Elsevier

Fluid Phase Equilibria

Volume 427, 15 November 2016, Pages 429-437
Fluid Phase Equilibria

Measurements for isobaric specific heat capacity of ethyl fluoride (HFC-161) in liquid and vapor phase

https://doi.org/10.1016/j.fluid.2016.07.034Get rights and content

Highlights

  • A flow calorimeter was developed to measure the isobaric specific heat capacity.

  • The isobaric specific heat capacity of HFC-161 was measured in liquid phase.

  • The isobaric specific heat capacity of HFC-161 was measured in gaseous phase.

Abstract

In this paper, a flow calorimeter was developed to measure the isobaric specific heat capacity of ethyl fluoride (HFC-161) in both liquid and vapor phase. 161 data of isobaric heat capacity of HFC-161 were obtained in liquid phase at temperatures from 303.51 K to 383.71 K and pressures up to 12.0 MPa 38 data were acquired in vapor state in the temperature range of 315.43 K–365.40 K and pressures from 1.0 MPa to 3.0 MPa. The uncertainties of the heat capacity for HFC-161 were estimated to be less than 1.0% in liquid phase and 1.5% in vapor phase, respectively. The equations of state based on specifying the Helmholtz free energy were employed to calculate the isobaric heat capacity for HFC-161. In addition, the experimental values of heat capacity in liquid phase were also compared with the literature data.

Introduction

Ethyl fluoride (HFC-161) is recently considered a promising refrigerant due to its excellent cycle performance. In addition, it has zero ozone-depletion potential (ODP) and a very low global warming potential (GWP) of 12. It has not been widely used in engineering applications for its flammability, but the rosy prospect makes it a very valuable alternative. The thermophysical properties of HFC-161 are necessary for the scientific research and engineering applications. Some thermophysical properties of HFC-161 have been published in recent years, such as the gaseous PVT properties [1], surface tension [2], viscosity [3], [4] in liquid and vapor phase, and the thermal conductivity [5]. Its heat capacity in liquid phase was measured with a C80 by He [6] in 2015.

In this work, the isobaric heat capacity of HFC-161 was investigated by means of a flow calorimeter. 161 data of heat capacity for HFC-161 were acquired at temperatures from 303.51 K to 383.71 K and pressures up to 12.0 MPa 38 data were obtained in vapor phase in the temperature range from 315.43 K to 365.40 K. Those data are very useful for research and applications of HFC-161.

Section snippets

Material

The sample of HFC-161 was supplied by Zhejiang Lantian Environmental Protection Hi-tech Co.Ltd. The mass fraction purity was greater than 99.95%. No further purification was done before use. The detailed information of the sample used in this study was summarized in Table 1.

Apparatus

The schematic of the experiment system is shown in Fig. 1. The apparatus fundamentally includes several parts: an air thermostatic bath without a cooling system, flow calorimeter, a mass flowmeter, temperature and pressure

Uncertainties

The uncertainties of the two platinum resistance thermometer used in the system are less than 10 mK. The pressure sensor's uncertainty is estimated to be less than 15 kPa. The uncertainty of the flow rate (m) was 0.05% in liquid phase, 0.5% in vapor state caused by the flow instability. The uncertainty of the heater is determined to be less than 0.01%. Uncertainties mentioned in this paragraph are without any coverage factor. So the uncertainty of cp can be calculated by follow equation.Uc,cp=k(

Results and discussions

To check the performance of the isobaric heat capacity experimental system, heat capacity of pure water were studied at temperatures from 304.33 K to 577.12 K and pressures up to 15 MPa (see Fig. 4). The measurements and the comparisons with Sirota [7], Naziev's [8] interpolation of initial experimental results and Wagner's (a general state equation for water) data [9] are listed in Table 3. Compared with Sirota and Naziev's experimental results, the absolute relative deviation is less than

Conclusion

The heat capacity measurement of HFC-161 was carried out with a flow calorimeter. The heat capacity in liquid phase covered a temperature range of 303.51 K–383.71 K and a pressure range of saturated pressure to 12.0 MPa 161 heat capacities were presented along 9 isotherms. The heat capacity in vapor state covered a temperature range of 315.43 K–365.40 K and a pressure range of 1.0 MPa to saturated pressure. 38 heat capacities were presented along 6 isotherms.

Acknowledgement

We acknowledge the support of the National Natural Science Foundation of China (Grant No. 51276143).

References (20)

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