picture resolution increase when exporting

But then i investigated on one picture that was originally geolocalised and i discovered that 

- original picture is 2.7MB with horizontal resolution 72 PPP and vertical resolution 72 PPP

- exported picture is 4.35MB  with horizontal resolution 240 PPP and vertical resolution 240 PPP

Is that normal ? Would that means that the exported picture is better than the original ? May be i did something wrong ?

By @lesireg

The efficiency of jpg compression depends on image content.

An image with predominantly smooth, flat or out of focus areas will compress well, which will result in a small file size.

An image with lots of busy, sharp detail (or noise) will be harder to compress, which will result in a large file size.

If you have sharpened the original jpg in LrC, or otherwise accentuated detail, with for instance Texture or Clarity, the exported file could well have a larger file size than the original, especially if you used a high quality setting.

PPI (Pixels Per Inch) works like this.

Pixel dimensions divided by PPI = Printed dimensions in inches.

So your 4032 x 1816 will print at approximately 56 x 25 inches (142 x 63 cm) at 72 PPI

The same 4032 x 1816 image will print at approximately 17 x 8 inches (43 x 20 cm) at 240 PPI.

For screen viewing, PPI is irrelevant, and not even required. Only the pixel dimensions matter.

in the future, to find the best place to post your message, use the list here, https://community.adobe.com/

p.s. i don't think the adobe website, and forums in particular, are easy to navigate, so don't spend a lot of time searching that forum list. do your best and we'll move the post (like this one has already been moved) if it helps you get responses.

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- original picture is 2.7MB with horizontal resolution 72 PPP and vertical resolution 72 PPP

- exported picture is 4.35MB  with horizontal resolution 240 PPP and vertical resolution 240 PPP

By @lesireg

This is a common misunderstanding. PPI has nothing to do with image size or file size. It is just an instruction for printing, it tells the printer how many pixels should be printed on one inch of paper (so it influences the print size, not the file size). The exported picture at 240 PPI is not bigger than the original at 72 PPI, unless you also upscaled the pixel dimensions on export, which can happen if you increase the PPI value, but keep the dimensions in inches -not pixels- the same.

BTW, you set the PPI in the export dialog, so you made this change yourself. If you are not sure about this, then post a screenshot of the export dialog.

- original picture is 2.7MB with horizontal resolution 72 PPP and vertical resolution 72 PPP

- exported picture is 4.35MB with horizontal resolution 240 PPP and vertical resolution 240 PPP

If you are exporting as JPG (you didn't say you were, are you?), and the Image Quality slider in the export dialog box is set to 100, then this is a reasonable result. Generally, there is no reason to export at Image Quality 100, it just produces larger files with no detectable image quality increase compated to Image Quality 70 to 80. (Please read An Analysis of Lightroom JPEG Export Quality Settings)

Would that means that the exported picture is better than the original ?

No, that is not possible. Do not confuse file size of a JPG with image quality, the two are unrelated to a large extent. One tells you nothing about the other.