Cooling and dehumidification over a coil: Compared with the entering air, the relative humidity of the leaving air is generally…

Introduction / Context:
During coil cooling with condensation, the air state moves toward the apparatus dew-point. Although moisture is removed, the relative humidity of the remaining air usually increases because temperature drops faster than the vapour content on a percentage basis.

Given Data / Assumptions:

• Cooling coil below the entering air dew-point, causing condensation.
• Steady flow and standard psychrometric behaviour.
• No reheat applied immediately after the coil.

Concept / Approach:
Relative humidity compares actual vapour partial pressure to saturation pressure at the same temperature. When air is cooled, the saturation pressure decreases steeply. Even if some moisture is removed, the ratio often rises, pushing RH closer to 100% at the coil exit (unless followed by reheat).

Step-by-Step Solution:

Verification / Alternative check:
Plot inlet and outlet on a psychrometric chart. The path moves down-left toward the saturation curve; RH lines indicate an increase unless a reheat stage follows.

Why Other Options Are Wrong:

Lower/unchanged: not typical during active dehumidification without reheat.“Indeterminate” disregards the strong, standard trend on typical comfort-cooling coils.Always 100%: only true if leaving state is exactly at saturation; in practice it is high but not necessarily 100%.

Common Pitfalls:
Confusing absolute moisture removal with relative humidity behaviour; removing water does not automatically mean lower RH if temperature drops significantly.

Final Answer:

higher