original writing:
Christian KÜHL

in case of no German Umlaute you can also write:
Christian KUEHL

the pronounciation translated into japanese is (family name first):
kyuuru kurisutian (katakana)

my japanese friend found some suitable kanjis for my name:
kyuuru kurisuchian (kanji)

the meaning of these kanjis are the following:
kyuu ru  ku ri su chi an (kanji)