On the use of Water and Methanol with Zeolites for Heat Transfer

Reducing carbon dioxide emissions has become a must in society, being crucial to find alternatives to supply the energy demand. Adsorption-based cooling and heating technologies are receiving attention for thermal energy storage applications. In this paper, we study the adsorption of polar working fluids in hydrophobic and hydrophilic zeolites by means of experimental quasi-equilibrated temperature-programmed desorption and adsorption combined with Monte Carlo simulations. We measured and computed water and methanol adsorption isobars in high-silica HS-FAU, NaY, and NaX zeolites. We use the experimental adsorption isobars to develop a set of parameters to model the interaction between methanol and the zeolite and cations. Once having the adsorption of these polar molecules, we use a mathematical model based on the potential theory of adsorption of Dubinin-Polanyi to assess the performance of the adsorbate-working fluids for heat storage applications. We found that the use of molecular simulation is an alternative for investigating energy storage applications since we can reproduce, complement, and extend experimental observations. Our results highlight the importance of controlling the hydrophilic/hydrophobic nature of the zeolites by changing the Al content to maximize the working conditions of the heat storage device.