If the number of tubes in series is 4 or less, the software considers the exchanger as cross-flow. In this configuration, there are no analytical equations, only empirical formulas, which generally indicate a reduction in exchanger efficiency.
According to our engineers, a prudent approach is to apply a reduction of the exchanger's efficiency, which on average is 30 per cent, as provided for in the current modification. If you feel that this decrease is not appropriate for your applications, you can select the option with no reduction in efficiency.
