Hi!

With a power dissipation of 0.35 Watt your LM317/TO220 doesn't need a heat sink.

Code:
How to calculate:

PD MAX = TjMAX − TaMAX
         _____________
             Rja

PD MAX = Maximum Power Dissipation (Watt)

TjMAX= maximum junction temperature (°C) 
For the LM317/TO220 is 125 °C.

TaMAX= maximum ambient air temperature (°C) 
Room temperature or temperature inside enclosure, example 30°C.

Rja= thermal resistance from junction to ambient without heat sink (°C/W) 
For the LM317/TO220 is 50 °C/W.

125 − 30
__________   = 1.9 Watt 
   50
1.9 watt is the maximum power dissipation of the LM317/TO220 without a heat sink.
(If you use the LM317 at TjMAX its life will be reduced).

In your case the input voltage of the LM317 is 16V and the output voltage is 13.5V.
The voltage difference is 2.5V. (16V - 13.5V).

The current is 140 mA. (0.14A)

The power dissipation of your LM317 is:
2.5V * 0.14 = 0.35 Watt

With a power dissipation of 0.35 Watt your LM317/TO220 doesn't need a heat sink.

Best regards,

Luciano