Preliminary assessment of an ammonia-lithium nitrate absorption system.


This paper reports the design, construction and preliminary evaluation of a 5 kW absorption cooling system operating with ammonia-lithium nitrate solution. The system has been designed in the Renewable Energy Institute of the National Autonomous University of Mexico (In Spanish: Universidad Nacional Autónoma de México) and can be used for food conservation and air conditioning. The absorber and generator operate with a horizontal configuration. The condenser, evaporator and solution heat exchanger are compact heat exchangers, each designed for the power required according to the design conditions. Both absorber and generator are shell and tube heat exchangers with square arrangement. In the generator, the solution with a high concentration of refrigerant is conducted through the upper tubes of the heat exchanger, which are drilled, allowing the solution to fall in drops forming a falling film along each of the tubes. Inside the tubes circulates hot water in a range from 80°C to 90°C, allowing the separation of the solution and ammonia vapor, which exits on the top of the shell. Due to the fact that the absorbent (lithium nitrate) does not evaporate during the generation process, is not necessary to use a rectifier. The system is still being evaluated but preliminary results show that the system can operate from generation temperatures of 80°C. Although the coefficients of performance are still low, approximately 0.25, it is expected that these can be increased. This can be achieved through the following: i) isolating the system perfectly, ii) correcting some details in the absorber construction in order all the ammonia vapor could be absorbed in the absorber and iii) operating the system at the design mass flow rates which could not be reached due to the problems in the absorber.

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  • Original title: Preliminary assessment of an ammonia-lithium nitrate absorption system.
  • Record ID : 30014416
  • Languages: English
  • Source: International sorption heat pump conference (ISHPC2014), College Park, United States, March 31-April 2, 2014.
  • Publication date: 2014/03/02


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