HXAIR - Tube Side Data

Use this window to enter details of the Tube side Data Window where you enter data related to the Tube side. Two types of option namely In-line and Staggered Tube Pattern are available for selecting the Tube Pattern. The Radio Buttons in the left side allows the user to select the Outside Diameter Specification or NPS Specification. Depending upon the specification, the program will consider the Tube Outside Diameter and the Inside Diameter.

Usage

LENGTH

Rating only. Specifies the exchanger tube length. The default value is 20 ft (English), or 6.1 m (metric and SI).

ID

Specifies the inside diameter of the tube. If not specified, this value will be automatically computed from the OD and THICKNESS or BWG entries. The default values are 0.584 in. (English), or 14.834 mm (metric and SI).

OD

Specifies the outside diameter of the tube. The default is 0.75 in. (English), or 19.05 mm (metric and SI).

BWG

Specifies an integer value from the Birmingham Wire Gauge, an alternate way to define tube thickness.

THICKNESS

Specifies the thickness of the tube wall.

Note: Either BWG or THICKNESS may be given if OD is entered, but not both. If both ID and OD are given, neither BWG nor THICKNESS is allowed.

NPS

Specifies the "nominal" pipe size. You cannot enter both NPS and ID on the same statement. You must enter values for NPS and SCHEDULE together. There is no default. If neither ID nor an NPS and SCHEDULE combination is entered, the default ID will be used for the pipe inside diameter.

SCHEDULE

Defines the schedule number for steel pipe. You cannot enter both SCHEDULE and ID on the same statement. An entry for SCHEDULE is required only if NPS is entered. You must enter SCHEDULE and NPS together. There is no default. If neither ID nor an NPS and SCHEDULE combination is entered on the LINE statement, the default ID will be used for the pipe inside diameter.

NUMBER

Rating only. Specifies the number of tubes per tube bundle.

TPITCH

Specifies the value of the tube pitch, i.e., the center-to-center distance between tubes in the direction normal to air flow. If not entered, this value will be set equal to 1.25 times the tube diameter for bare tubes, or 1.25 times the fin OD for finned tubes. If values for the tube or fin OD are not specified, the default values will be used. The range for LPITCH is greater than zero.

LPITCH

Specifies the longitudinal tube pitch, which is the center-to-center distance between tubes in direction parallel to air flow. If not entered, the value will be set equal to 1.25 times the tube diameter for bare tubes, or equal to 1.25 times the fin OD for finned tubes. If values for the tube or fin OD are not specified, the default values will be used.

Pattern

Select the pattern formed by the bundles. Bundles have either an in-line or staggered tube arrangement. The following end view illustrates both

Patterns:

O O O O O O

In-Line Staggered

Specifications:

For rating cases, specify a known outlet condition, the temperature approach, or the process duty. PROII calculates the required area, required fouling, the remaining outlet conditions, and the dirty U value.

You can specify one of the following:

Temperature (Tube side and Air Side Product temp)
Liquid Fraction (Tube side liquid Fraction)
Duty
Temperature Approach (HOCI, HIHO, HICO, COCI)

If you enter a duty, PROII calculates the required fouling factor, the required U value, and the required area. For a new exchanger, you must choose one of the above specifications.

Specifications can be used with old exchangers for performance monitoring, check rating, and for feasibility data with changes in operating conditions. Specify one of the exchanger's outlet temperatures or the exchanger duty. These specifications enable PROII to calculate an overall fouling factor, required (effective) heat transfer area, and the required U value.

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