## 3 Results and Discussion
### Reactor Hygrothermal Behavior
The moving bed concept was designed with an idea of keeping the thermal power constant, that might resolve the problem of the gradual decrease of the heat production over time. The experimental results of the reactor running in the moving bed mode are the curves with \"\(\Box\)\" and \"\(\triangle\)\" markers in Figures 5-8. The shape of these curves is irregular that proves that the material was not densely packed in the bed. The appearance of discontinuities in the material packing was due to the non-homogeneous flow of the granular medium through the bed, which resulted in the sharp decrease of the outlet temperature (see Figure 5, test 2) and the drop of the thermal power (see Figure 8, test 2). The  
Figure 5: Inlet and outlet temperatures for the fixed bed (test 1) and the moving bed (test 2) reactors. Figure 6: Inlet and outlet water vapor pressures for the fixed bed (test 1) and the moving bed (test 2) reactors. discontinuities of the material flow can be clearly observed at different time, when the sharp raise of the outlet vapor pressure coincides with the drop of the sorption rate (see Figures 6 and 7, test 2). The adsorption potential in the reactor inlet conditions was lower than for test 1, namely \(\Delta F_{1}\)\({}^{\prime}=1.1\) kJ/mol, before the hydration reaction started. Since the initial dehydration state of the material used for tests 1 and 2 was the same (see Table 3), the initial \(\Delta F_{0}\) was also the same. With account of \(\Delta F_{1}\)\({}^{\prime}\) and using the data in Figure 4, the maximum loading lift for test 2 can be predicted as high as 0.9 kg/kg, that is 11% greater than for test 1. This explains the steep temperature jump observed at \(t=2\) min in  
Figure 8: Thermal power for the fixed bed (test 1) and the moving bed (test 2) reactors. Figure 7: Water mass uptake (left axis) and sorption rate (right axis) for the fixed bed (test 1) and the moving bed (test 2) reactors. Figure 5 (see test 2). But once the solid was heated up, the dynamic adsorption potential increased to \(\Delta F_{1}\)' = 4.6 kJ/mol, causing the drop of the virtual equilibrium to 0.37 kg/kg. The additional heat from the fan and the activation of the heat recovery had likewise a negligible effect on the sorption process: the both adsorption potentials changed only to 4.3 kJ/mol. Therefore, the main drawback of the moving bed reactor came from the non-homogeneous granular flow that did not allow the thermal power to be stable. This drawback can be potentially eliminated by optimizing the thickness of bed and the particles size in face of the reasonable pressure drop through the bed. Nevertheless, the value of \(\sim\)421 W of the thermal power produced in the moving bed test can be considered as a constant on the time span from 20 min to 56 min (see Figure 8, test 2), and because the outlet air temperature, the vapor pressure and the sorption rate encountered little variations (see Figures 5-7, test 2). The point at 42 min is the outlier. This time span also matches the end of the transient hydration process of the moving bed, when the material hydration state reached the stable level of \(\sim\)0.1 kg/kg (see Figure 8, uptake curve for test 2). The water mass uptake for the moving bed was verified with the moisture analyzer HE73 from Mettler Toledo after 33 min and 1 h 15 min. The measured values were 0.13 kg/kg and 0.09 kg/kg that generally confirmed the correctness of the uptake estimation with equation (8) as shown in Figure 7. As follows from Figure 7, the hydration state of the material leaving the reactor is significantly lower compared to the fixed bed test because of the discontinuities and the non-homogeneous sorption through the moving bed (see Figure 7). Also, the solid residence time in the reactor was not enough to reach an adequate hydration level. As a consequence, the energy density of material in the moving bed energy storage system is 2.5 times lower than for the equivalent fixed bed installation (see data in Table 4).