Experimental investigation of optimal operational jet-to-target plate of multiple jet impingement heat transfer

Multiple jet impingement has become an established method of convectively cooling or heating surfaces in a wide multiplicity of process and thermal control applications. Impinging jets are extensively utilized in higher heat transfer applications for cooling purposes in various engineering fields such as tempering of glass and metals, heat reduction in microelectronic devices, drying of textiles and papers, gas turbine blades, aircraft deicing etc. This research work focuses on the experimental investigation of the optimal operational jet-to-target plate of multiple jet impingement heat transfer. Air jet impingement apparatus was used for the exercise. An 11×11 array with jet diameter 0.3 mm and jet-to-jet spacing of 2 mm was used to analyze the jet-to-target distance, H in the range 0.53mm ≤ H ≤ 3.97 mm at flow rates of 1.67x10-5 m3/s, 3.33x10-5 m3/s , 5x10-5 m3/s , 6.66x10-5 m3/s , 8.3x10-5 m3/s , 1x10-4 m3/s , 1.17x10-4 m3/s and 1.33x10-4 m3/s. The array was tested by hanging it on the aluminium holder of the experimental apparatus. The heating element of wattage capacity 1000Wwas connected to the power source. The heater was switched on to heat the target plate. Simultaneously, heat was supplied at the bottom side of the copper plate and the blower was turned on to impinge air on the smooth and flat target plate. Air was regulated to the desired flow rate using a gate valve. The jet temperature as well as the surface temperature were measured using an infrared thermometer at every flow rate tested. Result showed that the optimum jet-to target distance was found to be in the range 5d ≤ H ≤ 6d.