As humidity rises, what happens to the air temperature difference across an evaporator coil?

As humidity rises, the air temperature difference across an evaporator coil decreases. This is because higher humidity levels indicate that the air has more moisture content, which affects the cooling efficiency of the evaporator coil. The evaporator coil operates by absorbing heat from the incoming air, and when the air contains more moisture, the coil must work harder to remove both heat and humidity from the air.

When humidity is higher, the latent heat load, which is the energy required to remove moisture from the air, increases. This means that while the evaporator cooling capacity remains the same, a significant portion of that capacity is now directed toward dehumidification rather than cooling the air temperature. As a result, the temperature difference from the air entering the coil to the air leaving the coil is reduced, leading to decreased efficiency in cooling the air to lower temperatures.

Understanding this relationship is important for optimizing air conditioning performance and ensuring comfortable indoor environments, especially in areas with high humidity.