STUDY ON HEAT TRANSFER PERFORMANCES OF CIRCUMFERENTIAL OVERLAP TRISECTION HELICAL BAFFLE HEAT EXCHANGERS

The circumferential overlap trisection helical baffle shell-and-tube heat exchangers are suitable for equilateral triangular layout of tubes and can dampen shortcut leakage in triangular zones of adjacent baffles. The performance tests were conducted on oil-water heat transfer in circumferential overlap trisection helical baffle heat exchangers with inclination angles of 12 degrees, 16 degrees, 20 degrees, 24 degrees, and 28 degrees, and compared with a segmental baffle heat exchanger. The results show that both the shell-side heat transfer coefficient h(0) and pressure drop Delta p0 increase while the comprehensive index h0/Delta p0 decreases with increase in the mass flow rate of all schemes. The shell-side heat transfer coefficient, pressure drop, and the comprehensive index h0/Delta p0 decrease with increase in the baffle inclination angle at a certain mass flow rate. The average values of the shell-side heat transfer coefficient and the comprehensive index h0/Delta p0 of the 12 degrees helical baffle scheme are above 50% higher than those of the segmental one correspondingly, while the pressure drop is approximate and the ratios of the average values are about 1.664 and 1.596, respectively. The shell-side Nusselt number Nu(0) and the comprehensive index Nu(0.)Eu(z0)(- 1) increase with the Reynolds number of the shell-side axial Reynolds numberRe(z0) in all schemes. The correlation equations for the shell-side Nusselt number and axial Euler number are presented varying with the axial Reynolds number, Prandtl number, and with the helical baffle inclination angle; the deviations are within +/- 10%.