procedure TForm1.Button1Click(Sender: TObject);
var
  Outfile: TextFile;
begin
  AssignFile(Outfile, 'test_chinese.txt', CP_UTF8);
  Rewrite(Outfile);

  //This is the UTF-8 BOM
  Write(Outfile, #$FEFF);

  Writeln(Outfile, '总结');
  Writeln(Outfile, '°C');
  CloseFile(Outfile);
end;