Clamshell mode harm

As long as you allow free intake of fresh air along the sides and exit of heated air out the back you should be fine.

Fan speeds are adjusted based on measured temperatures from multiple sensors inside.

I'm starting to use a 16" 2019 MBP for audio and video which will put a lot of strain on processing: Here are some questions related to clamshell operation and cooling that I haven't been able to find answers to. Any authoritative advice appreciated.

Is the cooling efficiency reduced in clamshell mode, as there is less surface area to dissipate heat? And might this therefore result in throttling down the processors when performing intensive CPU and GPU tasks?

I was considering buying a vertical stand for my 16" 2019 MBP. There seem to be two vents at the back edge of the MBP. Would it be better to have those facing upwards if the MBP was secured in a vertical stand?

Are the vents on the back inflow or outflow, or does air circulate in from one and out of the other?

It is possible to run the MBP in "closed clamshell mode" in a vertical orientation but with the screen opened say twenty degrees to allow air to flow over the keyboard?

Is it possible to have an external monitor connected to a MBP which is sitting flat on the desk with the screen open, but with the MBP screen disable to save GPU and power?

Thanks

Your computer will not be harmed due to using it in clamshell mode. You can orient it in any way as long as the air vents are clear. You can not use the computer in open display mode if using clamshell mode. That would kind of make clamshell mode useless. There is no reason to open the screen when in clamshell mode (wouldn't that mean you are no longer in clamshell mode?)

Just as BobThe Fisherman says, as long as the exit (out the rear) and the intakes (along the sides are clear, there will be no damage. Some users prefer to place it in a Stand with the hinge-side UP, but that is not required, it is only a personal preference.

Your MacBook Pro has a Micro-Controller (the System Management Controller or SMC) running at all times, even when nominally OFF, that reads temperature sensors multiple times a second. When temperatures are seen to increase, the fan speeds are adjusted to dissipate the measured heat, in a feedback loop. No damage will result.

If that Micro-Controller does not get around to resetting the fan speeds more often than once a second, the fans fail-safe at FULL BLAST to provide maximum cooling -- and that is loud. If the temperature increases to near 100 C, the processor will do an uncontrolled power off to prevent damage.

No your computer will not be harmed.

Bob and Grant - thanks for the helpful replies.