Experimental study on enhanced heat transfer by water spraying in the cooling air flow

Water spraying into the cooling air flow is one of the most efficient methods for heat transfer enhancement. Consequently, it is currently used in several applications and is analysed as a solution for others, where compactness is very important. Considering two practical cases, an air cooled steam condenser and a compact automotive radiator, authors performed an experimental study applying this method for a fin-and-tube heat exchanger with inline tube arrangement. Experiments were carried out using a wind tunnel. Reynolds number varied in the range 2082… 4432, which includes entire transient flow range. Maximum specific sprayed water flow was 1.5⋅10⁻³ kg of water per kg of dry air. For this specific flow, an increase of 52 to 73% was achieved for the overall specific heat transfer coefficient. The cooling air pressure loss in heat exchanger almost doubled at maximum Reynolds number, compared to the case described by minimum Reynolds number. (paper)