Measurement Of Gaseous PVT Property Of HFO-1234Yf Based On The Magnetic Suspension Densimeter And Analysis Of Its Replacement In Automotive Air Conditioner

"Montreal Protocol" and "Kyoto Protocol" had provided a clear legal constraints to ozone layer and greenhouse gas emission issues. F-gas regulations that legislated by the EU furthered the limitation of usage of the refrigerants that containing fluorine with high GWP value. The search for alternative refrigerants is an urgent task. In the development of searching new refrigerant, the basic step is to measure the PVT properties. At the beginning of this work, a wide range of improvements were accomplished to replace the original heating system, which heated the top and conducted heat to the experimental chamber, with the new system that red copper coil directly heat the chamber itself, and thermal conductive silicone rubber was filled in the thin seam to enlarge the contact area of the red copper and the chamber. The precision and speed of temperature control were improved significantly. The standard uncertainty of the temperature control system was0.005k. On the basis of these work, the fluid PVT property measuring system was established with the magnetic suspension densimeter.According to the mechanism of magnetic suspension densimeter, force transmission error was analyzed, and the main factor that effect the force transmission error was determined and calculated. The PVT properties of high purity nitrogen was measured with temperature ranged271K-345K, pressure ranged0.8MPa-5.9MPa, and the measuring results was corrected according to the force transmission error analysis. The results were compared to the NIST REFPROP9.0database. The average relative deviation was0.072%. The virial equation of nitrogen was fitted with the experimental data and the system’s total uncertainties were analyzed. The results proved the reliability and accuracy of this PVT measuring systemThe gaseous PVT properties of HFO-1234yf were measured with temperature ranged252K-345K, and pressure ranged0.07MPa～1.91MPa. The corrected results were compared to the NIST REFPROP9.0database. The average absolute deviation was0.003kg· m-3and the average relative deviation was0.082%. According to the measured PVT data, together with other’s measured values, virial equation of HFO-1234yf was fitted and the density were calculated under the same condition of this work and other researcher’s paper, the average deviation was -0.0416kg·m-3.At last, the cycle performance between HFO-1234yf and HFC-134a in typical operating conditions in automotive air conditioner were discussed systematicly under varied evaporation temperature, condensation temperature, superheat and subcooling condition. The exhaust temperature, cooling capacity per unit mass, cooling capacity per unit volume, COP, and other thermodynamic parameters were calculated and analyzed. Then the method to improve the HFO-1234yf circulate performance was proposed, which were changing the filling substance of the temperature response bag, adjusting the force of spring and adding regenerative cycle to the HFO-1234yf system.This paper provides valuable reference to the HFO-1234yf replacement of HFC-134a.