A $2.5 \mathrm{~m}$ long pipe is insulated at both ends. It has $\mathrm{ID}$ and $\mathrm{OD}$ as $50 \mathrm{~mm}$ and $56 \mathrm{~mm}$, respectively. Its log-mean heat transfer area in $\mathrm{m}^{2}$ is______________

A $2.5 \mathrm{~m}$ long pipe is insulated at both ends. It has $\mathrm{ID}$ and $\mathrm{OD}$ as $50 \mathrm{~mm}$ and $56 \mathrm{~mm}$, respectively. Its log-mean heat transfer area in $\mathrm{m}^{2}$ is______________

127