No, it is not a "refundable" credit.  It can only offset your income tax (Line 47 of your Form 1040).  The amount of unused credit can be carried forward for up to 5 more years (for a total of 6 tax returns).  The credit is also limited if your income is over $200,000-ish.

For example, let's say the income tax on your tax return (Line 47 of Form 1040) is $10,000, and let's say you had $12,000 of Federal Income taxes withheld from your W-2.  That would usually mean you would get a $2000 refund.

Now let's say you qualify for the full $54,280 of adoption credit for 4 Special Needs children.  Now the Adoption credit would offset the $10,000, and you would get a refund of $12,000 (all of your W-2 withholding).  The unused Adoption Credit of $44,280 would be carried to next year to be used.

Does that make sense?

Because your Adoption Credit is quite large, if you do not think you will be able to use up the entire credit during the 6 year period, you may consider some tax-planning.  For example, if you have some Traditional IRAs, it would make sense to convert them to Roth IRAs.  The Roth conversion 'creates' taxable income, but your credit would offset that.