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Coupling of chemical reaction and heat transfer
Posted Jun 8, 2017, 11:31 a.m. EDT 2 Replies
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Hi to everyone,
I have to prepare a model describing a chemical reaction (dehydration of an hydrated salt).
I have to couple heat transfer interface, laminar flow interface and chemistry interface.
My doubt is the following: in the heat transfer interface, I have to insert the thermal conductivity, density and specific heat. I am using a constant value for the thermal conductivity. However, the density and specific heat will vary at each instant according to the fact that the salt is progressively dehydrated. From what I have understood, I can couple the density from chemical reaction interface to heat transfer, but how can I define the specific heat according to the degree of conversion of my reaction?
I have to prepare a model describing a chemical reaction (dehydration of an hydrated salt).
I have to couple heat transfer interface, laminar flow interface and chemistry interface.
My doubt is the following: in the heat transfer interface, I have to insert the thermal conductivity, density and specific heat. I am using a constant value for the thermal conductivity. However, the density and specific heat will vary at each instant according to the fact that the salt is progressively dehydrated. From what I have understood, I can couple the density from chemical reaction interface to heat transfer, but how can I define the specific heat according to the degree of conversion of my reaction?
2 Replies Last Post Jun 12, 2017, 3:38 a.m. EDT
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Posted:
8 years ago
Updated:
8 years ago
Valeria,
You may define it as a variable:
Cp_mix = Cp1*x1 + Cp2*x2 + Cp3*x3 + ...
where xi are the mass fractions (which vary with time) and Cpi are the heat capacities of pure substances.
Note that it is a linear approximation. For a more accurate approximation, you need to find the heat capacity of the mixture by using thermodynamic relations and mixing rules, which I wouldn't do.
Amin,
You may define it as a variable:
Cp_mix = Cp1*x1 + Cp2*x2 + Cp3*x3 + ...
where xi are the mass fractions (which vary with time) and Cpi are the heat capacities of pure substances.
Note that it is a linear approximation. For a more accurate approximation, you need to find the heat capacity of the mixture by using thermodynamic relations and mixing rules, which I wouldn't do.
Amin,
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Posted:
8 years ago
Thank you,
I will do it like that. I know it's an approximation, but for the specific case should be accurate enough.
I will do it like that. I know it's an approximation, but for the specific case should be accurate enough.