Thermal Conductivity of Aqueous Sugar Solutions under High Pressure

Molecular energy transport in aqueous sucrose and glucose solutions of different mass fractions and temperatures is investigated up to 400MPa, using the transient hot-wire method. The results reveal an increasing thermal conductivity with increasing pressure and decreasing mass fraction of sugar. No significant differences between sucrose and glucose solutions were observed. Different empirical and semiempirical relations from the literature are discussed to describe and elucidate the behavior of the solutions with pressure. The pressure-induced change of the thermal conductivity of sugar solutions is mainly caused by an increase of the thermal conductivity and the decrease of molar volume of the water fraction. A simple pressure adapted mass fraction model permits an estimation of the thermal conductivity of the investigated solutions within an uncertainty of about 3%.