General Performance Metrics and Applications to Evaluate Various Thermal Energy Storage Technologies

2012 ◽  
Author(s):  
Zhiwen Ma ◽  
Greg C. Glatzmaier ◽  
Michael Wagner ◽  
Ty Neises
Keyword(s):  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Performance Metrics ◽  
Storage System ◽  
Thermal Storage ◽  
Energy Storage System ◽  
Performance Model ◽  
Heat Transfer Fluid ◽  
Integral Approach

The solution proposed in this paper presents a new modeling approach that integrates a generalized thermal storage performance model into a concentrating solar power (CSP) plant. The overall performance, including round trip efficiency, for a thermal energy storage system is highly dependent on the operating parameters and operation strategy of the complete power plant. Previous methods used for analysis of thermal storage have followed one of two approaches: The first requires time-intensive customized detailed performance models of the thermal storage system and the power cycle to account for the effects of charging and discharging storage on conversion efficiency and heat transfer fluid (HTF) return temperature to the solar field. The second method uses a simple energy balance with “derate” factors that do not accurately predict the effects of storage on other plant components. In this paper, we develop a generalized method based on efficiency metrics and discuss the application in TES sizing and performance evaluation for an early concept study. The method is an integral approach and complements the detailed models that simulate yearly operation of a CSP plant.

Computational Analysis of a Pipe Flow Distributor for a Thermocline Based Thermal Energy Storage System

2013 ◽  
Vol 136 (2) ◽  
Author(s):  
Samia Afrin ◽  
Vinod Kumar ◽  
Desikan Bharathan ◽  
Greg C. Glatzmaier ◽  
Zhiwen Ma
Keyword(s):  
Energy Storage ◽  
Molten Salt ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Computational Analysis ◽  
Storage System ◽  
Flow Distribution ◽  
Energy Storage System ◽  
Heat Transfer Fluid ◽  
Case Scenario

The overall efficiency of a concentrating solar power (CSP) plant depends on the effectiveness of thermal energy storage (TES) system (Kearney and Herrmann, 2002, “Assessment of a Molten Salt Heat Transfer Fluid,” ASME). A single tank TES system consists of a thermocline region which produces the temperature gradient between hot and cold storage fluid by density difference (Energy Efficiency and Renewable Energy, http://www.eere.energy.gov/basics/renewable_energy/thermal_storage.html). Preservation of this thermocline region in the tank during charging and discharging cycles depends on the uniformity of the velocity profile at any horizontal plane. Our objective is to maximize the uniformity of the velocity distribution using a pipe-network distributor by varying the number of holes, distance between the holes, position of the holes and number of distributor pipes. For simplicity, we consider that the diameter of the inlet, main pipe, the distributor pipes and the height and the width of the tank are constant. We use Hitec® molten salt as the storage medium and the commercial software Gambit 2.4.6 and Fluent 6.3 for the computational analysis. We analyze the standard deviation in the velocity field and compare the deviations at different positions of the tank height for different configurations. Since the distance of the holes from the inlet and their respective arrangements affects the flow distribution throughout the tank; we investigate the impacts of rearranging the holes position on flow distribution. Impact of the number of holes and distributor pipes are also analyzed. We analyze our findings to determine a configuration for the best case scenario.

scholarly journals Experimental Investigation of PCM Spheres in Thermal Energy Storage System

2013 ◽  
Vol 367 ◽  
pp. 228-233 ◽  
Author(s):  
N.A.M. Amin ◽  
Azizul Mohamad ◽  
M.S. Abdul Majid ◽  
Mohd Afendi ◽  
Frank Bruno ◽  
...  
Keyword(s):  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Storage System ◽  
Packed Bed ◽  
Energy Storage System ◽  
Heat Transfer Fluid ◽  
Experimental Result ◽  
Small Scale ◽  
Storage Unit

This paper presents the experimental result of a small scale packed bed of random spheres with encapsulated PCM being charged and discharged. A vapor compression refrigerator and heated room with fan heater were used to supply constant heat transfer fluid at a minimum temperature of -28°C for charging and 16°C for discharging. Even though the temperature differences were not fixed in the experiments, the performance of the thermal energy storage is depicted in the form of effectiveness values. Different results were obtained for charging and discharging the thermal storage unit. The differences are expected to come from natural convection and super cooling. The super cooling during the charging process was as high as 6°C.

Experimental Study of Thermal Energy Storage Using Natural Porous Media

2017 ◽  
Author(s):  
A. J. Al Edhari ◽  
C. C. Ngo
Keyword(s):  
Experimental Study ◽  
Porous Media ◽  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Storage System ◽  
Thermal Storage ◽  
Heat Transfer Fluid ◽  
Storage Unit ◽  
Storage Media

Thermal energy storage has been an area of research interest due to the need to store solar energy or excess energy for later use in many applications including district heating. The focus of a lot of research is on exotic and expensive storage media. This paper presents an experimental study of thermal energy storage using porous media readily available and commonly found in nature such as sand, soil, pebble rocks and gravel. This study also considers a simple and inexpensive thermal storage system which could be constructed easily and examines what could be done to increase the thermal storage performance. The thermal storage system examined in the present study was a thermal energy storage unit with embedded horizontal pipes carrying water as the heat transfer fluid for thermal charging. Different thermal storage configurations were examined by adjusting the thermal charging temperature and using different storage media. The temperature distribution within the storage media was monitored for 10 hours using a data acquisition system with K-type thermocouples. The results indicate that a thermal storage system using sand as storage media is slightly better compared with gravel or pebble rocks as storage media.

Experimental Investigation of Latent Heat Thermal Energy Storage System Enhanced by Annular and Radial Fins

2021 ◽  
Author(s):  
Saeed Tiari ◽  
Addison Hockins ◽  
Samantha Moretti
Keyword(s):  
Energy Storage ◽  
Latent Heat ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Storage System ◽  
Energy System ◽  
Energy Storage System ◽  
Heat Transfer Fluid ◽  
Charging Time ◽  
Thermal Energy Storage System

Abstract In the current study, the thermal characteristics of a latent heat thermal energy storage system enhanced with annular and radial fins are investigated experimentally. Rubitherm RT-55 is used as the phase change material (PCM) and is enclosed within a vertical cylindrical container. Water is used as the heat transfer fluid (HTF) which is circulated in a copper pipe that passes through the center of the container. The hot HTF is circulated through the system until the entire mass of solid PCM inside the container is melted. Twelve k-type thermocouples are inserted into the container at different levels to monitor the PCM temperature during the charging processes. A thermal imaging camera is used to take thermal images of the latent heat thermal energy system as it operates. The effects of different number of annular and radial fins attached to the central pipe on the thermal performance of the latent heat thermal energy storage system during the charging processes have been studied. It was found that the inclusion of 10 and 20 annular fins decreased the charging time by 79.5% and 82.8%, respectively. The two radial fin designs of 4 fins and 8 fins were assessed and found to decrease charging time by 81.9% and 86.6%, respectively.

scholarly journals Advancements in Thermal Energy Storage System by Applications of Nanofluid Based Solar Collector: A Review

2020 ◽  
Vol 24 (1) ◽  
pp. 310-340
Author(s):  
Vednath P. Kalbande ◽  
Pramod V. Walke ◽  
C. V. M. Kriplani
Keyword(s):  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Solar Collector ◽  
Cooling System ◽  
Storage System ◽  
Thermal Storage ◽  
Energy Storage System ◽  
Research Progress ◽  
Thermal Energy Storage System

AbstractIn the recent years, a lot of research has been carried out in the field of nanofluid based solar collector, leading towards the enhancement of working efficiency even at low atmospheric temperature or at low sunlight levels regions of the world. The present review pertains to the research progress related to the performance execution of solar collector using nanofluid. It is observed that the thermal energy storage system (TES), using solar collector, is a useful device for storing sensible and latent heat in a unit volume. Nanofluid plays an important role in various thermal applications such as heat exchanger, solar power generation, automotive industries, electronic cooling system, etc. The nanoparticles find the use in various industrial applications because of its properties, such as thermal, mechanical, optical and electrical. Most of the investigations carried out earlier on the applications of nanofluid in solar energy are related to their uses in the solar collector and thermal storage system. The parabolic solar collector using nanofluid is still a challenge. This article presents an exhaustive review of thermal storage system using nanofluid based solar collector and a scope of using nanofluid based solar collector for performance enhancement.

scholarly journals Experimental study of solidification of paraffin wax in solar based triple concentric tube thermal energy storage system

2018 ◽  
Vol 22 (2) ◽  
pp. 973-978 ◽  
Author(s):  
Rengarajan Ravi ◽  
Karunakaran Rajasekaran
Keyword(s):  
Heat Transfer ◽  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Storage System ◽  
Solidification Process ◽  
Energy Storage System ◽  
Paraffin Wax ◽  
Heat Transfer Fluid ◽  
Thermal Energy Storage System

This paper addresses an experimental investigation of a solar based thermal energy storage system to meet current energy demand especially for milk industry in Tamil Nadu, India. A solar based energy storage system has been designed to study the heat transfer characteristics of paraffin wax where it is filled in the middle tube, with cold heat transfer fluid flowing outer tube, inner tube, and both tubes at a time during solidification process in a horizontal triple concentric heat exchanger. In this study, main concentrations are temperature distributions in the energy storage materials such as paraffin wax during solidification process and total solidification time. Three heat recovery methods were used to solidify paraffin wax from the inside tube, outside tube, and both tubes methods to improve the heat transfer between heat transfer fluid and phase change materials. The experiment has been performed for different heat transfer fluid mass-flow rates and different inlet temperatures and predicted results shows that solidification time is reduced.

scholarly journals The Effect of PCM Capsule Material on the Thermal Energy Storage System Performance

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
R. Meenakshi Reddy ◽  
N. Nallusamy ◽  
K. Hemachandra Reddy
Keyword(s):  
Energy Storage ◽  
Mild Steel ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Supply And Demand ◽  
Storage System ◽  
Internal Heat ◽  
Energy Storage System ◽  
Heat Transfer Fluid ◽  
Capsule Material

Phase change material (PCM) based thermal energy storage (TES) systems are gaining increasing importance in recent years in order to reduce the gap between energy supply and demand in solar thermal applications. The present work investigates the effect of PCM capsule material on the performance of TES system during charging and discharging processes. The TES unit contains paraffin as PCM filled in spherical capsules and is integrated with flat plate solar collector. Water is used as sensible heat material as well as heat transfer fluid (HTF). The PCM capsules are of 68 mm diameter and are made using three different materials, namely, (i) high density polyethylene (HDPE), (ii) aluminum (Al), and (iii) mild steel (MS). The experimental investigation showed that the charging and recovery of stored energy are less affected by the spherical capsules material. The variables, like charging time and discharging quantity, are varied around 5% for the different capsule materials. Even though aluminum thermal conductivity is much higher than HDPE and mild steel, its influence on the performance of TES system is very low due to the very high internal heat resistance of PCM material stored in the spherical capsules.

Fluid Charge and Discharge Strategies of Dual-Media Thermal Storage Systems in the Starting-Up Process of Daily Cyclic Operations

2014 ◽  
Author(s):  
Ben Xu ◽  
Peiwen Li ◽  
Cholik Chan
Keyword(s):  
Energy Storage ◽  
Power Plant ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Storage System ◽  
Thermal Power ◽  
Thermal Storage ◽  
Energy Storage System ◽  
Solar Thermal Power ◽  
Thermal Energy Storage System

Because of the capability of large capacity thermal storage and extended operation during night and cloudy days, concentrated solar thermal power generation is getting more and more attention in the recent years. Dual-media thermal energy storage system is typically adopted in industry for reducing the use of the heat transfer fluid, which is usually expensive. In such a dual-media system, the solid filler material can be a phase change material relying on latent heat or a regular solid material using sensible heat for energy storage. Two strategies of starting-up fluid charge and discharge are considered for the operation of a concentrated solar thermal power plant incorporated with a dual-media thermal storage system. These two strategies include: 1) starting daily cyclic charge and discharge operation with an initially cold tank; 2) to fully charge the thermal storage system before operation of the cyclic discharge/charge for the power plant. The energy storage efficiency and the effects to the power plant operation due to the application of these two strategies are studied in the current work based on an enthalpy-based 1-D model, and significant difference is found in starting-up process of the daily cyclic operations, which will help us decide the best strategy of operating a thermal energy storage system with more electrical energy output.

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