| The technology of refrigeration and air-conditioning has greatly facilitated our human lives.However,massive use of traditional refrigerants CFC and HCFC has also caused environmental irreversible disasters,causing environmental problems such as "greenhouse effect" and "ozone layer destruction." Different countries are now dealing with the challenge of searching new promising environmentally friendly refrigerants.The pvT properties of fluid are indispensable for the selection of the green refrigerants,and the properties are also the most fundamental and essential properties to calculate cooling effects and optimizing refrigeration systems.Under the background,a high precision experimental measurement system for the liquids pv T properties was developed.R1243 zf,as the fourth generation of new working fluid,has superior environmental performance and excellent cooling efficiency,and has broad prospects in the field of air conditioning;R1233zd(E)has both good cooling performance and foaming performance.In this paper,the R1243 zf gas phase pvT data was measured,and the equation of state was fitted on this basis for the calculation of thermal properties;the vapor pressure equation of R1233zd(E)is carried out theoretical researchThe high-precision measurement methods of pvT properties of fluids were summarized and compared.Based on this,an experimental system of U-shaped vibrating tube was built for measurements liquid phase properties: with the commercial vibrating tube densimeter Anton Paar HPM as the core component of the system,a high pressure vibrating tube densimeter system was developed,including a vibrating tube densimeter,temperature and pressure control system,temperature and pressure measurement system,and a high vacuum system.By comparing the calibration methods,the single substance calibration method was selected to calibrate the system.The range of temperature and pressure for this experimental system are-10～200 ℃ and 0～140 MPa.The expanded(k=2)measurement uncertainty for temperature and pressure was better than 14 mK,94 kPa(0～70 MPa)and 266 kPa(70～140 MPa),respectively.The gaseous pvT properties of DME were measured via the Burnett-isochoric method.123 groups of data were measurement.The second and third virial coefficients of every isotherm were obtained.Based on these,a truncated viral equation of state was obtained for calculating the thermodynamic properties of R1243 zf.The experimental data well can be reproduced well by the equation.The average absolute deviation of the fitted data from the measured pressure and density were 0.13 % and 0.14%,respectively.The saturated vapor pressure data of R1233zd(E)based on published literatures were collected and were screened by analyzing the accuracy of every experimental data.Application the Least squares algorithm,the screening data were regressed by using Wagner equations with different number of items(3,4,5,6,7).After making a comparison of fitting deviation and equation form among equations with different item number,respectively,the Wagner equation of five optimal terms was recommended for describing the saturated vapor pressure properties of R1233zd(E),which is wide application range and high precision.The applicable temperature range of the equation is 234.15～437.91 K,and the pressure interval is 7.2～3521 k Pa.The maximum relative deviation between the predicted results and literature data is-1.5%,and the average absolute deviation is 0.28%,respectively.At the same time,the normal boiling point and acentric factor of R1233zd(E)are calculated with the equation. |
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