ISSN:0145-7632    

DOI:10.1080/01457638708962789

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The search for the optimal profile for a longitudinal fin has occupied a portion of the mathematics and engineering communities for almost 60 years. Heuristic and rigorous arguments have led to definitive answers only when the “length of arc” idealization is involved. This paper reviews the chronology of these research efforts and offers some counterexamples, with regard to the usual models, which indicate that fins of mathematically unbounded performance are theoretically (although not practically) achievable. The construction of such fins, in the practical limit, suggests some promising new horizons in extended-surface heal transfer.

ISSN:0145-7632    

DOI:10.1080/01457638708962790

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The subject of bond resistances and maximum acceptable operating temperatures for various types of high-finned tubes is updated from the status of the last pertinent publications in the 1960s. The formation mechanism of the bond resistance under high and low temperatures is analyzed. Presently accepted industrial practices are critically evaluated. The lack of progress in the standardization of test procedures is noted with regret.

ISSN:0145-7632    

DOI:10.1080/01457638708962791

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

New thermal conductance correlations based on improved metal, gap. and joint contact models are presented for determining the thermal inlerfacial resistance in compound cylinders. The new theory utilizes models involving measured surface parameters, material hardness, thermophysical properties, and ileratively evaluated contact stresses. The predictions of previous and proposed models are compared to recently published experimental investigations on compound cylinders. Accuracy to within 5% of experimental data is obtained by means of the proposed models. It was found that the alternative models grossly overestimated the thermal contact resistance in compound cylinders, with error ranges from 25 to 100% (Ross and Stoute, Shlykov and Ganin) and 100 to 200% (Veziroglu) of the experimental results. The experimental verifications thereby support the new models in the analysis of compound cylinders, with direct applications in analyzing the performance of finned-tube heal exchangers.

ISSN:0145-7632    

DOI:10.1080/01457638708962792

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

This paper presents a survey based on the scattered literature dealing with the heat transfer and pressure drop performance of low-finned tube banks. Only the turbulent forced-convection mode of heat transfer is considered for pure cross flow. Heat transfer and pressure drop correlations are recommended for a wide Reynolds number range of 1000 to 200,000. The necessary corrections for nonequilateral lube arrangements. temperature-dependent fluid properties, row number effects, and bundle side leakage are also identified.

ISSN:0145-7632    

DOI:10.1080/01457638708962793

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

A simple method of assessing the uncertainties of thermal hydraulic parameters in the design of heat exchangers is described. Assuming a Gaussian form of data distribution for “uncertain” parameters leads to a root-sum-square (RSS) method of establishing the probability, or confidence level, that the heat exchanger design will meet Us thermal hydraulic performance requirements. An example is provided to illustrate the method. Various other design considerations to provide proper margins for the final sizing of the heat exchanger are also discussed.

ISSN:0145-7632    

DOI:10.1080/01457638708962794

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The effects of several types and patterns of maldistribution in heat exchangers on the exchanger thermal performance are investigated. For turbulent flow most exchangers show only a small reduction in performance; however, for laminar flow the reduction can be large. It is shown that substantial errors in the apparent heat transfer coefficient occur for nonuniform flows.

ISSN:0145-7632    

DOI:10.1080/01457638708962795

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Several double-wall stainless steel cylindrical capsules containing37Cs (CsCl salt) are used as a source of gamma rays in a proposed food irradiation facility. The capsules, normally stored in a water pool, are withdrawn into air when in use. The radioactive decay of the37Cs is a heat source (approximately 213 W/capsule). A key element in the facility design is to ensure that the temperature of the radioactive source capsules, when in air, is maintained below specified limits. The thermal analysis performed to ensure that the cooling provided is adequate, in spite of the capsule stacking arrangement, is presented in this paper. A thermal model is presented for the heat transfer through a single capsule and the thermal interaction among the stacked capsules and with the surrounding air. Also presented is an analysis of the transient heat transfer phenomenon associated with the potential loss of the forced-convection cooling employed.

ISSN:0145-7632    

DOI:10.1080/01457638708962796

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Personal computer spreadsheet programs are widely recognized for their business applications but are also well suited for performing numerical thermal analysis. Following a description of the basic steps in numerical thermal modeling, the methodology of implementing spreadsheet solutions is presented. Memory requirements, iteration time, and the structure for parametric studies are discussed. Three techniques for deriving the nodal equations used in numerical thermal modeling are given in detail, Included are the finite-difference approach, the energy balance approach, and the thermal resistance approach. The paper concludes with a detailed example showing how to implement a spreadsheet numerical solution for two-dimensional heat flow through a plate. Heat flux, insulated, isothermal, and convecting boundaries are illustrated.

ISSN:0145-7632    

DOI:10.1080/01457638708962797

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor