One of a kind ammonia heat pump projects show technology's energy saving benefits

By Janaina Topley Lira, Oct 08, 2013, 13:25 3 minute reading

Ammonia heat pump technology can be used to capture waste heat and to put it to beneficial use. Across the world, end-users are increasingly turning to this technology to eliminate or greatly reduce the need for inefficient boiler systems, thereby saving energy and reducing GHG emissions. looks at three different ammonia heat pumps projects to examine the benefits such installations.

Norway: COP of 12,9 for hybrid ammonia absorption heat pump used to recover heat from wastewater
Combining absorption and compression, a hybrid heat pump is capable of heat energy transfer from low to high temperature levels. The system allows the use of alternative energy sources like waste-heat, biomass, or even solar energy. What is more, thanks to a higher condensation temperature as compared to conventional compression machines, due to a saturation pressure that is much lower, a large temperature lift, and high COP is possible.
In 2013 such a heat pump, using the natural refrigerants ammonia and water, was installed at a waste water treatment plant in Dynea, Norway. The system, which has the following characteristics, has a payback time of two years, and achieves a COP of 12,9: 
  • Operates at a low pressure (below 25bar)
  • Heat pump: 416 kW
  • Yearly operating time: 4000 hours
  • Cooling WWTP outlet from 18°C to 11°C @ 50m3/hr
  • Heating WWTP inlet from 12°C to 20°C @ 50m3/hr
The ammonia/water hybrid heat pump consists of the following components:
  • Desorber: extracts waste heat from the environment
  • Separator: separates water and ammonia
  • Pump: the pump increases the water pressure
  • Compressor: compressed ammonia to a high pressure
  • Absorber: release useful heat towards the environment
  • Expansion element: lowers the pressure of the mixture

France: 70% energy savings for French Fries dryers thanks to ammonia heat pump

An ammonia heat pump installed at the plant of a French fries producer, provides most of the energy needed for the drying of French fries before they are baked, generating energy savings on the dryers' energy consumption of 70%. 
The innovative deisgn by De Kleijn Energy Consulting connects an ammonia heat pump is to a belt dryer that operates at a maximum temperature of 70°C. The heat pump, designed to condensate 1.500 kg of water per hour, has within it two reciprocating compressors, a Grasso 45 HP and a Grasso 65 HP. 
The compressor's COP in depends on the drying conditions and varies between 5 to 8. The payback time for this installation has been calculated at around 4 years, whilst a potential annual energy saving of 800.000 Nm3 of natural gas is possible. 

South Africa: ammonia heat pump installation saves 300 kW
At Rainbow Chicken's P1 Plant in Hammarsdale, KwaZulu Nata, South Africa, an ammonia heat pump harnesses the waste heat generated by ammonia compressors to produce hot water in the processing plant. The project has achieved a saving of 90%, or an average saving of 300 kW, which exceeds the savings target of 85% promised by the system supplier Magnet. The payback period has been calculated at just less than two years.
New in South Africa, the heat pump replaces an electrode boiler used to generate steam, which was then used to heat the water used for washing. The ammonia heat pump, which was installed in an existing refrigeration plant, is used to further compress hot ammonia gas, already compressed by the high stage compressors. This is then condensed in the plate heat exchanger, at which point the heat is transferred to the water on the other side of the plate heat exchanger.


By Janaina Topley Lira

Oct 08, 2013, 13:25

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