Calculation of air temperature at heat exchanger outlet:
t = tint+keff*(text - tint) / 100,
Where
tint - intake air temperature 0С,
text - extract air temperature 0С,
keff - heat exchanger efficiency (as per diagram), %
Calculation of water heater parameters
How to use water heater diagrams:
Air Speed. Starting from 650 m3/h on the air flow scale draw a vertical line 1 till the air speed axis which makes about 2.35 m/s.
- Supply air temperature. Prolong the line 1 up to the point where it crosses the outside air temperature (blue curve), e.g. +5°C; then draw a horizontal line 2 from this point to the left till crossing water in/out temperature curve (70/50 °C). From this point draw a vertical line 3 to the supply air temperature axis on top of the graphic (+26°С).
- Heating coil capacity. Prolong the line 1 up to the point where it crosses the outside air temperature indicated as red curve (e.g., +5°С) and draw a horizontal line 4 from this point to the right to the intersection of water in/out temperature curve (e.g., 70/50 °С). From this point draw a vertical line 5 up to the scale of heating coil capacity (5.8 kW).
- Water flow. Prolong the line 6 down to water flow axis at the bottom of the graphic (0.04 l/s).
- Water pressure drop. Draw the line 7 from the point where line 6 crosses the black curve to the pressure drop axis (0.5 kPa).