Heat Release Calculations Per GR-63-CORE
To calculate Heat Dissipation or Heat Release for a shelf-level product:
Need to know:
Height of the unit
Includes the height of any required air ramps or spacers.
Width of the frame
For a 23-inch mounting, use a width of 26 inches.
NOTE: Equipment mounts on 23 inch, but total width equals 26 inches. The calculator shows a width of 23 inches, but will use 26 inches in the calculation.
Depth of the frame
Depth of the frame (Front and Rear aisle dimensions are from GR-63-CORE):
i. 12 inch
FrontAisle = 30 inches
RearAisle = 24 inches
ii. 18 inch
FrontAisle = 54 inches
RearAisle = 30 inches
iii. 24 inch
FrontAisle = 42 inches
RearAisle = 30 inches
Equipment power in Watts
Multiply operating voltage (-48 Vdc) by maximum load current (A).
Calculate the floor area (use Front and Rear aisle dimensions from item 3):
FloorArea = [Width*(depth + (FrontAisle/2 + RearAisle/2))]
Calculate the Heat Release per Shelf:
HeatReleaseperShelf = Equipment Power/FloorArea
Calculate the Heat Release per Unit Height:
HeatReleaseperUnitHeight = HeatReleaseperShelf/Height
Compare values to Table 4-6 of GR-63-CORE Shelf and use appropriate value based on Forced-Air Fans or Natural Convection.
Example Calculation
Forced-air fans used to cool unit
Height of unit = 24.5 inches (2.042 ft)
Width of Frame = 26 inches (2.167 ft)
Depth of Frame = 12 inches (1 ft)
FrontAisle = 30 inches (2.5 ft)
RearAisle = 24 inches (2 ft)
Equipment power in watts = 457 Watts
Calculate the floor area (use Front and Rear aisle dimensions from item 3):
FloorArea = [Width*(depth + (FrontAisle/2 + RearAisle/2))]
FloorArea = [2.167 ft*(1 ft +(2.5 ft/2 + 2 ft/2))] = 7.042 ft2
Calculate the Heat Release per Shelf: o HeatReleaseperShelf = Equipment Power/FloorArea
HeatReleaseperShelf = 457 Watts/7.042 ft2 = 64.95 W/ft2
Calculate the Heat Release per Unit Height:
HeatReleaseperUnitHeight = HeatReleaseperShelf/Height
HeatReleaseperUnitHeight = 64.95 W/ft2 /2.042 ft = 31.8 W/ft2/ft
31.8 W/ft2/ft is greater than 27.9 W/ft2/ft therefore this unit does not meet the GR-63-CORE Heat Release Objective.