Abstract
A new model of adsorption isotherms Type IV and V is proposed as a basis for theoretical calculations and modelling of adsorption systems such as adsorption heat storage and heat pumps. As the current models have decent yet limited applicability, in this work, we present a new combined model with universal use for micro-mesoporous silica/water adsorption systems. Experimental measurement of adsorption isotherm of water onto seven different samples of micro and mesoporous silica and aluminium-silica were used to fit new adsorption models based on a combination of classical theories and a distribution function related to the pore-size distribution of the selected materials. The fitting was conducted through a repeated non-linear regression using Trust Region Reflective algorithm with weighting factors to compensate for the scalability of the adsorption amount at low relative pressure with optimization of the absolute average deviation fitting parameter. The results display a significant improvement for most of the samples and fitting indicators compared to more common models from the literature with average absolute deviation as low as AAD = 0.0025 g g−1 for material with maximum uptake of q = 0.38 g g−1. The newly suggested model, which is based on a combination of BET theory and adjusted normal distribution function, proved to bring a higher degree of precision and universality for mesoporous silica materials with different levels of hydrophilicity.
Highlights
IntroductionHeat driven thermodynamic cycle is as an alternative to the common mechanical vapour compression cycle, where an abundance of waste heat or low potential heat (low-temperature difference) is available
Heat driven thermodynamic cycle is as an alternative to the common mechanical vapour compression cycle, where an abundance of waste heat or low potential heat is available
The goodness of fit of these models somehow lacks certain aspects, the results of the selected models prove to provide sufficient fit with the present mesoporous silica materials and the results are comparable to the new models
Summary
Heat driven thermodynamic cycle is as an alternative to the common mechanical vapour compression cycle, where an abundance of waste heat or low potential heat (low-temperature difference) is available. The adsorption models are readily used in simulations of adsorption heat storage (AHS) [5,6] and adsorption heat pump (AHP) [7,8,9,10,11] systems. Majority of the research of the adsorption heat-based technologies involves AHP thanks to their more efficient performance and significantly less mass of the deployed system as well as the lower amount for the expensive adsorption materials. Both the AHP and the AHS systems can be Energies 2020, 13, 4247; doi:10.3390/en13164247 www.mdpi.com/journal/energies
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
