Asymptotic Effectiveness-NTU Formulas for Multipass Plate Heat Exchangers

The effectiveness of a plate heat exchanger with a finite number of plates is affected by the end channels, and the channels between two adjacent passes. These effects become less significant as the number of thermal plates becomes large, N > 40, as shown by Kandlikar and Shah (1989). In the present paper, closed-form equations are derived for plate heat exchangers with N = ∞ in terms of temperature effectiveness P₁ as a function of the capacity rate ratio R₁ and the number of transfer units NTU₁ for the following pass arrangements: 1–1, 2–1, 2–2, 3–1, 3–2, 3–3, 4–1, 4–2, 4–3, and 4–4.