where *U* may depend on wind speed in analogy to (4.118). The collector gain is now given by ${E}_{c}^{gain}={E}_{c}^{sw}+{E}_{c}^{lw}+{E}_{c}^{sens},$ where the first term is proportional to *A*, while the two last terms are proportional to *A*_{a}. Assuming now a fluid flow ${J}_{m}^{c}$ through the absorber, the expression for determination of the amount of energy extracted becomes [cf. (4.128)]

$\begin{array}{ll}{J}_{m}^{c}{C}_{p}^{c}({T}_{c,out}-{T}_{c,in})\hfill & ={E}_{c}^{gain}(\overline{T}c)-{A}_{a}C\prime \mathrm{d}\overline{T}c/\mathrm{d}t\hfill \\ ={E}_{c}^{sw}+{E}_{c}^{lw}(\overline{T}c)+{E}_{c}^{sens}(\overline{T}c)-{A}_{a}C\prime \mathrm{d}\overline{T}c/\mathrm{d}t),\hfill \end{array}$ (4.137) ...

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