A gas-atomized spray cooling system integrated with an ejector loop: Ejector modeling and thermal performance analysis

Experimental Investigation on Heat Transfer Mechanism of Air-Blast-Spray-Cooling System with a Two-Phase Ejector Loop for Aeronautical Application

“…Tremendous studies regarding the heat transfer attainability and discovered that the two-phase convection could afford two-to three-orders-of-magnitude higher heat transfer coefficients over single-phase convection in addition to maintaining closer temperature tolerances [2][3][4][5][6]. Spray cooling is considered as one of the most effective methods of high-flux-waste-heat removal and has long enjoyed a reputation of unavoidable cooling method [7]. It has several remarkable advantages: not only the high heat flux dissipation capacity but also the low-temperature difference with low coolant mass flux in the given condition and its latent heat of vaporization absorbs great amounts of heat with a minimal temperature variation [8,9].…”

“…Many parameters affect the thermal performance such as arrangement of multi-nozzle [5], heat transfer surface roughness [6], coolant type [12][13][14], spray flow rate [13,[15][16][17], spay height [18], spray angle [19], nozzle inlet pressure [20], droplet size [21], impact velocity [22], gravity [4,23], target surface structure [24][25][26][27], and sub-cooling degree [28,29], which all have been contributed to the variation in behavior of spray cooling technology. Furthermore, each of the factors is mutual interference and restriction [7], for instance, the factors of droplet size, impact velocity, spray angle, even the spray flow rate would change as the variation of the nozzle inlet pressure. Hence, the heat transfer performance would be affected mainly reflects in both the heat transfer coefficient raises and surface temperature declines with the increasing of inlet pressure (4.5 bar~7.5 bar) under the same operating conditions (spray height with 18 mm and nozzle inlet temperature with 10 • C) and several independent heating powers (500 W, 800 W, 1000 W and 1400 W), published by Zhou et al [20].…”

“…Moreover, nozzle type is one of the most critical components affecting the spray parameters of the atomization quality [7,[30][31][32][33], especially for the droplet size and impact velocity are proven significantly correlated with the effectiveness of SCS. Apparently, liquid atomization is an important process contributing to obtain the desired performance of the spray quality.…”

“…The SMD of ABAN is far less than that of other type nozzles such as cone nozzle which order of SMD is around 250 µm [33]. Nowadays, the ABAN has been widely employed and played an important role in spray cooling technology in many cases of industrial application because of its excellent atomization quality which directly affects the heat transfer performance of SCS [7,34].…”

“…The unit is not limited to start the airplane's main aeroengines, but also provides pneumatic such as aircraft pressurizing [35]. Therefore, the high-pressure air is so available [7] that could provide the primary gas-flow for SCS. Another problem is how to dissipate the waste heat from the sprayed droplet should be resolved to ensure the stability of the system.…”