Effectiveness of Series Assemblies of Divided-Flow Heat Exchangers

1986 ◽  
Vol 108 (1) ◽  
pp. 141-146 ◽  
Author(s):  
A. Pignotti
Keyword(s):  
Heat Capacity ◽  
Heat Exchangers ◽  
Rate Ratio ◽  
Parallel Flow ◽  
Direct Coupling ◽  
Explicit Solutions ◽  
Flow Heat

Formulas are derived for the effectiveness of a series assembly of two divided-flow exchangers, as a function of the heat capacity rate ratio, and the partial effectivenesses of the components. Six possible connections are discussed: overall parallel flow and counterflow, with either mixing of the intermediate divided streams, or direct or crossed coupling of the same. It is shown that when both exchangers are alike, and direct coupling is used, the simplifying mixing assumption leads to a systematic overestimate of the effectiveness of the assembly. The size of this effect is discussed and illustrated with explicit solutions for TEMA J exchangers with one and two tube passes.

Thermal Effectiveness of Multiple Shell and Tube Pass TEMA E Heat Exchangers

1988 ◽  
Vol 110 (1) ◽  
pp. 54-59 ◽  
Author(s):  
A. Pignotti ◽  
P. I. Tamborenea
Keyword(s):  
Heat Transfer ◽  
Heat Capacity ◽  
Heat Transfer Coefficient ◽  
Heat Exchangers ◽  
Rate Ratio ◽  
Algebraic Solution ◽  
Tube Heat Exchanger ◽  
Transverse Mixing ◽  
Shell And Tube ◽  
The Heat Transfer Coefficient

The thermal effectiveness of a TEMA E shell-and-tube heat exchanger, with one shell pass and an arbitrary number of tube passes, is determined under the usual symplifying assumptions of perfect transverse mixing of the shell fluid, no phase change, and temperature independence of the heat capacity rates and the heat transfer coefficient. A purely algebraic solution is obtained for the effectiveness as a function of the heat capacity rate ratio and the number of heat transfer units. The case with M shell passes and N tube passes is easily expressed in terms of the single-shell-pass case.

Minimum Irreversibility Criteria for Heat Exchanger Configurations

1999 ◽  
Vol 121 (4) ◽  
pp. 241-246 ◽  
Author(s):  
F. E. M. Saboya ◽  
C. E. S. M. da Costa
Keyword(s):  
Heat Capacity ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
Cross Flow ◽  
Second Law Of Thermodynamics ◽  
The Other ◽  
Maximum Heat ◽  
Transfer Rates ◽  
Mass Flow Rates ◽  
Flow Heat

From the second law of thermodynamics, the concepts of irreversibility, entropy generation, and availability are applied to counterflow, parallel-flow, and cross-flow heat exchangers. In the case of the Cross-flow configuration, there are four types of heat exchangers: I) both fluids unmixed, 2) both fluids mixed, 3) fluid of maximum heat capacity rate mixed and the other unmixed, 4) fluid of minimum heat capacity rate mixed and the other unmixed. In the analysis, the heat exchangers are assumed to have a negligible pressure drop irreversibility. The Counterflow heat exchanger is compared with the other five heat exchanger types and the comparison will indicate which one has the minimum irreversibility rate. In this comparison, only the exit temperatures and the heat transfer rates of the heat exchangers are different. The other conditions (inlet temperatures, mass flow rates, number of transfer units) and the working fluids are the same in the heat exchangers.

Multipass Plate Heat Exchangers—Effectiveness-NTU Results and Guidelines for Selecting Pass Arrangements

1989 ◽  
Vol 111 (2) ◽  
pp. 300-313 ◽  
Author(s):  
S. G. Kandlikar ◽  
R. K. Shah
Keyword(s):  
Heat Capacity ◽  
Heat Exchanger ◽  
Finite Difference Method ◽  
Heat Exchangers ◽  
Rate Ratio ◽  
Plate Heat Exchanger ◽  
Tabular Form ◽  
Plate Heat ◽  
Number Of Passes ◽  
Selection Of

Plate heat exchangers are classified on the basis of number of passes on each side and the flow arrangement in each channel, taking into account the end plate effects. This results in four configurations each for the 1–1 (1 Pass–1 Pass), 2–1, 2–2, 3–3, 4–1, 4–2, and 4–4 arrangements, and six configurations for the 3–1 arrangement. These arrangements are analyzed using the Gauss–Seidel iterative finite difference method; the plate arrangement that yields the highest effectiveness in each pass configuration is identified. Comprehensive results are presented in tabular form for the temperature effectiveness P1 and log-mean temperature difference correction factor F as functions of the number of transfer units NTU1, the heat capacity rate ratio R1, and the total number of thermal plates. On the basis of these results, specific guidelines are outlined for the selection of appropriate plate heat exchanger configurations.

CFD simulation for flow distribution in manifolds of central-type compact parallel flow heat exchangers

2017 ◽  
Vol 126 ◽  
pp. 670-677 ◽  
Author(s):  
Jian Zhou ◽  
Zhongning Sun ◽  
Ming Ding ◽  
Haozhi Bian ◽  
Nan Zhang ◽  
...  
Keyword(s):  
Heat Exchangers ◽  
Cfd Simulation ◽  
Flow Distribution ◽  
Parallel Flow ◽  
Central Type ◽  
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.

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