Tube Diameter and Length

For a given working pressure the cost of a tube varies approximately as the square of the diameter. Return headers, being geometrically similar, vary in weight and cost approximately as the cube of the diameter. For a given total surface, smaller tubes are obviously cheaper. On the other hand, the pressure drop per unit length varies as the inverse of the diameters, 1/T . To use smaller diameter tubes and have a reasonable pressure drop, it is usually necessary to have some passes in parallel. 

If the tube length is L and the diameter D for a single pass, for n passes the length of each pass would be L = L/ ny and the diameter D = D/(n). The total weight of the tubes would be proportional to l/(n) for n passes as compared with a single pass. Thus the cost of the tubes for four passes will be half that for one pass. These relations are, of course, approximate. They are based on the inside diameter for pressure drop. The weight is approximately the inside diameter plus the tube thickness. No account is taken of the 

Average absorption rate compared with most exposed element 0.465 0.56 0.635 0.68 

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Choose the tube diameters and length. Calculate the number of tubes required. 

A new process configuration, that for deep-shaft wet-air oxidation, is available as a more satisfactory and economical engineering approach to the application of the wet-oxidation concept (see Figure 9.4-10). The deep-shaft wet-air oxidation reactor is unique to its purpose. The tube-diameter and length are designed so that sufficient reaction time and the desired pressure can be attained during fluid-waste oxidation. The pressure is developed naturally by... 

In Section 8.3.3, the safety performance of the tubular reactor was compared to the stirred tank reactor. This comparison can now be extended to a micro reactor. For this, we take a 10 m3 stirred tank vessel, a tubular reactor with 10 mm tube diameter length 1 m, and a micro reactor with 0.1 mm tube diameter and length 1 cm. We compare the following criteria that are important for the reactor safety ... 

Estimate the heat transfer area, using the maximum allowable heat flux. Take as 39,700 W/m for vertical and 47,300 W/m for horizontal reboilers. Choose the tube diameters and length. Calculate the number of tubes required. Estimate the recirculation ratio, not less than 3. 

Cathode material also shows certain effects on the morphology of anodic Ti02. Nanotubes with different tube diameters and lengths can be obtained with different cathode materials under the same anodization conditions. The appearance of surface precipitates was dependent on cathode materials. The difference in overpotential for cathode materials was suggested to be the cause for different morphologies [54], Some materials such as Fe, Co, Pd and C showed promising results to replace the conventional expensive Pt cathode. The... 

Figure 1. Schematic representation of relationships between tube diameter and length and number of bifurcations In the human lung.

Several diffusers having bell-shaped, conical, and straight entry regions with diameters varying from 0.016 to 0.05 m, and different mixing tube diameters and lengths were used. Diffuser combinations denoted as A, B, C, D, and E. Holding vessel diameter, 7 jjy=0.3m and ///7 =3.33. 

One common case is that actual pressure drop could be less than allowable pressure drop on either tube or shell side. This opportunity may be used to enhance the U value via increasing the fluid velocity. Velocity increase can be achieved by increasing flow passes on either tube side or shell side depending on which side is the controlling side on U value. Due to the fact that tube side pressure drop rises steeply with increase in tube passes, it often happens that pressure drop is much lower than the allowable value for a given number of tubes and two tube passes, but it exceeds the allowable value with four passes. In this case, the tube diameter and length could be varied to increase pressure drop with the result of a higher tube side velocity obtained. 

Extensive experimental work has been conducted to study the gas and particle flow characteristics in a 20 cm diameter, 1.2 m tall semi-cylindrical acrylic unit (Muir et al., 1990). Sand particles, having a mean diameter of 1 mm have been utilized to study the effects of spouting gas velocity, draft tube diameter and length of the entrainment region on the solids circulation rates achievable. Typical results obtained in this work are illustrated in Figure 19. 

The foam indices in Fig. 5.104 are functions of capillary-tube diameter and length, a characteristic of foams observed by other investigators, Foam-behavior indices are also known to be functions of the foam composition and quality, as well as temperature and pressure. 

Only certain combinations of musical notes are pleasing when sounded together. One of the most pleasing is the pentatonic scale, a group of five notes that can be played on a piano s black keys. It takes some fairly involved calculations to determine the pipe lengths that make the desired tones, so this project includes the required tube diameters and lengths. Deviating from these measurements may result in some odd sounds. You ll also need to choose the material of your pipes—steel or copper tubes work well. 

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