Year-Round Experimental Demonstration of a Thermal Energy Storage–Integrated Heat Pump for Space Cooling and Heating Load Shifting
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Qiao, Yiyuan [ORNL] (ORCID:0000000164986153)↗
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Peak cooling load shift capability of a thermal energy storage system integrated with an active insulation system in US climate zones
This study aims to evaluate a thermal energy storage (TES) system integrated with an active insulation system (AIS) to form a TES + AIS integrated wall system as a partition and as a secondary cooling system to shift the peak load and reduce cooling energy consumption. To understand and demonstrate its cooling performance, the TES + AIS integrated wall system was installed in an office building in Oak Ridge, Tennessee. To investigate the effect of the TES + AIS integrated wall system in a typical office building and various climate zones, the US Department of Energy’s prototype office building model was modified to accommodate the proposed system. In this work, results showed that the minimum size of the proposed system to achieve energy savings varies depending on climate conditions. The minimum size of the proposed system for cooling energy saving and shifting peak cooling demand in climate zones 2, 3, and 5 is 29.7 m 2 , whereas it is 44.6 m 2 in zones 4 and 6. By installing the minimum size of the proposed system, 11.3 % to 16.4 % of cooling energy can be shifted during discharge hours in a representative summer day.
25 ENERGY STORAGE↗
Dual-season thermal energy storage-integrated heat pump system for load shifting: experiments, modeling and nationwide analysis
Here, this paper proposes and validates a dual-season thermal energy storage-integrated heat pump (TES-HP) system that shifts building electric load in both cooling and heating modes using a single phase-change TES. The design uses the TES as a heat sink for the condenser in summer and a heat source for the evaporator in winter, thereby reducing on-peak electric demand while ensuring compatible with existing air-distribution systems. A 14-kW TES-HP prototype with six operating modes and novel refrigerant charge management strategies was experimentally tested under varied conditions. Subsequently, data-driven polynomial performance curves were developed and validated against experiments, then coupled with a phase change material (PCM) model and a calibrated building model within a rule-based controller. Single-day case studies demonstrated effective on-peak demand reduction while maintaining thermal comfort. During cooling, hourly power was lowered by up to 1.5 kW; in heating, average hourly power decreased from over 3.5 kW to 1.8 kW, compared to an HP-only system, achieving 64.5 % load shifting, and the need for resistance heating was eliminated. Seasonal simulations showed typical on-peak electricity savings of 25–35 % in cooling and 40–65 % in heating, with the largest benefits on the hottest and coldest days. Extended response-surface analysis and nationwide mapping quantified load shifting as functions of ambient and TES temperatures, revealing a seasonal trade-off in TES phase-change temperature. These results demonstrate the TES-HP system as a practical and scalable solution for grid-interactive buildings that reduces on-peak demand and electricity use while maintaining thermal comfort and enhancing grid flexibility and reliability.
Grid-interactive buildings↗
Status of the Atlas of Neutron Resonances [Slides]
The Atlas of Neutron Resonances is the most comprehensive compilation of neutron resonances, thermal cross sections, resonance integrals and Maxwellian averaged cross sections generally available. For decades, the Atlas was carefully curated and maintained by Dr. Said Mughabghab who sadly passed on during the summer of 2018 after publishing the 2018 edition of the Atlas . We are continuing the development of this important compendium. To a large extent, the Atlas book is generated from a series of text files given in a single purpose domain-specific format. Therefore, we developed a software API and began the systematic assessment of the Atlas files. With this work past, we are now focusing on new efforts to expand the quality and scope of the Atlas . Current and recently completed projects include a cross comparison of the Atlas bibliography with Nuclear Science References and the EXFOR data library, a better determination of average resonance parameters, and using machine learning to assess the correctness of the spin group assignments of resonances tabulated in the Atlas .
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Thermally Anisotropic Building Envelope Integration into Panelized Metal Construction: Laboratory Evaluation in Guarded Hot Box
The Thermally Anisotropic Building Envelope (TABE) is an active building envelope system that can exchange thermal energy with a storage medium to reduce the building’s energy demand. TABE redirects thermal energy along thin conductive layers in the building envelope to hydronic loops that are connected to thermal energy storage (TES), where it will be available to offset future energy demand when the conditions are favorable. TABEs can also be connected with a geothermal loop to reduce the building’s heating and cooling loads. Due to the importance of thermally conductive metal layers to TABE function, this technology has potential for easy adoption into panelized metal construction. In this study, we illustrate the construction process of prototype metal panels containing TABE and the laboratory evaluation in Oak Ridge National Laboratory’s rotatable guarded hot box. The thermal performance of the prototype panel was assessed for both baseline and operational cases and the total heat flow extracted from the panel by TABE was quantified.
Howard, Daniel↗
Phenomenon Identification and Ranking Table Analysis for Thermal Energy Storage Technologies Integration with Advanced Nuclear Reactors
This report provides an overview of the Phenomena Identification and Ranking Table (PIRT) analysis of thermal energy storage (TES) systems for possible integration with various types of advanced nuclear power plants (NPPs). Advanced NPPs will potentially need to operate in environments where power generation flexibility is more highly valued than the stability or baseload generation capability for conventional demand curves. TES systems would enable NPPs to respond nimbly to market variability and could also position advanced NPPs to participate differently in restructured markets, thus further enhancing their economic competitiveness. TES systems could also benefit the electric grid by eliminating the need for peaking plants, as well as by improving the economic performance of baseload NPPs. While TES technologies afford a unique opportunity to address many of these challenges, the applicability of these systems is also complicated by the fact that various advanced NPPs are designed differently, each with its own temperature range, size, operating fluids, and operating conditions. Hence, TES systems face significant barriers to investment, as more information on their compatibility and performance metrics is needed to quantify the advantages provided by each, as well as the challenges these technologies might face if coupled with a particular type of advanced NPP. This report explores the possibility of integrating a wide variety of TES technologies with various categories of advanced NPPs, based on their operating characteristics. To help users and developers decide which TES technology is best suited to a particular category of advanced NPPs, this research developed a PIRT of 10 TES systems that could potentially be coupled with advanced NPPs, which themselves are divided into nine categories based on their operating conditions. Each advanced NPP category is evaluated for compatibility with the 10 TES systems by assembling and discussing a database of information concerning 10 engineering questions (defined herein in as figures of merit [FOMs]), such as: technology readiness level (TRL), temperature compatibility, energy density, size, cycle frequency, ramp time, realignment frequency, geographic needs, environmental impact, and interventions. By assembling a database of information concerning the TES technologies’ compatibility with various advanced NPP systems, this study can help developers acquaint themselves with a particular TES technology before choosing to build a new integrated installation.
22 GENERAL STUDIES OF NUCLEAR REACTORS↗
Nuclear—thermal energy storage configurations for industrial combined heat and power supply—conceptual and thermodynamic study with high temperature gas-cooled reactor
Nuclear systems are promising candidates for delivering resilient heat and power for future energy security and independence. Traditionally, nuclear plants have been used for baseload electricity production and cogeneration of heat has seen relatively limited application utilizing typically only small portion of a reactor's thermal output. This paradigm may shift due to the increasing penetration of intermittent renewables and need for resource flexibility, various decarbonization efforts aimed at both electricity and heat demands, along with the perspective of small modular nuclear reactor applications, which can be sized based on local industrial needs. Here, this study provides a comprehensive guide for the nuclear and industrial sectors, emphasizing controllability in the combined heat and power configuration options for high temperature gas-cooled reactor and process steam supply. It investigates the integration of thermal energy storage to improve nuclear energy's responsiveness to varying industrial demands. The study emphasizes placing thermal energy storage between the nuclear primary loop and steam cycle to achieve greater efficiency and flexibility in power and heat output, surpassing traditional combined heat and power systems and avoiding efficiency losses seen in other thermal energy storage integration approaches.
combined heat and power (CHP)↗
Thermal Systems Modeling for Integration of Industrial Processes with Advanced Nuclear
Applying combined heat and power concepts to advanced nuclear reactors can enable increased nuclear utilization in the future clean economy, as well as provide safe and reliable clean energy to industrial systems. Analyses have been performed to evaluate the integration of nuclear energy with industrial processes for both clean electricity production and providing process heat for direct use to reduce emissions in the production of chemical commodities. The key research question that needs to be answered is: "What are the prospective approaches for integrating nuclear-generated heat energy into non-electric applications that can facilitate combined heat and power operations by advanced nuclear reactor systems?" This presentation will highlight several case studies showing conceptual designs for thermal delivery systems to integrate small modular reactor (SMR) process steam and electricity with industrial processes including oil refining, hydrogen production, and methanol production.
hydrogen↗
Thermal Analysis of Liquid and Air Cooling of High-Power-Density Integrated Motor Drives
Thermal management is a crucial aspect in the design of motor and drive systems. This paper introduces a coordinated cooling approach utilizing both liquid and air to enhance the integrated motor drive's power density. The proposed solution incorporates a shared water jacket to cool both the machine and power electronics, combined with forced air ventilation for the end windings and rotor. This approach is structurally simpler, less expensive, and more effective than conventional non-interacting cooling schemes. The paper addresses the modeling of key thermal features and nonlinearities including material anisotropy, contact thermal resistance, and uneven winding loss distributions. In addition, this study utilizes a more detailed model of the loss distribution among the winding turns in each slot that delivers a higher level of accuracy. Finite Element Analysis (FEA) results demonstrate the effectiveness of the integrated cooling system for efficiently cooling the designed integrated motor drive system.
42 ENGINEERING↗
Identification and Evaluation of Thermal Transport Components for Integrated Energy Systems
A proper evaluation and selection of component technologies is a critical aspect in the development of Integrated Energy System (IES). This study aims to investigate the key components and associated technologies required to build high-temperature heat transport systems for IES. Of particular interest is the component technologies needed to design and construct IES that combines advanced nuclear reactors with high-temperature industrial processes. This study particularly delved into knowledge base, evaluation metrics, and state-of-the-art commercial technologies, aiming to facilitate the evaluation and selection process of various thermal transport components. In addition, an evaluation process was proposed in order to assist in the optimal selection of the thermal transport components based on the knowledge base and evaluation metrics investigated through this study.
42 ENGINEERING↗
Parametric and sensitivity analysis of a PCM-integrated wall for optimal thermal load modulation in lightweight buildings
Load modulation in buildings is becoming increasingly important due to growing disparity in energy demand during peak and off-peak hours. Integrating phase change material (PCM) in building envelopes and using a controlled precooling strategy can provide substantial thermal load modulation; however, it may greatly increase the total energy use. Previous studies have employed PCM in building envelopes primarily for energy savings and, to some extent, peak load shedding and shifting. However, the load modulation capacity of a PCM-integrated envelope has not been well explored in the literature. In this study, we perform an extensive parametric and sensitivity analysis on PCM-integrated lightweight building walls and examine the combinatory effects of various PCM parameters on thermal load modulation and wall-related heat gains in buildings. Using numerical simulations, we investigate eight PCM parameters: PCM location in the wall, transition temperature, thickness, latent heat, transition range, density, specific heat, and thermal conductivity. Here, we evaluate their impact and relative importance to achieve maximum load modulation in buildings without compromising occupants’ thermal comfort or total energy use. The results show that the optimized PCM proposed in this study can completely invert the transient heat gain profile of the wall, providing up to 70% reduction of wall-related heat gain during peak hours without a major increase in the cumulative heat gain.
42 ENGINEERING↗
Adaptive thermal stabilization of an integrated photonic spectrometer using parasitic interference fringes
Parasitic fringe drift from unwanted scatterings limits the long-term stability of waveguide-based optical spectrometers. Yet their spectral features provide relevant information that can be used to improve performance of the spectrometer. We show that fringe drift can be extracted and utilized to perform accurate thermal stabilization, especially in the case of integrated waveguide sensors. In this Letter, effective stabilization of a methane silicon photonic sensor is demonstrated, and significant reduction in fringe noise is clearly observed.
Teng, Chu C.↗
Surrogate-driven Variance-based Sensitivity Analysis of Thermal Storage Tanks in Integrated Energy Systems
Sensitivity analysis and uncertainty quantification are essential steps for enhancing the accuracy of computational models by identifying and mitigating uncertainties. This study focuses on these steps for the Thermal Energy Delivery System at Idaho National Laboratory, specifically targeting the thermocline tank. Using a Modelica/Dymola simulation model, the study perturbed various design parameters and boundary conditions, including shape factor, porosity, outlet temperature, inlet mass flow rate, and system pressure, to predict and quantify uncertainty in the tank’s ax- ial temperature. A dataset of over 1,000 simulations was generated, and surrogate models were developed using the pyMAISE (Michigan Artificial Intelligence Standard Environment) library, which is an Automatic Machine Learning library for nuclear engineering applications. The optimal model, a feedforward neural network with two hidden layers, achieved an R2 score above 0.99 and a mean absolute error below 1 Kelvin. Sensitivity analyses using Sobol indices and Fourier amplitude sensitivity testing methods on this surrogate model revealed that the inlet mass flow rate at initial timestamps and porosity significantly impacts predicted temperatures across all sensors and time steps.
22 - GENERAL STUDIES OF NUCLEAR REACTORS↗
Optimized dispatch and component sizing for a nuclear-multi-effect distillation integrated energy system using thermal energy storage
Not Available
Thermal Energy Storage (TES), Co-generation, Nucle↗
Multilevel Analysis, Design, and Modeling of Coupling Advanced Nuclear Reactors and Thermal Energy Storage in an Integrated Energy System
This report discusses the different options for coupling thermal energy storage (TES) systems to advanced nuclear power plants (A-NPPs) in order to enable flexible and hybrid plant operation. An advanced light-water reactor (A LWR), a high-temperature gas-cooled reactor (HTGR) and a liquid-metal fast reactor (LMFR) were selected as the initial use cases for demonstrating a thermally balanced energy storage coupling design for thermal power extraction. The models presented herein showcase several design considerations, focusing on optimal deployment methodologies for achieving steady-state and transient-state operation with minimum disruption to the nuclear power cycle. This first part of the study presents steady-state models developed using Aspen HYSYS®, with the thermal energy bypass for NPP-TES coupling being varied at up to 50%. The various components were sized using the Aspen Process Economic Analyzer (APEA) and Aspen Exchanger Design and Rating (EDR), when applicable. Cost functions from these models were developed using the latest publicly available data obtained from APEA V11. The TES-coupled A-NPP steady-state models and cost functions then provided a baseline for dynamic operation and process optimization by using Idaho National Laboratory (INL)’s Framework for Optimization of Resources and Economics (FORCE) tools. A stochastic optimization of the various energy storage systems coupled to the A-NPPs was then performed using the Risk Analysis Virtual Environment (RAVEN) and its dispatch optimization plugin, the Holistic Energy Resource Optimization Network (HERON). The signal processing and synthetic history capabilities of RAVEN were used to account for the unpredictable behavior of electricity markets. An autoregressive moving average (ARMA) model was used to analyze price signals from the Pennsylvania-New Jersey-Maryland (PJM) market and were applied to the HERON analysis in order to optimize a system with the best economics. Transient modeling evaluation was then performed using Modelica models within the HYBRID repository, which was developed at INL for the Department of Energy Integrated Energy Systems program for the characterization of dynamic integrated system behavior and feedback. This includes evaluation of the TES-coupled A-LWR systems’ impact on physical and thermal system response during imposed system demands. Additional TES-coupled reactor types, coupling approaches, markets, and TES technologies will be evaluated in future work.
22 GENERAL STUDIES OF NUCLEAR REACTORS↗
Demonstration and characterization of insertable passive thermal switches for dynamic building envelopes
A dynamic building envelope integrated with thermal energy storage, such as phase change material (PCM), is an emerging technology that offers a promising solution to improve the energy efficiency of buildings. This study reports the development of insertable thermal switches, which modulate thermal resistance, thereby making building envelopes dynamic and enhancing the use of free ambient heating and cooling. The reported thermal switches are passive, meaning they work solely based on indoor and outdoor temperatures. A single switch when inserted into 10 × 10-in (0.064-m 2 ) XPS foam board insulation demonstrates effective thermal conductivity of 0.050 W/m-K in the resistive state and 0.285 W/m-K in the conductive state. Thermal switches exhibit an effective switching ratio of 5.7, with no noticeable degradation in performance over 770 cycles. Additionally, when integrated into a wall sample containing a PCM layer, switches significantly reduce the PCM solidification time by 43.2% during the cooling process.
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
Analysis of pumped thermal energy storage using particle media integrated with concentrating solar power
Pumped Thermal Energy Storage (PTES) is an electricity storage system that converts electricity into thermal energy which is stored and later transformed back into electricity. Previous work has illustrated that particles have low capital costs and can be operated over a wide range of temperatures. PTES with particle storage achieves higher round-trip efficiency and specific power output than when molten salt thermal energy storage is used. This article explores hybrid systems that combine PTES with Concentrating Solar Power (CSP). Hybrid systems share the majority of components thereby reducing costs compared to two stand-alone devices. In addition, hybrid systems can provide multiple services (such as renewable power generation and electricity storage services). Using particle thermal storage in these hybrid concepts provides freedom in choosing the design conditions, since a wide range of operating temperatures is allowable, therefore making it possible to identify hybrid system designs that have good performance. In this article, two concepts for hybrid PTES-CSP are introduced. Thermodynamic models are developed and these are used to evaluate the performance of two hybrid systems. These models account for turbomachinery efficiency, and approach temperature and pressure loss in heat exchangers, as well as other sources of inefficiency, such as motor-generator losses, and air fan power. The “Solar Top-Up” Concept uses CSP to increase the temperature delivered by the charging heat pump. The discharging system uses a topping gas cycle and a bottoming steam cycle to fully exploit the available energy. Using solar heat to increase the maximum temperature from 750 K to 1100 K increases the round-trip efficiency from 41 % to 62 % and the specific work output from 88 kJ/kg to 301 kJ/kg. The second concept is a “Dual-Mode” device which provides both electricity storage and solar electricity generation with the same set of components. The PTES-mode and CSP-mode performance are optimized at different design values but careful parameter selection leads to good performance of both modes: one design produces PTES round-trip efficiency > 60 %, CSP heat engine efficiency > 40 %, and specific work outputs > 150 kJ/kg (for both cycles), when the particle receiver temperature is > 1200 K and maximum heat pump temperature is 1100 K.
14 SOLAR ENERGY↗
Performance evaluation of a dynamic wall integrated with active insulation and thermal energy storage systems
Thermal energy storage systems in buildings can store cooling/heating energy during non-peak load hours or when renewable energy sources are available for later use when demanded. Using the building envelope as a thermal battery can help to shave the peak load, reduce the burden in electric grids, and enhance the occupant's thermal comfort. Sensible energy storage on wall systems such as thermally activated building systems can provide an active thermal storage strategy. However, most of the stored energy is used through passive means directed by the thermal lag, which can impede the on-demand release of the stored energy. Integrating active insulation systems with building thermal storage systems can increase the flexibility of charging and discharging time and duration. In this study, a wall system equipped with an active insulation system and thermally activated storage system was designed, and its performance on active cooling energy contribution was studied. The performances of energy storage (charging), release (discharging) of the thermal energy storage energy, and the active insulation system were studied separately and together as an integrated system. Results showed that the thermal properties of the thermal energy storage core material and the pipe spacing of both embedded pipes in the thermal energy storage and hydronic pipes used in the active insulation system affected the wall performance the most out of all the tested wall system parameters. During discharging, the heat flux into the wall was as high as 81.92 W/m 2 . This active insulation system's dynamic R-value varied between less than 1ft 2 •°F•h/BTU (0.18 m 2 •K/W) to 98% of the equally thick foam insulation's R-value.
25 ENERGY STORAGE↗