scholarly journals New calculation method for tube cross-flow heat exchangers

2021 ◽  
Vol 323 ◽  
pp. 00032
Author(s):  
Katarzyna Węglarz ◽  
Dawid Taler ◽  
Jan Taler ◽  
Mateusz Marcinkowski
Keyword(s):  
Heat Exchangers ◽  
Cross Flow ◽  
Analytical Models ◽  
Temperature Dependent ◽  
Flow Tube ◽  
Thermal Calculations ◽  
Analytical Formulas ◽  
Flow Heat ◽  
Control Volumes ◽  
Good Agreement

A new method for thermal calculations of the cross-flow tube heat exchangers was proposed. The temperature of both fluids and the wall temperature are determined. The heat exchanger is divided into control volumes, in which outlet fluid temperatures are calculated by closed analytical formulas. Two examples of the application of the method for the calculation of two-pass cross-co-current and cross-countercurrent superheaters were presented. An exact analytical model was also developed for both superheaters to estimate the accuracy of the proposed method. The results of the superheater calculations using the developed method are in good agreement with the results obtained by the exact analytical models. The proposed method can be used to calculate heat exchangers with a complicated flow system in which the physical properties of fluids are temperature-dependent.

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.

Transient Response of Cross Flow Heat Exchangers Subjected to Simultaneous Temperature and Flow Perturbations

2015 ◽  
Vol 799-800 ◽  
pp. 665-670
Author(s):  
Karthik Silaipillayarputhur
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Convection Heat Transfer ◽  
Cross Flow ◽  
Balance Equations ◽  
Transfer Resistance ◽  
Mass Flow Rates ◽  
Flow Heat ◽  
Transient Thermal ◽  
Central Finite Difference

This paper compares the transient thermal performance between counter and parallel cross flow heat exchangers subjected to time varying inlet mass flow rates and inlet temperatures that hasn’t been previously discussed in the available literature. Specifically the transient performance of 2 pass and 3 pass cross flow heat exchangers is discussed in this paper. In the present study the energy balance equations for the hot and cold fluids and the heat exchanger wall were solved using an implicit central finite difference method. Representative values of NTU were considered, and the NTU’s of the heat exchanger were assumed to be uniformly distributed among the heat exchanger passes. Other physically significant parameters such as the capacity rate ratio and the convection heat transfer resistance ratio were systematically varied. A detailed summary based on the observations has been presented.

Performance Analysis of Multi-Pass Cross-Flow Heat Exchangers

2018 ◽  
Author(s):  
Kiran Lankalapalli ◽  
Ahmed ElSawy ◽  
Stephen Idem
Keyword(s):  
Heat Exchanger ◽  
Performance Analysis ◽  
Thermal Performance ◽  
Heat Exchangers ◽  
Cross Flow ◽  
Threshold Value ◽  
Finned Tube ◽  
Flow Heat ◽  
Rate Ratios ◽  
Side Flow

A steady state sensible performance analysis of multi-pass cross-flow finned-tube heat exchangers is reported. The investigation considers various flow circuiting, such as counter cross-flow, parallel cross-flow, and cross-flow where the tube-side flow is in parallel. A previously developed matrix approach is used to evaluate the heat exchanger performance in each tube pass. The equations required to model the thermal performance of these configurations are presented, and the thermal performance is compared for each type of flow circuiting. Thereafter a parametric study on cross-flow heat exchanger performance is performed by varying physically significant parameters such as number of transfer units (NTU) and capacity rate ratios, and the graphical results for each type of flow circuiting are presented both for both two-pass and three-pass arrangements. A consistent criterion is proposed for each case, wherein increasing the NTU beyond a certain threshold value does not significantly improve heat exchanger thermal performance.

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