Effectiveness-NTU equations are derived for counter and parallel-flow heat exchangers with fluids having high velocities. In this case, the change in the kinetic energy occurring within the heat exchanger will significantly affect the temperature profiles. The effectiveness is found to depend on the usual non-dimensional variables that compare the heat exchanger conductance to the hot- and cold-side capacity rates and on four additional nondimensional quantities that reflect the magnitude and distribution of the kinetic energy on the hot and cold-sides of the heat exchanger. The governing differential equations are derived, nondimensionalized, and solved analytically for the case of an exponentially distributed kinetic energy. Graphical solutions are presented and interpreted for several cases. The solutions are applied to a particular case involving high velocities within a counter-flow heat exchanger used to produce cryogenic temperatures.
Effectiveness-NTU Relations for Heat Exchangers With Streams Having Significant Kinetic Energy Variation
Contributed by the Heat Transfer Division for publication in the JOURNAL OF HEAT TRANSFER. Manuscript received by the Heat Transfer Division April 23, 2001; revision received November 6, 2002. Associate Editor: M. K. Jensen.
Nellis, G. F. (March 21, 2003). "Effectiveness-NTU Relations for Heat Exchangers With Streams Having Significant Kinetic Energy Variation ." ASME. J. Heat Transfer. April 2003; 125(2): 377–387. https://doi.org/10.1115/1.1560154
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