Isobaric heat capacity of liquid polyoxymethylene dimethyl ethers (OMEx) under ambient pressure

Polyoxymethylene dimethyl ethers (OME${}_x$) are frequently considered as a promising alternative to diesel fuel. However, for the development of the respective technology, a sound knowledge about their thermophysical properties is required. Isobaric heat capacity measurements of five OME${}_x$ with a chain length $x$ = 1 to 5 are conducted under ambient pressure in the temperature range from about 248 K to 390 K. These are: 2,4-Dioxapentane (OME${}_1$), 2,4,6-Trioxaheptane (OME${}_2$), 2,4,6,8-Tetraoxanonane (OME${}_3$), 2,4,6,8,10-Pentaoxaundecane (OME${}_4$) and 2,4,6,8,10,12-Hexaoxatridecane (OME${}_5$). To validate the employed apparatus and measurement procedure, water, methanol and ethanol are sampled as well. The measurements are carried out with a differential scanning calorimeter $\mu$DSC by Setaram with an overall relative expanded ($k=2$) uncertainty $U_r\left(c_p\right)$ of $\pm$1%. Polynomial equations in terms of temperature are fitted to the measured data. An extensive comparison to literature data is made.