Thermal-hydraulic performance of TiO2-water nanofluids in an offset strip fin heat exchanger

Abstract

The flow and heat transfer characteristics of the TiO2-water nanofluid assuming as a single-phase in the rectangular offset strip fin structure for different Reynolds number (500-1000) and TiO2 nanoparticle volume concentration values (0%-4%) were investigated numerically under three-dimensional, steady state and laminar flow conditions. Simulations were also performed for 1% and 4% nanoparticle volume concentrations of Al2O3-water nanofluid, and the results were compared with those of TiO2-water nanofluid. Results show that when the TiO2-water nanofluid is used, the heat transfer rate, heat transfer coefficient and Nusselt number increase with increasing both Reynolds number and nanoparticle volume concentration, and parallel to these, both pressure loss and pumping power increase. Considering the values of the performance evaluation criteria (PEC) number, it is clear that the use of TiO2-water nanofluid in offset strip fin structure at all Reynolds numbers examined between 1%-4% volume concentration values is quite advantageous. It is observed that TiO2-water nanofluid is much superior to Al2O3-water considering the PEC number. When the Reynolds number is 1000 and the volume concentration value of the TiO2 nanoparticle is 4%, the PEC number value is found to be 1.19, that is, there is a 19% increase compared to water. It is considered that the results of this study can be used as important data on the design of automobile radiators, air-conditioning and defense.

Comprehensive performance investigation and optimization of a plate fin heat exchanger with wavy fins

“…As it is widely used in fields of aerospace, refrigeration, air conditioning and oil refining, the heat transfer enhancement of the compact heat exchanger has been of industrial and academic interests for decades [1,2]. The extended surface [3] is one of the effective ways to enhance heat transfer by interrupting the boundary layer, restarting it, creating secondary flows, and/or generating flow unsteadiness [4] with typical channels of wavy fins [5], offset strip fins [6][7][8] and louvered fins [9]. However, as the pressure drop and pump power increase with the enhancement of heat transfer, it is important to evaluate the comprehensive performance [7,10,11] of the heat exchanger.…”