In fact, I did this for several constant values.
#Webook nist gov heat solidication water code#
I did as you and Mapes suggested and changed the enthalpy output from the thermo calculations to make it positive (the transport code may only like positive enthalpy data) by adding a constant. As far as the code is concerned, there is a solidifying substance with solidification behaviour defined by the H versus T data from the thermo calculation. But the transport code doesn't care about chemical changes. I am dealing with multiphase, multicomponent (i.e., liquid and solid) solutions.
I am expecting to hear from the transport code people tomorrow (will let you know), but I'm pretty sure that the transport code only cares about the H versus T relationship and other boundary conditions that I define. They don't describe heat flow into or out of the melting or solidifying system. The thermo results describe the properties of 1) the melting or 2) the solidifying substance at a given T. So I can't simply remove the negative signs from either one of the thermo calculations (H vs.
#Webook nist gov heat solidication water software#
In my transport calculations, the software requires that enthalpy versus T is positive. Can the negative enthalpies of formation from both separate calculations be used in the same calculation? You have identified my problem (here's where my weak thermo background comes in): putting the two separate calculation results together. There's a separate calculation for each material (solidifying or melting) and I think the thermo software always adjusts so that H is negative. I think it's because in the thermo model, the system is (1) the container walls or (2) the solidifying stuff, but not both together. Please see the examples I attached to my previous post. Can someone point me in the right direction for resolving this? I may not have explained myself very well here. But if I remove the negative, then the values decrease with increasing temperature and this can't be right. Is this OK? I mean, can I use these negative values in my other transport calculations? My understanding is that a system can be defined so that enthalpy is positive or negative. The enthalpy values from this solidification calculation are all negative. Could it be that for phase change, the equation above doesn't account for latent heat? If this is the case, then my problem is solved and I will use the enthalpy values in my new calculations. The thermo data are from multiphase solidification calculations. I can't calculate/reproduce the enthalpy data using the other parameters and would really appreciate some clues as to where I'm going wrong (because I need to know if I should use the enthalpy data or the other data in my new calculations, or if there's some other problem). I have enthalpy, heat capacity, temperature, and density, as well as other data. The compiler estimates the reproducibility of the temperature measurement to be about 2 ☌.I am not really a thermo person, but need to use thermo data in some other calculations. The only information given is that a self-constructed apparatus was used. R.approximate ratio of the amount of upper layer in that of the lower layer. t 4.The temperature at which the first crystal appeared during cooling. t 3.The temperature at which the last crystal disappeared.
t 2.The temperature at which the other liquid phase appeared. Table 2 b The meaning of the terms is as follows: t 1.The temperature at which one liquid phase was observed during heating. Table 2 a These data were calculated by the compiler. Table 1 b These values were calculated by the compiler. The compiler's opinion is that these are the results of repeated measurements. Table 1 a The meaning of t 1 and t 2 is not defined. The characterization of the miscibility gap in the above solutions. The temperature at which the last crystal disappeared in the NH 3-H 3PO 4-H 2O-system. (Please see footnotes following the table(s).) Part I. 1936, 177, 7.Ĭoncentration = Composition and temperatureĮxperimental Data: (Notes on the Nomenclature) (3) Water H2O NIST Chemistry WebBook for detail (2) Phosphoric acid H3PO4 NIST Chemistry WebBook for detail (1) Ammonia NH3 NIST Chemistry WebBook for detail
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