Cold Thermal Energy Storage System Research Articles

Optimization of a cold thermal energy storage system with micro heat pipe arrays by statistical approach: Taguchi method and response surface method

Optimization of a cold thermal energy storage system with micro heat pipe arrays by statistical approach: Taguchi method and response surface method

Photovoltaic-powered seasonal snow storage-assisted district cooling system: Site suitability analysis and performance assessment

District cooling (DC) plants coupled with cold thermal energy storage (TES) and photovoltaic (PV) systems are getting attention worldwide. Utilising winter snow is a successfully implemented TES technology, with little scale-up. Its site identification and cooling potential are not yet fully explored, especially for DC applications. The objective of this paper is to carry out site suitability analysis and performance assessment for PV-powered snow storage-assisted DC system. The site selection methodology is based on multi-criteria decision-making techniques and geographic information system. Performance analysis is carried out mathematically by considering ten indicators. The robustness of the study is enhanced by multiple sensitivity analysis. For the base case scenario, the dominant selection criteria are observed to be cooling load density (30 %), proximity to electric grids (17 %) and air temperature (13 %). Out of the selected land cover (vacant/crops/rangeland) in Estonia, around 34 km2 was observed to be moderately-suitable for the development of the proposed system. For a specific site, the theoretical generation potential of snow cooling facility is estimated as 1728 MWh with an annual cooling share of 80 %. With annual energy output of 1823 MWh and performance-ratio of 78 %, rooftop PV plants is capable to fully power the proposed system. A satisfactory economic and environmental performance is observed at the whole system level. This study is expected to scientifically support the effective utilisation of locally available energy sources (i.e. winter snow and solar energy) for space cooling applications in cold regions.

Experimental performance of avocado seed oil as a bio-based phase change material for refrigeration applications

Bio-based phase change materials (BPCMs) derived from agro-industrial residues represent an ecofriendly alternative for refrigeration applications. In this work, a BPCM was obtained by steam extraction from avocado seed and studied as a suitable cold thermal energy storage system. First, differential scanning calorimetry was used to determine that the solid-liquid phase transition occurred from -27°C to 15°C. This temperature range is of interest for the conservation different food products. The study aimed to determine the best distribution of the material, which was stored in plastic packaging bags, and placed in an insulated polystyrene thermal container. Two configurations were evaluated: (i) four bags of 75 mL, (ii) two bags of 75 mL and one of 150 mL. The temperatures of the avocado seed oil, and of the air inside the container, were measured during 6 to 8 h. It was concluded that, despite working with the same amount of avocado seed oil (300 mL) in different experiments, there was a better performance when the same volume of material was distributed in each wall. Furthermore, the utilization of avocado seed oil allowed to maintain low temperatures, suitable for food preservation during two additional hours. In the same way, in a yogurt storage experimentation of 8 h, the utilization of the avocado oil enhanced the temperature preservation by 6°C on the phase change range from 4°C to 14°C. While compared to water, the temperature difference was evaluated showing a good performance of the BPCM and an important stability on the temperature heating rate.

EN Optimization strategy for system management of cold thermal energy storage (CTES) in conditions of dynamic changes in energy carrier value

In 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 optimizing energy generation systems, taking into account the utilization of alternative and renewable energy sources. Specifically, thermal energy storage becomes crucial as an effective economic option. Thermal 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 electricity tariffs, cooling loads, and ambient temperature. This leads to suboptimal achievement of maximum savings in the utilization of 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 simplified 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 surfaces 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 consumption. Conversely, if heat transfer occurs at the liquid's temperature for storage, a greater portion of exergy 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

Exergoeconomics of a Solar-Assisted Double-Effect Absorption Cogeneration System Integrated With a Cold Thermal Energy Storage System

Abstract The cogeneration system described in this paper is constructed based on a solar-assisted double-effect absorption cogeneration cycle with an adjustable cooling-to-power ratio. As a proposed technique to benefit from the ability to adjust the cooling-to-power ratio, this system is integrated with a cold thermal energy storage system. The procedure described here will be applied to a combined cooling and power system with a thermal energy storage capability for a large medical center in Jeddah, Saudi Arabia. Through an exergoeconomic analysis of the integrated system on a typical summer day in Jeddah, we found that the integrated system could fulfill the cooling and power demands of the medical center under study with an exergetic efficiency of 53.97%. From an economics perspective, the integrated system was found to deliver cooling and power with average unit costs of 222.89 $/GJ and 17.06 $/GJ, respectively. These costs were found to be lower than the unit costs of the respective cooling and power costs delivered to the medical center if they were obtained from an electrically-driven vapor compression system and the electric grid, respectively. For the case study investigated, it has been found that using the integrated system is a desirable approach due to the system’s lower unit costs as well as its relatively short payback period. Additionally, it has been found that although cogeneration systems constructed based on the double-effect combined cooling and power cycle have higher exergy destruction and capital investment rates, they have a lower unit cost for the produced exergy in comparison with those of cogeneration systems constructed based on a single-effect combined cooling and power cycle.

Optimal insulation of underground spherical tanks for seasonal thermal energy storage applications

The literature deals specifically with compressed gas characteristics, solar radiation, storage volume and heat load fluctuation in aboveground storage and thermal energy storage (TES) applications. To prevent their negative effects, the use of underground insulated spherical tanks in the storage process has been overlooked. This study details the physical and economic aspects of using insulation in underground spherical tanks for seasonal TES systems. In determining the storage heat load, the degree-time method is recommended for the heat transfer mechanism between soil and storage temperature degrees. Using life cycle cost analysis, the insulation thickness, energy saving and payback period in the underground spherical tank are discussed in detail for hot and cold storage capacities. The results of the study indicated that the degree-hour method can be used in the design of hot and cold TES systems despite the temperature fluctuation. Insulation can be taken care of in hot fluid storage instead of cold alternative. With insulation in the underground spherical tank, it is observed than about 200 % energy savings is possible with approximately 50 % shorter payback period. For the hot fluid storage with insulation, as the storage fluid temperature, soil thermal conductivity and tank diameter rise and the depth falls, but the optimum insulation thickness value increases. As a result, this study is expected to be a guide for further seasonal TES applications using insulation in underground spherical tanks.

Lattice Boltzmann simulation of coupled depressurization and thermal decomposition of carbon dioxide hydrate for cold thermal energy storage

CO2 hydrate is a potential cold thermal energy storage material with latent heat of 500 kJ/kg, however, the dissociation principle of CO2 hydrate is different from that of solid-liquid phase change materials and therefore, exploring the dissociation mechanism of CO2 hydrate is of great significance for efficient cold storage. In this paper, a new lattice Boltzmann model is proposed, considering dissociation kinetics, two phase flow, heat transfer, latent heat, surface reaction, thermal buoyancy and variable parameter depended with temperature. The necessity of the temperature consideration related with latent heat and buoyancy is clarified. For the combined effect of depressurization decomposition and thermal decomposition of CO2 hydrate dissociation, depressurization decomposition diminishes as time increases and initial pressure increases and thermal decomposition enhances as hot wall temperature increases. The fully dissociated Fo is 0.544, 0.514, 0.604, 0.628, showing a first decreasing and then increasing trend while initial pressure increases from 0 to 0.002, 0.004, 0.006 lu. As hot wall temperature increases from 8, 10, 12–14 °C, the fully dissociated Fo is 0.566, 0.544, 0.473 and 0.419 respectively. This new lattice Boltzmann model is of significance in providing guidance for the future cold thermal energy storage system application by using CO2 hydrate.

Thermal performance of cold thermal energy storage system with fin and fin–foam structures

The heat transfer performance of most cold thermal energy storage (CTES) devices is limited by the low thermal conductivity of phase change materials (PCMs) and the increase in the thickness of PCMs. A comparative work was performed to explore the heat transfer performance of CTES systems with a fin structure (Fin-CTES) and a fin–foam structure (Fin–foam-CTES). The heat transfer performance, temperature distribution, and thermal effectiveness of Fin-CTES and Fin–foam-CTES at different inlet temperatures and volume flow rates of heat transfer fluid were investigated and compared. Results demonstrated that the overall heat transfer performance of Fin–foam-CTES is better than that of Fin-CTES. However, compared with the PCM in Fin-CTES, that in Fin–foam-CTES has a greater degree of supercooling, reaching 4.35 °C at the maximum. In the discharging (melting) process, Fin-CTES and Fin–foam-CTES have almost similar heat transfer effectiveness, in which the maximum difference is only 0.0107. That is, the enhanced heat transfer effect of the natural convection of the liquid PCM and the metal foam is basically the same during the discharging process.

Influence of various additives on stability and phase change characteristics of DI water-GnP-based NFPCM for cold thermal energy storage systems.

The present work aims to investigate the effects of various additives on the stability of graphene nanoplatelet (GnP)-based nanofluid phase change material (NFPCM) for cold thermal energy storage (CTES). The NFPCMs are prepared by dispersing six different types of surfactants (anionic, cationic, and non-ionictypes) in deionized (DI) water at a mass ratio of 1:0.5 GnP to surfactant. NFPCMs can be found to be stable with a suitable surfactant even after 30days using zeta-potential distribution, UV-vis absorption, visual inspection, and sedimentation tests at low temperature. The maximum enhancement in thermal conductivity of 8.3% and 48.3% is recorded in both liquid and solid states for the NFPCM with gum arabic (GA) respectively. The viscosity was enhanced by the dispersion of non-ionic surfactants, where the anionic surfactant (sodium dodecylbenzene sulfonate (SDBS)) NFPCM had a 29.9% lower augmentation compared to DI water. Furthermore, differential scanning calorimetry (DSC) results demonstrate that the phase change properties of the NFPCM are significantly affected depending on the surfactant type. The maximum phase change enthalpy is lowered (10.6%) in the Tween 80 NFPCM as compared to the base PCM. The long-term stability with the highest thermal transport property of the NFPCM storage unit integrated with the chiller is capable of achieving environmental pollution remediation by minimising the time it takes to charge the PCM.

Compound Heat Transfer Augmentation of a Shell-and-Coil Ice Storage Unit with Metal-Oxide Nano Additives and Connecting Plates.

Due to the high enthalpy of fusion in water, ice storage systems are known as one of the best cold thermal energy storage systems. The phase change material used in these systems is water, thus it is inexpensive, accessible, and completely eco-friendly. However, despite the numerous advantages of these systems, the phase change process in them is time-consuming and this leads to difficulties in their practical application. To solve this problem, the addition of nanomaterials can be helpful. This study aims to investigate the compound heat transfer enhancement of a cylindrical-shaped unit equipped with double helically coiled coolant tubes using connecting plates and nano additives as heat transfer augmentation methods. Complex three-dimensional numerical simulations are carried out here to assess the best heat exchanger material as well as the impact of various nanoparticle types, including alumina, copper oxide, and titania, and their concentrations in the PCM side of the ice storage unit. The influence of these parameters is discussed on the charging rate and the temperature evolution factor in these systems. The results suggest that using nano additives, as well as the connecting plates, together is a promising way to enhance the solidification rate by up to 29.9%.

Experimental and unified mathematical frameworks of water-ice phase change for cold thermal energy storage

Cold thermal energy storage (CTES) is a process that supplies cold thermal energy to a medium for storage and extracts it whenever is needed. The storage medium is phase change material (PCM), which makes great use of the large quantity of latent heat released during solidification or melting. However, some key fundamental and applied issues have not yet been resolved: how do we overcome the thermal interference in PCMs from unstable microscopic crystallization and external mechanical forces? Are there any unified and robust models to predict the whole time evolution of phase change accurately and rapidly? To fulfill these research gaps, we firstly establish a novel, well-controlled experimental system for PCMs that mitigates the thermal disturbance over a medium to large volume during solidification, capable of measuring transient temperature data and characterizing freezing stages at both macro- and micro-scale. We also develop in detail a unified semi-analytical mathematical framework to model the solidification of PCMs, consisting of five subsequent stages: liquid supercooling, nucleation, recalescence, equilibrium freezing, and solid subcooling. The modeling results yield a good agreement with our experimental data in several scenarios, particularly the nucleation temperature and time as well as the total freezing time are accurately predicted. Lastly, we extend our study to investigate the thermal effects of various radial positions, geometries, initial temperatures, heat transfer fluid temperature, and heat transfer coefficients in the context of CTES system.

Experimental investigation of the heat transfer from the helical coil heat exchanger using bubble injection for cold thermal energy storage system

This study investigates cold thermal energy storage (CTES) using a helical coil heat exchanger modified with bubble injection. One of the effective methods for increasing the heat transfer rate in heat exchangers is using bubble injection. A helical coil heat exchanger is immersed inside a cylindrical water storage tank, where the helical coil is the evaporator of a vapor compression refrigeration cycle (VCRC) and provides the designed cooling. Experimental studies were carried out to examine the impact of bubble injection on Nusselt number, the temperature differences in the storage tank, exergy degradation in the evaporator, and cycle coefficient of performance (COP). The bubbles were injected from the bottom of the storage tank in four different geometries at airflow rates ranging from 3 to 11 L/min. The experimental results of this study revealed that bubble injection could significantly increase the COP and heat transfer rate from the storage tank, as well as the exergy destruction and Nusselt number (Nu). This increase was highly dependent on the geometry and flow rate of the bubble injection. The results also indicated that the bubble injection has an optimal flow rate value, which was 9 L/min in this study. More specifically, the COP of the refrigeration cycle and the Nu number increased by 124% and 452%, respectively, compared to the non-bubble injection mode. Finally, for calculating the outside Nusselt number of the helical coil, an empirical correlation as a function of bubble flow rate and bubble injection angle was proposed.

Development of composite phase change materials based on n-tetradecane and β-myrcene based foams for cold thermal energy storage applications

β-myrcene based foam / n-tetradecane composite phase change materials (PCMs) were prepared for cold thermal energy storage systems. β-myrcene based foams were synthesized as PCM support material, while n-tetradecane was selected as organic phase change cold storage material due to its appropriate phase change temperature and high heat storage capacity for supplying temperature requirements of the food refrigeration, storage and transportation systems. The polymer foams were prepared in presence of different nanoclay particles by using β-myrcene as bio-based monomer and ethylene glycol dimethacrylate as crosslinker. The form-stable composite PCMs were obtained via impregnation of n-tetradecane into the porous frameworks in one-step. Based on the results, the highest latent heat was measured as 82.14 J/g for form-stable composite PCM, which has framework with higher cavity diameters besides to higher surface area, while the melting and crystallization temperatures determined as 4.37 °C and 1.73 °C.

Research Progress on the Phase Change Materials for Cold Thermal Energy Storage

Thermal energy storage based on phase change materials (PCMs) can improve the efficiency of energy utilization by eliminating the mismatch between energy supply and demand. It has become a hot research topic in recent years, especially for cold thermal energy storage (CTES), such as free cooling of buildings, food transportation, electronic cooling, telecommunications cooling, etc. This paper summarizes the latest research progress of the PCMs-based CTES. Firstly, the classification of PCMs for low temperature storage is introduced; the thermal physical properties (e.g., phase change temperature (PCT) and latent heat) of suitable PCM candidates (−97 to 30 °C) for CTES are summarized as well. Secondly, the techniques proposed to enhance the thermal properties of PCMs are presented, including the addition of nanomaterials, the microencapsulation and the shape stabilization. Finally, several representative applications (−97 to 65 °C) of PCMs in different CTES systems are discussed. The present review provides a comprehensive summary, systematical analysis, and comparison for the PCMs-based CTES systems, which can be helpful for the future development in this field.

Amine infused hydrogel-based CO2 gas storage technology for CO2 hydrate-based cold thermal energy storage

Carbon dioxide (CO2) hydrate-based cold thermal energy storage (CTES) is a promising method for load shifting and demand management of cooling systems and for CO2 utilisation. A challenge of CO2 hydrate-based CTES is to find a compatible CO2 gas storage, the CO2 regeneration and absorption conditions of which can be coupled with the charging and discharging conditions of the CTES, respectively. Amine diethanolamine infused hydrogels (DEAIHs) can be an effective CO2 absorber as the gas–DEA surface contact area is greatly enlarged by infusing the solution into a hydrogel. However, the influencing factors of the CO2 absorption and regeneration performance of DEAIHs are unknown. This paper investigates the performance of DEAIHs and explores the possibility of applying them in cyclic CO2 gas storage for CTES. The effects of pressure, temperature, DEAIH sample mass and amine diethanolamine (DEA) mass fraction on CO2 absorption and absorption rate are investigated. It was found that a higher pressure prompted CO2 absorption while a temperature of 12℃ resulted in the highest CO2 absorption rate. The average CO2 absorption rates in the first 100 min were 0.250, 0.228, 0.155 and 0.033 mmol min–1 for 20-g DEAIH sample with 30-wt% DEA and 60-g DEAIH sample with 30, 47 and 89-wt% DEA, respectively. CO2 regeneration from DEAIH under zero and non-zero gauge pressures are studied. Under non-zero gauge pressures, a pressure rise followed by a pressure drop caused by CO2 re-absorption appeared in the CO2 regeneration from DEAIH. It was found for the first time that the system passed through a meta-equilibrium state before it reached an equilibrium pressure. Cyclic absorption and regeneration at 110℃ under zero gauge pressure showed that the CO2 absorption decreased dramatically after the third cycle due to the volatility of amine. Operating a coupled CO2 hydrate-based CTES and CO2 gas storage system demonstrated the possibility of DEAIH material for CO2 gas storage in CTES systems.

Experimental Investigation on Enhanced Energy Storage Characteristics of Spherically Encapsulated 1-Decanol/Expanded Graphite Composite for Cold Storage System

The low solidification temperature (0°C), sporadic nucleation behaviour and supercooling phenomenon of ice are the major factors affecting the energy storage efficiency of an ice-based cold thermal energy storage system (CTESS). Due to the non-supercooling nature and high solidification temperature (~4.1°C), 1-Decanol-Expanded graphite composite (CPCM) is proposed as a prospective replacement for ice in CTESS. The CPCM was macro encapsulated inside the various diameter (42, 51 and 64 mm) spherical enclosures (S.Es), and its energy storage performance was studied at different wall temperatures (Tw) for charging (0,-3 and -6°C) and discharging (10, 13 and 16°C). It is found that the latent heat can be stored in CPCM even at a higher wall temperature (-3°C), which is not possible in the case of ice. To freeze the same mass of 1-Decanol at Tw = -6°C, the CPCM filled 51 mm S.E requires 85.37% lower time than that of PCM filled S.E. Based on experimental results, -3 and 13°C is found as an optimum wall temperature for charging and discharging, respectively. The charging and discharging rates increase with diameter. Besides, in a 51 mm S.E, the time required to store (Tw = -3°C) and recover (Tw = 16°C) a stated amount of energy in CPCM is 81.27%, and 76.45% lower than that of PCM, respectively. CPCM has superior phase change and energy storage characteristics. Therefore, the use of CPCM in CTESS ensures effective storage and recovery of cold energy.

Experimental Study of Semiclathrate Hydrates Formation TBAOH, TBAF, and TBAC in the Presence of SDS and Tween Surfactants as a Cold Thermal Energy Storage System for Air Conditioning Applications

Experimental Study of Semiclathrate Hydrates Formation TBAOH, TBAF, and TBAC in the Presence of SDS and Tween Surfactants as a Cold Thermal Energy Storage System for Air Conditioning Applications

Amassing of Cold Thermal Energy by Utilizing Phase Shift Material: A Review

Storing of cold energy is a predominant area in the cold thermal energy storage system in which the PCM plays a major role in hosting this energy storage process. This study fetches an encyclopedic review based on the current and erstwhile research in the field of cold energy storage using PCM. This dissertation provides an expansive view of the PCM solidification with the methodology of reducing the sub-cooling with the ramping up of heat flow rate besides of variegated nano-particulate and with protrusions. The effect of the fill volume of PCM in solidification is also delineated and how the size and material of PCM containment plays a role in solidification is also scrutinized and eventually, the application area of PCM cold storage is also explored.

Facile approach to fend off the supercooling phenomenon of water in a spherical enclosure for energy-efficient and sustainable cold thermal energy storage system

Performance of an ice-based cold thermal energy storage system (CTESS) is immensely affected by its supercooling nature. In this research, it was mitigated entirely using 1-Decanol as a nucleating agent, which has favourable properties such as absence of supercooling, low cost, suitable phase change temperature (5 °C) and reasonable freezing enthalpy (200 J g−1). The optimum concentration of 1-Decanol required to eliminate the supercooling nature of water is found to be 2 wt%. Moreover, charging characteristics of water with 2 wt% 1-Decanol were explored in various diameter spherical capsules (42, 51, 64, 75, 85, and 105 mm) at −3, −6, and −9 °C wall temperatures. The addition of 2 wt% 1-Decanol eliminated the supercooling nature of water in all diameter capsules at all wall temperatures. As a result, complete solidification time is considerably reduced. Based on freezing time and charging rate, the optimum wall temperature is found to be −6 °C. Experimental results concede that 1-Decanol is highly reliable in eliminating supercooling, and its addition only led to 0.79% reduction in energy storage capacity. Mitigation of supercooling significantly reduced the chiller operating time and wall temperature required for charging, which further leads to utilisation of energy efficiently and sustainably.

A techno-economic assessment on the adoption of latent heat thermal energy storage systems for district cooling optimal dispatch & operations

The adoption of high-density phase change materials as cold thermal energy storage media have been considered as potential alternatives to water and ice. In this paper, the implementation of these media has been investigated in the context of district cooling in mixed-used building micro-grids whereby the cold thermal energy storage is retrofitted into an existing eco-building cluster. The techno-economic feasibility of implementing phase change materials, which includes eutectic salt, polyethylene glycol and paraffin as cold thermal energy storage media for district cooling, have been evaluated by computing the economic dispatch of a cooling bus network using mixed-integer quadratic programming. Furthermore, the impact of high-density storage media with a reduced footprint on the integration and design of cold thermal energy storage systems in district cooling has been included in the analysis. The capital expenditure of cold thermal energy storage systems, the land rental price for required occupancy and operating expenditure are used to determine the net present value after 20 years. Through peak shaving, optimally sized cold thermal energy storage has shown a better alternative substituting one of the two chillers. The smaller chiller (1200 kWc) is no longer required in the plant, giving significant savings in capital expenditure. The cost-benefit analysis also showed that only eutectic salt phase change materials are competitive with ice, with a net present value approaching 200,000 $ after 20 years. When phase change materials are adopted, especially if compared with water, the building operations and related costs are significantly less affected by large fluctuations in land rental price given its smaller footprint, thus posing significantly lower financial risks.