4 ms·

One use case not being discussed here is that by using these types of devices, you can power a device/sensor out in the field without a really expensive install

One use case not being discussed here is that by using these types of devices, you can power a device/sensor out in the field without a really expensive installation. You can run these off of a motor housing, compressor discharge, steam line, etc. It is about being able to provide power where it is very costly to bring. To install a sensor/instrument in a plant,refinery,etc., you have to set up scaffolding and/or use a cherry picker, run cable (usually armored) through cable trays, bend and install conduit, have all of the right junction boxes, glands, etc. You've already spent 10's of thousands just to get power out to your device. Solar is not really an option in some places. Either you've got no sunlight because you're in a pipe rack and you've got to route a cable from a PV panel (go back to installation cost) or you're in a hazardous rated area of the plant where you have explosive atmospheres and need special Ex rated equipment.

Normal_gaussian 5y ago
This of course brings in its own failure modes which can often go undetected - sensor stopped reporting because the motor broke / was replaced with a cooler model / was used less by a production change / doesn't get as hot in winter / not enough diff in summer. Not reasons to not use it, but edge cases = bugs.
- alexpotato 5y ago
  Wouldn't a heartbeat function help identify most of the above?
  - Normal_gaussian 5y ago
    Yes, I was a bit hasty with undetected. The situation is complex. I have a site which has sensors that go off for various reasons. I add heartbeats to detect this. Now I have a site with sensors that may go off for a number of reasons, and an alert panel telling me they are off all the time. As the alerts aren't actionable (ie, I expect sensor Y to go off every day in the winter around midnight and come back again when it warms up) I add a filter to ignore the alert from it around midnight. I now have to make sure I handle all the other edge cases - how long is it safe to have this sensor off? 50% of the sensors off? Every third sensor off? What if there is a really cold/hot snap lasting through the day or several days? All of these questions are edge cases, and they require complexity to solve them. Complexity means bugs. The most common bug by far is that situation X was detected by the sensor, but didn't make its way to us for edge cases.
- rickspencer3 5y ago
  That's why you always add a deadman check to your sensor monitoring.
gwbas1c 5y ago
I'd think that's already a thing. I have a Peltier-powered fan that I put on top of my wood stove. It spins extremely fast. I like it because I can tell how hot my stove is by looking at the fan, instead of walking over to the wood stove and looking at the thermometer: https://www.amazon.com/s?k=wood+stove+fan&sprefix=wood+st%2Caps%2C71&ref=nb_sb_ss_ts-doa-p_1_7 https://www.amazon.com/s?k=wood+stove+fan&sprefix=wood+st%2C... You can even find devices that you can put into a campfire to charge a phone: https://www.iphoneness.com/cool-finds/campfire-chargers-for-iphone-usb-devices/ https://www.iphoneness.com/cool-finds/campfire-chargers-for-...
- RationPhantoms 5y ago
  I wish they had Peltier-powered devices for traditional wood fireplaces. I really love the concept.
- mikewarot 5y ago
  Hot air engines used to do that 100+ years ago. You can buy them today, but their more common name, Stirling engines.

Normal_gaussian 5y ago

This of course brings in its own failure modes which can often go undetected - sensor stopped reporting because the motor broke / was replaced with a cooler model / was used less by a production change / doesn't get as hot in winter / not enough diff in summer. Not reasons to not use it, but edge cases = bugs.

alexpotato 5y ago
Wouldn't a heartbeat function help identify most of the above?
- Normal_gaussian 5y ago
  Yes, I was a bit hasty with undetected. The situation is complex. I have a site which has sensors that go off for various reasons. I add heartbeats to detect this. Now I have a site with sensors that may go off for a number of reasons, and an alert panel telling me they are off all the time. As the alerts aren't actionable (ie, I expect sensor Y to go off every day in the winter around midnight and come back again when it warms up) I add a filter to ignore the alert from it around midnight. I now have to make sure I handle all the other edge cases - how long is it safe to have this sensor off? 50% of the sensors off? Every third sensor off? What if there is a really cold/hot snap lasting through the day or several days? All of these questions are edge cases, and they require complexity to solve them. Complexity means bugs. The most common bug by far is that situation X was detected by the sensor, but didn't make its way to us for edge cases.
rickspencer3 5y ago
That's why you always add a deadman check to your sensor monitoring.

gwbas1c 5y ago

I'd think that's already a thing. I have a Peltier-powered fan that I put on top of my wood stove. It spins extremely fast. I like it because I can tell how hot my stove is by looking at the fan, instead of walking over to the wood stove and looking at the thermometer: https://www.amazon.com/s?k=wood+stove+fan&sprefix=wood+st%2Caps%2C71&ref=nb_sb_ss_ts-doa-p_1_7 https://www.amazon.com/s?k=wood+stove+fan&sprefix=wood+st%2C... You can even find devices that you can put into a campfire to charge a phone: https://www.iphoneness.com/cool-finds/campfire-chargers-for-iphone-usb-devices/ https://www.iphoneness.com/cool-finds/campfire-chargers-for-...

RationPhantoms 5y ago
I wish they had Peltier-powered devices for traditional wood fireplaces. I really love the concept.
mikewarot 5y ago
Hot air engines used to do that 100+ years ago. You can buy them today, but their more common name, Stirling engines.