4 ms·

Do heat pumps still have a high enough efficiency at temperatures of over 150 degrees to justify the investment? I suppose the theoretical efficiency is still a

Do heat pumps still have a high enough efficiency at temperatures of over 150 degrees to justify the investment? I suppose the theoretical efficiency is still around 300% but I'm not sure how close heat pumps can get to the theoretical limits.

adgjlsfhk1 4y ago
they should. in general, the main time they drop significantly below theoretical efficiency is when the cold end gets iced up which wouldn't be a problem here.
sokoloff 4y ago
Page 79 has a bit of info on COP (efficiency) vs LLT (leaving liquid temp). With intelligent management of LLT, your install will spend a lot of the year at 120°F or lower, where the efficiency is fairly high. If you end up with 2-3 days of COP under 2.0, that’s not catastrophic if you spend 40-50x as much of the season at COP of 3.5+. You can probably find the outdoor temperature histogram for your area and figure out what your overall heating profile looks like. But, if you need 150°F water a lot, AWHPs are probably not a good fit.
- contravariant 4y ago
  Oh were the temperatures mentioned in Fahrenheit? Then that makes things a bit easier, I thought they needed 150°C.
  - sokoloff 4y ago
    In that article (for industrial process heating), it could be in °C. For home heating, 150°C would be far too dangerous to circulate.
  - nkurz 4y ago
    No, the temperatures are in Celsius. From the white paper linked from the main article: "This paper makes a distinction between low temperature (<200°C) and high temperature (>200°C) process heat". https://www.sintef.no/globalassets/sintef-energi/industrial-heat-pump-whitepaper/2020-07-10-whitepaper-ihp-a4.pdf https://www.sintef.no/globalassets/sintef-energi/industrial-...
  - hanche 4y ago
    Your original guess is right. I checked the original Norwegian text. It says 150 grader (degrees), and that surely means Celsius when used unqualified in Norwegian. So we’re talking high pressure superheated water here, for industrial purposes.
    - MobiusHorizons 4y ago
      Another clue is that they call 150 deg 5 bar steam.
- ZeroGravitas 4y ago
  Note that the article talks about a different design of heat pump, compared with the common home and industrial HVAC units, for use in industry at that higher temp. Especially valuable when you have some waste heat from another process. Probably a good fit for existing district heating systems too.
- csours 4y ago
  I completely missed the link to the whitepaper and thought it was just a really bad article. Does the pdf talk about which working fluids are used? Are there any details at all about implementation?
icegreentea2 4y ago
One of the demo projects listed in the linked white paper is aiming for >50% of theoretical efficiency in that temperature range > LowCapex and FUSE (TNO): Demonstration of heat pump technology on an industrial scale (2 MW), producing process steam at temperatures between 120°C to 150°C from waste heat at 60°C to 90°C with efficiencies above 50 % of the theoretical maximum. Elsewhere in the white paper: > Comparing these alternatives, it has been shown that high temperature heat pumps, with COPs as low as 2, are competitive in levelized cost of heat with biomass boilers and natural-gas based boilers under consideration of a CO2 tax of 50 €/tonne. So... definitely not slam dunk.

adgjlsfhk1 4y ago

they should. in general, the main time they drop significantly below theoretical efficiency is when the cold end gets iced up which wouldn't be a problem here.

sokoloff 4y ago

Page 79 has a bit of info on COP (efficiency) vs LLT (leaving liquid temp). With intelligent management of LLT, your install will spend a lot of the year at 120°F or lower, where the efficiency is fairly high. If you end up with 2-3 days of COP under 2.0, that’s not catastrophic if you spend 40-50x as much of the season at COP of 3.5+. You can probably find the outdoor temperature histogram for your area and figure out what your overall heating profile looks like. But, if you need 150°F water a lot, AWHPs are probably not a good fit.

contravariant 4y ago
Oh were the temperatures mentioned in Fahrenheit? Then that makes things a bit easier, I thought they needed 150°C.
- sokoloff 4y ago
  In that article (for industrial process heating), it could be in °C. For home heating, 150°C would be far too dangerous to circulate.
- nkurz 4y ago
  No, the temperatures are in Celsius. From the white paper linked from the main article: "This paper makes a distinction between low temperature (<200°C) and high temperature (>200°C) process heat". https://www.sintef.no/globalassets/sintef-energi/industrial-heat-pump-whitepaper/2020-07-10-whitepaper-ihp-a4.pdf https://www.sintef.no/globalassets/sintef-energi/industrial-...
- hanche 4y ago
  Your original guess is right. I checked the original Norwegian text. It says 150 grader (degrees), and that surely means Celsius when used unqualified in Norwegian. So we’re talking high pressure superheated water here, for industrial purposes.
  - MobiusHorizons 4y ago
    Another clue is that they call 150 deg 5 bar steam.
ZeroGravitas 4y ago
Note that the article talks about a different design of heat pump, compared with the common home and industrial HVAC units, for use in industry at that higher temp. Especially valuable when you have some waste heat from another process. Probably a good fit for existing district heating systems too.
csours 4y ago
I completely missed the link to the whitepaper and thought it was just a really bad article. Does the pdf talk about which working fluids are used? Are there any details at all about implementation?

icegreentea2 4y ago

One of the demo projects listed in the linked white paper is aiming for >50% of theoretical efficiency in that temperature range > LowCapex and FUSE (TNO): Demonstration of heat pump technology on an industrial scale (2 MW), producing process steam at temperatures between 120°C to 150°C from waste heat at 60°C to 90°C with efficiencies above 50 % of the theoretical maximum. Elsewhere in the white paper: > Comparing these alternatives, it has been shown that high temperature heat pumps, with COPs as low as 2, are competitive in levelized cost of heat with biomass boilers and natural-gas based boilers under consideration of a CO2 tax of 50 €/tonne. So... definitely not slam dunk.