Showing papers by "Ralph L. Webb published in 1990"
TL;DR: In this paper, an analytical model for predicting condensation on integral fin tubes is presented, which is applicable to fins of two basic profile shapes: the special continuous profile shapes previously described by Gregorig, Adamek, or Webb, or fins having rectangular or trapezoidal cross-sections.
50 citations
TL;DR: In this article, a test cell was constructed to condense Refrigerant-11 on the shell side of a vertical bank of five horizontal tubes and four distinctly different commercially available tubes were tested.
Abstract: Experimental results of a condensation row effect study on enhanced tubes are presented A test cell was constructed to condense Refrigerant-11 on the shell side of a vertical bank of five horizontal tubes Four distinctly different commercially available tubes were tested The tubes are a 1024-fpm integral fin, the Wolverine Tube-C, Wieland GEWA-SC, and the Tred-D A modified Turbo-C tube was also tested Experimental and visual observations are used to understand the row effect due to condensate loading By plotting the data in the form of the local condensation coefficient versus condensate Reynolds number, the results may be interpreted for any number of tube rows, up to the maximum Reynolds numbers tested Bundle average condensation coefficients may be established by integrating the h versus Re values over the number of tube rows
46 citations
22 citations
TL;DR: In this article, a theoretical method was proposed to predict the condensation rate in a drainage channel of rectangular cross-section, where the condensate generated on the special convex profile is drained by gravity force.
16 citations
TL;DR: In this article, a standard nomenclature for definition of the six different forms of the driving potential and the mass transfer coefficient was proposed, and the Lewis number was defined as the ratio Sc/Pr.
13 citations
TL;DR: In this paper, a new family of high-performance fin profiles for surface-tension-drained condensation was proposed, based on the fin tip radius, the fin height, and the fin base thickness.
Abstract: This paper introduces a new family of high-performance fin profiles for surface-tension-drained condensation. Previously described profiles for this situation have been defined in terms of the fin curvature and arc length. The existing profiles are generally not suitable for commercial manufacture. The fin profiles presented in this paper are conveniently defined by the fin tip radius, the fin height, and the fin base thickness. Consequently, the designer may easily specify a fin shape with parameters that are compatible with those used by the manufacturing industry. The heat transfer performance of the new profiles provides an improvement over existing, commercial fin shapes. An analysis is presented to show the R-11 condensation performance of the new profiles as a function of the geometric variables. A recommended design practice for fins for surface-tension-drained condensation is given also.
12 citations
TL;DR: In this article, an analytically based computer program was used to calculate the performance benefits provided by the use of enhanced tube geometries in an R-11 flooded refrigerant evaporator.
Abstract: An analytically based computer program was used to calculate the performance benefits provided by the use of enhanced tube geometries in an R-11 flooded refrigerant evaporator. Three different boiling surface geometries are evaluated: integral fins, and two different high-performance enhanced boiling surface geometries. Four water-side surface geometries are evaluated: a plain surface, a 10-ridge ribbed tube, a 30-ridge ribbed tube, and a corrugated tube. The performance analysis is applied to a 250-ton (879-kW) R-11 chiller operating at full load condition. The reference evaporator bundle has 180 tubes 135 in. (3.43 m7rpar; long, with two water-side passes. The analysis compares the performance benefits provided by the enhanced boiling surface with a plain internal diameter (ID7rpar; and with an enhanced ID. Analysis are provided to define the shell length reduction for specified operating conditions, and to define how much the saturation temperature may be increased for a bundle of fixed size. Analysis ...
9 citations
7 citations
TL;DR: In this article, the authors compared the performance of finned tubes of two R-11 water chillers and two 2-pass condensers in a building and found that the use of enhanced finned tube improved the UA value in the condenser by an average of 60% and in the evapora...
Abstract: Today, the refrigeration industry can choose among a wide variety of enhanced tubes for evaporators and condensers of chilled water systems. To evaluate the performance of such tubes under field conditions, the standard finned tubes of one of the two 250-ton (879-kW) water chillers in a building have been replaced by specific enhanced finned tubes for comparison. The 2-pass evaporators of the two R-11 water chillers have 170 tubes, and two 2-pass condensers 178 tubes each, all of which are 12.6 ft (3.86 m) long. The standard copper finned tubes have a plain inside surface and a fin diameter of 0.75 in. (18.7 mm) with 23 fins/in. (905 fins/m). The enhanced finned tubes have a wavy inside surface, the same fin diameter, but only 19 fins/in. (740 fins/m) and a T-shaped fin cross section on the outside surface. In experiments conducted over a period of 3 years and approximately 9000 operating hours, the use of enhanced finned tubes improved the UA value in the condenser by an average of 60% and in the evapora...
6 citations