Methods fo obtaining heat tansfer correlations for plate finned heat exchangers using experimental and CFD simulated data
The following paper presents numerical methods for determining heat transfer coefficients in cross-flow compact heat exchangers. Primary measurements consist of the flow rates of each fluid stream, the inlet and outlet fluid temperatures on the liquid-side and the air temperature in front of the heat exchanger. Three inverse methods are developed to determine correlations for the heat transfer coefficients. In the first method, only the air-side heat transfer coefficient is determined from the condition that the calculated and measured coolant outlet temperatures are equal. The heat transfer coefficient on the liquid-side is calculated using the Gnielinski or Dittus-Boelter correlations. In the second method, the problem of determining correlations for average heat transfer coefficient on air- and liquid-sides is formulated as a parameter estimation problem by selecting the functional form for the Nusselt numbers. The non-linear, least-square problem is solved using the Lavenburg-Marquardt method. The third method is based on the results of the CFD simulations of flow and heat transfer in the heat exchanger. The aid-side heat transfer correlation is determined from the condition that air temperature differences across the heat exchanger obtained from the CFD simulation and from analytical model of the heat exchanger are equal.
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