A study on the effects of system pressure on heat and mass transfer rates of an air cooler

2002 ◽  
Vol 16 (5) ◽  
pp. 696-702
Author(s):  
Hyung Ho Jung
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Transfer Rates ◽  
System Pressure ◽  
Air Cooler

HEAT AND MASS TRANSFER AND RESISTANCE CHARACTERISTICS OF EVAPORATIVE AIR COOLER WITH HIGH FINNED-TUBE BUNDLES

2018 ◽  
Vol 49 (17) ◽  
pp. 1705-1720 ◽  
Author(s):  
Qing Zhang ◽  
Xuesheng Wang ◽  
Weicheng Ruan ◽  
Qinzhu Chen ◽  
Zilong Liu
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Finned Tube ◽  
Tube Bundles ◽  
Air Cooler

scholarly journals Effects of Variable Transport Properties on Heat and Mass Transfer in MHD Bioconvective Nanofluid Rheology with Gyrotactic Microorganisms: Numerical Approach

Coatings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 231
Author(s):  
Muhammad Awais ◽  
Saeed Ehsan Awan ◽  
Muhammad Asif Zahoor Raja ◽  
Nabeela Parveen ◽  
Wasim Ullah Khan ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Transport Properties ◽  
Heat And Mass Transfer ◽  
Group Analysis ◽  
Numerical Approach ◽  
Validity Of Results ◽  
Gyrotactic Microorganisms ◽  
Transfer Rates ◽  
Buongiorno’S Model ◽  
Density Distributions

Rheology of MHD bioconvective nanofluid containing motile microorganisms is inspected numerically in order to analyze heat and mass transfer characteristics. Bioconvection is implemented by combined effects of magnetic field and buoyancy force. Gyrotactic microorganisms enhance the heat and transfer as well as perk up the nanomaterials’ stability. Variable transport properties along with assisting and opposing flow situations are taken into account. The significant influences of thermophoresis and Brownian motion have also been taken by employing Buongiorno’s model of nanofluid. Lie group analysis approach is utilized in order to compute the absolute invariants for the system of differential equations, which are solved numerically using Adams-Bashforth technique. Validity of results is confirmed by performing error analysis. Graphical and numerical illustrations are prepared in order to get the physical insight of the considered analysis. It is observed that for controlling parameters corresponding to variable transport properties c2, c4, c6, and c8, the velocity, temperature, concentration, and bioconvection density distributions accelerates, respectively. While heat and mass transfer rates increases for convection parameter and bioconvection Rayleigh number, respectively.

Computational analysis of heat and mass transfer in a micropolar fluid flow through a porous medium between permeable channel walls

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Sohail Ahmad ◽  
Muhammad Ashraf ◽  
Kashif Ali ◽  
Kottakkaran Sooppy Nisar
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Micropolar Fluid ◽  
Numerical Data ◽  
Substantial Effect ◽  
Linearization Method ◽  
Transfer Rates ◽  
Micropolar Fluid Flow ◽  
Permeable Walls ◽  
Model Equations

Abstract The present work numerically investigates the mass and heat transport flow of micropolar fluid in a channel having permeable walls. The appropriate boundary layer approximations are used to convert the system of flow model equations in ODEs, which are then numerically treated with the quasi-linearization method along with finite difference discretization. This technique creates an efficient way to solve the complex dynamical system of equations. A numerical data comparison is presented which assures the accuracy of our code. The outcomes of various problem parameters are portrayed via the graphs and tables. The concentration and temperature accelerate with the impacts of the Peclet numbers for the diffusion of mass and heat, respectively. It is also found that the porosity of the medium has a substantial effect on the skin friction but low effect on the heat and mass transfer rates. Our results may be beneficial in lubrication, foams and aerogels, micro emulsions, micro machines, polymer blends, alloys, etc.

scholarly journals Influence of Frost Growth and Migration in Cryogenic Heat Exchanger on Air Refrigerator

2019 ◽  
Vol 9 (4) ◽  
pp. 753 ◽  
Author(s):  
Shanju Yang ◽  
Zhan Liu ◽  
Bao Fu ◽  
Yu Chen
Keyword(s):  
Mass Transfer ◽  
Heat Exchanger ◽  
Numerical Model ◽  
Heat And Mass Transfer ◽  
Frost Formation ◽  
Transient Model ◽  
Transfer Rates ◽  
Low Humidity ◽  
And Migration ◽  
Frost Layer

Frost formation degrades the performance of heat exchangers greatly, thus influencing the cryogenic refrigerator. Different from frost formation on the evaporator surface, the growth and migration of frost layer inside the heat exchanger is of low temperature and humidity. In addition to the constantly changing boundary conditions, the effective prediction is difficult. In the present study, a numerical model was proposed to analyze the frost formation in the cryogenic heat exchanger of a reverse Brayton air refrigerator. Under small amounts of moisture, the growing of frost layer was simulated through the numerical heat and mass transfer by adopting semiempirical correlations. The frost formation model was inserted into the transient model of refrigerator, and numerical calculations were performed on heat and mass transfer rates, and growth and migration of frost layers in forced convection conditions. Experiments were conducted under different air humidity to investigate the frost formation and verify the numerical model. Through the model, the influences of frosting on the refrigerator were evaluated under different moisture contents and running time. It can be used to predict the performance of air refrigerators with low humidity and provide a basis for improving the system operation and efficiency.

scholarly journals Analysis of Heat and Mass Transfer for Second-Order Slip Flow on a Thin Needle Using a Two-Phase Nanofluid Model

Symmetry ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1176
Author(s):  
Siti Nur Alwani Salleh ◽  
Norfifah Bachok ◽  
Fadzilah Md Ali ◽  
Norihan Md Arifin
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Slip Flow ◽  
Second Order ◽  
Two Phase ◽  
Specific Domain ◽  
Transfer Rates ◽  
Similarity Transformations ◽  
The Stability ◽  
Good Agreement

The present paper concentrates on the second-order slip flow over a moving thin needle in a nanofluid. The combined effects of thermophoresis and Brownian motion are considered to describe the heat and mass transfer performance of nanofluid. The resulting system of equations are obtained using similarity transformations and being executed in MATLAB software via bvp4c solver. The physical characteristics of embedded parameters on velocity, temperature, concentration, coefficient of skin friction, heat and mass transfer rates are demonstrated through a graphical approach and are discussed in detail. The obtained outcomes are validated with the existing works and are found to be in good agreement. It is shown that, for a specific domain of moving parameter, dual solutions are likely to exist. The stability analysis is performed to identify the stability of the solutions gained, and it is revealed that only one of them is numerically stable. The analysis indicated that the percentage of increment in the heat and mass transfer rates from no-slip to slip condition for both thin and thick surfaces of the needle ( a = 0.1 and a = 0.2 ) are 10.77 % and 12.56 % , respectively. Moreover, the symmetric behavior is noted for the graphs of reduced heat and mass transfer when the parameters N b and N t are the same.

Numerical simulation of unsteady double-diffusive natural convection within an inclined parallelepipedic enclosure

2014 ◽  
Vol 25 (11) ◽  
pp. 1450058 ◽  
Author(s):  
Fakher Oueslati ◽  
Brahim Ben-Beya ◽  
Taieb Lili
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Three Dimensional ◽  
Transfer Rates ◽  
Flow Energy ◽  
Wide Range ◽  
Inclination Angles ◽  
Volume Method ◽  
Buoyancy Ratio ◽  
Double Diffusive

Unsteady three-dimensional (3D) double diffusive convection in tilted enclosure having a parallelepipedic shape has been analyzed numerically. The governing unsteady, 3D flow, energy and concentration transport equations, have been solved using an accelerated multigrid implicit volume method. Main attention was paid to the effects of the Rayleigh number Ra , buoyancy ratio N and the inclination angle γ of the cavity on the flow structure and heat and mass transfer rates. Typical distributions of velocity contours, temperature and concentration fields in wide range of defining parameters 103 ≤ Ra ≤ 2 × 104, -5 ≤ N ≤ 5 have been obtained. It is found, that the optimal heat and mass transfer rates for the aiding situation have been observed at two particular inclination angles namely 30° and 75° about the horizontal direction. It should be noted that the flow undergoes a periodic behavior for particular parameters Ra = 104 and γ = 75° according to the aiding flow case. The results also suggest that when N is in range -2 ≤ N ≤ -0.6, the flow continues to be three-dimensional keeping different heat and mass rates. Furthermore, it has been argued that the 2D assumption can be adopted for the 3D flows when the buoyancy ratio N is in range (-0.5–0).

Combined Buoyancy Effects of Thermal and Mass Diffusion on Laminar Mixed Convection in Vertical and Horizontal Semicircular Ducts

2016 ◽  
Vol 138 (9) ◽  
Author(s):  
A. Budabous ◽  
A. A. Busedra
Keyword(s):  
Mass Transfer ◽  
Mixed Convection ◽  
Heat And Mass Transfer ◽  
Convection Boundary Layer ◽  
Input Concentration ◽  
Transfer Rates ◽  
Thermal Boundary Conditions ◽  
Laminar Mixed Convection ◽  
Boundary Layer Development ◽  
Semicircular Ducts

The development of laminar mixed convection with heat and mass transfer in vertical and horizontal semicircular ducts has been investigated for the case of thermal boundary conditions of uniform heat input, concentration at the fluid–solid interface axially, and uniform peripheral wall temperature at any axial station. The governing equations were solved numerically over the following conditions: Pr = 0.7, Le = 1, Re = 500, Grt = 1.66 × 105, and Grc = 1.66 × 105. The combined effects of solutal and thermal Grashof numbers on the flow and thermal fields were observed in terms of the axial velocity, temperature, and concentration distributions, as well as, friction factor, Nusselt number, and Sherwood number. Further, the development of velocity, temperature, and concentration at different axial stations was found to be influenced by the solutal and thermal Grashof numbers. The results also showed that the forced-convection boundary layer development dominates very close to the duct inlet, while further downstream, the heat and mass transfer rates are enhanced due to the effect of solutal buoyancy.

Design of Microscale Heat and Mass Exchangers for Absorption Space Conditioning Applications

2011 ◽  
Vol 3 (2) ◽  
Author(s):  
Ananda Krishna Nagavarapu ◽  
Srinivas Garimella
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Flow Distribution ◽  
Mass Transfer Process ◽  
High Heat ◽  
Heat Pumps ◽  
Operating Conditions ◽  
Pressure Drops ◽  
Transfer Rates ◽  
Small Absorption

This paper presents the development of a miniaturization technology for heat and mass exchangers used in absorption heat pumps. The exchanger consists of an array of parallel, aligned alternating shims with integral microscale features, enclosed between cover plates. These microscale features facilitate the flow of the various fluid streams and the associated heat and mass transfer. In an absorber application, effective vapor and solution contact and microscale features for the flow of both the solution and the coolant induce high heat and mass transfer rates without any active or passive surface enhancement. The geometry ensures even flow distribution with minimal overall pressure drops. A model of the coupled heat and mass transfer process for ammonia-water absorbers using this configuration under typical operating conditions demonstrates the potential for extremely small absorption components. The proposed concept is compact, modular, versatile, and in an eventual implementation, can be mass produced. Additionally, the same concept can be extended to the other absorption heat pump components as well as for several other industries involved in multicomponent fluid processes.

scholarly journals Heat and Mass Transfer to a Cryosurface in Free Convection

1965 ◽  
Vol 87 (4) ◽  
pp. 499-506 ◽  
Author(s):  
R. F. Barron ◽  
L. S. Han
Keyword(s):  
Mass Transfer ◽  
Free Convection ◽  
Heat And Mass Transfer ◽  
Cryogenic Temperatures ◽  
Transfer Rates ◽  
Experimental Heat ◽  
Experimental Heat Transfer ◽  
Laminar And Turbulent Flow ◽  
And Diffusion ◽  
Good Agreement

Heat and mass transfer rates were measured experimentally and compared with analytically developed correlations for frost formation on a vertical flat plate in free convection. The plate was cooled internally to cryogenic temperatures (−310 F or liquid nitrogen temperatures), and both the laminar and turbulent flow regimes were investigated. In the laminar flow correlation, the effects of thermal diffusion and diffusion thermoeffect were included. The analytical and experimental heat transfer rates were in good agreement; however, the mass transfer results were affected by the presence of macromolecules of frost within the boundary layer.

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