Brandon White, Engineer, Experimental Research
In 1958, Tinker introduced the concept of treating shellside flow in baffled shell‑and‑tube exchangers as a network of hydraulic resistances, analogous to electrical resistors. Each flow path—or stream—was assigned a resistance that depended on its location and geometry, providing a systematic way to predict pressure drops and temperature profiles.
Building on this foundation, Palen and Taborek (1960s) derived detailed correlations for the individual stream resistances using extensive experimental data collected at HTRI and by other research groups, eventually developing the HTRI Stream Analysis Method (SAM). SAM captures the mixing of streams (e.g., the C‑stream re‑joining the B‑stream after bypassing the bundle), which directly influences the mean temperature difference used in the overall heat‑transfer equation. Figure 1 illustrates the concept of hydraulic resistances around a single baffle in a shell-and-tube heat exchanger.
The original SAM correlations were calibrated exclusively on TEMA E‑shell (transversely baffled) units. Consequently, unbaffled configurations such as TEMA X shells exhibit a different stream topology and resistance pattern. Because physical data for X shells are scarce, current approaches rely on theoretical adjustments rather than experimental validation.
HTRI is addressing this gap through a dedicated research program on seal‑strip design for X‑shell exchangers. The results extend SAM to unbaffled shells, delivering more reliable hydraulic and thermal predictions for a broader class of heat‑exchanger designs. Refer to our article HTRI Advances Seal Strip Analysis for X‑shell Heat Exchangers for more information on this research.
Nomenclature
KA, A-stream resistance coefficient
KB, B-stream resistance coefficient
KC, C-stream resistance coefficient
KE, E-stream resistance coefficient
ΔPc, Crossflow pressure drop, kPa
ΔPw, Window pressure drop, kPa