ISSN:0145-7632    

DOI:10.1080/01457639408939813

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Recent assessment studies of current and future heat transfer research have identified some future directions for a national coordinated effort. These assessment exercises raise the question of the proper role of government laboratories in the effort. In this article the author makes several suggestions regarding government's role in promoting a national heat transfer research effort. These suggestions evolve from the author's experience in a government laboratory, his monitoring of relevant research in industry and universities, and experience as a private consultant. In essence the suggestions focus on strengthening the ties and interdependence of the university, industry, and government heat transfer communities. The constraints of a tighter economy, plus limited facilities and personnel, require the strengthening of these ties in order to meet the challenge of advancing the science and technology of heat transfer through carefully selected and executed research.

ISSN:0145-7632    

DOI:10.1080/01457639408939814

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

An analytical study of transient heat conduction process with moving heat source/sink was considered. In this study a closed-form solution for the heat conduction equation is obtained. Using the obtained solution, the spatial temperature distribution and the temperature time history could be obtained. The obtained results are compared with numerical and experimental data in the literature. The comparison shows that the present solution can be used do determine the effect of different heat flow parameters on the temperature pattern and history in any similar heat conduction problem.

ISSN:0145-7632    

DOI:10.1080/01457639408939815

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Radiation heat transfer between rectangular electronic components on a printed circuit board and the walls of its enclosure is studied analytically using a Monte Carlo method. The radiation heat transfer between the electronic components and the cover is determined for the cases of diffuse and specular surfaces with constant properties, and for diffuse and specular surfaces with variable temperature and direction-dependent properties. The radiation interchange between the components and the cover of the enclosure are determined and presented for various dimensionless parameters and surface emissivities in tabular and graphical forms. The radiation heat transfer, in general, is found to be comparable in magnitude to natural-convection heat transfer at operating conditions encountered in practice. It is shown that radiation can serve as an effective heat transfer mechanism for the cooling of electronic components in sealed enclosures cooled externally.

ISSN:0145-7632    

DOI:10.1080/01457639408939816

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The temperature of water in large water reservoirs remains essentially constant at approximately 60° F throughout the year and therefore is attractive for space-conditioning applications. The energy exchange with the water reservoir is accomplished through a heat exchanger. In the present work, two heat-recovery heat exchangers were designed using a simplified computer model. Design-1, which used smooth tubes, was tested at a flooded abandoned mine vein at Scranton, Pennsyluania. The subsequent design, which used the spirally fluted tubes, was tested at the Ohio State University ( OSU) and at a lake in Lackawanna Stale Park in Pennsylvania. A more detailed thermal hydraulic model was developed for the analysis of these heat-recovery heat exchangers. The data obtained at OSU and Lackawanna were analyzed using the thermal hydraulic model to develop a correlation for natural convection. Finally, using this correlation, it was found that the design with spirally fluted tube clearly offers advantages in terms of reduced size of the heat exchanger for a given heat duty.

ISSN:0145-7632    

DOI:10.1080/01457639408939817

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Heat transfer and pressure drop correction factors based on the Bell-Delaware method have been compared for an optimized segmental baffle heat exchanger and a helical baffle heat exchanger. In general, the results showed that properly designed helical baffles offer a significant improvement in heat transfer while providing a reduced exchanger pressure drop. The enhancement in heat transfer for helical baffles was reflected by the so-called turbulence enhancement correction factor, which accounted for the increase in heat transfer observed at a critical baffle inclination angle of 25°. As the baffle inclination angle was increased beyond this critical angle, the turbulence enhancement factor continued to increase and eventually produced a maximum heal transfer enhancement of 1.39 times that for ideal cross-flow conditions. The reduction in pressure drop due to the helical baffles was found to vary from 0.26 to 0.60 depending on the helical inclination angle.

ISSN:0145-7632    

DOI:10.1080/01457639408939818

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor