Hi!<\/p>\n
I was hoping to get some clarification on something that I think may help me with my 2D VOF model. I have a closed system that is driven by the temperature wall boundary conditions (in the bottom of my pipe the temperature is set higher than the top of the pipe). Initially, the bottom half of the pipe (where the wall temperature is set high) has the liquid phase of my fluid and the top half of the pipe (where the wall temperature is set low) has the gas phase of my fluid. I hope to see some of the liquid phase evaporate because of the heat of the wall, and some of the gas phase condense because of the low temperature wall.<\/p>\n
I used water as the fluid to start out to make sure my model could work. From the short simulation I have completed (12sec) I can see condensation and evaporation if I set very extreme wall temperatures. I am now trying to run the same evaporation\/condensation model for a different fluid (adjusted the pressure and fluid temperatures according to the saturation temperature\/pressure curve for the fluid of interest). ANSYS has the material properties defined for the gas phase and I defined the material properties for the liquid phase according to values I found in literature. When I initialize the model I get an error stating that the latent heat cannot be less than zero (I did not get this error when I ran the model with water). <\/p>\n
My understanding is that the latent heat is the difference of the the liquid phase standard state enthalpy and the gas phase standard state enthalpy. I have tried a few variations for the standard state enthalpy I define for my liquid phase; after the value I found in literature for the standard state enthalpy gave the latent heat error, I set the enthalpy to be equal and opposite that defined by the gas phase and on another try I set the enthalpy for the liquid phase to be zero. All attempts I have made give the same latent heat error though with a different latent heat value displayed (even if I check that the difference between the standard state enthalpies of the two phases is positive). <\/p>\n
I noticed that the standard state enthalpy defined by ANSYS for water (liquid phase) is -2.858e+08J\/kgmol while the standard state enthalpy defined by ANSYS for water (vapor phase) is -2.418e+08J\/kgmol. The difference of the liquid and vapor phase enthalpies in this case is not positive, so I am wondering if I have an incorrect understanding of how ANSYS Fluent defines latent heat?<\/p>\n
I ran the model with the fluid other than water dispite the latent heat error warning. The simulation ran for a little time before quitting because of floating point error. When I look at the results there is no condensation or evaporation to be seen. I assume this has to do with the latent heat error warning which is caused by my material property definitions. I think it might be important to mention that I have checked that my mass transfer model is defined with liquid as the “from” phase and gas as the “to” phase.<\/p>\n
I know this was long-winded. I appreciate you taking the time to read and offer any help.<\/p>\n
Thank you!<\/p>\n","protected":false},"template":"","class_list":["post-288558","topic","type-topic","status-closed","hentry","topic-tag-evaporation-condensation","topic-tag-latent-heat"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_subscription":["265652","852"],"_bbp_author_ip":["23.217.200.71"]," _bbp_last_reply_id":["0"]," _bbp_likes_count":["0"],"_btv_view_count":["3080"],"_bbp_topic_status":["unanswered"],"_bbp_status":["publish"],"_bbp_topic_id":["288558"],"_bbp_forum_id":["27792"],"_bbp_engagement":["852","265652"],"_bbp_voice_count":["2"],"_bbp_reply_count":["5"],"_bbp_last_reply_id":["290790"],"_bbp_last_active_id":["290790"],"_bbp_last_active_time":["2023-06-28 17:47:40"]},"test":"laughlerclarkson-edu"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/288558","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics"}],"about":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/types\/topic"}],"version-history":[{"count":0,"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/288558\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=288558"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}