▁non - fl amm able ▁and ▁non - expl os ive ▁materials ▁ ▁Econom ic ▁properties ▁ ▁Low ▁cost ▁ ▁Av ail ability ▁ ▁Th erm oph ys ical ▁properties ▁ ▁Common ▁PC M s ▁ ▁Vol um et ric ▁heat ▁capacity ▁( V HC ) ▁J · m − 3 · K − 1 ▁ ▁Th erm al ▁in ert ia ▁( I ) ▁= ▁Th erm al ▁eff us ivity ▁( e ) ▁J · m − 2 · K − 1 · s − 1 / 2 ▁ ▁Com mer cially ▁available ▁PC M s ▁ ▁The ▁above ▁dataset ▁is ▁also ▁available ▁as ▁an ▁Excel ▁spread sheet ▁from ▁U CLA ▁Engineering ▁ ▁Technology , ▁development ▁and ▁enc aps ulation ▁ ▁The ▁most ▁commonly ▁used ▁PC M s ▁are ▁salt ▁hyd r ates , ▁fat ty ▁ac ids ▁and ▁est ers , ▁and ▁various ▁para ff ins ▁( such ▁as ▁oct ade c ane ). ▁Rec ently ▁also ▁ion ic ▁liqu ids ▁were ▁investig ated ▁as ▁novel ▁PC M s . ▁ ▁As ▁most ▁of ▁the ▁organ ic ▁solutions ▁are ▁water - free , ▁they ▁can ▁be ▁exposed ▁to ▁air , ▁but ▁all ▁salt ▁based ▁PC M ▁solutions ▁must ▁be ▁enc aps ulated ▁to ▁prevent ▁water ▁ev ap oration ▁or ▁u pt ake . ▁Both ▁types ▁offer ▁certain ▁advantages ▁and ▁dis adv antages ▁and ▁if ▁they ▁are ▁correctly ▁applied ▁some ▁of ▁the ▁dis adv antages ▁becomes ▁an ▁advantage ▁for ▁certain ▁applications . ▁ ▁They ▁have ▁been ▁used ▁since ▁the ▁late ▁