Experimental study on interfacial heat-transfer coefficients at the casting/die interface in squeeze casting under transient condition

2018 ◽  
Vol 41 (7) ◽  
pp. 802-807
Author(s):  
A. P. Venkatesh ◽  
K. Logesh ◽  
Sirigireddy. Manjith Kumar Reddy ◽  
Omer Ahmed Khan ◽  
Syed Sadiq Ur Rehman ◽  
...  
2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Xuezhi Zhang ◽  
Li Fang ◽  
Henry Hu ◽  
Xueyuan Nie

Squeeze casting of wrought aluminum 7075 was carried out on a 75-ton hydraulic press. Metal/die interface heat transfer phenomena in squeeze casting of the alloy were investigated. To facilitate experimental measurements, a five-step casting mold was designed for the experiments. The five-step casting consisted of five different section thicknesses of 2, 4, 8, 12, and 20 mm. Squeeze casing experiments were performed under the applied hydraulic pressures of 30, 60, and 90 MPa. Temperatures were measured at the casting surface and at various specific locations inside the die. At each step, thermocouples were placed at 2, 4, and 6 mm away from the inside die face. Based on the measured temperature results, the interfacial heat transfer coefficients (IHTCs) and heat fluxes were determined by solving the one-dimensional transient heat conduction equation with the inverse method. With increasing the casting section thicknesses from 2 to 20 mm, the peak IHTC values varied from 1683.46 W/m2 K to 9473.23 W/m2 K, 2174.78 W/m2 K to 13,494.05 W/m2 K, and 3873.45 W/m2 K to 15,483.01 W/m2 K for the applied hydraulic pressures of 30, 60, and 90 MPa, respectively.


1983 ◽  
Vol 105 (3) ◽  
pp. 433-439 ◽  
Author(s):  
N. Seki ◽  
S. Fukusako ◽  
A. Yamaguchi

Experimental measurements are presented for free convective heat transfer across a parallelogrammic enclosure with the various tilt angles of parallel upper and lower walls insulated. The experiments covered a range of Rayleigh numbers between 3.4 × 104 and 8.6 × 107, and Prandtl numbers between 0.70 and 480. Those also covered the tilt angles of the parallel insulated walls with respect to the horizontal, φ, of 0, ±25, ±45, ±60, and ±70 deg under an aspect ratio of H/W = 1.44. The fluids used were air, transformer oil, and water. It was found that the heat transfer coefficients for φ = −70 deg were decreased to be about 1/18 times those for φ = 0 deg. Experimental results are given as plots of the Nusselt number versus the Rayleigh number. A correlation equation is given for the Nusselt number, Nu, as a function of φ, Pr, and Ra.


Author(s):  
Massimiliano Rizzi ◽  
Ivan Catton

An experimental study of a pin fin heat sink was carried out in support of the development of heat sink optimization methods requiring more detailed measurements be made. Measurements of heat flux and temperature are used to separately determine heat transfer coefficients for the pins and the base region between the pins. Three pitch to diameter ratios (distance from pin center to pin center measured diagonally) were studied: P/d = 3/1, 9/4, 3/2. Heat generation was accomplished using cartridge heaters inserted into a copper block. The high thermal conductivity of the copper ensured that the surface beneath the heat sink would be at a constant temperature. The cooling fluid was air and the experiments were conducted with a Reynolds numbers based on a porous media type hydraulic diameter ranging from 500 to 25000. The channel had a shroud that touches the fin tips, eliminating any flow bypass. The pin surface heat transfer coefficients match the values reported by Kays and London and by Zukauskas. The base region heat transfer coefficients were, surprisngly, larger than the pin values.


1969 ◽  
Vol 91 (4) ◽  
pp. 568-580 ◽  
Author(s):  
P. J. Hlavac ◽  
O. E. Dwyer ◽  
M. A. Helfant

An experimental study of heat transfer to mercury flowing in line through an unbaffled rod bundle was carried out. The “rods” were special electrical heaters whose claddings had different thicknesses and thermal conductivities. The experiments were carried out under a thermal boundary condition approaching that of uniform heat flux in all directions at the inner wall of the rod cladding. It was found that displacement of a rod from its symmetrical position can result in a large reduction in its average heat transfer coefficient. This reduction increases exponentially with the amount of displacement. For a given direction and amount of displacement, the reduction is little affected by variations in cladding thickness and conductivity but is affected considerably by flow rate. Not only does the displaced rod suffer a reduction in its own average heat transfer coefficient, but so do those toward which it is displaced. At the same time, the average coefficients of the rods from which it is displaced remain about the same. Thus the overall average coefficient of the group of affected rods goes down when a single rod is displaced.


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