Heat exchange of dynamic powder beds with a heat-transfer surface. II. A dust-laden gas flow

1999 ◽  
Vol 72 (1) ◽  
pp. 7-10
Author(s):  
D. S. Pashkevich ◽  
V. N. Krasnokutskii ◽  
V. B. Petrov ◽  
V. L. Korolev
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Gas Flow ◽  
Heat Transfer Surface

The Transient Response of Gas-Turbine-Plant Heat Exchangers—Regenerators, Intercoolers, Precoolers, and Ducting

1959 ◽  
Vol 81 (4) ◽  
pp. 433-448 ◽  
Author(s):  
A. L. London ◽  
F. R. Biancardi ◽  
J. W. Mitchell
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Transient Response ◽  
Heat Exchangers ◽  
Gas Flow ◽  
Heat Transfer Surface ◽  
Complete Coverage ◽  
Turbine Plant ◽  
Capacitance Effect ◽  
Gas Turbine Plant

This is the second report of a program dealing with the transient response of heat exchangers [1a], [1b]. Analog solutions are used to supplement some analytical solutions so as to provide fairly complete coverage for the heat exchangers encountered in gas-turbine plants. Because a gas flow exists on at least one side of the heat-transfer surface, these exchangers are characterized by a large wall-capacitance effect. Where greater generality is possible, the extension to other heat exchangers is indicated.

Mechanisms of Heat Transfer Enhancement of Gas–Solid Fluidized Bed: Estimation of Direct Contact Heat Exchange From Heat Transfer Surface to Fluidized Particles Using an Optical Visualization Technique

1995 ◽  
Vol 117 (1) ◽  
pp. 104-112 ◽  
Author(s):  
Y. Kurosaki ◽  
I. Satoh ◽  
T. Ishize
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Fluidized Bed ◽  
Flow Rate ◽  
Direct Contact ◽  
Heat Transfer Surface ◽  
Heat Transfer Tube ◽  
Transfer Tube ◽  
Contact Frequency ◽  
Fluidized Particles

This paper deals with mechanisms of heat transfer in a gas–solid fluidized bed. Heat transfer due to heat exchange by direct contact from a heat transfer tube immersed in the bed to fluidized particles was studied by means of visualization of contact of the fluidized particles to the heat transfer surface. The results show that the duration of contact of fluidized particles was almost uniform over the tube circumference and was hardly affected by the flow rate of fluidizing gas. On the other hand, the contact frequency between the particles and heat transfer tube was evidently influenced by the gas flow rate and particles diameter, as well as the location on the tube circumference. Using the visualized results, the amount of heat conducted to fluidized particles during the contact was estimated. This result showed that unsteady heat conduction to the fluidized particles plays an important role in the heat transfer, especially at the condition of incipient fluidization.

scholarly journals INTENSIFICATION OF HEAT EXCHANGE IN DIABATIC RECTIFICATION COLUMNS

2020 ◽  
pp. 511-518
Author(s):  
Nikolay Aleksandrovich Voinov ◽  
Denis Andreyevich Zemtsov ◽  
Anastasiya Viktorovna Bogatkova ◽  
Nina Vladimirovna Deryagina
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Film Flow ◽  
Heat Removal ◽  
Heat Transfer Surface ◽  
Water Mixture ◽  
Gravitational Flow ◽  
Intensification Of Heat Exchange ◽  
The Cost ◽  
Intensify Heat Transfer

The heat exchange in a diabatic column was investigated during the rectification of an ethanol-water mixture, in which partial condensation of rising vapors on the surface of vertical heat exchange tubes installed vertically along the height of the installation was carried out, as well as the evaporation of intermediate condensate on the surface of horizontal plates. Based on the review of diabatic columns, it is shown that they can reduce the cost of conducting the rectification process. Heat-exchange devices placed on trays of rectification units are considered and ways to intensify heat transfer in them are proposed. It has been established that the most efficient heat removal in heat exchangers of diabatic columns is achieved when using a film flow of a coolant on a heat transfer surface. Heat transfer in a diabatic column is investigated during gravitational flow of surfaces of heat exchange tubes, as well as when organizing an ascending and descending co-current film flow, both in the case of heating and boiling of the coolant. To intensify heat transfer in the coolant film, a helical artificial roughness was installed on the surface of the pipes, made in the form of a wire spiral tightly mounted on the heat transfer surface. The geometric parameters of the helical roughness, such as the distance between the turns of the spiral and the height of the wire, which have the greatest influence on the intensity of heat transfer, have been established. Dependences for determining the value of the heat transfer coefficient are presented and an estimate of the value of the specific heat flux in the diabatic column is given.

Compressible pipe flow

2018 ◽  
Author(s):  
Marcel Escudier
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Pipe Flow ◽  
Gas Flow ◽  
Wall Friction ◽  
Perfect Gas ◽  
Flowing Fluid ◽  
One Dimensional ◽  
Flow Through ◽  
Key Parameter

In this chapter gas flow through pipes is analysed, taking account of compressibility and either friction or heat exchange with the fluid. It is shown that in all cases the key parameter is the Mach number. The analyses are based upon the conservation laws for mass, momentum, and energy, together with an equation of state. So that significant results can be achieved, the flowing fluid is treated as a perfect gas, and the flow as one dimensional. Adiabatic pipe flow with wall friction is termed Fanno flow. Frictionless pipe flow with heat transfer is termed Rayleigh flow. It is found that both flows, and also isothermal pipe flow with wall friction, can be limited by choking.

Calculation of Heat Exchange Characteristics Transpiration Cooling Systems

2015 ◽  
Vol 756 ◽  
pp. 365-371
Author(s):  
A.S. Yakimov
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Physical Properties ◽  
Gas Flow ◽  
Transpiration Cooling ◽  
Cooling Systems ◽  
High Enthalpy ◽  
Thermo Physical Properties

The effect of high-enthalpy gas flow on transpiration cooling systems is considered. The influence of thermo-physical properties and porosity of some metals on heat transfer of the models is studied.

scholarly journals Aerodynamics and Heat Transfer of Swirling Natural Gas Flow in a Vortex Heat Exchanger of the Heating System of a Gas Control Point

2020 ◽  
Vol 24 (3) ◽  
pp. 99-110
Author(s):  
N. P. Grigorova ◽  
P. V. Monastyrev ◽  
E. G. Pakhomova ◽  
N. E. Semicheva
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Heat Exchange ◽  
Thermal Energy ◽  
Gas Flow ◽  
Heating System ◽  
Comprehensive Analysis ◽  
The Heat Transfer Coefficient ◽  
Two Parameter

Purpose of research. To obtain a two-parameter model characterizing the aerodynamic and heat exchange processes occurring in a vortex heat exchanger, giving a better agreement between the calculated and experimental values of the heat transfer coefficient taking into account the curvature of the swirling gas flow in a vortex heat exchanger, in which a controlled gas pressure drop is used as a source of thermal energy. This technical solution will make it possible to abandon the installation of autonomous sources of thermal energy, which will reduce the cost of gas as a fuel in the heating system of the industrial premises of the gas distribution point (GDP), as well as provide more comfortable working conditions for the hydraulic fracturing pressure regulator. Methods. Comprehensive analysis of thermal and hydraulic characteristics in a vortex heat exchanger is based on well-known theoretical positions and equations of motion of a swirling gas flow and heat exchange laws. Results. It is obtained a dependence that characterizes the intensification of heat transfer based on the influence of the axial and rotational speed, as well as the path of motion of the swirling gas flow. This dependence is obtained on the basis of a comprehensive analysis of the aerodynamic and heat exchange characteristics of a vortex heat exchanger, in which a controlled gas pressure drop is used as a source of thermal energy. Conclusion. The obtained two-parameter model gives the best agreement of the calculated values of the heat transfer coefficient with the values obtained experimentally, which were used in the thermal engineering calculation of the design parameters of the vortex heat exchanger.

scholarly journals Heat Exchange Between Air and a Liquid Film Flowing Down Along a Profiled Surface

2020 ◽  
Vol 38 (3) ◽  
pp. 622-628
Author(s):  
Vitaly V. Dubrovsky ◽  
Aleksandr A. Shraiber
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Liquid Film ◽  
Heat Exchangers ◽  
Cross Flow ◽  
Heat Transfer Surface ◽  
Optimal Conditions ◽  
Counter Flow ◽  
Surface Profiling ◽  
Exchange Intensity

The laws of heat exchange between air and a liquid film flowing down along a solid surface with spherical dimples were investigated experimentally. Three cases of heat transfer were considered: quiescent air, air – liquid counter flow, or their cross flow. In all cases, a significant growth of the heat exchange intensity, especially at air – liquid cross flow, was observed. This is caused by the substantial turbulization of flow and mixing of liquid layers in the film. As a result, it was established that surface profiling (manufacture of dimples) under the optimal conditions leads to an increase in heat exchange intensity by an unexpended factor of 2.5 – 2.8 as compared with a smooth surface, other conditions being equal. The obtained experimental data were generalized in the form of dimensionless dependences Nu vs. Re. The best heat transfer surface can be recommended for use in different heat exchangers.

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