An Analytical Study of Heat and Mass Transfer Within an Oil Sand Bed

1987 ◽  
Vol 109 (2) ◽  
pp. 66-70
Author(s):  
M. A. Abdrabboh ◽  
G. A. Karim
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Oil Sands ◽  
Operating Conditions ◽  
Oil Sand ◽  
Mass Transfer Processes ◽  
Wide Range ◽  
Gaseous Stream ◽  
Fluid Concentration ◽  
Experimental Values

The physical processes that occur typically within an oil sand bed are considered when the bed is subjected to a hot gaseous stream. In this study, the extent of fluid volatilization was obtained from a consideration of the simultaneous heat and mass transfer processes within the oil sands. The resulting system of equations together with the boundary conditions were solved numerically using an implicit finite difference method. The transient fluid concentration and temperature distributions within the oil sand bed were then obtained under a wide range of operating conditions. The resulting theoretical rates of volatilization and temperatures show generally good agreement with corresponding experimental values that were obtained for the purpose.

An Analytical Approach to the Heat and Mass Transfer Processes in Counterflow Cooling Towers

2006 ◽  
Vol 128 (11) ◽  
pp. 1142-1148 ◽  
Author(s):  
Chengqin Ren
Keyword(s):  
Mass Transfer ◽  
Differential Equations ◽  
Heat And Mass Transfer ◽  
Analytical Model ◽  
Operating Conditions ◽  
Cooling Towers ◽  
Accurate Analysis ◽  
Transfer Resistance ◽  
Transfer Processes ◽  
Mass Transfer Processes

Quick and accurate analysis of cooling tower performance, outlet conditions of moist air, and parameter profiles along the tower height is very important in rating and design calculations. This paper developed an analytical model for the coupled heat and mass transfer processes in counterflow cooling towers based on operating conditions more realistic than most conventionally adopted Merkel approximations. In modeling, values of the Lewis factor were not necessarily specified as unity. Effects of water loss by evaporation and water film heat transfer resistance were also considered in the model equations. Within a relatively narrow range of operating conditions, the humidity ratio of air in equilibrium with the water surface was assumed to be a linear function of the surface temperature. The differential equations were rearranged and an analytical solution was developed for newly defined parameters. The analytical model predicts the tower performances, outlet conditions, and parameter profiles quickly and accurately when comparing with the numerical integration of the original differential equations.

scholarly journals Thermal Performance Evaluation of Seawater Cooling Towers

2011 ◽  
Author(s):  
Mostafa H. Sharqawy ◽  
Iqbal S. Husain ◽  
Syed M. Zubair ◽  
John H. Lienhard
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Fresh Water ◽  
Thermal Performance ◽  
Operating Conditions ◽  
Thermal Design ◽  
Cooling Towers ◽  
Detailed Model ◽  
Transfer Processes ◽  
Mass Transfer Processes

Seawater has been used for long time as a cooling fluid in heat exchangers to reduce fresh water usage in industry and power plants. The thermophysical properties of seawater are different from those of fresh water due to the salt content or salinity. This difference is sufficient to affect the heat and mass transfer processes which in turn change the thermal performance. Thermal design of fresh water cooling towers is described in detail in many textbooks and handbooks. However, only a rule of thumb is frequently used for designing of seawater cooling towers. This rule recommends degrading the tower performance by approximately 1% for every 10,000 ppm of salts in the feed water. In this paper, the thermal performance of seawater cooling towers is presented using a detailed model of counterflow wet cooling towers which takes into consideration the coupled simultaneous heat and mass transfer processes and uses state-of-the-art seawater properties from the literature. The model governing equations are solved numerically and the validity of this model is checked using new experimental data that has been measured using a bench top counterflow seawater cooling tower. The effect of the variation of seawater salinity as well as other operating conditions on the effectiveness and Merkel number is investigated.

scholarly journals The Mathematical Model and Numerical Study of Heat and Mass Transfer Processes in the Combustion Chamber of Diesel-Generator Units with a Valve-Inductor Generator

2020 ◽  
pp. 611-625
Author(s):  
Dmitriy V. Guzei ◽  
Andrey V. Minakov ◽  
Vasiliy I. Panteleev ◽  
Maksim I. Pryazhnikov ◽  
Dmitriy V. Platonov ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Mass Transfer ◽  
Combustion Chamber ◽  
Heat And Mass Transfer ◽  
Operating Conditions ◽  
Diesel Generator ◽  
Transfer Processes ◽  
Mass Transfer Processes ◽  
Actual Geometry ◽  
The Mathematical Model

The mathematical model of heat and mass transfer processes in the combustion chamber of diesel generator units with valve inductor generators has been developed. The mathematical model takes into account the actual geometry of the combustion chamber and the operating conditions of the diesel engine. A study of the main characteristics of a diesel generator in a wide range of modes of operation has been carried out. In addition to energy characteristics, environmental parameters have been considered

An Analytical Examination of the Behavior of Oil Sand Fragments in Heated Streams

1982 ◽  
Vol 104 (2) ◽  
pp. 121-129
Author(s):  
A. Hanafi ◽  
G. A. Karim
Keyword(s):  
Analytical Study ◽  
Chemical Processes ◽  
Operating Conditions ◽  
Transient Effects ◽  
Oil Sand ◽  
Wide Range ◽  
Experimental Values ◽  
Physical And Chemical ◽  
Simultaneous Heat ◽  
Good Agreement

The physical and chemical processes that occur typically within and around an oil sand fragment are considered when the fragment is suddenly introduced into a hot, low-uniform velocity, gaseous oxidizing stream. In this analytical study, the extent of bitumen volatilization was obtained from a consideration of the simultaneous heat and mass transfer within spherical oil sand fragments combined with a simplified cracking scheme of the heavy oil and asphaltene into coke and distillate. The resulting system of equations together with the boundary conditions arising from subjecting the fragments to hot convective streams were solved using Laplace transformation. The transient concentrations of bitumen and temperature within the fragments were then obtained under a wide range of operating conditions. The similarity of the expression obtained for the extent of bitumen volatilization to the expression derived from simplified analysis, based on a dropletlike model, was demonstrated for cases where the transient effects within the fragments were considered to be negligible. The results of the theoretical analysis show relatively good agreement with their corresponding experimental values at high stream temperatures, while they showed relatively inferior agreement at low temperatures.

scholarly journals Modeling heat and mass transfer processes during evaporation of a water film in a horizontal channel with a cocurrent flow of moist air

2021 ◽  
Vol 2119 (1) ◽  
pp. 012150
Author(s):  
M V Gorbachev ◽  
V I Terekhov
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Air Flow ◽  
Water Film ◽  
Horizontal Channel ◽  
Cocurrent Flow ◽  
Moist Air ◽  
Transfer Processes ◽  
Mass Transfer Processes ◽  
Wide Range

Abstract Modeling of heat and mass transfer processes in a horizontal channel during evaporative cooling of a moist air flow with regard to the finite thickness of the liquid film is considered. The mathematical model consists of a system of differential equations in the boundary layer approximation. The simulation results have been obtained in a wide range of initial parameters: temperature T 0 = 10÷50°C, humidity φ0=0÷100%, Reynolds number Re=100÷2000. Calculations were carried out at atmospheric pressure. Quantitative analysis of influence of initial parameters of flows on values of parameters of wet air flow at the outlet of the channel with and without taking into account the final thickness of the water film was carried out.

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.

Research on thermophysical characteristics of food products

2021 ◽  
Vol 12 (3) ◽  
Author(s):  
Z. A. Burova ◽  
◽  
S.O. Ivanov ◽  
T.O. Roman ◽  
V. P. Vasyliv ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Thermal Effects ◽  
Food Products ◽  
Thermophysical Characteristics ◽  
Transfer Processes ◽  
Mass Transfer Processes ◽  
Wide Range

Healthy diet is one of the most important elements in maintaining health and strengthening the nation's immunity, an essential condition for achieving active longevity of present and future generations. Inventing new ingredients and creation of food products based on them, development of new and improvement of existing technologies requires reliable information about the basic thermophysical characteristics of raw materials and biological substances to calculate and optimize heat and mass transfer processes during processing and production. Modern science offers a wide range of studies on the thermodynamic and heat and mass transfer process parameters, determination of the thermophysical characteristics of new substances and products using metrologically certified devices and information measuring systems. The main problem in the study of materials of biological origin is their inhomogeneity and sample structure heterogeneity. Measuring the effective thermal conductivity coefficient of bulk materials and cereals should be carried out in a stationary thermal mode on the device for determination of the thermophysical properties of materials and thermal effects, which implements a symmetrical scheme of the thermometric method of measurement using heat flow and temperature sensors. Using four measuring cells allows synchronous comparative analysis of several samples, and the rotary clamping mechanism helps to minimize contact resistance. The developed technique for measuring the coefficient of effective thermal conductivity takes into account the characteristics of bulk food products and significantly increases the accuracy of their thermal conductivity determination by introducing a correction for the contact resistance of the wall layer. The possibility of long-term observations allows to study thermolabile materials, analyze the thermal effects in the samples, to estimate the volumetric and integral heat dissipation. Calorimetric studies of a wide range of biological materials and substances can be performed with sufficient accuracy by the STA system, which implements step-by-step scanning and synchronous thermal analysis methods to determine the specific heat capacity and heat of evaporation, the ratio of free and bound moisture in heterogeneous materials. These characteristics are integral parameters in the study of the kinetics of heat and mass transfer processes, including drying, for the calculation and design of process equipment. Research on the thermophysical characteristics of heterogeneous materials and substances will optimize production processes and further develop technologies in the food, biotechnology, and processing industries.

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.

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