Thermodynamic performance of a double-effect absorption heat-transformer using TFE/E181 as the working fluid

Trifluoroethanol(TFE)-tetraethylenglycoI dimethylether (TEGDME or E181) is a new organic working-pair which is non-corrosive, completely miscible and thermally stable up to 250 degrees C. It is suitable for upgrading low-temperature level industrial waste-heat to a higher temperature level for reuse. In this paper, the thermodynamic performance of the double-effect absorption heat-transformer (DEAHT) using TFE/E181 as the working fluid is simulated, based on the thermodynamic properties of TFE/E181 solution. The results show that, when the temperature in the high-pressure generator exceeds 100 degrees C and the gross temperature lift is 30 degrees C, the coefficient of performance (COP) of the DEAHT is about 0.58, which is larger than the 0.48 of the single-stage absorption heat-transformer (SAHT), the increase of COP is about 20%. But it is still less than 0.64 of the DEAHT using LiBr-H20 as the working fluid. Meanwhile, the COP of the DEAHT decreases more rapidly with increases of the absorption temperature than that for the SAHT. The range of available gross temperature-lift for the DEAHT is narrower than that of the SAHT. The higher the temperature in the high-pressure generator, the larger the gross temperature-lift could be. So the double-effect absorption heattransformer is more suitable for being applied in those circumstances of having a higher-temperature heat-resource and when a higher temperature-lift is not needed. (c) 2004 Elsevier Ltd. All rights reserved.