced convection was calculated from bird surface temperature and biophysical modelling of convective heat transfer coefficients. The legs, head and ventral brachial areas (under the...