Experimental assessment of enhanced 2x3 Semi-Closed microstructure tube bundle as an alternative in shell and tube heat exchangers

The use of various types of modified surfaces to promote passive two-phase heat transfer rate is an area of active research since 1931. In the present study, a long-lived semi-closed microstructure tubular surface with stable thermal performance over time is created by the deformational cutting method to be used in a tube bundle (TB). The investigation includes finding the efficacy of a 2x3 microstructure TB in comparison to a 2x3 and 5x3 smooth TB subject to varied parameters of heat flux, mass flux, and pitch to diameter ratio (P/D). The results show that the performance of a semi-closed microstructure TB is superior to smooth TBs owing to its lower boiling inception wall superheat and increased surface area. The effectiveness is greater than 2 fold at the highest P/D, implying that the 2x3 microstructure TB outperforms the matching smooth TB by more than 100%. The effec-tiveness of the 2x3 microstructure TB is also analyzed and compared with the 5x3 smooth and porous copper-coated enhanced TB at their best-performing P/D. The calculated effectiveness of the 2x3 microstructure TB is in the range of 2.6-1.4 for equivalent 2x3 and 5x3 smooth TBs (25 mm diameter tubes). Furthermore, when compared to the previous research findings for 5x3 smooth and porous copper-coated TBs (20 mm diameter tubes), its effectiveness is found to be 2.1-1.3 and 1.4-0.8, respectively. Interestingly, the 2x3 microstructure TB demonstrates greater performance at the higher P/D in contrast to the smooth and coated TB. Therefore, the current research demonstrates a semi-closed microstructure TB as a promising technology that is favorable in terms of compactness and cost-effectiveness.

Automated summary

The present study focuses on the development of a long-lived semi-closed microstructure tubular surface using the deformational cutting method for passive two-phase heat transfer enhancement. The results show that the semi-closed microstructure tubular surface outperforms smooth tubular surfaces in terms of lower boiling inception wall superheat and increased surface area. Furthermore, it demonstrates better performance compared to smooth and coated tubular surfaces at higher pitch to diameter ratios.