<?php

$re = '/(\d+)\s*([\p{Pd}xх]|na|на)\s*(\d+)/u';
$str = '100 на 60, 100 руб';
preg_match_all($re, $str, $matches, PREG_SET_ORDER);
foreach ($matches as $m) {
	echo $m[1] . ", " . $m[2] . ", " . $m[3] . "\n";
}