สร้างไฟล excel เป็นนามสกุล csv แล้วภาษาไทยเป็นต่างดาวครับ

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.IO;
using System.Data.OleDb;
using System.Data;
using System.Data.SqlClient;
using System.Collections;
using System.Configuration;
using System.Web.Security;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;
using System.Reflection;
using System.Text;
using System.Text.RegularExpressions;
using System.Net;
using System.Net.Sockets;
using System.Web.Configuration;

namespace testexcel
{
    public partial class createcsv : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            Response.Charset = "tis-620";
        }

        protected void Button1_Click(object sender, EventArgs e)
        {
            DataTable dt = new DataTable();
            dt.Columns.Add("ID");
            dt.Columns.Add("Name");
            dt.PrimaryKey = new DataColumn[] { dt.Columns["ID"] };

            DataRow dr = dt.NewRow();
            dr["ID"] = 1;
            dr["name"] = "ทดสอบ";
            dt.Rows.Add(dr);

            dr = dt.NewRow();
            dr["ID"] = 2;
            dr["name"] = "B";
            dt.Rows.Add(dr);

            dr = dt.NewRow();
            dr["ID"] = 3;
            dr["name"] = "C";
            dt.Rows.Add(dr);

            CreateCSVFile(dt, "c:\\dell\\csvData.csv");
        }
        public void CreateCSVFile(DataTable dt, string strFilePath)
        {
            // Create the CSV file to which grid data will be exported.
            StreamWriter sw = new StreamWriter(strFilePath, false);
            
            // First we will write the headers.
            //DataTable dt = m_dsProducts.Tables[0];
            int iColCount = dt.Columns.Count;
            for (int i = 0; i < iColCount; i++)
            {
                sw.Write(dt.Columns[i]);
                if (i < iColCount - 1)
                {
                    sw.Write(",");
                }
            }
            sw.Write(sw.NewLine);
            // Now write all the rows.
            foreach (DataRow dr in dt.Rows)
            {
                for (int i = 0; i < iColCount; i++)
                {
                    if (!Convert.IsDBNull(dr[i]))
                    {
                        sw.Write(dr[i].ToString());
                    }

                    if (i < iColCount - 1)
                    {
                        sw.Write(",");
                    }
                }
                sw.Write(sw.NewLine);
            }
            sw.Close();
        }
    }
}