Overall Optimization and Exergy Analysis of an Air Conditioning System Using a Series-Series Counterflow Arrangement of Water Chillers

Phu, Nguyen Minh

doi:10.1142/s2010132519500342

Cited by 9 publications

(3 citation statements)

References 22 publications

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“…Generally, the efficiency was rather low (less than 2%) for all eleven of the considered roughness elements. This was mainly due to exergy losses caused by the absorption of radiation by the absorber plate (EXloss,Tap,Tsun) and optics (EXloss,opt) [29]. At very low temperature rise parameters, EXloss,Tap,Tsun was remarkably high.…”

Section: Exergy Efficiencymentioning

confidence: 99%

A Review of Energy and Exergy Analyses of a Roughened Solar Air Heater

Phu

Luân

2020

ARFMTS

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In this paper, eleven roughness elements in solar air heater duct analysed both energy and exergy were reviewed. Various roughness geometries such as ribs, twisted tap, baffles, and metal waste were surveyed about heat transfer and friction when the air flow is passing absorber plate. Evaluation criteria of roughness on the absorber plate including thermohydraulic performance parameter, thermal efficiency, effective efficiency, and exergy efficiency were presented and compared. Results showed that protruded ribs in arc shape indicated the largest Nusselt number. The ribs exhibited the highest thermohydraulic performance parameter at a Reynolds number greater than 5000. Jet impingement with arc-shaped ribs and roughness elements of metal waste were found the smallest exergy efficiencies. The biggest effective and exergy efficiencies were obtained to be 70% and 1.9%, respectively. The thermohydraulic performance parameter varied from 0.5 to 2.0. The review paper aims to provide information about roughness geometries investigated both first and second laws of thermodynamics and figure of merits to overview artificial roughness in a solar air heater.

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Section: Exergy Efficiencymentioning

confidence: 99%

A Review of Energy and Exergy Analyses of a Roughened Solar Air Heater

Phu

Luân

2020

ARFMTS

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“…Another type is the shell-and-tube heat exchanger which is commonly used in the large-capacity field exchanger [4]. The finned-tube heat exchanger is a compact HE which is widely used in household and industrial applications [5][6][7][8]. These can be mentioned as microprocessor coolers that use a liquid coolant and dissipate heat to the surrounding environment via the air blowing through the fins, or the outdoor and indoor units of air conditioners [9].…”

Section: Introductionmentioning

confidence: 99%

Thermohydraulic Performance of a Fin and Inclined Flat Tube Heat Exchanger: A Numerical Analysis

Minh

Thao

2021

CFDL

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Proper determination of inclination angle of a flat tube may increase the overall heat transfer performance without extending heat transfer surface. In this paper, the inclined flat tube heat exchanger with plain fins is numerically investigated. The influence of flat tube inclination angle and Reynolds number on the thermo-hydraulic performance index was evaluated. Tube pitch, fin spacing and flat tube size are fixed. Solving 3D computational domain with the symmetric boundary condition is used to reduce computation time. The results show that when increasing the inclination angle of the flat tube from 0 to 45°, both heat transfer and pressure loss increase because the free area of air flow decreases leading to an increase in air velocity and impingement heat transfer. The variation of inclination angle from 0 to 15°, the increase in heat transfer is stronger than the increase in the pressure loss penalty, so the performance index reaches a maximum of 0.405 at the angle of 15°. Contours of temperature, pressure and velocity at different inclination angles are presented to clarify the thermo-hydraulic characteristics of finned-tube heat exchangers using inclined flat tubes. The current work yields heat transfer enhancement ability by adjusting inclination angle of a heat transfer flat tube.

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“…The above works have been done regarding the thermo-hydraulic properties of natural convection in an enclosure. Entropy generation or exergy destruction is a second consideration to comprehensively evaluate an energy system to fulfill the laws of thermodynamics [9][10][11]. However, the entropy generation assessment due to natural convection in an enclosure with internal objects has been little interest by researchers.…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation of Natural Convection and Entropy Generation of Water near Density Inversion in a Cavity Having Circular and Elliptical Body

Phu¹,

Hap²

2021

Computational Overview of Fluid Structure Interaction

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In this chapter, a water-filled square cavity with left hot wall and right cold wall was numerically investigated. The hot and cold wall temperatures are 10°C and 0°C respectively to examine the density inversion of natural convection water, i.e. water at 4°C. In the middle of the square, there are circular and elliptical bodies to study fluid–structure interaction in terms of the thermohydraulic behavior and entropy generation. 2D numerical simulation was performed using finite volume method in Ansys fluent software with the assumption of laminar flow. The simulation results are compared with benchmark data to determine reliability. The results indicate that the body insertions increase the convection heat transfer coefficients at the best heat transfer positions due to impingement heat transfer. An increase in heat transfer rate of 1.06 times is observed in the case of circular body compared to none. There are three primary eddies in the cavity with bodies, whereas the cavity without body has two primary eddies. Maximum entropy generation was found in the upper right corner of cavity mainly due to high horizontal temperature gradient. Bodies of circle and vertical ellipse have almost the same thermohydraulic and entropy generation characteristics due to the same horizontal dimension which mainly effects on the downward natural convection current. The entropy generation of cavity with circular body is 1.23 times higher than that of the cavity without body. At positions y/L = 1 on the hot wall and y/L = 0.74 on the cold wall, the convection heat transfer coefficient is close to zero due to stagnant fluid.

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Overall Optimization and Exergy Analysis of an Air Conditioning System Using a Series-Series Counterflow Arrangement of Water Chillers

Cited by 9 publications

References 22 publications

A Review of Energy and Exergy Analyses of a Roughened Solar Air Heater

A Review of Energy and Exergy Analyses of a Roughened Solar Air Heater

Thermohydraulic Performance of a Fin and Inclined Flat Tube Heat Exchanger: A Numerical Analysis

Numerical Investigation of Natural Convection and Entropy Generation of Water near Density Inversion in a Cavity Having Circular and Elliptical Body

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