Thermal Energy Storage Tank Research Articles

AN INVESTIGATION STUDY ON OPERATIONAL STATE OF A WATER THERMAL STORAGE SYSTEM

A multi-connected complete mixing type thermal energy storage tank consists of divided tanks with connecting holes. Connecting holes should be installed to promote complete mixing of each divided tank alternatively. However, their arrangements, especially in aged tanks, are not always the most suitable, and mixing state in each divided tanks could be deteriorated. Aiming to investigate mixing state of thermal storage tank, we carried out detailed measurement in aged thermal storage tank after remodeling. It was found that divided tank with inappropriate arranged connecting holes results in thermal stratification.

Experimental investigation on heat recovery from diesel engine exhaust using finned shell and tube heat exchanger and thermal storage system

The exhaust gas from an internal combustion engine carries away about 30% of the heat of combustion. The energy available in the exit stream of many energy conversion devices goes as waste, if not utilized properly. The major technical constraint that prevents successful implementation of waste heat recovery is due to its intermittent and time mismatched demand and availability of energy. In the present work, a shell and finned tube heat exchanger integrated with an IC engine setup to extract heat from the exhaust gas and a thermal energy storage tank used to store the excess energy available is investigated in detail. A combined sensible and latent heat storage system is designed, fabricated and tested for thermal energy storage using cylindrical phase change material (PCM) capsules. The performance of the engine with and without heat exchanger is evaluated. It is found that nearly 10–15% of fuel power is stored as heat in the combined storage system, which is available at reasonably higher temperature for suitable application. The performance parameters pertaining to the heat exchanger and the storage tank such as amount of heat recovered, heat lost, charging rate, charging efficiency and percentage energy saved are evaluated and reported in this paper.

Experimental Testing of a Thermoelectric-Based Hydronic Cooling and Heating Device With Transient Charging of Sensible Thermal Energy Storage Water Tank

Experiments were performed to charge either cold or hot water thermal energy storage tanks using a heat exchanger equipped with multiple thermoelectric (TE) modules. The primary objective was to design a simple, but effective, modular Peltier heat pump system component to provide chilled or hot water for domestic use at the appliance level, and when arranged in multiple unit combinations, a system that can potentially satisfy small home cooling and heating requirements. Moreover, when the TEs are directly energized using solar photovoltaic (PV) panels, the system provides a renewable, pollution-free, and off-the-grid solution to supplement home energy needs. The present work focuses on the design and testing of a thermoelectric heat exchanger component that consists of two water channels machined from two aluminum plates with an array of three, five, or eight thermoelectric modules placed in between to transiently cool and/or heat the water in the thermal energy storage tank. The water passing over either the cold or hot side of the TE modules is recirculated to charge the cold or hot thermal storage tank, respectively. The temperatures in the prototype Peltier heat exchanger test component and thermal energy water storage tank were measured during both cold and hot tank charging operations. The thermal efficiencies of the TE heat pump cooling/heating system are reported. The effects of the TE power input, number of TE units, rate of fluid flow, and heat sink/source temperature are studied.

Analysis of Thermal Energy Storage for a Pharmaceutical CompanyAnalyse eines thermischen Energiespeichers für ein pharmazeutisches Unternehmen

Abstract A pharmaceutical facility located in Southern Germany is experiencing a trend of growing cooling loads to be met by the chilled water plant composed of ten chillers of greatly varying cost effectiveness. With a capacity shortfall inevitable, the question arises whether to install an additional chiller or improve the utilization of the existing chillers, in particular those with low operating costs per unit cooling, through the addition of a chilled water thermal energy storage (TES) system. To provide decision support in this matter, an optimization environment was developed and validated that adopts mixed integer programming as the approach to optimizing the chiller dispatch for any load condition, while an overarching dynamic programming based optimization approach optimizes the charge/discharge strategy of the TES system. In this fashion, the chilled water plant optimization is decoupled but embedded in the TES control optimization. The approach was selected to allow for arbitrary constraints and optimization horizons, while ensuring a global optimum to the problem. The results show that a relatively small TES tank provides significant economic and operational benefits. Yet, in order to facilitate long-term supply security, a larger TES tank capacity was decided on and the TES system was constructed in 2008.

Cold storage with ice slurries

The storage of ‘cold’ with ice slurries—a special type of thermally multi-functional fluids or phase change slurries (PCS)—is discussed. At first an example of a calculation of a thermal energy storage tank in an ice slurry system with a peak load demand is presented. Then a new concept of ice slurry storage without mixing is introduced. It leads to ice particle stratification and front propagation in the storage vessel. The stratification of ice particles in ice slurry is theoretically described by multi-component multi-phase fluid dynamics. The resulting stratification process is calculated and front propagation times are compared with experimental results; they compare fairly well. Copyright © 2007 John Wiley & Sons, Ltd.

Extension of heat transfer area using carbon fiber cloths in latent heat thermal energy storage tanks

Carbon fiber cloths are stretched among heat transfer tubes to extend the heat transfer area in latent heat thermal energy storage tanks. The thermal responses of the tanks into which paraffin wax as the thermal energy storage material is packed are experimentally investigated. The experimental results show that the carbon fiber cloths of only 0.4 vol.% improve the heat exchange rate in the tanks. A numerical model describing the heat transfer in the tank well predicts the experimental results. Moreover, the effect of the carbon fiber cloths on the thermal performance for a practical scale tank is numerically discussed.

06/00781 Performance analysis of a solar-assisted ground-source heat pump system for greenhouse heating: an experimental study: Ozgener, O. and Hepbash, A. Building and Environment, 2005, 40, (8), 1040–1050.

This paper investigates the techno-economic feasibility of geothermal deep direct-use for heating, cooling, and thermal energy storage in the United States. The six 2017–2019 deep direct-use projects funded by the U.S. Department of Energy are reviewed and evaluated using the simulation tool GEOPHIRES, and results are compared with prior studies, existing geothermal district heating systems in Europe and the United States, as well as non-geothermal centralized and non-centralized heating, cooling, and thermal energy storage systems. Analysis indicates that deep direct-use feasibility varies widely, depending on subsurface characteristics, system design, and financial conditions. Project base case levelized cost of heat values ranged between $13 and $350/MWh; key drivers lowering the levelized cost of heat include higher reservoir temperatures, shallower reservoir depths, higher well flow rates, higher utilization rates, lower drilling costs, and lower discount rates. Incentives such as grants and an investment tax credit resulted in small improvements in project economics. Base case levelized cost of heat values for four projects fell within the range of levelized cost values for existing systems in Europe and the United States, and were comparable to values found in previous studies, including the 2019 GeoVision study. The lowest-cost projects for district heating had comparable levelized cost of heat values to existing fossil-fuel-driven district heating systems, and lower values than decentralized heating with natural gas boilers or heat pumps. Chilled water production with absorption chillers driven by a high-quality geothermal resource obtained attractive levelized cost of cooling values, in line with values from typical centralized cooling production facilities and lower than domestic decentralized cooling with air-conditioning units. Also, thermal energy storage is a potential deep direct-use application, where levelized cost of storage values can be obtained that are comparable to those of other thermal storage techniques such as borehole thermal energy storage and hot water storage tanks. Other aspects of deep direct-use, which are not captured in a standard levelized cost of energy metric, include the ability to decarbonize the heating and cooling supply, and provide reliability and resiliency to the energy infrastructure. These attributes are gaining increased attention and improve overall project feasibility. Finally, this paper identifies technical, market, policy, and social barriers for deep direct-use development in the United States, and provides potential approaches for reducing these barriers.

06/00609 Latent heat thermal energy storage tanks for space heating of buildings: Comparison between calculations and experiments: Hamada, Y. and Fukai, J. Energy Conversion and Management, 2005, 46, (20), 3221–3235.

06/00609 Latent heat thermal energy storage tanks for space heating of buildings: Comparison between calculations and experiments: Hamada, Y. and Fukai, J. Energy Conversion and Management, 2005, 46, (20), 3221–3235.

Latent heat thermal energy storage tanks for space heating of buildings: Comparison between calculations and experiments

Latent heat thermal energy storage tanks, where carbon fiber brushes are inserted to improve the heat transfer rates in the phase change materials, are installed in an air conditioning system of a building as a space heating resource. The measured outlet fluid temperatures are compared with the numerical ones predicted by a previously developed three dimensional heat transfer model. The preliminary numerical results had unallowable prediction errors, which probably resulted from poor contact between the brushes and the heat transfer tubes due to an installation problem of the brushes. However, the numerical results predicted by a corrected model agree well with the experimental ones under various operating conditions. The effect of the brushes on the thermal outputs of the tanks is then investigated using the corrected model. The result shows that the brushes contribute to saving space and reducing the cost of the tanks.

Computational model for a ground coupled space cooling system with an underground energy storage tank

A computational model for determining annual periodic performance of a cooling system utilizing a ground coupled chiller and a spherical underground thermal energy storage tank is developed. An analytical solution for the transient heat transfer problem outside the storage tank is obtained by the application of complex finite Fourier transform (CFFT) technique. Analytical expressions for heat gain to the space and energy consumption of the chiller are acquired, and these expressions are coupled with the transient temperature field problem to obtain computational model. Variation of water temperature in the storage tank is calculated using the transient solution of the problem over an entire year for different soil, chiller, and storage tank characteristics. Temperature profile of earth surrounding the storage tank and the COP of the cooling unit are also investigated under various assumptions and varying system design and operating conditions. The results show that water temperature in the storage tank remains under ambient air temperature during summer months, and thus the proposed ground coupled cooling system should yield higher COP values compared to a corresponding air source system.

鉛直弾性発熱体群からの熱抽出特性に関する研究(オーガナイズドセッション3 蓄冷・蓄熱および熱輸送機器)

Flow and heat transfer characteristics were examined experimentally on vertical flexible channels in a heat exchanger simulating the thermal energy storage tank with PCM rod capsules. The channels were formed as the gaps, which were composed of 7 flexible circular heating rods, 34 mm OD. x 1.5 m high, packed vertically in a tubular container of 104 mm ID. One rod in the center of the container was surrounded by the other 6 rods. Difference between the water flow rates in 6 smaller channels (around the central rod) and in the other larger ones (composed of the outer 6 rods and the container wall) was much smaller than expected. This showed the existence of the cross flow between the inner and outer channels caused by the deformation of the rods. The heat transfer rate was increased by about 25 %, which might be due to the heat transportation by this cross flow.

炭素繊維クロスを用いた潜熱蓄熱槽の性能予測(オーガナイズドセッション3 蓄冷・蓄熱および熱輸送機器)

炭素繊維クロスを用いた潜熱蓄熱槽の性能予測(オーガナイズドセッション3 蓄冷・蓄熱および熱輸送機器)

Determination of the amount of thermal energy in the tanks of buildings heating systems

The distribution of temperature according to the height in the heat storage stratified water tanks designed for the heating of premises is uneven. In order to determine possible thermal energy amount stored in the tank it is necessary to know the residual water temperature in the tank. In the experiments with vertical thermal energy storage tanks of 0.31, 0.9 and 1.5 m diameter, we determined that at a duration of charging of 8 h, and discharging of 16 h, the value of temperature transitional zone height at 90% probability is 0.47±0.03 m. Using analytical methods we worked out carry-overs for the determination of residual temperature of heat accumulating tanks with external and internal heat sources. It was determined that in the heat storage tanks with internal heat source fitted at the bottom of the tank the residual water temperature is higher, and the amount of accumulated thermal energy is lower than in the tanks with external heat source.

Efficient heat utilization of a space cooling system over a range of atmospheric temperatures and solar radiation

Behavior of a space cooling system using the diurnal range of atmospheric temperatures in the summer is examined by numerical simulation. The system consists of radiators, a thermal energy storage tank, fan-coil coolers, and an electric cooler. Conditions for the calculation were obtained from actual weather records and characteristics of appliances. Total consumption of electric power was used for evaluating the system performance. The larger the volume of the storage tank becomes, the smaller the consumption. The consumption is smaller when the radiator is operated for a period of some limited hours than when operating through the night. To decrease the consumption, there are optimum values of the flow rate of the pumps and in the on–off temperature of the fan-coil cooler. Stratified tanks could reduce the consumption compared with mixed ones. This system has the possibility of reducing demand for electricity or of shifting the demand to off-peak hours. © 2001 Scripta Technica, Heat Trans Asian Res, 30(2): 126–138, 2001

Efficient heat utilization of a space cooling system over a range of atmospheric temperatures and solar radiation

Behavior of a space cooling system using the diurnal range of atmospheric temperatures in the summer is examined by numerical simulation. The system consists of radiators, a thermal energy storage tank, fan-coil coolers, and an electric cooler. Conditions for the calculation were obtained from actual weather records and characteristics of appliances. Total consumption of electric power was used for evaluating the system performance. The larger the volume of the storage tank becomes, the smaller the consumption. The consumption is smaller when the radiator is operated for a period of some limited hours than when operating through the night. To decrease the consumption, there are optimum values of the flow rate of the pumps and in the on–off temperature of the fan-coil cooler. Stratified tanks could reduce the consumption compared with mixed ones. This system has the possibility of reducing demand for electricity or of shifting the demand to off-peak hours. © 2001 Scripta Technica, Heat Trans Asian Res, 30(2): 126–138, 2001

Experimental and theoretical investigation of a solar heating system with heat pump

In this study, the performance of a solar heating system with a heat pump was investigated both experimentally and theoretically. The experimental results were obtained from November to April during the heating season. The experimentally obtained results are used to calculate the heat pump coefficient of performance (COP), seasonal heating performance, the fraction of annual load met by free energy, storage and collector efficiencies and total energy consumption of the systems during the heating season. The average seasonal heating performance values are 4.0 and 3.0 for series and parallel heat pump systems, respectively. A mathematical model was also developed for the analysis of the solar heating system. The model consists of dynamic and heat transfer relations concerning the fundamental components in the system such as solar collector, latent heat thermal energy storage tank, compressor, condenser, evaporator and meteorological data. Some model parameters of the system such as COP, theoretical collector numbers ( N c), collector efficiency, heating capacity, compressor power, and temperatures ( T 1, T 2, T 3, T T) in the storage tank were calculated by using the experimental results. It is concluded that the theoretical model agreed well with the experimental results.

Investigation of a combined solar-heat pump system for residential heating. Part 2: simulation results

In this study, a mathematical model of a solar-assisted heat pump system with latent heat energy storage for residential heating in Turkey was developed. The model consists of dynamic and heat transfer relations concerning the fundamental equipment in the system such as solar collector, latent thermal energy storage tank, compressor, condenser, evaporator and building heating load. Some model parameters of the system were calculated by using experimental results. It was found that the model agreed well with the experimental results. Copyright © 1999 John Wiley & Sons, Ltd.

Effective Heat Utilization of Range of Atmospheric Temperature and Solar Radiation. Performance of System using Diurnal Range of Atmospheric Temperature.

Behavior of space cooling system using the diurnal range of atmospheric temperature in the summer is characterized by numerical simulation. The system consists of radiators, a thermal energy storage tank, fan-coil coolers, and an electric cooler. Conditions for the calculation are assumed from the actual weather and characteristics of appliances. Total consumption of electric power is used for evaluating the system performance. The larger the volume of the storage tank becomes, the smaller the consumption becomes. The consumption is smaller in case the radiator is operated for a period of some limited hours than in case through the night. To decrease the consumption, there are also the most suitable values in the flow rate of the pumps and in the on off temperature of the fan-coil cooler. Stratified tanks could reduce the consumption by 3.3% compared with mixed ones. This system has a possibility to reduce demand for electricity or shift the demand to off-peak hours.

Modeling of an ice-on-coil thermal energy storage system

Stand-alone analytical models were developed for an ice-on-coil thermal energy storage (TES) system for both charging and discharging modes. This paper describes the basic heat transfer analysis and presents the characteristics of the charging and discharging modes determined from the model. The output results of the cooling charge model were the volume of ice in the TES tank and the cooling charge rate. Error analyses of the ice volume and cooling rate indicated that the model predictions were within 5 and 12%, respectively, of the experimental values. A factorial design sensitivity analysis was conducted to show that the variable T f - T max and the interactions ( T f - T max) × h o, h i × F, and h i × h o × F had significant effects on both the cooling charge rate and the ice radius. The output results of the cooling discharge model showed that the tank bulk water temperatures were within 5% of the experimental values. The sensitivity analysis showed that the variables h o and T ci, as well as the interactions m ̇ × % ice × T ci and m ̇ × h o × % ice , had significant effects on the bulk water temperature. Although the models involved various assumptions, the results were considered helpful for the design and understanding of the evaporator/ice storage tank.

95/05154 Challenges and achievements of a thermal energy storage tank

This article tracks the performance of a 1-million-gallon thermal energy storage (TBS) tank over a six-year period, 1986 through 1991, in a commercial application. Between 1986 when the TES came on line and 1991, the building occupancy rate increased from 40% to 90% while at the same time total cost to charge the TES dropped by 6%. In 1991 the yearly chiller run time (hours) to charge the TES was cut by 52% from the previous year. This article reports on the TES operational and maintenance practices between 1986 and 1990, the problems faced during that period, and the 1991 modifications that were implemented to improve performance and cut cost. As the division manger in charge of operation, maintenance and energy management, the author directed and implemented the various programs described.