Experimental Investigation Of Heat Exchange Research Articles

Experimental Investigation of Heat Exchange in Cooling the Surface by a System of Submerged Dielectric-Liquid Jets

Experimental Investigation of Heat Exchange in Cooling the Surface by a System of Submerged Dielectric-Liquid Jets

EXPERIMENTAL INVESTIGATION OF HEAT TRANSFER IN INTERFIN CHANNELS OF PUNCHED SPIRAL TUBE FINNING

To reduce the metal consumption of boilers of steam-turbine power units and waste-heat boilers of gas-steam turbine units, the spiral-tape finning of low-temperature convection heating surfaces is applied. However, the heat transfer in the bundles of such tubes has not been studied sufficiently, the influence of the geometric dimensions of the cut portion of the fins has not been experimentally investigated. In most heat exchange calculation methods, based on the generalization of the results of experimental studies, this influence is also not taken into account. It is proposed to take into account the influence of the finning geometry on heat transfer by introducing correction coefficients in the generalizing equations, determined from the results of a numerical research. To evaluate the validity of the introduction of the results of numerical research into generalizing equations, an experimental investigation of heat exchange in the interfin channels of the punched spiral finning of the tubes is carried out. A research method is developed based on the results of measurements of the surface temperatures of the fins and air in different zones of the interfin channel along its height, as well as the air temperature in front of the bundle and the air flow through the bundle. The study is carried out by placing the calorimeter tubes in the transverse rows of the chess and corridor bundles of tubes at different Reynolds numbers. The results of the investigation of one of the bundle. The calorimeter is installed in the fifth row of a six-row tube bundle with fin interval of Sf = 6 mm and tube steps in the bundle S1 = 85 mm, Ś2 = 85 mm. At the Reynolds number, Red = 10042: the heat flux in the interfin channels Q = 711.0 W, the same according to electrical measurements - 731.0 W; discrepancy - 2.73 %; the heat transfer coefficient in the blade zone is αifcb = 162.0 W/m2°C; discrepancy – 2.88 %. The average surface heat transfer coefficient in the interfin channel is ͞ αifc = 132.35 W/m2°C; by numerical calculation - 122.6; discrepancy is 7.31 %. The average surface heat transfer coefficient of a single transverse row of tubes, taking into account the flow of a part of the air through the intertubular channels, is ͞ αc = 83.05 W/m2°C; the discrepancy is 5.12 %. In the remaining experiments, the difference in the values of the heat transfer coefficients is 3.19 ... 15.7 %. The results of the investigation confirm the validity of the use of the results of numerical investigation in generalizing equations for calculating the heat transfer of bundles of tubes with a spiral finning

Experimental Investigations of the Characteristics of Heat-Exchange and Temperature Fields in the Channels and Fuel-Element Assemblies of Lead-Cooled Fast Reactors

The results of experimental investigations of heat exchange and temperature fi elds in channels and fuel assemblies in lead-cooled fast reactors performed at the Leipunskii Institute for Physics and Power Engineering are presented. The main investigations were performed using mercury and lead-bismuth and sodium-potassium alloys. The effect of the contact thermal resistance on heat exchange is analyzed. Data on heat transfer and the azimuthal temperature nonuniformity of the fuel elements are compared for assemblies with a wide lattice, relative spacing s/d = 1.33, smooth fuel elements, and spacing of fuel elements by an ‘edge on edge’ double winding and transverse lattices are compared.

Experimental Investigation of Heat Exchange in Turning Chambers of Compact Coils

Results are presented for an experimental investigation of heat exchange in turning Π-shape niched chambers, which are a component part of the compact coil of heat exchangers. The spacing of the tubes in the coil and the length of the niches were varied in the experiments. A similitude equation describing the heat exchange in the turning chambers is derived. The rate of heat exchange in the turning chambers is several times higher than that in a straight tube and smoothly curving turns.

An investigation of heat exchange of liquid metal during flow in a vertical tube with non-uniform heating in the transverse magnetic field

The results of experimental investigations of heat exchange during the downflow of liquid metal in a vertical tube with non-uniform heating in the transverse magnetic field are presented. The experiment was more realistic in terms of conditions of the blanket of a fusion reactor of the tokamak type. Profiles of the average temperature, distribution of local and mean heat transfer coefficients (Nusselt numbers), and the intensities and spectra of temperature pulsations have been measured. On certain combinations of operating parameters in the strong magnetic field low-frequency temperature pulsations with abnormal intensity were found.

Thermal and flow characteristics of the condensation of R404A refrigerant in pipe minichannels

This article presents the results of experimental investigations of heat exchange and pressure drop during the condensation of R404A refrigerant in stainless steel pipe minichannels with internal diameters of 1.4–3.30mm. A review is provided of the present state of knowledge concerning the condensation of this refrigerant in conventional channels and in small-diameter channels. It is emphasized that there are few prior publications concerning this issue. The test setup is described as well as the results of the experimental tests. We discuss the dependence of the heat transfer coefficient and the pressure drop of the R404A refrigerant on both minichannel diameter and process parameters. The pressure drop during the condensation of this refrigerant is satisfactorily described by the Friedel and Garimella correlations. Based on the experimental tests, we propose a new correlation for the calculation of the local heat transfer coefficient. The values calculated from this correlation were in agreement with the experimental results to within ±20%.

Heat Exchange and Aerodynamic Drag in Cross-Flow Staggered Banks of Aluminum-Finned Tubes

Results are presented for an experimental investigation of heat exchange and loss of air pressure in staggered six-row banks of air coolers (AC). Curves are presented for the coefficient of convective heat transfer of the fifth transverse row and the aerodynamic drag of six-row banks versus air velocity. It is pointed out that the results obtained can be used in optimizing tube spacing in the heat-exchange sections of AC.

High-Temperature Radiative-Convective Heat Exchange on the Surface of Glass-Reinforced Plastics

The results of experimental investigations of heat exchange on the surface of a thermal‐protective material — glass‐reinforced plastic — in the flows of high‐temperature gases have been presented. It has been established that the influence of injection on the value of the heat flux does not exceed 10% in the range of variation of gas temperatures 300–2000 K and Reynolds numbers 350–9800.

Heat exchange of a swirled stream of a gas suspension in a pipe

The results of an experimental investigation of heat exchange during turbulent flow of a gas containing suspended particles of a solid material in a horizontal pipe are presented.

Heat exchange in annular channel with intermediate heat carrier

The article explains the results of the experimental investigation of heat exchange in an annular channel with an intermediate heat carrier. A comparison is presented with coaxial cylinders rotating in the same direction. The experimental devices are described.

Experimental investigation of heat exchange in a porous annular channel

The problems connected with the intensification of heat exchange in an annular channel with a porous inner wall are considered. A method for calculating a “tube-intube” heat exchanger with a porous inner tube is described.

Heat exchange and hydraulic resistance in micronozzle grids

We give the results of an experimental investigation of heat exchange and hydraulic resistance when air flows through micronoazle grids.

An experimental investigation of heat exchange for oil heat carriers during turbulent motion in a straight tube

An experimental investigation of heat exchange for oil heat carriers during turbulent motion in a straight tube

Heat exchange at a plate during longitudinal turbulent stream flow past it

Results are given of theoretical and experimental investigations of heat exchange at a surface past which a turbulent jet stream with strong transverse nonuniformity flows, and data are given from an investigation of the distribution of the gasdynamic parameters at the initial part of the supersonic turbulent submerged stream.

Experimental investigation of heat exchange between a turbulent airflow and a short rotating cylindrical tube

The experimental measuring equipment and procedure are described. It is found that the local and mean heat transfer between the wall of a totating tube and a turbulent airflow decreases with increasing rpm. Generalized equations are derived in dimensionless form.