Experiments and entropy generation minimization analysis of a cross-flow heat exchanger

Oğulata, R. Tuğrul; Doba, Füsun

doi:10.1016/s0017-9310(97)00129-4

Cited by 58 publications

(18 citation statements)

References 5 publications

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“…The EGM is based on the theory that a thermodynamically optimized system is the least irreversible, or minimum entropy generation in the system. Doba and Ogulata [14] used the EGM to optimize the cross-flow heat exchanger. They found that the minimum entropy generation number depended on flow path length, dimensionless mass velocity, and dimensionless heat transfer.…”

Section: Introductionmentioning

confidence: 99%

Optimal Design of an Air-to-Air Heat Exchanger with Cross-Corrugated Triangular Ducts by Using a Particle Swarm Optimization Algorithm

et al. 2017

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Air-to-air heat exchangers with cross-corrugated triangular ducts are widely used in various industrial fields to recover waste heat. The geometric parameters of the heat exchangers greatly affect the performance and total annual cost of these systems. In this study, the effectiveness-number of transfer units (ε-NTU) method was utilized to develop the thermal mathematical model, which was verified by comparing it with previous research. The configuration parameters of the heat exchanger were optimized in this study. The particle swarm optimization (PSO) algorithm was applied using both single and multi-objective algorithm. The colburn factor (j factor), friction factor (f factor), and comprehensive thermal hydraulic performance index (JF factor) were considered as objective functions to be optimized using a single objective and multi-objective algorithm. Then, the entropy generation rate and total annual cost were optimized by using a multi-objective PSO algorithm. In addition, to identify the influential geometric parameters, a global sensitivity analysis was performed. The sensitivity analysis showed that the apex angle θ, channel height H, and heat exchanger height L h influenced the performance and annual total cost of these systems.

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Section: Introductionmentioning

confidence: 99%

Optimal Design of an Air-to-Air Heat Exchanger with Cross-Corrugated Triangular Ducts by Using a Particle Swarm Optimization Algorithm

et al. 2017

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“…From the second law of thermodynamics, we know that for real processes the sum of increases in entropy in the system should be greater than zero [19,[24][25][26][27][28].ṁ…”

Section: Entropy Generation In a Condensermentioning

confidence: 99%

“…As was shown in [19,23], the average cold fluid temperature can be, approximately, replaced with the arithmetic mean of water temperatures at the inlet and outlet of the condenser according to relation (10). Assuming that the average cold fluid temperatures, as calculated from relation (24), which stems from the definition of entropy, and using the logarithmic mean temperature difference (8), are approximately equal, the average cold fluid temperature can be calculated from relation (18), which contains only the cooling water temperatures at the inlet and outlet of the condenser. Other relations for mean temperature difference, which allow to determine the mean fluid temperature, can be found in [20,29,30].…”

Section: Entropy Generation In a Condenser And Its Connection With Itmentioning

confidence: 99%

Entropy generation in a condenser and related correlations

Askowski¹,

Jaworski²,

Smyk³

2015

Archives of Thermodynamics

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The paper presents an analysis of relations describing entropy generation in a condenser of a steam unit. Connections between entropy generation, condenser ratio, and heat exchanger effectiveness, as well as relations implied by them are shown. Theoretical considerations allowed to determine limits of individual parameters which describe the condenser operation. Various relations for average temperature of the cold fluid were compared. All the proposed relations were verified against data obtained using a simulator and actual measurement data from a 200 MW unit condenser. Based on data from a simulator it was examined how the sum of entropy rates, steam condenser effectiveness, terminal temperature difference and condenser ratio vary with the change in the inlet cooling water temperature, mass flow rate of steam and the cooling water mass flow rate. Keywords: Steam condenser; Entropy generation

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“…The study results showed the effects of certain geometrical parameters, such as the total volume, the ratio between length and width of a heat exchanger, on entropy generation. Ogulata et al [5] conducted an irreversibility analysis of a cross flow heat exchanger and obtained its optimum design parameters such as flow path length, heat transfer area and heat transfer volume. Lerou et al [6] studied the optimization of a counter flow heat exchanger through minimization of entropy generation by combining the losses in heat transfer and pressure drop.…”

Section: Introductionmentioning

confidence: 99%

Optimisation of Direct Expansion (DX) Cooling Coils Aiming to Building Energy Efficiency

Liang¹,

Yang²,

Chan³

et al. 2015

JBCPR

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Efficient Air Conditioning (A/C) system is the key to reducing energy consumption in building operation. In order to decrease the energy consumption in an A/C system, a method to calculate the optimal tube row number of a direct expansion (DX) cooling coil for minimizing the entropy generation in the DX cooling which functioned as evaporator in the A/C system was developed. The optimal tube row numbers were determined based on the entropy generation minimization (EGM) approach. Parametric studies were conducted to demonstrate the application of the analytical calculation method. Optimal tube row number for different air mass flow rates, inlet air temperatures and sensible cooling loads were investigated. It was found that the optimal tube row number of a DX cooling coil was in the range of 5 -9 under normal operating conditions. The optimal tube row number was less when the mass flow rate and inlet air temperature were increased. The tube row number increased when the sensible cooling load was increased. The exergy loss when using a non-optimal and optimal tube row numbers was compared to show the advantage of using the optimal tube row number. The decrease of exery loss ranged from around 24% to 70%. Therefore the new analytical method developed in this paper offers a good practice guide for the design of DX cooling coils for energy conservation.

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Experiments and entropy generation minimization analysis of a cross-flow heat exchanger

Cited by 58 publications

References 5 publications

Optimal Design of an Air-to-Air Heat Exchanger with Cross-Corrugated Triangular Ducts by Using a Particle Swarm Optimization Algorithm

Optimal Design of an Air-to-Air Heat Exchanger with Cross-Corrugated Triangular Ducts by Using a Particle Swarm Optimization Algorithm

Entropy generation in a condenser and related correlations

Optimisation of Direct Expansion (DX) Cooling Coils Aiming to Building Energy Efficiency

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