Estrella Álvarez

The seasonal performance of a heat pump indicates its average performance during the heating and/or cooling season, taking into account the different energy demands and their variability over time. Several European and international regulations and policies related with energy efficiency and the reduction of the carbon footprint of energy related products are affecting the heat pump industry. Among them, the ecodesign regulations impose minimum energy efficiency values for heat pumps, efficiencies that are based on the seasonal coefficient of performance. This work is focused on a domestic brine-to-water heat pump for low-temperature applications. The methodology to determine its seasonal coefficient of performance (SCOP) according to the European standard EN 14825 is explained and evaluated based on experimental results. The impact on the SCOP of using some technology options such as fixed or variable speed compressors, and fixed or variable outlet temperature operation is evaluated. Results show that between the lowest and highest efficient option, the SCOP can be improved by 26%.

The use of tertiary methyldiethanolamine (MDEA) as an absorbent for the CO₂ removal from process gas streams has increased due to its advantages over primary and secondary amines. Methanol is also widely used as an organic physical solvent for the CO₂ capture. Mixed solvents are expected to have a higher capacity for the acid gases than the solvent alone. The chemical absorption rate of CO₂ was measured in mixtures of MDEA (weight 5%, 15% and 30%) and water-methanol solutions at different % weight relations by using a stirred-cell reactor with plane gas-liquid interface. Experiments provided data measured at a range from 283.15 K to 313.15 K operation temperatures. Results show how the solubility of CO₂ varies in all systems involved focusing on temperature and concentration changes. The solubility of CO₂ in the aqueous mixed MDEA with methanol as a solvent becomes significantly greater than in the aqueous amine alone.