| Absorption thermal energy storage (ATES) technology has the advantages of highenergy storage density (ESD), small heat loss and can adopt environment-friendlyrefrigerants and utilize low-grade waste heat. Benefit for these technical features, theATES technology is important for environmental protection and energy saving. As aneffective means of matching heat source and load, higher storage density and efficiency,and effective method of dynamic regulation are the two core objectives of thetechnology. Based on this, the paper carries out the following researches:Firstly, based on three working pairs with refrigerant water, a mathematical modeland evaluation method of ATES cycle is established to analyze the energy storageefficiency (ESE) and ESD of two-phase cycle, three-phase cycle and cycle with booster.It is shown that:(1) LiBr/H2O has similar performance with LiCl/H2O, and NaOH/H2Ohas better performance but is more corrosive than the other working pairs;(2) Inthree-phase storage cycle or storage cycle with booster, increasing terminal solutionconcentration or improving the compression ratio can enlarge storage density.Secondly, in order to obtain the charging and discharging performance of ATES, atwo-phase ATES experimental rig with storage capacity of10kWh is designed andbuilt using working pair of LiBr/H2O, and a dynamic model of ATES system withcrystallization and pressure booster is established. In the experiment, the7oC chilledwater,65oC heating water and43oC domestic hot water are produced successfully. Theenergy storage efficiency are0.51,0.97and1.03, and the energy storage density are42,88and110kWh/m3, respectively. Both the experiment and simulation results show thatenergy charging and discharging process in ATES is a heat transfer process of thedriving force transfer between "temperature difference" and "concentration difference ".The charging process can be divided into heating dominated phase and concentratingdominated phase; raising the temperature of heat source, reducing the cooling watertemperature and increasing pressure ratio can increase storage power and shorten thestorage time. In discharging process, dilution and cooling process occurs simultaneously,and reducing the cooling water temperature and increasing pressure ratio can greatlyimprove the power of energy release and shorten the release time. The power in concentrating and diluting process decays by time, but in the crystallization anddissolution process of crystals, the power can be stabilized.Thirdly, to solve the problem of crystallization of solution with high concentrationfor long time energy storage, the crystals forming and dissolving characteristics of highconcentration LiBr/H2O solution is experimentally studied when the solution is standingor spraying in the interim period. And a structure to store high-concentration solutionbased on the active crystallization technology and its availability is experimentallyverified. Then, a large-concentration ATES system based on the structure is proposed toimprove the energy storage density，and the design method and operation strategy isgiven. The device provides a better energy storage methods and approaches for longtime energy storage.Finally, taking a medical service stations with94kW peak cooling capacity for theapplication object, a solar-energy refrigerating system with ATES system has beendesigned and a typical day’s operation is analyzed. Results show that, the system canprovide the total cooling capacity of the building with area of1000m2in night. Thesolar cooling efficient of the system can respectively reach45%. |
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