ISSN:0145-7632    

DOI:10.1080/01457639408939832

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

A correlation was developed for laminar film condensation on vertical fluted surfaces. The theoretical analysis of Panchal and Bell was used for defining important physical property groups. The experimental data of Combs et al. were used to validate the proposed correlation. The experimental database used in the present study included four flute geometries that could be approximated to cosine-type flutes and seven fluids. The resulting correlation can predict the average condensate heat transfer coefficient within ±20%.

ISSN:0145-7632    

DOI:10.1080/01457639408939833

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The effective pore radius in screen-wick heat pipes was investigated, which is very important for the prediction of maximum heat transfer rates due to capillary limitation. An equation for the effective pore radius of the screen wicks was derived based on the model of the screen geometry. The capillary height for stainless steel and phosphor bronze screens was measured using water, ethyl alcohol, and Freon 113 as the test liquids. The effect of surface treatment (acid cleaning and oxidation) on the capillary height was also examined. From the comparison of the experimental data for water and ethyl alcohol with those for Freon 113, it was indicated that the contact angle was 24.2° for water and 16.9° for ethyl alcohol. Consequently, it was found that the effective pore radius of the screen wicks could be predicted fairly well from the expression presented in this study, and that the contact angle should be taken into consideration to evaluate the maximum capillary pressure accurately.

ISSN:0145-7632    

DOI:10.1080/01457639408939834

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The design and construction of a novel heat pipe apparatus is described, and results from experiments that employed the apparatus are presented. The apparatus is designed to permit visual and photographic study of liquid flow and vapor formation within the heat pipe wick structure, artery, and vapor flow channel. The vapor temperature field in the vapor flow channel is displayed by use of thermochromic liquid crystal material. Liquid and vapor flow phenomena observed during normal and the approach to boiling-limited heat pipe operation are described.

ISSN:0145-7632    

DOI:10.1080/01457639408939835

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

In this article the absorption process in a smooth-tube heat exchanger (GAX absorber) with a porous medium is analyzed and a countercurrent model for GAX absorber that includes an absorption process within the porous medium is proposed. The absorption process is separated into three regions, a vapor region without a porous medium (region I), a vapor region within a porous medium (region II), and a liquid region within a porous medium (region III). The effects of thermal conductivities and porosities of the porous medium on the absorption rate and the required tube length are investigated, and the Nusselt number within each region is also predicted. The results show that the absorption rate increases with an increase of the thermal conductivity and with a decrease in porosity of the porous medium. The optimum value of the ratio of thermal conductivities (kp/ k1)was found to be 5.0, and the optimum value of the porosity was found to be larger than 0.2.

ISSN:0145-7632    

DOI:10.1080/01457639408939836

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Hydrodynamically developed and thermally developing laminar incompressible forced-connective flow in ducts containing twisted-tape inserts is analyzed. The flow is subjected to either uniform temperature or uniform heat flux on the curved duct surface, and the straight duct surfaces are insulated. The heat input into the fluid is only from the curved duel surface and is uniform axially. The thermal properties are assumed constant; the axial conduction and viscous dissipation are negligibly small. Numerical calculations of the temperature field and Nusselt number march forward axially in the thermal entrance region. The solutions of die developing temperature field as well as the heat transfer coefficient are presented as functions of axial distance for different opening angles of sector. Comparisons are made between computed results and some analytical and numerical findings reported in the literature. In all cases, satisfactory comparisons are attained.

ISSN:0145-7632    

DOI:10.1080/01457639408939837

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Experimental results for average heat transfer coefficients have been obtained for a slot jet, a single row of round jets, and a triple row of round jets impinging onto a concave semicylindrical surface. Average Nusselt numbers have been expressed as functions of Reynolds number, Prandtl number, and non-dimensional geometric parameters of jet-target configuration.

ISSN:0145-7632    

DOI:10.1080/01457639408939838

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

When trying to determine the bulk temperature of a process stream, engineers must take care to determine whether measuring the pipe wall temperature will give a reasonable approximation of the bulk temperature. If the pipe wall temperature will not give a reasonable approximation of the bulk fluid temperature, further calculations must be performed.

ISSN:0145-7632    

DOI:10.1080/01457639408939839

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor