Air–water contact in an insulated spray chamber Air passes through an insulated chamber containing water sprays maintained at a temperature higher than the entering air’s dew-point but lower than its dry-bulb temperature. The resulting air process is best described as:

Introduction / Context:
Spray chambers are classical psychrometric devices where air exchanges sensible and latent heat with water droplets. The relative position of spray water temperature to the air’s dry-bulb (DBT) and dew point (DPT) governs whether moisture is added or removed.

Given Data / Assumptions:

• Insulated chamber → no external heat gain/loss.
• Spray water temperature T_w satisfies DPT < T_w < DBT_in.
• Adequate contact for approach toward adiabatic saturation line.

Concept / Approach:
If T_w is below the air DBT, the air tends to cool sensibly. If T_w is above the air dew point, the droplets remain unsaturated relative to the entering air, so evaporation from droplets to air can occur, adding moisture and increasing humidity ratio. Thus the combined effect is cooling (sensible) plus humidification (latent).

Step-by-Step Solution:
Check condensation criterion: since T_w > DPT, the air will not condense moisture on the droplets.Check sensible direction: since T_w < DBT_in, heat flows from air to water → air cools.Mass transfer: with air not at saturation and droplets present, evaporation increases humidity ratio.

Verification / Alternative check:
On the psychrometric chart, the path trends toward the adiabatic saturation line from the initial state, moving left (cooler DBT) and upward (higher humidity ratio).

Why Other Options Are Wrong:

• Cooled and dehumidified: would require T_w below dew point or a cooled coil to condense moisture.
• Heated and humidified/dehumidified: inconsistent with T_w relative to DBT and DPT and with chamber insulation.

Common Pitfalls:
Assuming any spray always humidifies without temperature change; ignoring dew-point criterion for condensation versus evaporation.

Final Answer:
cooled and humidified