Notices
Results 1 to 6 of 6

Thread: Widening Thermodynamics

  1. #1 Widening Thermodynamics 
    Forum Freshman
    Join Date
    Jul 2014
    Posts
    37
    Thermodynamics was originally created to understand the interaction between heat and work in steam engines. The internal energy U of the steam, presumed to exist in a tube with mobile plug, is said to be given by:
    dU = where Q is heat, W work and stands for so called 'inexact differential', which means that only the sum of heat and work counts. Individually they can have any value and their value is path dependant, if one or the other comes first. This is true even if the work is applied reversibly.
    When no work is applied dQ = T dS where T is temperature and S entropy. When the steam is being heated with no work transfer, the last entropy added required TdS heat. Earlier entropies required less heat because the temperature was then lower. In heat transfer, temperature is the intensive variable and entropy the extensive variable. We can plot temperature versus entropy. At zero temperature the entropy is zero. Temperature is the slope of the curve.
    When work is applied adiabatically dW = FdX, where F is force and X the column length. X is the extensive and F the intensive variable. At X = infinite the steam can no longer transfer work and the compressive energy of the steam is zero. We can plot energy versus column length.
    The two plots allow us to generate a 3D plot, energy versus entropy and column length, with energy as a surface and temperature and force as directional slopes. At zero entropy and infinite column length the surface is at zero. The surface is continuous.
    According to Maxwell, the slopes of the surface are related as:
    which can be given as integral as:
    F =
    or: F dX =
    This means for steam compression: Work input means the increase of the heat requirements of all the entropy differentials of the steam but no entropy increase.
    Heat input increases the entropy at the last heat requirement but does not alter the heat requirements of pre-existing entropies.
    The last two equations can not be evaluated over its whole width since dT can only be measured while the steam is stable and we do not know the absolute value of entropy.
    The question is if other forces, force against external force fields or altering the centre-of-mass velocity, have the same influence on the internal conditions of the system.


    Last edited by Rudiger von Massow; August 17th, 2014 at 11:34 AM.
    Reply With Quote  
     

  2.  
     

  3. #2  
    Forum Sophomore
    Join Date
    Aug 2013
    Posts
    193
    Congratulations, you arrived in 18th century. Sadly your version of "Maxwell relation" doesnt make any sense and has different units on other sides. Your integrals doesnt make any sense either.


    Reply With Quote  
     

  4. #3  
    Bullshit Intolerant PhDemon's Avatar
    Join Date
    Feb 2013
    Location
    Newcastle-upon-Tyne, UK
    Posts
    5,533
    Read his other threads, the guy's an irredeemable nut. Trash please.
    Reply With Quote  
     

  5. #4  
    Forum Freshman
    Join Date
    Jul 2014
    Posts
    37
    If the surface is continuous, it is a standard mathematical formula that two directional slopes , in this case T and F, are related with the extensive variables as
    . The formula is one of several formula developed by Maxwell, a friend of Newton's, (18th century).
    Last edited by Rudiger von Massow; August 8th, 2014 at 06:49 AM.
    Reply With Quote  
     

  6. #5  
    Forum Freshman
    Join Date
    Jul 2014
    Posts
    37
    Quote Originally Posted by Gere View Post
    Congratulations, you arrived in 18th century. Sadly your version of "Maxwell relation" doesnt make any sense and has different units on other sides. Your integrals doesnt make any sense either.
    Let us dimensionally analyse the tree equations: Dimensions of F =
    of entropy S =
    of temperature T =
    1.


    2. F =


    3. F dX=


    Obviously the three equations have passed the dimensional analysis.
    Last edited by Rudiger von Massow; August 10th, 2014 at 04:41 PM. Reason: Another obvious statement.
    Reply With Quote  
     

  7. #6  
    Forum Freshman
    Join Date
    Jul 2014
    Posts
    37
    I am rather disappointment by the unfairness of reviews. If you do not understand an equation, why not ask for an explanation. I was looking forward to a further development of the ideas. If you do not know Maxwell relationships that is understandable. I could have used another method to develop the equation. It is quite clear that, according to equation 2, the force pressing on the plug of the tube containing the steam is related to temperature increases of each entropy differential of the steam when the volume or column length is is altered. That can be checked in any steam table. I have not been able to find out how I can put a drawing into a reply. That might have made it clearer.
    Reply With Quote  
     

Similar Threads

  1. Thermodynamics
    By Iqra Javed in forum General Discussion
    Replies: 4
    Last Post: August 7th, 2014, 06:08 PM
  2. the thermodynamics
    By khaled mohamed hussein in forum General Discussion
    Replies: 0
    Last Post: April 19th, 2013, 02:00 AM
  3. Widening of Cheekbones
    By Abacus in forum Health & Medicine
    Replies: 18
    Last Post: February 3rd, 2012, 02:30 PM
  4. ThermodynamicS
    By vevo90 in forum Chemistry
    Replies: 0
    Last Post: October 10th, 2010, 12:46 AM
  5. Thermodynamics
    By aid in forum Physics
    Replies: 2
    Last Post: November 17th, 2007, 12:59 PM
Tags for this Thread

View Tag Cloud

Bookmarks
Bookmarks
Posting Permissions
  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •