lindab | we simplify construction Active chilled beam Plexus Dimensioning Capacity correction for water flow e qw Example 2 Heating: Which heating capacity does a Plexus IS/ISA 60 give with an airflow of 20 l/s and a static pressure of 60 Pa? Temperature conditions: Δ t rw = 24 K, Δ t w = 3 K, Δ t ra = 0 K We have to start as in example 1 with finding out specific cooling capacity. Diagram 2 shows a specific (cooling) capacity with the value P T = 51.8 W/K. Since we use a battery with both cooling and heating, the capacity P T must be reduced with 6%: P T = 51.8 × 0.94 = 48.7 W/K This gives a water capacity: P w = 48.7 W/K × 24 K = 1169 W in the water circuit. Using the heating curve in diagram 8 for capacity correction e qw leads us to the heating capacity. Water flow rate: q w = 1169 W/ (4200 Ws/(kg K) × 3 K) = 0.093 l/s. Then the capacity correction factor: e qw = 0.42. Obtained capacity: P w = 1169 W × 0.42 = 491 W. The new water flow is calculated: q w = 491 W / (4200 Ws/(kg K) × 3 K) = 0.039 l/s. Then the new capacity correction factor e qw = 0.41. Obtained capacity: P w = 1169 W × 0.415 = 485 W. Calculate again: q w = 485 W / (4200 Ws/(kg K) × 3 K) = 0.039 l/s. The new capacity correction factor is shown as 0.415. Then the new optained capacity is: P w = 1169 W × 0.415 = 485 W. Seeing that the flow is near stabile at this point in the calcula- tion, the new heating capacity water is now: P w = 485 W. From the calculated water flow the corrections factor e qw is determined for the efficiency of utilization. The calculations are repeated until calculated capacity in roughly matches earlier calculations. Corrected capacity is easily calculated with Product Calculator Water in Lindab’s Quick Selection Tool – lindQST.com. Capacity correction e qw 1.1 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 15°C Cooling 50°C Heating S60 S120 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1 Water flow rate q w [l/s] Diagram 8. Capacity correction for water flow e qw for both heating and cooling. Lindab reserves the right to make changes without prior notice 11 2021-05-21
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