Gasketed plate heat exchangers (GPHEs) are widely used in thermal systems, yet substantial discrepancies persist among published friction-factor correlations, even for nominally similar corrugated geometries. A key unresolved cause is plate pack breathing—elastic deformation driven by inlet-pressure asymmetry and tightening—which creates expanded and constricted channels with distinct hydraulic behavior. This work reports a systematic experimental investigation of three corrugation patterns (Chevron, Zigzag, and Four-Quadrant) tested at three tightening levels (0.98 A, 1.00 A, and 1.02 A) under controlled inlet-pressure differences. Local friction factors ( f ), overall heat-transfer conductance ( UA ), and Nusselt numbers ( Nu ) were determined independently for each channel to quantify breathing effects. Results show that friction factors are highly sensitive to deformation: depending on geometry and tightening level, differences on f- values between expanded and constricted channels reach up to 100%, explaining much of the scatter in existing f–Re correlations. In contrast, heat-transfer performance is comparatively robust, with tightening level-induced data dispersion in Nu limited to 3–10% (Chevron), 4–12% (Zigzag), and 3–16% (Four-Quadrant). Predictive models were developed using symbolic regression and a multilayer perceptron (MLP) neural network. The symbolic models achieved mean absolute percentage errors (MAPE) of 3–9%, corresponding to a reduction in prediction uncertainty of up to 50% compared with classical correlations that neglect tightening and inlet-pressure asymmetry. The MLP model showed superior performance, retaining MAPE ≈ 3.5% and strong generalization under Reynolds-range exclusion tests. This study clarifies the causes regarding friction-factor inconsistencies in GPHEs and provides validated predictive tools for operation under asymmetric or non-uniform tightening conditions. • Local friction factors measured in expanded and constricted channels of GPHEs. • Plate breathing shown as key cause of scatter in f–Re correlations. • Nusselt only mildly affected by tightening across all geometries. • Chevron plate shows best overall thermo-hydraulic performance. • Symbolic regression and ANN accurately predict GPHE behavior.
Martins et al. (Sun,) studied this question.