TY - JOUR

T1 - Dynamics and useful heat of the discharge stage of adsorptive cycles for long term thermal storage

AU - Palomba, Valeria

AU - Sapienza, Alessio

AU - Aristov, Yuri

N1 - Publisher Copyright: © 2019 Elsevier Ltd

PY - 2019/8/15

Y1 - 2019/8/15

N2 - Interest towards adsorption heat storage, especially for long-term (seasonal) applications, is growing. The previous studies have always treated the heat storage cycle as a fully temperature-initiated process, similarly to common adsorption cooling and heating cycles. However, in long term storage applications, the discharge stage of the cycle is initiated by a jump of pressure rather than by a traditional drop of temperature. This requires specific investigations on the useful heat recoverable as well as on the adsorption dynamics. In the present paper, an appropriate experimental methodology was applied for studying the heat discharge stage. Three well known adsorbents (Mitsubishi AQSOA FAM-Z02, silica Siogel and composite LiCl/silica) were experimentally tested in a lab-scale heat storage unit, evaluating the effect of cycle operating parameters. The results, elaborated in terms of useful heat recoverable from the charged adsorbent, highlighted that the evaporation temperature and the flow rate of heat transfer fluid have a great influence on the adsorption dynamics and the useful heat. For the silica gel and FAM Z02, the maximum heat storage capacity 450 kJ/kg is reached at the evaporation temperature of 25 °C. The composite performs better at low evaporation temperatures, allowing heat upgrade even at 5 °C. The flow rate of the heat transfer fluid has a more significant effect on FAM Z02 than on the other adsorbents, for which an optimal flow rate of 1.2 kg/min was found.

AB - Interest towards adsorption heat storage, especially for long-term (seasonal) applications, is growing. The previous studies have always treated the heat storage cycle as a fully temperature-initiated process, similarly to common adsorption cooling and heating cycles. However, in long term storage applications, the discharge stage of the cycle is initiated by a jump of pressure rather than by a traditional drop of temperature. This requires specific investigations on the useful heat recoverable as well as on the adsorption dynamics. In the present paper, an appropriate experimental methodology was applied for studying the heat discharge stage. Three well known adsorbents (Mitsubishi AQSOA FAM-Z02, silica Siogel and composite LiCl/silica) were experimentally tested in a lab-scale heat storage unit, evaluating the effect of cycle operating parameters. The results, elaborated in terms of useful heat recoverable from the charged adsorbent, highlighted that the evaporation temperature and the flow rate of heat transfer fluid have a great influence on the adsorption dynamics and the useful heat. For the silica gel and FAM Z02, the maximum heat storage capacity 450 kJ/kg is reached at the evaporation temperature of 25 °C. The composite performs better at low evaporation temperatures, allowing heat upgrade even at 5 °C. The flow rate of the heat transfer fluid has a more significant effect on FAM Z02 than on the other adsorbents, for which an optimal flow rate of 1.2 kg/min was found.

KW - Adsorption dynamics

KW - Adsorption heat storage

KW - Heat rejection

KW - Long term heat storage

KW - Useful heat

KW - TRANSFORMATION

KW - SYSTEM

KW - PERFORMANCE

KW - OPERATING-CONDITIONS

KW - SORPTION

KW - WATER-ADSORPTION

KW - CHILLERS

KW - AMBIENT HEAT

KW - WORKING PAIR

KW - ENERGY-STORAGE

UR - http://www.scopus.com/inward/record.url?scp=85064627559&partnerID=8YFLogxK

U2 - 10.1016/j.apenergy.2019.04.134

DO - 10.1016/j.apenergy.2019.04.134

M3 - Article

AN - SCOPUS:85064627559

VL - 248

SP - 299

EP - 309

JO - Applied Energy

JF - Applied Energy

SN - 0306-2619

ER -