Yes, DEWARS is a Scrabble word!

Letter values in Scrabble US: D 2, E 1, W 4, A 1, R 1, S 1.

Is it a valid word?

DEWARS is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

vacuum flask that holds liquid air or helium for scientific experiments
Scottish chemist and physicist noted for his work in cryogenics and his invention of the Dewar flask (1842-1923)

Also: dewar flask, sir james dewar.