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Compression resorption heat pumps (CRHP) are a promising option to upgrade waste heat from industry. Alternative working fluids can further improve the efficiency of CRHP. The ternary mixture NH3-CO2-H2O has been identified as a promising working fluid for CRHP and has the potential to further enhance the coefficient of performance (COP) of the cycle compared to the traditionally used ammonia water mixture. So far the studies on the NH3-CO2-H2O mixture have focused mainly on carbon capture applications. But the desired operating conditions are different than for CRHP applications, e.g. the NH3 concentration. Additionally the absorption process with the mixture in tubular absorbers has not yet been reported. The focus of this study is therefore to investigate experimentally the absorption process of a CRHP with this ternary mixture. To reach this goal a model is developed for ammonia-water that takes into account the kinetics and mass transfer during the absorption process. To validate the model, experiments were performed for an absorption process in a mini channel heat exchanger with NH3 concentration of 35 wt%. The results show a good match between the model and the experiments. Additionally CO2 has been added to the solution and the experimental performance was compared with the experimental performance of the NH3-H2O mixture. A concentration of 2 wt% CO2 resulted in a performance increase of up to 5% however the working fluid flow became limited by pumping instabilities.
Original languageEnglish
Title of host publicationProceedings 12th IEA Heat Pump Conference
PublisherStichting HPC 2017
Number of pages12
ISBN (Print)978-90-9030412-0
Publication statusPublished - 2017
Event12th IEA Heat Pump Conference - Rotterdam, Netherlands
Duration: 15 May 201718 May 2017
Conference number: 12
http://hpc2017.org/

Conference

Conference12th IEA Heat Pump Conference
CountryNetherlands
CityRotterdam
Period15/05/1718/05/17
Internet address

    Research areas

  • heat pumps, NH3-CO2-H2O mixture, NH3-H2O mixture, waste heat recovery, absorption, mini-channel heat exchangers

ID: 33896693