Reaction control of CaSO4 during hydration/dehydration repetition for chemical heat pump system

Water sorption-based thermochemical storage materials: A review from material candidates to manufacturing routes

“…CaSO 4 hydration CHPs offer certain advantages, such as high heat density, using only safe and economical materials, no deliquescence, very small hysteresis, negligible expansion in hydration, long-term storage of the absorbent and products, and low heat loss (Shiren et al, 2020). As the main disadvantages, previous studies have reported the problem of inactivation of CaSO 4 due to hydration under high water vapor pressure (Lee et al, 2014;Richter et al, 2018); however, CaSO4 has the potential to 2014) studied the same reaction also for a CHP system, storing heat at around 100 °C. The authors calculated the hydration and dehydration conversions after 450 cycles; they observed a reaction degradation given the irreversible transformation of III-CaSO 4 to II-CaSO 4 , which are different forms of the crystal structure.…”

Experimental Study of Hydration/Dehydration Behaviors of Metal Sulfates M2(SO4)3 (M = Sc, Yb, Y, Dy, Al, Ga, Fe, In) in Search of New Low-Temperature Thermochemical Heat Storage Materials

“…The hydration/dehydration reactions of some sulfates such as CaSO 4 , β-La 2 (SO 4 ) 3 , and Y 2 (SO 4 ) 3 have advantages in reaction temperature and reaction rate. They proceed rapidly and reversibly below 250 °C and even in low water vapor pressure p H 2 O such as that in air. − These characteristics can be attributed to their crystal structures where the insertion/deinsertion of water molecules occurs. ,, Furthermore, regarding Y 2 (SO 4 ) 3 , a larger heat storage capacity is expected through the characteristic multistep hydration/dehydration reaction …”

“…4 (III) to low-hydration-reactive CaSO 4 (II) during repetitive reaction6 β-La 2 (SO 4 ) 3 •H 2 O/β-La 2 (SO 4 ) 3 7 1567 3.18 no special drawbacks on the handling have been observed…”

Porous‐Resin‐Supported Calcium Sulfate Materials for Thermal Energy Storage

“…TheC aSO 4 /CaSO 4 ·0.5H 2 Or eaction system can store heat at approximately 423 Ka nd release heat between 333 Ka nd 373 K. [31] Thec onversion of the CaSO 4 /CaSO 4 ·0.5H 2 Or eaction system usually decreasesb ecauseo fp article agglomeration and secondary interaction reactions of the CTES material. Several crystal structures of CaSO 4 play arole in the reaction system:C aSO 4 ·2 H 2 O, CaSO 4 ·0.5 H 2 O( a or b types),I II-CaSO 4 (a or b types), II-CaSO 4 ,a nd I-CaSO 4 .E ach hydrate can be formed by controlling the dehydrationt emperature.…”

“…Thes econdary interaction reactionso ft hese hydrates occur as shown in Figure 2. III-b-CaSO 4 can be transformedt oI I-CaSO 4 at around 673 Kt o8 73 K, while CaSO 4 ·2 H 2 Oc an be transformed to II-CaSO 4 at around 363 Kt o4 74 K. [31][32][33] Those secondary interaction reactionsd ecreaset he hydration/dehydration rate of CTES materials.T he CaSO 4 ·0.5 H 2 O and CaSO 4 reaction pair can be applied in, for example, buildings or supercomputer centers that have low-temperature-level exhaust heat and high powerd emands for heating and cooling, with the following advantages: [27-29, 34, 35] (a) it is as afe reaction system,w ithout pollution;( b) the reaction material can be easily obtained, at al ow price;( c) the CaSO 4 reaction system is relatively easy to use because it does not attract moisture.…”