Wettability-controlled heat and moisture transfer in a wet chord-grid contactor: Experimental and exergy analysis

Wet chord grids intensify gas–liquid contact by converting a dispersed spray into a wire-supported interface, but the coupled roles of wettability, liquid morphology, and thermodynamic irreversibility remain unclear. Pristine, hydrophilic, and hydrophobic grids were compared under matched airflow and spray conditions using high-speed imaging, infrared thermography, inlet–outlet air-state measurements, and exergy analysis. Because repeated runs were unavailable, measurement uncertainty was evaluated conservatively from Type-B input bounds and propagated with a coverage factor k = 2. The hydrophobic grid maintained a denser population of discrete droplets and a more spatially uniform low-temperature region. Its nominal maximum air-temperature and humidity-ratio reductions were 4.2 °C and 3.7 g ·kg −1 , compared with 2.9 °C and 3.0 g ·kg −1 for the pristine grid and 2.9 °C and 2.6 g ·kg −1 for the hydrophilic grid. Expanded uncertainty was 0.82 °C for the temperature reduction and 1.85–1.92 g ·kg −1 for the humidity-ratio reduction; thus, the temperature separation is marginal, whereas the humidity-ratio ranges overlap. Nominal exergy efficiency increased from about 90.5% for the single spray to about 92% with the grid, but the propagated bounds do not resolve this small difference. The combined images and nominal responses support a wettability-dependent balance among retention, drainage, and interface renewal, while quantifying the repeatability and calibration evidence required for a transferable design claim.