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Experimental determination of correlations for mean heat transfer coefficients in plate fin and tube heat exchangers

Taler D.

Archives of Thermodynamics

2012

Vol. 33, no. 3

3-26

This paper presents a numerical method for determining heat transfer coefficients in cross-flow heat exchangers with extended heat exchange surfaces. Coefficients in the correlations defining heat transfer on the liquid- and air-side were determined using a nonlinear regression method. Correlation coefficients were determined from the condition that the sum of squared liquid and air temperature differences at the heat exchanger outlet, obtained by measurements and those calculated, achieved minimum. Minimum of the sum of the squares was found using the Levenberg-Marquardt method. The uncertainty in estimated parameters was determined using the error propagation rule by Gauss. The outlet temperature of the liquid and air leaving the heat exchanger was calculated using the analytical model of the heat exchanger.

Methods fo obtaining heat tansfer correlations for plate finned heat exchangers using experimental and CFD simulated data

Taler D.

Archives of Thermodynamics

2004

Vol. 25, no. 4

31-54

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.