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Optimization strategy for system management of cold thermal energy storage (CTES) in conditions of dynamic changes in energy carrier value
(2024) Gryshchenko, Roman; Forsyuk, Andriy; Ivashchenko, Nataliia; Kryvosheiev, Maksym; Pylypenko, Oleksii
In the world of contemporary challenges involving the continual increase in demand for energy resources and corresponding environmental pollution, the necessity has arisen to develop and implement advanced technologies to reduce energy consumption. This calls for enhancing energy utilization efficiency and op-timizing energy generation systems, taking into account the utilization of alternative and renewable ener-gy sources.Specifically, thermal energy storage becomes crucial as an effective economic option. Ther-mal energy storage systems enable meeting heating or cooling needs during optimal periods when it is more energy-efficient. Traditional management methods rarely prove optimal due to fluctuating electrici-ty tariffs, cooling loads, and ambient temperature. This leads to suboptimal achievement of maximum savings in utilising thermal energy storage systems.In this work, the advantages of Cold Thermal Energy Storage (CTES) systems based on Ice Thermal Energy Storage (ITES) were analysed alongside existing management strategies implemented in most enterprises and buildings utilizing ITES. A simpli-fied engineering methodology for analysing the thermodynamic efficiency of CTES was proposed. It was determined that cold losses during exergy analysis during storage are caused by both losses through sur-faces and internal exergy losses (i.e., exergy consumption due to irreversibility within the reservoir). For modern systems, exergy losses encompass both external and internal components. As an example, if the heat transfer at the external surface temperature of the storage reservoir equals the ambient temperature, external exergy losses would be zero, while total exergy losses would be entirely due to internal consump-tion. Conversely, if heat transfer occurs at the liquid's temperature for storage, a greater portion of exer-gy losses will be due to external losses. In all cases, the cumulative exergy losses, comprising internal and external exergy losses, remain constant.The implementation of CTES allows for shifting the use of electrical energy from peak to off-peak hours. During off-peak hours, electrical energy is used to charge the storage to fulfil (fully or partially) the peak demand for refrigeration equipment. Ice-based ITES has the potential to reduce maximum energy consumption, peak demand, and most importantly, the average cost of energy consumed.
A study of water ice formation and melting processes on vertical cooled pipes
(2016) Zasiadko, Yaroslav; Pylypenko, Oleksii; Forsyuk, Andriy; Gryshchenko, Roman
The use of cold accumulators based on the principle of water ice formation on the cooled surfaces during off-peak periods and water ice melting during on-peak periods is an effective method of electricity bills reduction. Within comparatively short periods of on-peak demand a noticeable amount of thermal energy related to ice melting is to be released, it becomes clear that not only sizing of ice accumulators based on balance calculations is actual, but also the determination of time periods of ice accumulation becomes critical. This work presents an experimental unit for obtaining data on the ice formation on the vertical cooled pipes and later on to continuously register data on the ice thickness diminishing at the regimes of ice melting when cooling of pipe stops. The data for ice formation and melting for some regimes have been presented and analyzed. The data form the base for deriving semi-empirical correlations allowing to determine time intervals necessary to generate of water ice layers of given thickness.
3-D modeling of water flow and cooling down within the temperature range close to inversion point
(2016) Gryshchenko, Roman; Zasiadko, Yaroslav; Forsyuk, Andriy; Pylypenko, Oleksii
The research and simulation of heat transfer during water refrigeration in the experimental section close to the vertical pipe which is cooled down considering abnormal character of water density change from the temperature in close to inversion point (+4°C) section were investigated. The graphs of water temperature velocity distribution throughout the height of experimental section were constructed and analyzed. The results obtained allow estimating the impact of water temperature that is closely situated to inversion point on the dynamics of water ice melting and generation as well as on the form factors of cold accumulators. Such software and analytical research will allow increasing effectiveness and efficiency at the heat and bulk transfer equipment engineering.
Experimental and theoretical study of ice formation on vertical cooled pipes
(2015) Zasiadko, Yaroslav; Pylypenko, Oleksii; Gryshchenko, Roman; Forsyuk, Andriy
Dynamics of ice accumulation on the surface at different ∆t (refrigerant evaporation temperature and the temperature of water that overflows surface) has been studied. Series of experiments have been carried out with 2 refrigerants (R12 and R22). The temperatures of water and that of refrigerant evaporation have varied within the intervals +1,5÷+4,50C; -10÷-200C, respectively. The mass flow rate and the velocity of water within the experimental sections were kept constant during a whole series of experiments. The ice-layer thickness was measured by means of optical method. The instantaneous images of the experimental pipe with the ice layer were processed with the graphic processing software.

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