Chowdhury Md. Feroz

Boiling heat transfer characteristics of R-113 in a vertical small diameter tube under natural circulation condition

Abstract Boiling heat transfer characteristics of freon R-113 are experimentally investigated in a vertical small diameter tube, D=1.45 mm and L=100 mm at a wide pressure range of 19–269 kPa under natural circulation condition. Except the entrance region of the test section, the flow regime is annular in view of the measured vapor flux. The pool boiling correlations of Stephan and Abdelsalam and McNelly equally well predict the experimental data within an error of ±20%. No enhancement of heat transfer coefficient is obtained although D/B is less than 1.5, which differs from the finding of Klimenko.

Micro heat pipes - a promising means of thermal solution for desktop computers

Heat transfer performance of parallel micro heat pipes (MHPs) used for the cooling of desktop computer processor has been investigated in this paper. MHPs consists of six single tube micro heat pipes connected by a copper block at the evaporator section and fifteen parallel copper sheets used as external fins at the condenser section. Ethanol was used as working fluid. The copper block is placed above the heat source (on the top of the processor) and the condenser section is provided with external fins perpendicular to the MHPs. Heat transfer characteristics of MHPs are determined experimentally, based on the principle of phase change of the working fluid. The experimental results show that, the maximum and steady state temperature of the processor has been reduced significantly by using micro heat pipes instead of the cooling fan. Addition of fan at the condenser section of MHPs gives much low and steady state temperature of the processor.

Effect of Geometry on the Performance of Miniature Heat Pipe

An experimental study is performed to investigate the effect of geometry on the performance of miniature heat pipe (MHP). The experiment is conducted with circular and square MHPs having the same hydraulic diameter of 5 mm and length of 150 mm with acetone as the working fluid. The major findings in the investigation are as follows. At a constant heat flux, coolant flow rate and inclination angle, wall temperatures of evaporator section of circular MHP are higher than that of the square MHP. With the decrease in both inclination angle and coolant flow rate, the rate of increase in wall temperature of the evaporator section for circular MHP is higher than that of square MHP. Thermal resistance of the circular MHP is almost independent of coolant flow rate but for square MHP, thermal resistance decreases with the increase in coolant flow rate. Again at a constant coolant flow rate, heat flux and inclination angle, the thermal resistance for square MHP shows much smaller value than that of circular MHP. Overall heat transfer coefficient for square MHP is maximed at vertical orientation.© 2007 ASME

Experimental and Computational Analysis of Natural Convection Over Flat Plate

Natural convection heat transfer over a flat plate with a heat source at bottom side of plate is studied experimentally and numerically. We consider the two-dimensional problem of both steady and unsteady natural convection over the flat plate at vertical, horizontal and inclined position. Experimental analysis is done for three different constant heat fluxes for each angle position. The Navier-Stokes and Energy equations with the Boussinesq approximation are written in Cartesian coordinate system. The problem is solved in the physical variables on the basis of a completely implicit Finite element Method order to examine the heat transfer characteristics. To see the effects of different angle position phenomena of natural convection over flat plate, the computational results presented in the form of streamlines for a wide range of Grashof number at different heat fluxes. The average Nusselt number of heated plate for different angle position has been observed.Copyright