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New finned heat exchanger development with low refrigerant charge.

Sviluppo dei nuovi scambiatori di calore alettati con basse carica di refrigerante.

Author(s) : FILIPPINI S., MERLO U.

Summary

Many types of air-cooled heat exchangers are used in the HVACR sector. The paper presents the results of development in new compact finned tube geometry 20 x 17.32 mm. The technology employs 5.0 mm diameter copper tubes and advanced louvered fins for condenser applications. First, the fin geometry development process and the definition of the new grooved tube generation is illustrated; the basis of development is CFD analysis of heat exchanger performance which is able to find the optimum compromise from several geometric parameters in order to maximize the heat transfer coefficient and minimize air pressure drop. Theoretical outcomes are then compared by an extensive testing campaign of sample coils in the wind tunnel and in the calorimetric room in condenser mode. The test results have been used as the basis of sophisticated software for performance calculations. Software prediction deviations from the accurate test results are also finally mentioned. The main advantages of the new technology are lower refrigerant charge due to the current finned tube technologies combined with high performance as a whole. These characteristics allow product with low life cycle costs to be designed, and help to reduce plant refrigerant charge required by the current strict European standardization. The article later compares the new geometry with traditional finned tube technology heat exchanger with geometry 25 x 21.65 m and 9.52 mm diameter copper tubes and microchannel tube heat exchanger with extruded aluminium tubes and corrugated fins. Thermal performance characteristics, fin efficiency, pressure loss characteristics, refrigerant charge, reliability (product installation, resistance in the field, dirt accumulation) and manufacturing flexibility are the technical arguments for the selection of the suitable technology. Hence the article collates characteristics of condensers with heat output of 20 kW. Calculation frontier properties are 25°C air temperature and condensing temperature 40°C. The chosen heat output is selected for comparability with real applications such as local air conditioning systems or small refrigeration units.

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Pages: 7 p.

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Details

  • Original title: Sviluppo dei nuovi scambiatori di calore alettati con basse carica di refrigerante.
  • Record ID : 30005678
  • Languages: Italian
  • Source: Green new deal - green economy. The latest technology in refrigeration and air conditioning: energy issues and climate change, new refrigerants, new European regulations, new plants. XIV European Conference: June 10-11, 2011, Milan.
  • Publication date: 2011/06/10

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