RESPONSE SURFACE BASED OPTIMIZATION OF RIBBED ISOSCELES TRIANGULAR TWISTED TAPE HEAT EXCHANGER USING ENTROPY AUGMENTATION GENERATION NUMBER WITH AL2O3 NANO WORKING FLUID

In this work, a combination of passive techniques like providing ribs on the duct surface, inserting twisted tapes were employed at different configurations and analysed using ANSYS Fluent 17.2. The enhancement is probed by placing ribs on the duct surfaces at various angles. Twisted tape inserts were used in conjunction with ribs on the duct and an output parameter, Entropy Augmentation Generation Number (EAGN) is analysed when having an Al2O3 nanofluid (phi=3%) as working medium. In furtherance, tapes of isosceles triangular projections with variable configuration, such as rib angles (30 degrees<alpha<90 degrees ), Internal angle (30 degrees<beta<90 degrees) and projection distance (1mm < x< 5mm) were also inserted in place of plain twisted tape inserts to verify the enhancement promised by this alteration. As expected, rate of heat transfer due to the presence of isosceles triangle projections gave decent augmentation. Later Response Surface based optimization was employed with non-parametric regression and genetic algorithm to make an investigative search of all the modified parameters so as to suggest best blend of inputs for low Entropy Augmentation Generation Number. Optimum performance was obtained at rib angle of 30 degrees, projection distance of 2.1mm and Internal angle of 44.4 degrees with entropy augmentation number value of 0.77. The performance of Genetic Algorithm was compared with Micro Genetic Algorithm; it shows that optimized result is obtained less than half the time using Micro Genetic Algorithm.