本文对大温度滑移非共沸工质CO_(2)/R152a在内径2 mm的水平小通道内流动沸腾换热特性进行了实验研究。实验工况范围为质量流速200~400 kg·m^(-2)·s^(-1)、热流密度12~36 k W/m^(2)、饱和温度5~15℃。结果表明管内流动沸腾两...本文对大温度滑移非共沸工质CO_(2)/R152a在内径2 mm的水平小通道内流动沸腾换热特性进行了实验研究。实验工况范围为质量流速200~400 kg·m^(-2)·s^(-1)、热流密度12~36 k W/m^(2)、饱和温度5~15℃。结果表明管内流动沸腾两相流型包括泡状流、塞状流、弹状流、分层波状流、环状流以及雾状流。对流换热系数随干度增加呈先缓慢增加后迅速下降的趋势,沸腾过程中存在临界干度。随着热流密度、质量流速以及饱和温度的增加,大温度滑移非共沸工质对流换热系数均呈现增加趋势。大温度滑移非共沸工质CO_(2)/R152a对流换热系数随温度滑移的减小而增大。考虑大温度滑移非共沸工质传热传质过程中的显热换热阻力和传质阻力影响,提出了新的换热系数预测模型,平均绝对偏差为22.05%。展开更多
This paper reports the PVT x properties of R22/R152a system in the ranges of temperature from 298.15K to 353.15K and pressure from 0.288 MPa to 1.288 MPa. Sixty seven PVT x measurements for three compositions, i...This paper reports the PVT x properties of R22/R152a system in the ranges of temperature from 298.15K to 353.15K and pressure from 0.288 MPa to 1.288 MPa. Sixty seven PVT x measurements for three compositions, i.e., 0.2712, 0.4094 and 0.7911 mole fraction of R22, have been measured along 16 isotherms. The uncertainties of temperature and pressure measurements are less than ±0.01K and ±500 Pa respectively. The reliability of the experimental measurements is confirmed by the CSD equation.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
R134a and R152a are two promising refrigerants to replace R12 that depletes the ozone layer. This paper presents how to determine the charge accurately when R134a or R152a is used to replace R12 for household refriger...R134a and R152a are two promising refrigerants to replace R12 that depletes the ozone layer. This paper presents how to determine the charge accurately when R134a or R152a is used to replace R12 for household refrigerators. A lot of experiments are done on a household refrigerator in order to choose a correct void fraction correlation for density calculations in two phase region. For HFC 152a, Hughmark model is fairly accurate, whose error is -6.0% or so. For HFC 134a, both Tandon model and Premoli model can get good results, their errors are around -1.8%, -2.4% respectively.展开更多
文摘本文对大温度滑移非共沸工质CO_(2)/R152a在内径2 mm的水平小通道内流动沸腾换热特性进行了实验研究。实验工况范围为质量流速200~400 kg·m^(-2)·s^(-1)、热流密度12~36 k W/m^(2)、饱和温度5~15℃。结果表明管内流动沸腾两相流型包括泡状流、塞状流、弹状流、分层波状流、环状流以及雾状流。对流换热系数随干度增加呈先缓慢增加后迅速下降的趋势,沸腾过程中存在临界干度。随着热流密度、质量流速以及饱和温度的增加,大温度滑移非共沸工质对流换热系数均呈现增加趋势。大温度滑移非共沸工质CO_(2)/R152a对流换热系数随温度滑移的减小而增大。考虑大温度滑移非共沸工质传热传质过程中的显热换热阻力和传质阻力影响,提出了新的换热系数预测模型,平均绝对偏差为22.05%。
文摘This paper reports the PVT x properties of R22/R152a system in the ranges of temperature from 298.15K to 353.15K and pressure from 0.288 MPa to 1.288 MPa. Sixty seven PVT x measurements for three compositions, i.e., 0.2712, 0.4094 and 0.7911 mole fraction of R22, have been measured along 16 isotherms. The uncertainties of temperature and pressure measurements are less than ±0.01K and ±500 Pa respectively. The reliability of the experimental measurements is confirmed by the CSD equation.
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.
基金the Fund of Natural Science of China,the Fund for
文摘R134a and R152a are two promising refrigerants to replace R12 that depletes the ozone layer. This paper presents how to determine the charge accurately when R134a or R152a is used to replace R12 for household refrigerators. A lot of experiments are done on a household refrigerator in order to choose a correct void fraction correlation for density calculations in two phase region. For HFC 152a, Hughmark model is fairly accurate, whose error is -6.0% or so. For HFC 134a, both Tandon model and Premoli model can get good results, their errors are around -1.8%, -2.4% respectively.
