下载时的数字格式为CSV格式

下面的代码返回给定秒的小时数，这是正常的。

<?php
$hrs = seconds_to_dezi(278280);
echo $hrs;
$filename = "test";
header("Content-type: application/vnd-ms-excel");
header("Content-Disposition: attachment; filename=$filename.xls");
function seconds_to_dezi($s) {
    $n = false;
    if ($s < 0) {
        $n = true;
        $s = -$s;
    }
    $h = round($s / 3600,2);
    $h = number_format($h,2, ',', ' ');
    $h = str_replace(".",",",$h);

    if ($n == true) {
        return ("-" . $h);
    } else {
        return ($h);
    }
}
?>

excel实际输出:- 77,3

预期输出:- 77,30

。在下载CSV格式的值时，十进制后的末尾零将被截断。我想在excel中显示0