1、Copyrighted material licensed to Stanford University by Thomson Scientific(),downloaded on Oct-05-2010 by Stanford University User.No further reproduction or distribution is permitted.Uncontrolled when printed.AIR COOLED HEAT EXCHANGERS ASME PTC 30-1991 Symbol Definjtion Dimensions U.S.Customary Uni
2、ts S I Units LMTD N N Nh N m M U Nu P P P Pr Q r R R R R.Re RPM S S SCFM St t T T,U V W Log mean temperature difference Number of tubes Number of measurements Number of fins per unit length Fan speed Number of transfer units Nusselt number,hD/k Air pressure Thermal effectiveness,(t,-tJ/F,-tJ Process
3、 stream pressure Prandtl number,c,rJk Heat transfer rate Radius Temperature difference ratio equal to(T,-T&-t,)Thermal resistance Hydraulic radius Gas constant of air Reynolds number,GD/p Rotational speed Net clear distance between fins Cross sectional flow area F Dimensionless Dimensionless ft-RPM
4、Dimensionless Dimensionless I bf/fta Dimensionless Ibf/ft Dimensionless Btuhr ft Dimensionless hrft.F/Btu ft 53.32 ft*lbf/lbmR Dimensionless Revolutions per minute ft ft2 C Dimensionless Dimensionless m-rPs Dimensionless Dimensionless Pa Dimensionless Pa Dimensionless W rn Dimensionless m Z W W m 28
5、6.9 JkgK Dimensionless m m2 Standard cubic feet per minute measured at ft3/min 70F and 14.696 psia,dry air Stanton number,hlc,C=-Nu RePr Dimensionless Dimensionless Air temperature F C Process fluid temperature O F C Torque I b f-ft N.m Overall heat transfer coefficient Btu/hrft*F W/ma.C Speed Wmin
6、m/S Air flow rate Ibm/hr k d s 9 Copyrighted material licensed to Stanford University by Thomson Scientific(),downloaded on Oct-05-2010 by Stanford University User.No further reproduction or distribution is permitted.Uncontrolled when printed.Air Cooled Heat Exchangers ASME PTC 30-1991 PERFORMANCE T
7、EST AN AMERICAN NATIONAL STANDARD T H E A M E R I C A N S O C I E T Y ,OF M E C H A N I C A L E N G I N E E R S United Engineering Center 345 East 47th Street New York,N.Y.1001 7 Copyrighted material licensed to Stanford University by Thomson Scientific(),downloaded on Oct-05-2010 by Stanford Univer
8、sity User.No further reproduction or distribution is permitted.Uncontrolled when printed.Date of Issuance:May 30,1991 The 1991 edition of this document is being issued with an automatic addenda subscription service.The use of an addenda allows revisions made in re-sponse to public review comments or
9、 committee actions to be published as necessary;revisions published in addenda will become effective 1 year after the Date of Issuance of the document.This document will be revised when the Society approves the issuance of the next edition,scheduled for 1996.ASME issues written replies to inquiries
10、concerning interpretation of technical aspects of this document.The interpretations will be included with the above addenda service.Interpretations are not part of the addenda to the document.ASME is the registered trademark of The American Society of Mechanical Engineers This code or standard was d
11、eveloped under prccedures accredited as meeting the criteria for American National Standards.The Consensus Committee that approved the code or standard was balanced to assure that individuals from competent and concerned interests have had an opportunity to participate.The proposed code or standard
12、was made available for public review and comment which provides an opportunity for additional public input from industry,academia,regulatory agencies,and the public-at-large.ASME does not approve,rate,or endorse any item,construction,proprietary device,or activity.ASME does not take any position wit
13、h respect to the validity of any patent rights asserted in connection with any items mentioned in this document,and does not undertake to insure anyone utilizing a standard against liability for infringement of any applicable Letters Patent,nor assume any such liability.Users of a code or standard a
14、re expressly advised that determination of the validity of any such patent rights,and the risk of infringement of such rights,is entirely their own responsibility.Participation by federal agency representative(s)or person(s)affiliated with industry is not to be interpreted as government or industrye
15、ndorsement of this code or standard.ASME acepts responsibility for only those interpretations issued in accordance with governing ASME procedures and policies which preclude the issuance of interpretations by individual vol-unteers.No part of this document may be reproduced in any form,in an electro
16、nic retrieval system or otherwise,without the prior written permission of the publisher.Copyright 0 1991 by THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS All Rights Reserved Printed in U.S.A.,Copyrighted material licensed to Stanford University by Thomson Scientific(),downloaded on Oct-05-2010 by Stanford University User.No further reproduction or distribution is permitted.Uncontrolled when printed.FOREWORD(This Foreword is not part of ASME PTC 30-1991.)In May 1960 the Board on Performance Test C