(232ah) Heat Transfer Enhancement from a Hot Steel Plate Using Triton X-100 Surfactant Additive in Water Jet

Abstract

Heat transfer is one of the most widely used
transport processes in industries. It is the most important phenomena in steel
industries for the production of high strength steel. The
mechanical properties of steel depend upon the finished roll temperature,
run-out table cooling and coiling temperature. Heat
transfer rate at run-out table (ROT) during hot rolling process in
steel industries determines the metallurgical
microstructure for specified mechanical properties required for particular
applications. The phase transformation of steel
occurs between a rolling temperature of 900 ^oC and a coiling
temperature of 600 ^oC. The phase microstructure and corresponding
mechanical properties depend upon the cooling intensity between the aforementioned
temperature ranges. Ultrafast cooling is a technique used to obtain high
strength steel.

The current work attempts to achieve ultrafast cooling
by introducing different cooling methods for steel. It focuses
on the enhancement of heat transfer from a hot steel plate by introducing non-ionic
surfactant additive, Triton X-100 in jet cooling. The characterization of surfactant
solution has been done in order to understand the reason for increment in heat
transfer. The concentrations of surfactant have been varied from 60 ppm to 140
ppm in intervals of 20 ppm and the results indicate that the addition of Triton
in water jet leads to an appreciable increase in cooling rate compared to that
of water. The maximum cooling rate is achieved at a surfactant concentration of
120 ppm which is attributed to the low values of surface tension (as shown in
Figure 1 below) and contact angle (as shown in Figure 2 below) obtained at this
concentration leading to higher spreadability and heat removal rate. The
highest cooling rate achieved is 170 ^oC/sec (as shown in Figure 3 below) which is 56% more than
that attained for pure water. The study reveals that ultrafast cooling can be
attained by the addition of Triton in water. Thus heat transfer plays an essential role in the production of high strength steel for
various industrial applications.

 Keywords: Heat transfer, jet
cooling, ultrafast cooling, Triton X-100, run-out table, cooling rate.

Figure
1: Variation of surface tension with varying concentration of Triton X-100

Figure
2: Variation of contact angle with varying concentration of Triton X-100

Figure
3: Variation of cooling rate with varying concentration of Triton X-100

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