استفاده از نانوسیالات برای افزایش عملکرد رادیاتورهای خودرو
Abstract
1- Introduction
2- Materials and methods
3- Results and discussions
4- Conclusions
References
Abstract
Advanced heat removal technologies are critical for high-performance automotive engines. The conventional fluids being used today are based on a mixture of distilled water (DW) and ethylene glycol (EG), which widens the operational temperature range but at the same time limits the heat removal. Therefore, the use of nanofluids for improving heat transfer performance has soared over the past few years. The problem is that most of the reports highlight the short-term heat transfer results which may not be true over time. In this paper, a suggested best practice for analyzing the usage of nanofluids in heat transfer applications is presented, specifically for an actual car radiator. This work investigates the use of aluminum oxide (Al2O3) and titanium dioxide (TiO2) nanoparticles dispersed in DW and EG at 50:50 volumetric proportions. The choice of these oxide-based nanofluids is motivated by their anti-corrosive properties that are usually not analyzed or discussed in most of the articles. Furthermore, the emphasis is given on the presentation of a comprehensive characterization of the nanofluids including thermophysical properties (size, density, viscosity, thermal conductivity, corrosive behavior) and long-term stability (zeta potential) which are essential for an end-user to have. The results showed a maximum enhancement of the thermal performance by 24.21% using Al2O3 at a volume fraction of 0.3%. Friction factor and performance evaluation criterion (PEC) for the radiator experiments are calculated in order to determine the penalty in the pressure drop and to evaluate it properly. Finally, it is found that the values of PEC lie in the range of 1.03–1.31 which indicates significant flow enhancement.
Introduction
The improvement in automotive technologies has led to increased thermal loads, and therefore higher cooling rates are required [1]. The addition of fins, microchannel, and turbulators are the traditional approaches used to increase cooling rates of the radiator which are already extended to their limits [1,2]. In recent years, the automotive industry has been focused on the weight reduction of the vehicle as it improves the fuel economy and the associated running costs [3]. Weight reduction can be achieved in the engine cooling system. Furthermore, many conventional coolants (lubricants and water) have characteristically shown poor heat transfer properties due to their lower thermal conductivities (TCs) [1,4]. Engine performance, fuel efficiency, and emissions are specific parameters of an automobile which are profoundly affected by convective heat transfer [5,6]. Therefore, a new compact and innovative coolants and/or coolant systems are needed to fulfill the growing needs for heat removal in a clean and eco-friendly way [7].