# Equation of State for the Thermodynamic Properties of Trans-1,2-dichloroethene [R-1130(E)]

## TL;DR

This paper provides a new equation to calculate thermodynamic properties of trans-1,2-dichloroethene across a wide range of temperatures and pressures.

## Contribution

An empirical equation of state for trans-1,2-dichloroethene with uncertainty estimates for various thermodynamic properties.

## Key findings

- The equation covers temperatures from 223.31 K to 525 K and pressures up to 30 MPa.
- Uncertainties for vapor pressure are 0.25% in the range 300 K < T < 454 K.
- The equation ensures physically realistic extrapolation for use in mixture models.

## Abstract

We present an empirical equation of state in terms of the Helmholtz energy for trans-1,2-dichloroethene [R-1130(E)]. The range of validity is from the triple-point temperature, 223.31 K to 525 K with pressures up to 30 MPa. It may be used to calculate all thermodynamic properties in the fluid phase, including liquid, gas, and supercritical regions. Comparisons are given with existing literature data and estimated uncertainties are provided. In addition, checks were made for correct extrapolation behavior so that the equation behaves in a physically realistic manner when used outside of its range of validity, enabling its use in mixture models. The estimated uncertainties (at a k = 2 or 95 % level of confidence) are based on comparisons with critically assessed data and are 0.25 % for vapor pressure for temperatures in the range 300 K < T < 454 K, rising to 1.5 % as the temperature decreases from 300 K to 265 K. For density in the liquid phase the estimated uncertainty is 0.14 % for temperatures 270 K < T < 410 K and for pressures up to 30 MPa. For the vapor phase the estimated uncertainty in density is 3 %. The uncertainty for liquid-phase heat capacity is 1 % at atmospheric pressure over the temperature range 268 K < T < 309 K, and the uncertainty for the speed of sound in the liquid phase is 0.25 % for temperatures 230 K < T < 420 K and for pressures up to 30 MPa. The uncertainties are larger outside of these specified ranges and in the critical region.

The online version contains supplementary material available at 10.1007/s10765-025-03535-3.