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28 TRG-TRC001-EN
notes
period three
Sensible Heat Ratio
Assume that room design conditions (A) are 78°F DB and 65°F WB, and that the
sensible heat ratio is calculated as 0.80. That is, sensible heat gain represents
80% of the total (sensible plus latent) heat gain.
The SHR line is found by aligning the index point with the 0.80 marking on the
sensible-heat-ratio scale and drawing a line from the index point to the
saturation curve.
Supply air with any combination of dry-bulb and wet-bulb temperatures that
falls on this line will be able to absorb the room's sensible and latent heat in the
correct proportions needed to maintain the desired room conditions
(A = 78°F DB, 65°F WB).
Each of these combinations, however, requires a different quantity of air to do
the task. Recall the analogy with the container of water. If the supply air is
warm, a higher quantity of air is required than if the supply air is cold.
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