An evaporator coil is being installed in a retail supermarket. The coil is designed to operate at a temperature of 35°F. The air entering the coil is at 75°F and 50% relative humidity. What is the sensible heat ratio for this coil?
- A0.4
- 0.6
- C0.8
- D1.0
Exam tip
Understand how to calculate the sensible heat ratio and its significance in evaporator coil design.
Why B is correct
The sensible heat ratio (SHR) is calculated as the ratio of the sensible heat load to the total heat load. The total heat load is the sum of sensible and latent heat loads. The latent heat load can be calculated using the enthalpy of the entering air and the enthalpy of the leaving air. Given the temperatures and humidity, the latent heat load is higher than the sensible heat load, resulting in an SHR less than 1. The correct calculation yields an SHR of approximately 0.6.