The thermal masses of components influence the performance of many adsorption heat pump systems. However, typically when experimental adsorption systems are reported, data on thermal mass are missing or incomplete. This work provides original measurements of the thermal masses for experimental sorption heat exchanger hardware. Much of this hardware was previously reported in the literature, but without detailed thermal mass data. The data reported in this work are the first values reported in the literature to thoroughly account for all thermal masses, including heat transfer fluid. The impact of thermal mass on system performance is also discussed, with detailed calculation left for future work. The degree to which heat transfer fluid contributes to overall effective thermal mass is also discussed, with detailed calculation left for future work. This work provides a framework for future reporting of experimental thermal masses. The utilization of this framework will enrich the data available for model validation and provide a more thorough accounting of adsorption heat pumps.
1 April 2021 in International Journal of Heat and Mass Transfer
Thermally-driven heat pumps can help to mitigate CO2 emissions by enhancing the efficiency of heating systems or by driving cooling systems with waste or solar heat. In order to make the thermally-driven systems more attractive for the end consumer, these systems need a higher power density. A higher power density can be achieved by intensifying the heat and mass transfer processes within the adsorption heat exchanger. For the optimization of this key component, a numerical model of the non-isothermal adsorption dynamics can be applied. The calibration of such a model can be difficult, since heat and mass transfer processes are strongly coupled. We present a measurement and simulation procedure that makes it possible to calibrate the heat transfer part of the numerical model separately from the mass transfer part. Furthermore, it is possible to identify the parts of the model that need to be improved. For this purpose, a modification of the well-known large temperature jump method is developed. The newly-introduced measurements are conducted under an inert N2 atmosphere, and the surface temperature of the sample is measured with an infrared sensor. We show that the procedure is applicable for two completely different types of samples: a loose grains configuration and a fibrous structure that is directly crystallized.