How is heat transfer calculated for an aqueous salt solution?

Question

I am familiar with using $dot{Q}=c_pcdotdot{m}cdotDelta T$ to calculate the heat transfer rate of a fluid given a singular value for specific heat capacity (such as with water), but how do I go about calculating heat transfer rate for an aequeous solution such as $MgCl_2 (aq)$? Do I somehow use the heat capacities of both water and salt together?

NMech · Accepted Answer

The formula you are quoting is for estimating the heat exchange rate of a fluid that enters a control volume with rate $dot m$ and has a change in temperature $Delta T$.
If you know

the mass rate of the solution
the precise per weight ratio of your solution
the heat capacity of the elements
the temperature difference

And provided there are not endothermal or exothermal reactions,  then its basically a pretty straight forward sum of the parts.
$$dot{Q}_{total} = dot{Q}_{water} + sum _{i=1}^n dot{Q}_{sub.1}   $$
$$dot{Q}_{total} = dot{m}_{water}c_{p,water}Delta T  + sum _{i=1}^n dot{m}_{sub.i}c_{p,sub.i}Delta T   $$
However, you will find that in most cases, because $c_p$ of water is so much greater that most other substances and the weight percentage in most solutions is much greater, you probably don't need to bother.

How is heat transfer calculated for an aqueous salt solution?

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