c#どうやって中国語をutf-8符号化に変換するの?

string s = BitConverter.ToString(System.Text.Encoding.UTF8.GetBytes(" "));

string s = " ";
            string code = "";
            foreach (byte b in Encoding.UTF8.GetBytes(s))
            {
                code += '%' + b.ToString("X");
            }
            Console.WriteLine(code);

public static string UrlEncode(string str)
{
    if (str == null)
    {
        return null;
    }
    return UrlEncode(str, Encoding.UTF8);
}