A. L. London

Bio: A. L. London is an academic researcher from Stanford University. The author has contributed to research in topics: Heat transfer & Heat exchanger. The author has an hindex of 9, co-authored 16 publications receiving 2775 citations.

Laminar Flow Forced Convection Heat Transfer and Flow Friction in Straight and Curved Ducts - A Summary of Analytical Solutions

Abstract: : Theoretical laminar flow solutions for heat transfer and flow friction are of importance in the development of compact heat exchangers. Generally the higher the degree of compactness, the lower is the Reynolds number and the greater is the relevance of the theory solutions. In the report these solutions are compiled for twenty one straight ducts and four curved ducts. Some new analytical solutions are obtained by writing a general computer program for three ducts. Application of the analytical solutions to the gas turbine regenerator is discussed.

Offset Rectangular Plate-Fin Surfaces—Heat Transfer and Flow Friction Characteristics

Abstract: : Basic heat transfer and flow friction design data are presented for nine offset rectangular plate-fin surfaces. Seven of the test cores were constructed of aluminum and two were constructed of stainless steel. One of the configurations had a heat transfer area density ratio of 1772 sq ft/cu ft, one of the most compact plate-fin surface ever tested at Stanford University. The present results are compared with the offset rectangular plate-fin surfaces previously tested at Stanford. Comparisons are also provided with a louvered fin and a perforated fin plate-fin surface, in terms of heat transfer power versus flow friction power and flow area characteristics. The various kinds of mal-flow distribution through the test cores and their effects on the test results for heat transfer and flow friction are examined. (Author)

Laminar Flow Gas Turbine Regenerators—The Influence of Manufacturing Tolerances

Abstract: Several current designs for high effectiveness gas turbine regenerators involve low Reynolds number fully developed, laminar flow type surfaces. Such surfaces consist of cylindrical flow passages, of small hydraulic radius, in parallel. The cylinder geometry may, as examples, be triangular, as in some glass-ceramic surfaces, or rectangular, as in deepfold metal foil surfaces. This presentation demonstrates that manufacturing tolerances of several thousandths of an in. in passage dimension have a significant influence on the overall heat transfer and flow friction behavior. The analysis is also useful in rationalizing the difference between theory and test results for the basic heat transfer (j factor) and friction (f factor) characteristics as a function of Reynolds number for various surfaces of the laminar flow type.

Ozone synthesis from oxygen in dielectric barrier discharges

Abstract: A comprehensive model of ozone generation in dielectric barrier discharges is presented. The model combines the physical processes in the micro-discharges with the chemistry of ozone formation. It is based on an extensive reaction scheme including the major electronic and ionic processes. The importance of excited atomic and molecular states is demonstrated. Theoretical limits are given for the ozone production efficiency and the attainable ozone concentration. The most important parameters influencing the performance of ozonisers are identified. All theoretical predictions are compared to measured data.

Experimental and theoretical scaling laws for transverse diffusive broadening in two-phase laminar flows in microchannels

Abstract: This letter quantifies both experimentally and theoretically the diffusion of low-molecular-weight species across the interface between two aqueous solutions in pressure-driven laminar flow in microchannels at high Peclet numbers. Confocal fluorescent microscopy was used to visualize a fluorescent product formed by reaction between chemical species carried separately by the two solutions. At steady state, the width of the reaction–diffusion zone at the interface adjacent to the wall of the channel and transverse to the direction of flow scales as the one-third power of both the axial distance down the channel (from the point where the two streams join) and the average velocity of the flow, instead of the more familiar one-half power scaling which was measured in the middle of the channel. A quantitative description of reaction–diffusion processes near the walls of the channel, such as described in this letter, is required for the rational use of laminar flows for performing spatially resolved surface chemistry and biology inside microchannels and for understanding three-dimensional features of mass transport in shearing flows near surfaces.