A closed loop spray cooling test setup is established for the cooling of high heat flux heat sources. Eight miniature nozzles in a multi-nozzle plate are used to generate a spray array targeting at a I x 2 cm(2) cooling surface. FC-87, FC-72, methanol and water are used as the working fluids. Thermal performance data for the multi-nozzle spray cooling in the confined and closed system are obtained at various operating temperatures, nozzle pressure drops (from 0.69 to 3.10 bar) and heat fluxes. It is exhibited that the spray cooler can reach the critical heat fluxes Up to go W/cm(2) with fluorocarbon fluids and 490 W/cm(2) with methanol. For water, the critical heat flux is higher than 500 W/cm(2). Air purposely introduced in the spray cooling system with FC-72 fluid has a significant influence on heat transfer characteristics of the spray over the cooling surface. (C) 2003 Elsevier Ltd. All rights reserved.