how to get 48 bytes encrypted data from AES 256 in C#

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C#

I want to get 48 bytes encoded string from AES 256 but it gives me 16 bytes of encrypted data.
== // Encrypt the string to an array of bytes.
byte[] encrypted = EncryptStringToBytes_Aes(hash, myAes.Key, myAes.IV);
here is my code

public static string Encrypt(string hash)
    {

        // Create a new instance of the AesManaged
        // class.  This generates a new key and initialization
        // vector (IV).
        using (AesManaged myAes = new AesManaged())
        {

          //  myAes.Key = File.ReadAllBytes("keyfile");
            myAes.Mode = CipherMode.ECB;
            myAes.IV = new byte[16] { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
            myAes.KeySize = 256;
            myAes.BlockSize = 128;
            myAes.Padding = PaddingMode.PKCS7;

            // Encrypt the string to an array of bytes.
            byte[] encrypted = EncryptStringToBytes_Aes(hash, myAes.Key, myAes.IV);

            // Decrypt the bytes to a string.
           // string roundtrip = DecryptStringFromBytes_Aes(encrypted, myAes.Key, myAes.IV);

            //Display the original data and the decrypted data.
            Console.WriteLine("Original:   {0}", hash);
          //  Console.WriteLine("Round Trip: {0}", roundtrip);

            // Encode
            string encoded = Convert.ToBase64String(encrypted);

            Console.WriteLine("Encoded:    {0}", encoded);
            return encoded;
        }
    }

    static byte[] EncryptStringToBytes_Aes(string plainText, byte[] Key, byte[] IV)
    {
        // Check arguments.
        if (plainText == null || plainText.Length <= 0)
            throw new ArgumentNullException("plainText");
        if (Key == null || Key.Length <= 0)
            throw new ArgumentNullException("Key");
        if (IV == null || IV.Length <= 0)
            throw new ArgumentNullException("Key");
        byte[] encrypted;
        // Create an AesManaged object
        // with the specified key and IV.
        using (AesManaged aesAlg = new AesManaged())
        {
            aesAlg.Key = Key;
            aesAlg.IV = IV;

            // Create a decrytor to perform the stream transform.
            ICryptoTransform encryptor = aesAlg.CreateEncryptor(aesAlg.Key, aesAlg.IV);

            // Create the streams used for encryption.
            using (MemoryStream msEncrypt = new MemoryStream())
            {
                using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
                {
                    using (StreamWriter swEncrypt = new StreamWriter(csEncrypt))
                    {

                        //Write all data to the stream.
                        swEncrypt.Write(plainText);
                    }
                    encrypted = msEncrypt.ToArray();
                }
            }
        }
        // Return the encrypted bytes from the memory stream.
        return encrypted;
    }