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# Effectivenss Calculations

## Effectivenss Calculations

(OP)
Effectiveness of heat exchanger can be calculated as (Tin - Tout)/Max Differential Temperature. I have Energy wheel to extract heat from outside air. OAT=46°C, after energy recovery it drop down to 30°C. Exhaust air Temperature EAT=24°C. so, Effectivess = (46-30)/(46-23), it gives 70% effectiveness which is matching with the manufacturer data. Flow rate is same. OA supply airflow rate is equal to exhaust flow rate.

But when I put Heat Pipe in series with energy wheel, I am getting relatively lower temperature of outside temperature after energy wheel i.e. 26°C. So overall heat recovery system effectiveness is (46-26)/(46-23) = 87%.
In some AHUs the OA temperature drop is even low, i.e. after Heat pipe - Energy wheel OAT is less than 26°C. But i think, in any case my OA temperature will not go below 24°C (EAT temp). So my effectivess of Heat recovery system may come to Unity.

Someone please confirm, if I am on the right track?

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