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Study on the Characteristics of an Auto-cascade Refrigeration System Using R744/R290 or R744/R600a Natural Binary Mixture
Author: PengBo
Tutor: XuShiMing
School: Dalian University of Technology
Course: Refrigeration and Cryogenic Engineering
Keywords: R744/R290 R744/R600a Self - cascade refrigeration Calculation of thermodynamic properties
CLC: TB65
Type: Master's thesis
Year: 2008
Downloads: 276
Quote: 0
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Abstract
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As people become increasingly concerned about the destruction of the ozone layer and global warming , the lower the ODP ( Ozone Depletion Potential ozone depletion potential ) and GWP ( Global Warming Potential global warming potential) refrigerants used in the refrigeration industry has become an irreversible trend. Natural refrigerants widespread attention for its no environmental impact . R744, R290, R600a are performance excellent natural refrigerants , they are mixed and applied to the self-healing cascade refrigeration systems , you can avoid weaknesses , to achieve the desired effect , become the object of attention of alternative refrigerants . Based on thermodynamic definition , conducted on the R744/R290, R744/R600a two mixed natural working fluid thermodynamic properties calculations, compare the accuracy of various calculation methods , determine appropriate theoretical formulas , and applied to both refrigerant mixtures self- cascade refrigeration system proposed refrigerant mixtures , the mole fraction of the method chosen , calculated from cascade refrigeration system cycle characteristics and its influencing factors . The results show that : R744/R600a than R744/R290 easier segregation , and applies to the lower pressure or higher temperature ; higher than the overall level of segregation R744 mole fraction in the gas below the general level of the liquid ; bubble point the dew point temperature is increased with increasing pressure ; two mixed working fluid is applied from the cascade system , the choice of refrigerant mixtures mole fraction To consider the refrigeration temperature , condenser pressure , evaporation condenser pressure and other factors ; there exists an optimum value of the degree of dryness of the refrigerant after dephlegmator , the low temperature the stream fully condensed in the evaporative condenser , while allowing the high temperature flows sufficiently evaporated in the evaporative condenser , and reaches the optimum value when the system performance ; appropriate increase regenerator the heat transfer coefficient helps to reduce evaporative condenser heat exchanger load , help improve compressor inlet refrigerant superheat , helps to improve system performance . In this paper, the numerical simulation method calculates the above conclusion , since cascade refrigeration system using of R744/R290 and R744/R600a the in-depth study and practical application provides a theoretical basis , and other refrigerant mixtures and the use of refrigerant mixtures since the cascade system of reference .
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CLC: > Industrial Technology > General industrial technology > Refrigeration Engineering > Refrigeration machinery and equipment
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