Heat transfer characteristics of single cone-jet electrosprays

Spray cooling is an attractive proposition for thermal dissipation due to its high efficiency and markedly lower power requirements compared with more conventional air cooling systems. The local convective heat flux to single source cone-jet electrospray using thin foil thermography has been investigated parametrically. Two-phase electrospray cooling using ethanol is explored for multiple nozzle sizes (Di = 0.33-1.37 mm), flow rates (Q = 2-16 μL min−1) and separation heights (H = 2.5-17.5 mm). The results show two distinct regimes of electrospray cooling; evaporative and pool electrospray cooling. Cooling performance was shown to be dependent on separation height and flow rate. Nozzle size was shown not to be a significant parameter except for small dependency for the smallest nozzle size tested. Importantly, the results demonstrate that very high peak heat transfer enhancement of up to 18.7 times over natural convection can be achieved with electrospray cooling for exceptionally low flow rates (4 μL min−1).