Why is there a d in fridge but not in refrigerator?
What’s the alternative? Frige would be a long I as in, uh, I. Frigg would be a hard g. Frijj would just be weird. The added D makes the I short and the E keeps the G soft.
It’s not required in refrigerator because the E is part of the “er” sound.
That seems accurate to me, someone who knows proper English like can translate it into the correct terms!