Yes, you can apply the elemental assault energy damage to your ranged attacks from a bow.
In general your projectile weapons confer their bonuses to their projectiles. They do not stack.
Ranged Weapons and Ammunition: The enhancement bonus from a ranged
weapon does not stack with the enhancement bonus from ammunition. Only
the higher of the two enhancement bonuses applies. Ammunition fired
from a projectile weapon with an enhancement bonus of +1 or higher is
treated as a magic weapon for the purpose of overcoming damage
reduction. Similarly, ammunition fired from a projectile weapon with
an alignment gains the alignment of that projectile weapon.
Exceptions may exist, such as the bless weapon spell from the Paladin spell list.
However, the general rule doesn't even really matter because the Suli racial trait Elemental Assault is a specific rule that overrides the general rule. Let's look at that:
Elemental Assault (Su): Once per day as a swift action, a suli can
shroud her arms in acid, cold, electricity, or fire. This lasts for
one round per level, and can be dismissed as a free action. Unarmed
strikes with her arms or hands (or attacks with weapons held in those
hands) deal +1d6 points of damage of the appropriate energy type.
From a strict rules as written standpoint, the bow is held in your hands, which satisfies one of the conditions for the damage to take effect. It does not specify a weapon type. Thus, attacks with that weapon held in your hands deal +1d6 damage of the energy type when you activate this racial trait.
If your GM argues against this, gently remind him that the projectile fired from the weapon is not the weapon, and that damage is applied from the weapon, not the projectile -- i.e., it's the bow's damage dice that you roll, and that's the roll to which you are adding the elemental damage die.