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COBEM 2017
24th ABCM International Congress of Mechanical Engineering
DESIGN OF A COUNTER-CURRENT COAXIAL CONDENSER FOR A REFRIGERATING MACHINE OPERATING WITH CO2 IN A SUBCRITICAL CYCLE
Submission Author:
Hélio Augusto Goulart Diniz , MG , Brazil
Co-Authors:
Carlos Henrique Neto da silva, Hélio Augusto Goulart Diniz, STELLA MARYS SILVA PINHEIRO, Grack Rodrigues Gama, Ernane Vinicius Silva
Presenter: Hélio Augusto Goulart Diniz
doi://10.26678/ABCM.COBEM2017.COB17-2582
Abstract
The emissions of some gases used in refrigerating systems have caused a worrying environmental impact, because they cause the disintegration of the ozone layer. The CO2 - Carbon Dioxide (R744) has been researched in recent years because it can be used as a refrigerant that is not so aggressive to the environment and presents good thermodynamic properties. Using an idealized air-water refrigerating machine working in a sub-critical cycle, a counter current coaxial condenser was projected and analyzed. The mathematical modeling of the project was programmed in MATLAB® software (MATrix LABoratory). A complete approach of the condenser design project was performed by analyzing the refrigerant heat transfer convective coefficients (single phase and biphasic) and the secondary fluid coefficients (single phase). These coefficients were calculated using the correlations present in the literature. The pressure drop was also calculated. The heat exchange rate between the fluids in the condenser was 4.82 kW operating at a pressure of 45.02 bar and a condensation temperature of 10 °C. A value of 26.5 meters was obtained for the condenser total length. The idealized refrigerating machine has a COP (Coefficient of Performance) of 3.47 being designed for a research laboratory and that allow the production of cold air at 8.1 °C which can be used to aid a room air conditioning system or be applied in laboratory domestic refrigerating machine tests.
Keywords
Refrigerating machine, CO2, R744, counter-current coaxial condenser
