A NEW CONCEPT TO THE GENERAL UNDERSTANDING OF THE EFFECT OF LONGITUDINAL CONDUCTION FOR MULTISTREAM COUNTER FLOW HEAT EXCHANGERS

2019 ◽  
Author(s):  
C. L. Pan ◽  
N. E. Welch ◽  
R. R. Head
Keyword(s):  
Heat Exchangers ◽  
Counter Flow ◽  
Flow Heat

A Transient Model for Parallel Flow and Counter Flow Heat Exchangers

2013 ◽  
Author(s):  
K. Abbasi ◽  
M. Del Valle ◽  
A. P. Wemhoff ◽  
A. Ortega
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Transient Behavior ◽  
Parallel Flow ◽  
Thermal Mass ◽  
Dimensionless Time ◽  
Internal Wall ◽  
Counter Flow ◽  
Thermal Capacitance ◽  
Flow Heat

The transient and steady-state response of single pass constant-flow (concentric parallel flow, concentric counter flow) heat exchangers was investigated using a finite volume method. Heat exchanger transients initiated by both step-change and sinusoidally varying hot stream inlet temperatures were investigated. The wall separating the fluid streams was modeled by conduction with thermal mass; hence the heat exchanger transient behavior is dependent on the thermal mass of the fluid streams as well as the internal wall. The outer wall is approximated as fully insulating. The time dependent temperature profiles were investigated as a function of heat exchanger dimensionless length and dimensionless time for both fluids. It was found that the transient response of the heat exchanger is controlled by a combination of the residence time and thermal capacitance of the fluid streams, the overall heat transfer coefficient between the fluid streams, and the thermal capacitance of the internal wall.

Effectiveness-NTU Relations for Heat Exchangers With Streams Having Significant Kinetic Energy Variation

2003 ◽  
Vol 125 (2) ◽  
pp. 377-387 ◽  
Author(s):  
Gregory F. Nellis
Keyword(s):  
Heat Exchanger ◽  
Kinetic Energy ◽  
Differential Equations ◽  
Heat Exchangers ◽  
Parallel Flow ◽  
Temperature Profiles ◽  
Cryogenic Temperatures ◽  
Cold Side ◽  
Counter Flow ◽  
Flow Heat

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.

MWR Approximation and Modal Control of Parallel- and Counter-Flow Heat Exchangers

1977 ◽  
Vol 10 (5) ◽  
pp. 423-435
Author(s):  
Akira Ito ◽  
Hideaki Kanoh ◽  
Masami Masubuchi
Keyword(s):  
Heat Exchangers ◽  
Modal Control ◽  
Counter Flow ◽  
Flow Heat

A Mathematical Confirmation for Higher LMTD Value of Counter Flow Versus Parallel Flow Heat Exchangers

2003 ◽  
Vol 125 (1) ◽  
pp. 182-184 ◽  
Author(s):  
Farshad Kowsary ◽  
Mohammad Biglarbegian
Keyword(s):  
Heat Exchangers ◽  
Parallel Flow ◽  
Counter Flow ◽  
Flow Heat ◽  
Increasing Function

A rigorous argument based on the characteristic of a monotonously increasing function is presented to establish the well-known fact of higher LMTD value of counter flow heat exchangers as compared to parallel flow ones.

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