Assessment of a novel technology for a stratified hot water energy storage – The water snake

Abstract

The increasing demand to enhance sustainability and reduce carbon emission and pollution is attracting the attention for implementing and integrating diverse heating technologies such as heat pumps, solar energy, gas boilers, Combined Heat and Power (CHP), and electric heaters. Integrated technologies for heating include low and high temperature district heating, domestic small-scale applications and commercial largescale buildings. Energy from flooded coalmines and water from other sources could also play a vital role in improving energy efficiency of heating and cooling applications. Stratified thermal storage are likely to significantly contribute to energy efficient heating, particularly when implementing a mixed-approach of diverse technologies. A stratified hot water tank, and naturally stratified reservoirs, are expected to play a central role in the integration of several heating technologies that operate efficiently at different levels of temperature with reduced cost. This paper presents a new innovative technology to improve stratification, namely 'the water snake', and an automated test rig to evaluate the new stratification method for energy utilisation using energy storage of hot water. An automated system is utilised to evaluate the performance. The results indicate that the test rig has been successful for the automated testing of the technology. Moreover, the results show that the water snake, as a new technology for stratification, is successful in minimising mixing and turbulence inside the thermal energy storage. The results prove that the technology could be implemented for a wide range of applications to enhance the efficiency of heating systems in buildings as well as district heating and cooling applications.

A Review on the Performance Indicators and Influencing Factors for the Thermocline Thermal Energy Storage Systems

“…Generally, the performance of the TES systems can be characterized by two distinc methodologies: the graphical manners (i.e., the cartographies for the temperature or flow fields within the storage tank) and the performance indicators (i.e., some parameters cal culated to describe one or several features of a TES system). The former ones are straight forward and can provide the detailed local features of temperature or velocity distribu tions [18,[23][24][25][26][27], but they cannot directly indicate the global performance of the thermo cline tanks. Since it is frequently needed to analyze the performance of a TES module in tegrated in a whole energy system, more general performance indicators are necessary Table 1 summarizes three categories of performance indicators for the thermocline TES systems.…”

“…Apparently, the temperature difference ∆T between the hot and cold fluids determines the buoyancy force of the thermal jets and then affects the fluid mixing driven by the buoyant plumes, and thus the working temperature range can be an important operating parameter. The experimental investigation of Al-Habaibeh et al [24] has clearly shown the trajectory movement by the means of the water 'snake' due to the temperature difference, including the positive ∆T or the negative ∆T. Table 4 summarizes the effects of ∆T for the various thermocline-based TES systems, including the systems without the packing, with the sensible solid fillers, and with latent PCM packing, respectively.…”

Surrogate modeling and optimization for the unequal diameter radial diffuser of stratified thermal energy storage tanks

“…There are two commonly used experimental measurement methods. One is inserting temperature sensors (e.g., thermocouples) at different heights of the tank 1 8–14 . The other is installing a temperature measurement cable vertically in the tank wall 15 .…”

Underground Hydro-Pumped Energy Storage Using Coal Mine Goafs: System Performance Analysis and a Case Study for China

“…These underground voids are usually left to be flooded, but often perpetual costs related to pumping to keep a safe water level or water treatment have to be maintained, becoming long-term liabilities. Some renewable/ sustainable post-mining solutions including underground reservoirs (Andrés et al, 2017), hydro-pumped energy storage (PHES) (Menéndez et al, 2017;Pujades et al, 2017), compressed air energy storage (CAES) (Kim et al, 2012;Fan et al, 2018a), thermal energy storage (Al-Habaibeh et al, 2018), and underground hydrogen storage (Simon et al, 2015) were proposed and proved viable by some researchers. The first documented CAES test using an abandoned mine was conducted in Japan.…”