Twin pulsating jets impingement heat transfer for fuel preheating in auto motives

Abstract

The problem of environmental pollution and depletion of fossil fuel can be reduced in auto motives by using an alternative bio-fuel and improve the ignition process in engine. Both solutions need to use the fuel preheating technique. This work presents the idea of fuel preheating by using exhaust impingement on the fuel tank. Heat transfer between twin pulsating hot air jets and flat copper target was investigated as an application for preheating of automotive fuel to improve ignition process in the engine. The nozzle of 20 mm was used to produce air jet of Reynolds number, Re ~ 5500 and a temperature of 54??C. The impinged target was imposed to still air surrounding at temperature of 24??C. Pulsating frequencies of 1 0-50 Hz were applied on air jets by using twin pulsating jet mechanism. The effect of pulsation frequency on heat transfer was measured using 1R camera and heat flux-temperature micro foil sensor. The results obtained by both of these methods showed well agreement. Also, the results revealed significant influence of flow rate difference between steady and pulsating jet cases. In addition, the highest Nusselt number, Nu ~7.2, was obtained at pulsation frequency of 20 Hz.