Numerical modelling and evaluation of a novel sorption module for thermally driven heat pumps and chillers using open-source simulation library

Abstract

Sorption modules are the core component of thermally driven heat pumps and chillers. The efficiency of these devices strongly depends on the advantageous design of sorption modules. In this paper a calibrated and validated numerical model for an innovative sorption module with a combined evaporator-condenser is presented. The adsorption heat exchanger is based on flat tube-lamella design directly crystallized with the zeotype adsorbent silico-alumino-phosphate-34. The prediction quality of the model regarding the efficiency is within the measurement uncertainty (±0.02 kJ/kJ). Besides the good prediction quality of this integral performance indicator, the root mean square deviation of the transient outlet temperatures is in the range of 1.1…1.9 K, which is a very good agreement. Since the performance indicators efficiency and power density strongly depend on the temperature boundary conditions and half cycle times, an in-depth analysis of the experimental data using the method of heat and mass transfer resistances is suggested that overcomes this limitation. This analysis allows for a direct comparison with other sorption module designs. In a first step this analysis revealed that the evaporator-condenser component limits the sorption process during evaporation. Compared to other designs the evaporator-condenser has a 3–5 times higher volume scaled heat and mass transfer resistance (17 dm3K/kW) in the evaporation phase underlining the necessity to further optimize this component in future modules.