ISSN:0145-7632    

DOI:10.1080/01457630050144442

出版商:Informa UK Ltd    

年代:2000

数据来源: Taylor

摘要:

Experimental data were obtained with two different commercially available, internally enhanced carbon steel tubes using glycol mixtures as the tube-side fluids. In the turbulent regime, these data show that enhancement levels of 2.5 or greater are possible and that the pressure-drop increase is about the same as or slightly less in magnitude than the heat transfer enhancement. However, these enhanced tubes are currently not recommended for most laminar-flow applications because of erratic behavior believed to be related to the wandering laminar?turbulent transition and of limited or no enhancement for some conditions.

ISSN:0145-7632    

DOI:10.1080/01457630050127900

出版商:Informa UK Ltd    

年代:2000

数据来源: Taylor

摘要:

An experimental study was carried out to examine the effect of the waffle height on air-side performance of typical fin-and-tube heat exchangers under dehumidifying conditions. The waffle heights examined in the present study are 1.18 and 1.58 mm, respectively. A total of 12 samples of heat exchangers, including eight having wavy fin and four having plain fin configurations were tested. The test results indicated that the effect of waffle height on the heat transfer enhancement ratio, compared to the plain-fin counterpart, is pronounced only for smaller fin pitch and larger waffle height, while its effect on the pressure drop is very pronounced throughout the test range, and is almost two times higher than in dry conditions.

ISSN:0145-7632    

DOI:10.1080/01457630050127919

出版商:Informa UK Ltd    

年代:2000

数据来源: Taylor

摘要:

The present article is aimed at evaluating six typical flow boiling heat transfer correlations selected from the open literature with experimental results. The selected correlations are correlations of Chen, Shah, Gungor and Winterton, Liu and Winterton, Klimenko, and Kandlikar. Experiments of upward flow boiling heat transfer with kerosene in a vertical smooth tube were conducted. The test tube has a length of 2.5 m and its outer and inner diameters are 19 mm and 15 mm, respectively. The experiments were performed at an absolute atmospheric pressure of 3. The input heat flux ranged from 28.5 to 93.75 kW/m² and the mass fluxes were selected at 410, 610, and 810 kg/m² s, respectively. The experimental flow boiling heat transfer coefficients were compared with flow boiling heat transfer coefficients calculated with the six typical correlations. By comparison, the most suitable correlations are recommended for the calculation of flow boiling heat transfer coefficients with kerosene in a smooth tube.

ISSN:0145-7632    

DOI:10.1080/01457630050127928

出版商:Informa UK Ltd    

年代:2000

数据来源: Taylor

ISSN:0145-7632    

DOI:10.1080/01457630050127937

出版商:Informa UK Ltd    

年代:2000

数据来源: Taylor

摘要:

Various designs of immersion coils for batch cooling or heating of liquids in tanks were investigated to determine which design was most efficient. This equipment has direct utility in chemical batch processing operations and, particularly, wort cooling-a critical step in small-scale batch brewing of beer. This operation does not use a stirrer or agitation for a variety of reasons, hence it is dependent on natural-convection mechanisms for heat transfer, yet quick cooling is desired. Four basic coil designs with several permutations were evaluated. The results fell into four groups - best, good, mediocre, and worst performers. We found that coil placement and shape were design parameters that had a critical effect on the rate of cooling. Coil spacing also had a significant effect on the cooling rate when it was less than about 2 diameters.

ISSN:0145-7632    

DOI:10.1080/01457630050127946

出版商:Informa UK Ltd    

年代:2000

数据来源: Taylor

摘要:

Transient three-dimensional heat transfer between a traversing, structured, and rectangular object and an enclosure is studied. This study investigates the heat transfer process that occurs in brazing an aluminum heat exchanger in a controlled-atmosphere furnace. A model's development is discussed with prescribed enclosure temperature boundary conditions. The program determines the radiant heat exchange between gray diffuse surfaces, and solves the three-dimensional conduction equation for a solid with a radiant heat flux boundary condition using an implicit finite-difference method. The structured object's conduction and radiant thermal properties are described by effective values. It was shown that radiative thermal properties of the traversing object and the enclosure's temperature have a strong impact on the object's temperature history. The effective thermal emissivity was found to influence the object's rate of temperature change. The enclosure's temperatures influenced the object's equilibrium temperature. Also, it was shown that the object's position and rotation can alter its temperature distribution, but not as strong as the effect of boundary conditions and thermal properties. In addition to numerical methods, experiments were performed to further understand the process.

ISSN:0145-7632    

DOI:10.1080/01457630050127955

出版商:Informa UK Ltd    

年代:2000

数据来源: Taylor

摘要:

This article describes the use of a spreadsheet program for the numerical solution of a two-dimensional Stefan problem. A complete Lotus 1-2-3 macro is presented and numerical results are given and compared with other known results.

ISSN:0145-7632    

DOI:10.1080/01457630050127964

出版商:Informa UK Ltd    

年代:2000

数据来源: Taylor

ISSN:0145-7632    

DOI:10.1080/01457630050127973

出版商:Informa UK Ltd    

年代:2000

数据来源: Taylor

ISSN:0145-7632    

DOI:10.1080/01457630050127982

出版商:Informa UK Ltd    

年代:2000

数据来源: Taylor