Heat exchange and hydraulic resistance in micronozzle grids

1980 ◽  
Vol 39 (5) ◽  
pp. 1177-1179
Author(s):  
A. A. Basovskaya ◽  
V. A. Reisig
Keyword(s):  
Heat Exchange ◽  
Hydraulic Resistance

Calculation of hydraulic resistance of clusters of rods with heat-exchange lattice-intensifiers

1980 ◽  
Vol 49 (3) ◽  
pp. 612-615 ◽  
Author(s):  
V. K. Ivanov ◽  
L. L. Kobzar'
Keyword(s):  
Heat Exchange ◽  
Hydraulic Resistance

scholarly journals MATHEMATICAL LOW-REYNOLDS MODELING OF HEAT EXCHANGE IIN TURBULENT FLOW IN FLAT CHANNELS WITH TURBULATORS SYMMETRICALLY LOCATED ON BOTH SIDES

2018 ◽  
Vol 45 (2) ◽  
pp. 70-93 ◽  
Author(s):  
I. E. Lobanov
Keyword(s):  
Heat Exchange ◽  
Hydraulic Resistance ◽  
Energy Equation ◽  
Transport Model ◽  
Theoretical Method ◽  
Flat Channel ◽  
Structured Grids ◽  
Calculation Results ◽  
Shear Stress Transport Model ◽  
Volume Method

ObjectivesThe aim of the study was to simulate the heat transfer in flat channel with turbulators, symmetrically located on its both sides, depending on the channel's geometric parameters and the coolant flow modes followed by the verification of the obtained calculated data by the existing experiment.MethodsThe calculation was carried out on the basis of a theoretical method based on the solution of the Reynolds equations, closed with the help of the Menter shear stress transport model, by factored finite-volume method, as well as the energy equation on multiscale intersecting structured grids (Fast COmposite Mesh method, FCOM).ResultsA theoretical mathematical calculation model for intensified heat exchange in turbulent flow for a flat channel with turbulators, symmetrically located on both sides, depending on the channel's geometric parameters and coolant flow modes was generated. The calculation results of the intensified heat exchange in flat channels with double turbulators, depending on the determining parameters, are in very good agreement with the existing experimental material and have an undeniable advantage over the latter, since the assumptions made in their derivation cover a much wider range of determining parameters than the limitations of the experiments (Pr = 0.7 ч 100; Re = 103ч 106; h / dЭ= 0.005 ч 0.2; t / h= 1 ч 200). ConclusionAccording to the calculation results based on the developed model, it is possible to optimise the heat exchange intensification in flat channels with double turbulators, as well as to control the process of heat exchange intensification. The comparative calculations of the intensified hydraulic resistance and heat exchange for flat channels with two-sided symmetrical flow turbulators with corresponding data for round channels with turbulators were carried out and analysed. From the point of view of heat exchange intensification, all other conditions being equal, the reduction of a flat channel with two-sided symmetrical turbulators with respect to a round tube with turbulators takes place because a smaller increase in heat exchange is achieved with a greater increase in hydraulic resistance. It was established by calculation that the relative hydraulic resistance ξП/ ξT for channels with turbulators is always higher than for smooth channels; however, the relative heat exchange NuП/ NuT for channels with turbulators can be higher than for smooth channels. Therefore, there is an enhanced redistribution of the temperature drop over the channel section with an intensified heat exchanger. The developed theoretical method based on the solution of the Reynolds equations by the factored finite-volume method, combined with the energy equation on multiscale intersecting structured grids and closed by means of the Menter shear stress transport model, makes it possible, with reasonable accuracy, to calculate heat exchange coefficients and hydraulic resistance in flat channels of practically any forms of double symmetrically located flow turbulators.

scholarly journals Mathematical Modeling of Hydraulic Resistance in Pipes With Rough Walls

2018 ◽  
Vol 1 (1) ◽  
pp. 74
Author(s):  
Lobanov Lgor Evgenjevich
Keyword(s):  
Mathematical Modeling ◽  
Heat Exchange ◽  
Hydraulic Resistance ◽  
Rough Walls ◽  
Intensification Of Heat Exchange ◽  
Extended Range

In recent years, the numbers of patents have been devoted to the development of rough pipes. The technique theoretical settlement determine of factor of hydraulic resistance for round pipes with rough walls is developed on the basis of a principle of a superposition of complete viscosity in turbulent a layer mainly distinguished from the existing theories. The received results of account for the extended range of determining parameters much distinguished from appropriate given for round pipes with turbulizers, specify a level и intensification of heat exchange.

scholarly journals METHOD AND RESULTS OF HYDRAULIC CALCULATION OF THE HEAT EXCHANGE SURFACE OF THE ONCE-THROUGH STEAM GENERATOR

2021 ◽  
Vol 1 (63) ◽  
pp. 60-77
Author(s):  
V. Kravchenko ◽  
◽  
Xiaolong Zhou ◽  
Keyword(s):  
Heat Exchange ◽  
Hydraulic Resistance ◽  
Steam Generator ◽  
Structural Parameters ◽  
Hydraulic Calculation ◽  
Working Fluid ◽  
Steam Generators ◽  
Small Modular Reactors ◽  
Heat Exchange Surface ◽  
Exchange Surface

Ukraine with her developed machine-building potential can take the deserving place in the production of small modular reactors. One of basic elements of small modular reactors equipment is steam generator. Among different types a deserving place is occupied by once-through steam generator. small modular reactors can exemplify to transport nuclear installation, for example KLT-40S. The calculation of hydraulic resistance is included in designing of steam generators, that it is necessary for the choice of pumps and optimization of structural parameters. In the presented article methodology of hydraulic calculation of once-through steam generator is examined with the coiling surface of heating. As a result of analysis of literature formulas were selected for the calculation of hydraulic resistance for four modes of flow: transverse flow of the coolant over horizontal coils, movement in bent tubes of a single-phase working fluid, boiling water and superheated steam. Results over of calculation of steam generators are brought by power 45 МВт with different structural parameters: diameter of coils, horizontal and vertical pitches of coils location in a bunch, speed of feedwater and coolant. The got results were verified by comparing to data of calculation on the code of ASPEN-TECH. It was found out as a result of research that increase of diameter of coils, as well as the increase of pitches of coils location in a bunch does not reduce hydraulic resistances, as expected, but increases them as a result of worsening of heat exchange and, accordingly, increase of heat-exchange surface. The increase of speed of coolant results in the height of resistance on the side of coolant and does not influence on resistance of working body. The increase of speed of feedwater increases resistance on the side of working fluid and does not influence on resistance of coolant.

Investigation of effect of depressant additives on hydraulic resistance and heat exchange in oil mixture flow

2004 ◽  
Vol 67 (4-5) ◽  
pp. 485-492 ◽  
Author(s):  
T.K. Aldyarov ◽  
U.K. Zhapbasbayev ◽  
G.I. Ramazanova
Keyword(s):  
Heat Exchange ◽  
Hydraulic Resistance ◽  
Mixture Flow

Heat-exchange and hydraulic resistance in the flow of air in tubes having bead packing

1975 ◽  
Vol 11 (10) ◽  
pp. 912-914
Author(s):  
M. V. Averkiev ◽  
E. F. Ratnikov
Keyword(s):  
Heat Exchange ◽  
Hydraulic Resistance

scholarly journals DEVELOPMENT OF HIGH EFFICIENT SHELL-AND-TUBE HEAT EXCHANGERS BASED ON PROFILED TUBES

2020 ◽  
Author(s):  
Djamalutdin Chalaev ◽  
◽  
Nina Silnyagina ◽  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Heat Exchange ◽  
Transfer Coefficient ◽  
Hydraulic Resistance ◽  
Heat Exchangers ◽  
Experimental Studies ◽  
Corrugated Tube ◽  
The Heat Transfer Coefficient

The use of advanced heat transfer surfaces (corrugated tubes of various modifications) is an effective way to intensify the heat transfer and improve the hydraulic characteristics of tubular heat exchangers. The methods for evaluating the use of such surfaces as working elements in tubular heat exchangers have not been developed so far. The thermal and hydrodynamic processes occurring in the tubes with the developed surfaces were studied to evaluate the efficiency of heat exchange therein. Thin-walled corrugated flexible stainless steel tubes of various modifications were used in experimental studies. The researches were carried out on a laboratory stand, which was designed as a heat exchanger type "tube in tube" with a corrugated inner tube. The stand was equipped with sensors to measure the thermal hydraulic flow conditions. The comparative analysis of operation modes of the heat exchanger with a corrugated inner tube of various modifications and the heat exchanger with a smooth inner tube was performed according to the obtained data. Materials and methods. A convective component of the heat transfer coefficient of corrugated tube increased significantly at identical flow conditions comparing with a smooth tube. Increasing the heat transfer coefficient was in the range of 2.0 to 2.6, and increased with increasing Reynolds number. The increase in heat transfer of specified range outstripped the gain of hydraulic resistance caused by increase of the flow. Results and discussion. CFD model in the software ANSYS CFX 14.5 was adapted to estimate the effect of the tube geometry on the intensity of the heat transfer process. A two-dimensional axially symmetric computer model was used for the calculation. The model is based on Reynolds equation (Navier-Stokes equations for turbulent flow), the continuity equation and the energy equation supplemented by the conditions of uniqueness. SST-turbulence model was used for the solution of the equations. The problem was solved in the conjugate formulation, which allowed assessing the efficiency of heat exchange, depending on various parameters (coolant temperature, coolant velocity, pressure). The criteria dependences were obtained Nu = f (Re, Pr). Conclusions. The use a corrugated tube as a working element in tubular heat exchangers can improve the heat transfer coefficient of 2.0 - 2.6 times, with an increase in hydraulic resistance in the heat exchanger of 2 times (compared with the use of smooth tubes). The criteria dependences obtained on the basis of experimental studies and mathematical modeling allow developing a methodology for engineering calculations for the design of new efficient heat exchangers with corrugated tubes.

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