ISSN:0145-7632    

DOI:10.1080/01457639108939742

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

A design procedure for offset strip-fin (OSF) heat exchangers is proposed, on the basis of a minimum-entropy-production evaluation criterion. Proper dimensionless operational and geometric-parameters are introduced, and the thermodynamic impact of the OSF augmentation technique is Analyzed, for assigned heat exchanger working conditions, using available correlations for heat transfer and fluid friction coefficients. The proposed method allows the designer to determine the most suitable geometric configuration in order to achieve—under given operational constraints—the minimum dissipation effects of OSF heat exchangers.

ISSN:0145-7632    

DOI:10.1080/01457639108939743

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Previous investigations into the use of interstitial inserts as a means of controlling the thermal conductance occurring across metallic contacts are reviewed. Vie factors influencing the choice of a suitable filler for a particular application are discussed. A mathematical model has been used to predict the behavior of a joint formed between the flat surfaces of two, originally isothermal, cylindrical components, one of duralumin and the other of a titanium alloy. Vie model was validated by comparing the predictions from it with experimental measurements. For this particular contact, aluminum cooking foil proved to be a superior insert to the more expensive, commercially advocated, thermal control materials for reducing contact resistances.

ISSN:0145-7632    

DOI:10.1080/01457639108939744

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The common methods of heat exchanger design are based on the assumption that the heat capacity of each fluid stream remains constant throughout the exchanger. Heat exchangers with variable specific heat, however, can be analyzed only by either numerical techniques or one of several approximate methods. While these approximate methods are generally satisfactory, they fail when fluid heat capacities change in such a way that the ratio of heat capacity rates changes from a value less than unity to one greater than unity along the exchanger. Such a situation results in a “pinch point,” or point of lowest temperature approach, inside the exchanger rather than at one of the ends. Complete information on possible pinch points is necessary for rating and sizing of these exchangers, particularly in high-Ntuunits. In this article a mathematical model is given to predict the existence and location of pinch points without computing complete temperature profiles. A step-by-step procedure is given for computer Simulation of heat exchanger performance with variable heat capacity of the working fluids.

ISSN:0145-7632    

DOI:10.1080/01457639108939745

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The analysis of visual patterns of flow distribution in finned tube banks with individual fins permits the Reparation of major factors affecting heat transfer and pressure drop. A flow model and governing dimensionless variables are established on the basis of this analysis and similarity with heat transfer phenomena in channels. Heat transfer and friction factor correlations are recommended for crossflow over staggered tube banks with plain and segmented fins in the range of Reynolds numbers Reh= 300−10,000. Correlation coefficients are evaluated using original and published experimental data. The correlations correspond with most of the available test data within 10%.

ISSN:0145-7632    

DOI:10.1080/01457639108939746

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor