For treatment of common discontinuous tractions in 3 D elastic boundary element method,a simple and practical approach is proposed in this paper.The problem of the 1/r integral singularity and its treatment are discus...For treatment of common discontinuous tractions in 3 D elastic boundary element method,a simple and practical approach is proposed in this paper.The problem of the 1/r integral singularity and its treatment are discussed and analyzed as well.The numerical results show that the appprach in this paper is satisfactory.展开更多
Aiming at solving the problem of high global warming potential of R134 a,a new mixed refrigerant R13 I1/R152 a(molar fraction ratio of 35:65)with no ozone depletion potential and low global warming potential was propo...Aiming at solving the problem of high global warming potential of R134 a,a new mixed refrigerant R13 I1/R152 a(molar fraction ratio of 35:65)with no ozone depletion potential and low global warming potential was proposed as a substitute for R134 a in automotive air conditioning.The computational models for the thermodynamic properties of R13 I1/R152 a were established by using the PR(Peng-Robinson)equation of state combined with the vdW mixing rule.Based on these models,the cycle performance of this working fluid was calculated,which was also compared with that of R134 a and R1234 yf under the different operating conditions.The results show that R13 I1/R152 a is a near azeotropic refrigerant whose temperature glide is approximately 0,and the saturated vapor pressure curve of which is equivalent to that of R134 a.Moreover,compared to R134 a,R13 I1/R152 a has an average 5.7%improvement in coefficient of performance as well as similar volumetric cooling capacity.The average coefficient of performance and volumetric cooling capacity of R13 I1/R152 a are significantly higher than those of R1234 yf by 13.8%and12.0%,respectively.However,the average discharge temperature of R13 I1/R152 a is approximately13.3 K higher than that of R134 a,but it is also within reasonable limits.Hence,the application of the proposed refrigerant R13 I1/R152 a in automotive air conditioning system is technically feasible.展开更多
文摘For treatment of common discontinuous tractions in 3 D elastic boundary element method,a simple and practical approach is proposed in this paper.The problem of the 1/r integral singularity and its treatment are discussed and analyzed as well.The numerical results show that the appprach in this paper is satisfactory.
基金supported by the National Natural Science Foundation of China(22068024)。
文摘Aiming at solving the problem of high global warming potential of R134 a,a new mixed refrigerant R13 I1/R152 a(molar fraction ratio of 35:65)with no ozone depletion potential and low global warming potential was proposed as a substitute for R134 a in automotive air conditioning.The computational models for the thermodynamic properties of R13 I1/R152 a were established by using the PR(Peng-Robinson)equation of state combined with the vdW mixing rule.Based on these models,the cycle performance of this working fluid was calculated,which was also compared with that of R134 a and R1234 yf under the different operating conditions.The results show that R13 I1/R152 a is a near azeotropic refrigerant whose temperature glide is approximately 0,and the saturated vapor pressure curve of which is equivalent to that of R134 a.Moreover,compared to R134 a,R13 I1/R152 a has an average 5.7%improvement in coefficient of performance as well as similar volumetric cooling capacity.The average coefficient of performance and volumetric cooling capacity of R13 I1/R152 a are significantly higher than those of R1234 yf by 13.8%and12.0%,respectively.However,the average discharge temperature of R13 I1/R152 a is approximately13.3 K higher than that of R134 a,but it is also within reasonable limits.Hence,the application of the proposed refrigerant R13 I1/R152 a in automotive air conditioning system is technically feasible.
