ASME Code Case Approval Using Vipertex® Tubes
ASME Code Case 2877 details the design of heat exchangers using Vipertex® tubes.
This code case details the conditions that austenitic stainless steel welded tubes in which the external tube surface, internal tube surface, or both internal and external tube surfaces have a modified configuration. In general the following is included:
(a) The grades applicable to this include those detailed in ASTM A1098
(b) The maximum nominal diameter is limited to 1.50 in. (38 mm), and the maximum wall thickness is limited to 0.079 in. (2 mm)
(c) For determination of minimum wall thickness on textured tubing, a point-to-point micrometer shall be used. Alternately, tubing shall be supplied with plain ends and all measurements and proof testing taken in the plain end section of the tubing.
(d) The tubing shall be used for heat transfer equipment and shall be a straight length. When the tubing is used with tubesheets, the tubing shall have a plain end with untextured surfaces for the full length inserted within the tubesheet. The untextured surface would need to be both on the I.D. and the O.D.
(e) Proof tests to establish maximum allowable working pressure. The maximum allowable working pressure of any component part proof tested by this method shall be established by a hydrostatic test to failure by rupture of a full-size sample of such pressure part.
Evaluation of Heat Exchanger Designs Using Enhanced Heat Transfer Tubes
Presented at the 2017 American Society of Thermal and Fluids Engineers (ASTFE) Conference and 4th International Workshop on Heat Transfer (IWHT)
Enhanced heat transfer tubes are widely used in many areas in order to reduce cost and create a smaller application footprint. A numeric study was performed that predicts performance of industrially relevant heat exchangers using the Vipertex® model 1EHT enhanced heat transfer tubes and compares them to the performance of heat exchangers that use smooth surface tubes. The Vipertex® model 1EHT tubes can be employed to design more efficient heat exchangers while at the same time decreasing the required mass flow rate and allowing the heat exchangers to operate at lower flows; and if needed, they also can reduce the footprint of the heat exchange device. In addition several cases also compared performance to other enhanced tubes. Some of the low fin options performed better for some cases; while for other cases the 1EHT tube performed better. Vipertex® 1EHT tubes produced the most consistent performing option for all the cases considered and demonstrate that it is a good overall tube choice for a wide range of conditions. Through the use of 1EHT enhanced heat transfer tubes, optimized design can reduce the number of tubes while maintaining design requirements. In some designs, the physical size of the heat exchanger can be reduced while maintaining design requirements. Additional case studies for a wider range of conditions will be the subject of future studies.
https://www.astfe.org/conferences/tfec2017/tfec2017_conference_technical_program.pdf