Timeline for First law of thermodynamics, steady flow energy equation (SFEE) and $Vdp$ work
Current License: CC BY-SA 3.0
7 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Jun 15, 2017 at 15:03 | comment | added | user158324 | I know it is a control volume but understand that the relation is defined for a closed system ie control mass and is being used for a open system ie control volume... How can we just use it like that ?? | |
| Jun 15, 2017 at 14:50 | comment | added | Rishabh Jain | this is not control mass but control volume and dh=Tds+Vdp in the first as well as second image.Plus, this derivation showed you how can generaize the first law for steady flows | |
| Jun 15, 2017 at 12:32 | comment | added | user158324 | In the derivation I don't have any issues until work or heat is written in terms of enthalpy... But when dh is replaced by TDs+Vdp then I don't understand because Tds = dh + Vdp is defined for a closed NON FLOW process(see image 1) | |
| Jun 15, 2017 at 12:29 | comment | added | user158324 | By identity I meant that suppose fluid particle A is present at a particular point in space and after some time it is replaced by B...this is control volume...but in control mass A remains A...and here because A and B have same properties and it is a steady process therefore....we are treating control volume as control mass...this is what I understand... | |
| Jun 15, 2017 at 12:23 | comment | added | Rishabh Jain | The fluid particles with same properties are coming in at a particular point at all times .This is what is meant by steady state.What do you mean by identity? I mentioned a general derivation for flow processes. For only the steady state derivation,go to ecourses.ou.edu/cgi-bin/… | |
| Jun 15, 2017 at 12:17 | comment | added | user158324 | So are you saying that despite the "identity" of the fluid particle changing (because fluid comes in and goes out) we treat it as a closed system because although the identity changes but all the properties are same....i.e they don't change over time for a particular position. | |
| Jun 15, 2017 at 11:47 | history | answered | Rishabh Jain | CC BY-SA 3.0 |