Mitsubishi Electric QAHV-N560YA-HPB Data Book page 37

4. System Design
Step 4 Calculation of the shearing stress
Calculate the shearing stress using the following method.
Values required for calculation
 Relationship between flow rate and pressure loss of corresponding heat exchanger (Obtain the data from the
heat exchanger manufacturer.)
Calculation method
Calculate the shearing stress using the following formula.
Representative length of 1 channel
Effective length:
Length between water inlet and water outlet
(refer to the figure on the right)
Representative length of 1 channel:
Distance between plates
(refer to the figure on the right) × 2
∆P: Pressure loss
A shearing stress of 16 Pa or higher is required to reduce the amount of scale that adheres.
If the shearing stress is low:
 Select a vertically short shape.
 Change the shape of the plates.
Reselect a heat exchanger that will increase the shearing stress by following methods described above.
MEES19K001
Effective length
Side of heat exchanger
Front of heat exchanger
Distance between plates
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