Experimental investigation of heat transfer and effectiveness of employing water and ethylene glycol mixture based Fe3O4 nanofluid in a shell and helical coil heat exchanger

A shell and helically coil heat exchanger (SCHE) is used to experimentally investigate the performance of 60% water and 40% ethylene glycol mixture based Fe3O4 nanofluid as a coolant. Chemical co-precipitation was used for the synthesis of large quantity of Fe3O4 nanoparticles with an average particle size of 11.42 nm. Correlations for the thermo-physical properties of the nanofluid were developed. The exergy analysis and heat transfer characteristics pertaining to the heat exchanger were also investigated. The frictional exergy destruction is found to contribute together with heat transfer exergy destruction to the total entropy of the SCHE system. The exergy efficiency of the SCHE can be increased by 21% using 1.0 vol% of nanofluid, but the improvement becomes modest as the volume concentration is increased further. The NTU of SCHE is improved only by 2% over that of the base fluid at the flow rate of 6 lit/min because of the limited improvement of the overall heat transfer co-efficient. Increasing the concentration of the nanofluid beyond 1.0 vol% shows a little improvement in the effectiveness of the heat exchanger. This study recommends that the volume concentration of Fe3O4/60:40 % W + EG nanofluid should not exceed volume concentration of 1.0% because the added benefit of working with concentrations higher than 1.0 vol% may not outweigh the added cost and complexities of the nanofluid.

Automated summary

The performance of a shell and helically coil heat exchanger using a 60% water and 40% ethylene glycol mixture based Fe3O4 nanofluid as coolant was experimentally investigated. Fe3O4 nanoparticles with an average particle size of 11.42 nm were synthesized using chemical co-precipitation. Correlations for the thermo-physical properties of the nanofluid were developed. The exergy efficiency of the heat exchanger can be increased by 21% using 1.0 vol% of nanofluid, but further increase in concentration shows limited improvement in heat transfer effectiveness. The study recommends not exceeding 1.0 vol% volume concentration of Fe3O4/60:40 % W + EG nanofluid due to cost and complexity considerations.