SCIENCE & EDUCATION

Article file: SE-BMSTU...o166.pdf (998.62Kb)

1 Bauman Moscow State Technical University, Moscow, Russia

The paper presents research results of thermo-hydraulic efficiency of heat transfer surface of pin-type radiator. Such a surface comprises the vertical corridor-arranged pins with 44 mm square section and longitu-dinal and transverse pitch of 8mm.
In the experiments a Reynolds number was changed from 9 000 to 14 000. Test stand was developed and constructed to conduct experi-ments aimed at obtaining the thermo-hydraulic characteristics of a pin-type radiator. The characteristics were obtained by a standard way as a ratio of Nusselt and Euler numbers depending upon Reynolds number. Reynolds number was calculated using the channel equivalent diameter, average combustion speed. The determinative temperature to calculate thermo- physical air parameters is the average mass temperature in a channel.
The thermo-hydraulic efficiency of surface was evaluated by the ratio of Nusselt number to Euler number referred to original (smooth) surface. To compare the results the original (smooth) surface is given the gas turbulent flow in the inner pipe at the stabilized site at Re=idem.
The experiments showed that the relative Nusselt number for the sur-face under consideration equals approximately 1.0 and the relative Euler number equals 3.0. Hence the surface thermo-hydraulic efficiency is low as the heat transfer corresponds to the original (smooth) surface, the sur-face resistance being about 3 times higher than that of the original (smooth) surface.
To increase thermo-hydraulic efficiency of the given heat transfer surface there is a proposal to redesign surface in such way that it could provide a 5-10 times increasing longitudinal pitch or instead of using pins make the channels along the flow current smooth.

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