Forced-Convection Mass Transfer From Wetted Grooves

1972 ◽  
Vol 94 (4) ◽  
pp. 715-719
Author(s):  
R. G. Bressler
Keyword(s):  
Mass Transfer ◽  
Forced Convection ◽  
Test Facility ◽  
Reynolds Analogy ◽  
Flow Rates ◽  
Capillary Action ◽  
Air Stream ◽  
Partial Pressures ◽  
Evaporative Heat Transfer ◽  
Wetted Wall Column

A wetted-wall column was used to measure liquid flow rates in capillary grooves on vertical surfaces. The test facility contained interchangeable grooved surfaces (2-in. OD) which contacted a liquid reservoir in such a way that the test surfaces were partially wetted by capillary action. The wetted portion was exposed to a forced-convection air stream, so that surface evaporation took place because of the different partial pressures of the vapor at the liquid-vapor interface and at the center of the air stream. All data were obtained in steady-state and nearly isothermal conditions. Experimental results with carbon tetrachloride on brass surfaces were in agreement with approximate predictions, which were computed for evaporative heat transfer and then related to mass transfer by using Reynolds analogy for pipe flow.

Prediction of Growth Parameters of Frost Deposits in Forced Convection

1981 ◽  
Vol 103 (1) ◽  
pp. 3-6 ◽  
Author(s):  
J. E. White ◽  
C. J. Cremers
Keyword(s):  
Mass Transfer ◽  
Forced Convection ◽  
Growth Parameters ◽  
Experimental Investigations ◽  
Experimental Conditions ◽  
Transfer Rates ◽  
Air Stream ◽  
Transient Period ◽  
Approximate Expressions ◽  
Frost Layer

Experimental investigations of frost deposition under forced convection conditions have shown that in most cases heat and mass transfer rates become constant after an initial transient period. It is shown that, in such cases, approximately half of the mass transfer from a humid air stream to a frost layer diffuses inward, condenses and increases the density of the frost. The other half is deposited at the surface and increases the thickness of the layer. Approximate expressions for density and thickness of the frost layer are derived and compared with data from the literature and also with experimental work reported in this paper. The correlations are shown to work well for a broad range of experimental conditions.

Falling-Film Absorption Around Microchannel Tube Banks

2013 ◽  
Vol 135 (12) ◽  
Author(s):  
Ananda Krishna Nagavarapu ◽  
Srinivas Garimella
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Water Solution ◽  
Small Diameter ◽  
Operating Conditions ◽  
Test Facility ◽  
Vapor Flow ◽  
Falling Film ◽  
Flow Rates ◽  
Wide Range

An experimental investigation of heat and mass transfer in a falling-film absorber with microchannel tube arrays was conducted. Liquid ammonia–water solution flows in a falling-film mode around an array of small diameter coolant tubes, while vapor flows upward through the tube array counter-current to the falling film. This absorber was installed in a test facility consisting of all components of a functional single-effect absorption chiller, including a desorber, rectifier, condenser, evaporator, solution heat exchanger, and refrigerant precooler, to obtain realistic operating conditions at the absorber and to account for the influence of the other components in the system. Unlike studies in the literature on bench-top, single-component, single-pressure test stands, here the experiments were conducted on the absorber at vapor, solution, and coupling fluid conditions representative of space-conditioning systems in the heating and cooling modes. Absorption measurements were taken over a wide range of solution flow rates, concentrations, and coupling fluid temperatures, which simulated operation of thermally activated absorption systems at different cooling capacities and ambient conditions. These measurements are used to interpret the effects of solution and vapor flow rates, concentrations, and coupling fluid conditions on the respective heat and mass transfer coefficients.

Falling-Film Absorption Around Microchannel Tube Banks

2011 ◽  
Author(s):  
Ananda Krishna Nagavarapu ◽  
Srinivas Garimella
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Water Solution ◽  
Small Diameter ◽  
Operating Conditions ◽  
Test Facility ◽  
Vapor Flow ◽  
Falling Film ◽  
Flow Rates ◽  
Wide Range

An experimental investigation of heat and mass transfer in a falling-film absorber with microchannel tube arrays was conducted. Liquid ammonia-water solution flows in a falling-film mode around an array of small diameter coolant tubes, while vapor flows upward through the tube array counter-current to the falling film. This absorber was installed in a test facility consisting of all components of a functional single-effect absorption chiller, including a desorber, rectifier, condenser, evaporator, solution heat exchanger, and refrigerant pre-cooler, to obtain realistic operating conditions at the absorber and to account for the influence of the other components in the system. Unlike studies in the literature on bench-top, single-component, single-pressure test stands, here the experiments were conducted on the absorber at vapor, solution, and coupling fluid conditions representative of space-conditioning systems in the heating and cooling modes. Absorption measurements were taken over a wide range of solution flow rates, concentrations, and coupling fluid temperatures, which simulated operation of thermally activated absorption systems at different cooling capacities and ambient conditions. These measurements are used to interpret the effects of solution and vapor flow rates, concentrations, and coupling fluid conditions on the respective heat and mass transfer coefficients.

Numerical Study of the Combined Free-Forced Convection and Mass Transfer Flow Past a Vertical Porous Plate in a Porous Medium with Heat Generation and Thermal Diffusion

2006 ◽  
Vol 11 (4) ◽  
pp. 331-343 ◽  
Author(s):  
M. S. Alam ◽  
M. M. Rahman ◽  
M. A. Samad
Keyword(s):  
Mass Transfer ◽  
Flow Field ◽  
Differential Equations ◽  
Forced Convection ◽  
Heat Generation ◽  
Numerical Study ◽  
Porous Plate ◽  
Integration Scheme ◽  
Suction Parameter ◽  
Transfer Flow

The problem of combined free-forced convection and mass transfer flow over a vertical porous flat plate, in presence of heat generation and thermaldiffusion, is studied numerically. The non-linear partial differential equations and their boundary conditions, describing the problem under consideration, are transformed into a system of ordinary differential equations by using usual similarity transformations. This system is solved numerically by applying Nachtsheim-Swigert shooting iteration technique together with Runge-Kutta sixth order integration scheme. The effects of suction parameter, heat generation parameter and Soret number are examined on the flow field of a hydrogen-air mixture as a non-chemical reacting fluid pair. The analysis of the obtained results showed that the flow field is significantly influenced by these parameters.

The effect of two-phase flow regime on hydrodynamics and mass transfer in a horizontal-tube gas-liquid reactor

1985 ◽  
Vol 50 (3) ◽  
pp. 745-757 ◽  
Author(s):  
Andreas Zahn ◽  
Lothar Ebner ◽  
Kurt Winkler ◽  
Jan Kratochvíl ◽  
Jindřich Zahradník
Keyword(s):  
Mass Transfer ◽  
Pressure Drop ◽  
Flow Regime ◽  
Liquid Flow ◽  
Horizontal Tube ◽  
Liquid Holdup ◽  
Two Phase ◽  
Flow Rates ◽  
Type Relation ◽  
Good Agreement

The effect of two-phase flow regime on decisive hydrodynamic and mass transfer characteristics of horizontal-tube gas-liquid reactors (pressure drop, liquid holdup, kLaL) was determined in a cocurrent-flow experimental unit of the length 4.15 m and diameter 0.05 m with air-water system. An adjustable-height weir was installed in the separation chamber at the reactor outlet to simulate the effect of internal baffles on reactor hydrodynamics. Flow regime maps were developed in the whole range of experimental gas and liquid flow rates both for the weirless arrangement and for the weir height 0.05 m, the former being in good agreement with flow-pattern boundaries presented by Mandhane. In the whole range of experi-mental conditions pressure drop data could be well correlated as a function of gas and liquid flow rates by an empirical exponential-type relation with specific sets of coefficients obtained for individual flow regimes from experimental data. Good agreement was observed between values of pressure drop obtained for weirless arrangement and data calculated from the Lockhart-Martinelli correlation while the contribution of weir to the overall pressure drop was well described by a relation proposed for the pressure loss in closed-end tubes. In the region of negligible weir influence values of liquid holdup were again succesfully correlated by the Lockhart-Martinelli relation while the dependence of liquid holdup data on gas and liquid flow rates obtained under conditions of significant weir effect (i.e. at low flow rates of both phases) could be well described by an empirical exponential-type relation. Results of preliminary kLaL measurements confirmed the decisive effect of the rate of energy dissipation on the intensity of interfacial mass transfer in gas-liquid dispersions.

scholarly journals Mass Transfer from a Rotating Sphere in Air Stream

1973 ◽  
Vol 37 (2) ◽  
pp. 151-157,a1 ◽  
Author(s):  
Hisaya Tanaka ◽  
Osamu Tago
Keyword(s):  
Mass Transfer ◽  
Rotating Sphere ◽  
Air Stream
Sign in / Sign up

Export Citation Format

Share Document