Break a long math equation and keep its aesthetic

Question

I would like to replicate the following equation

Unfortuntanely, the following MWE does not seem to work because: (i) I cannot write the brace ({}) symbols in math mode and (ii) because I do not know how to break the equation and keep its aaesthetic.

 \documentclass[]{article}
\usepackage{amsmath}
\begin{document}
\section{Equations}
\begin{equation}
PMV=0.303e^{-0.036M}+0.028\Bigg[(W-M)-3.05.10^{-3}[5733-6.99(M-W)-p_{a}]-0.42[(M-W)-58.15]
-1.7.10^{-5}M(5867-p_{a})-0.0014M(34-t_{a}) 
-3.96.10^{-8}.f_{cl}[(t_{cl}+273)^{4}-(\overline{t_{r}}+273)^4]-f_{cl}.h_{c}(t_{cl}-t_{a})
\Bigg]
\end{equation}
\end{document}

How can I replicate the above equation?

Answer 1

I squeezed the operator spacing slightly in the bracketed term

I think this does what you ask, although the layout seems a bit confusing to me, if I understand its meaning correctly it would be clearer not to use the large brackets and let the terms wrap over several lines at the outer level.

 \documentclass[]{article}
\usepackage{amsmath}
\begin{document}
\section{Equations}
\begin{multline}
\mathit{PMV}=0.303e^{-0.036M}+0.028\\
\Biggl[\medmuskip=2mu
\begin{gathered}
(W-M)-3.05.10^{-3}[5733-6.99(M-W)-p_{a}]-0.42[(M-W)-58.15]\\
-1.7.10^{-5}M(5867-p_{a})-0.0014M(34-t_{a})\\
-3.96.10^{-8}.f_{cl}[(t_{cl}+273)^{4}-(\overline{t_{r}}+273)^4]-f_{cl}.h_{c}(t_{cl}-t_{a})
\end{gathered}
\Biggr]
\end{multline}
\end{document}

Answer 2

I propose this other solution, with the Bmatrix environment `mathtools and various small improvements:

\documentclass[]{article}
 \usepackage{amsmath,mathtools, nccmath}
\usepackage{siunitx}


\begin{document}

\section{Equations}

\begin{fleqn}\sisetup{exponent-product =\,}
\begin{equation}
\begin{aligned}
 & PMV =0.303\,e^{-0.036M}+0.028 \times{}\\
 &\mathrlap{\begin{Bmatrix}(W-M)-\num{3.05 e-3}[5733-6.99(M-W)-p_{a}] \\
\mkern-5mu -0.42[(M-W)-58.15]-\num{1.7 e-5}M(5867-p_{a})-\num{1.4e-4} M(34-t_{a})\!\! \\
-\num{3.96 e-8}.f_{cl}[(t_{cl}+273)^{4}-(\overline{t_{r}}+273)⁴]-f_{cl}.h_{c}(t_{cl}-t_{a})
\end{Bmatrix}}
\end{aligned}
\end{equation}
\end{fleqn}

\end{document}