1.29.

η = \frac{T_{1} - T_{2}}{T_{1}}

${\eta = \frac {T_1 - T_2} {T_1}}$

η = \frac{T_{1} - T_{2}}{T_{1}}

$\eta = \frac {T_1 - T_2} {T_1}$

η

$\eta$

T_{1} (K)

$T_1\;\left(K\right)$

T_{1}

$T_1$

K

$K$

150

T_{2}

$T_2$

K

$K$

20