Thermal energy storage system with nucleation cooling: US Patent 11435145

Overview

The concept of the thermal energy storage system is defined by the technical specifications and operational framework outlined in United States Patent US 11435145. This patent represents a specific engineering approach to capturing, retaining, and releasing thermal energy to enhance efficiency in energy infrastructure. The intellectual property is owned by Rocky Research, an entity based in the US that has developed this technology to address specific challenges in thermal management and energy retention. The system described in the patent is designed to optimize the timing of energy usage, allowing for greater flexibility in how thermal power is generated, stored, and subsequently deployed within an energy network.

Rocky Research serves as the primary operator and owner of the technology detailed in US 11435145. The patent document provides the foundational legal and technical description of the system, establishing the parameters for its construction and operation. The system's design focuses on the efficient transfer of heat, utilizing specific materials and structural configurations to minimize thermal loss during the storage phase. This approach is critical for applications where the generation of thermal energy does not perfectly align with the immediate demand for heat, such as in certain industrial processes or integrated power generation cycles.

The technical architecture of the system involves a series of components that work in concert to manage the thermal load. While the patent provides the detailed mechanical and material specifications, the core principle relies on the ability to store significant amounts of thermal energy in a stable state. This stability is achieved through careful selection of storage media and insulation strategies, ensuring that the energy remains available for release when needed. The system is engineered to handle specific temperature ranges and pressure conditions, as defined in the patent claims.

The implementation of such thermal energy storage systems contributes to the broader goal of improving energy efficiency and reducing waste heat. By capturing thermal energy that might otherwise be lost, the system allows for a more effective utilization of the primary energy source. This is particularly relevant in contexts where variable energy inputs, such as solar thermal or waste heat from industrial processes, need to be smoothed out for consistent output. The patent US 11435145 provides the specific technical roadmap for achieving these efficiencies, detailing the unique configurations that distinguish this system from other thermal storage solutions.

The ownership by Rocky Research indicates a focused development effort on this particular thermal storage methodology. The patent serves as both a protective legal instrument and a technical reference for engineers and researchers looking to understand the specific innovations introduced by this system. The details within the patent cover the structural integrity, the thermal dynamics, and the operational protocols necessary for the system to function effectively. This level of detail ensures that the technology can be replicated and scaled according to the specific requirements of different energy infrastructure projects.

What is a thermal energy storage system with nucleation cooling?

A thermal energy storage system with nucleation cooling is an advanced concept designed to enhance the efficiency and capacity of thermal storage units, particularly in solar thermal power plants and industrial heat recovery systems. Developed by Rocky Research, this technology integrates the principles of nucleation—where phase changes occur at specific sites—to optimize the cooling and heating cycles within the storage medium. The system aims to address common limitations in traditional thermal storage, such as thermal stratification, heat loss, and slow response times, by leveraging controlled nucleation events to accelerate heat transfer.

Core Concept and Mechanism

The core mechanism of this system relies on the strategic use of nucleation sites within the storage medium, which can be a solid, liquid, or phase-change material (PCM). Nucleation is the initial step in the formation of a new thermodynamic phase or structure, such as the formation of bubbles in a liquid or crystals in a solid. By controlling where and when nucleation occurs, the system can manage the rate of heat absorption and release more precisely than conventional systems. In the context of cooling, nucleation helps to dissipate heat more rapidly by creating micro-bubbles or crystalline structures that increase the surface area for heat exchange. This process can be described by the classical nucleation theory, where the free energy change ΔG for forming a nucleus of radius r is given by:

ΔG = 4πr²γ - (4/3)πr³ΔGv

where γ is the surface tension and ΔGv is the volumetric free energy difference between the two phases. By manipulating these parameters, the system can optimize the nucleation rate, leading to more efficient heat transfer.

Advantages and Applications

The integration of nucleation cooling in thermal energy storage systems offers several advantages. First, it enhances the thermal conductivity of the storage medium, allowing for faster charging and discharging of thermal energy. This is particularly beneficial in solar thermal power plants, where the ability to quickly store and release heat can improve the overall efficiency of the system. Second, the controlled nucleation process helps to maintain thermal stratification within the storage tank, reducing heat loss and improving the quality of the stored energy. Third, the system can operate over a wider temperature range, making it versatile for various applications, including industrial process heat, district heating, and even building HVAC systems.

Rocky Research's approach to nucleation cooling also addresses the issue of material degradation over time. Traditional thermal storage materials can suffer from fatigue and cracking due to repeated thermal cycling. By using nucleation to manage the stress distribution within the material, the system can extend the lifespan of the storage medium, reducing maintenance costs and improving the reliability of the energy storage solution.

Technical Implementation

The technical implementation of a thermal energy storage system with nucleation cooling involves several key components. The storage tank is designed to accommodate the storage medium, which is often a PCM or a mixture of materials with different thermal properties. Nucleation sites are introduced into the medium through the addition of nucleating agents or by structuring the material at the microscale. These sites can be engineered to activate at specific temperatures, ensuring that nucleation occurs at the optimal points in the heating and cooling cycles. The system also includes sensors and control mechanisms to monitor the temperature and pressure within the tank, allowing for real-time adjustment of the nucleation process.

In solar thermal applications, the system is typically integrated with a field of parabolic troughs or solar towers that concentrate sunlight onto a receiver. The heated fluid from the receiver is then pumped into the storage tank, where the nucleation cooling process helps to efficiently transfer the heat to the storage medium. During periods of low solar irradiance, the stored heat is released by reversing the process, with nucleation sites facilitating the rapid transfer of heat from the medium back to the working fluid.

The development of this technology represents a significant advancement in the field of thermal energy storage, offering a more efficient and reliable solution for managing intermittent energy sources. By leveraging the principles of nucleation, Rocky Research has created a system that not only improves the performance of thermal storage but also opens up new possibilities for integrating thermal energy storage into a broader range of energy systems.

How does nucleation cooling enhance thermal storage?

Nucleation cooling enhances thermal energy storage (TES) by leveraging the latent heat of phase change materials (PCMs) to achieve higher energy density and more stable temperature profiles compared to sensible heat storage systems. In conventional TES, energy is stored by raising the temperature of a medium, such as water or molten salt, which requires continuous temperature gradients and often results in thermal stratification issues. In contrast, nucleation cooling focuses on the precise control of the phase transition point, allowing the material to absorb or release significant amounts of energy at a nearly constant temperature.

Mechanism of Latent Heat Absorption

The core mechanism relies on the thermodynamic properties of the PCM during its solid-liquid transition. When heat is introduced to the system, the PCM absorbs energy to break molecular bonds rather than increasing kinetic energy (temperature). This process is governed by the equation for latent heat:

Q = m × L

where Q is the heat energy absorbed, m is the mass of the PCM, and L is the specific latent heat of fusion. By optimizing the nucleation sites within the PCM, the system minimizes supercooling—a phenomenon where the liquid phase remains stable below its freezing point without solidifying. This ensures that the phase change occurs predictably, maximizing the effective capacity of the storage unit.

Role of Nucleation Control

Effective nucleation cooling requires precise management of the crystallization process. Without controlled nucleation, PCMs may exhibit hysteresis, where the melting and freezing temperatures differ significantly, reducing the efficiency of the round-trip energy cycle. Rocky Research’s approach, as indicated by the patent title, likely involves engineering the microstructure of the PCM or introducing nucleating agents to standardize the freezing point. This reduces the thermal resistance at the interface between the heat transfer fluid and the PCM, allowing for faster charge and discharge rates.

By maintaining a narrow temperature window during operation, nucleation cooling systems can better match the output temperature requirements of downstream thermal loads, such as steam turbines or absorption chillers. This reduces the need for additional heat exchangers and pumps, thereby lowering the overall exergy loss in the thermal energy storage system. The result is a more compact and efficient storage solution, particularly valuable in concentrated solar power (CSP) and industrial waste heat recovery applications.

Applications

The thermal energy storage system developed by Rocky Research is designed for versatile deployment across multiple energy infrastructure sectors, leveraging its modular architecture to address specific thermal management challenges. The primary application domain involves integration with concentrated solar power (CSP) facilities, where the system captures excess heat during peak solar irradiance and releases it during periods of low insolation or high demand. This capability enables CSP plants to achieve near-baseload power output, significantly enhancing grid stability compared to variable renewable sources. The system’s ability to store thermal energy at high temperatures allows for efficient steam generation in downstream Rankine cycle turbines, thereby maximizing the levelized cost of energy (LCOE) for solar thermal installations.

Industrial Process Heat Integration

Beyond electricity generation, the system serves critical roles in industrial process heating, particularly in sectors requiring consistent high-temperature inputs such as cement production, steel manufacturing, and chemical refining. By decoupling heat generation from heat consumption, Rocky Research’s technology allows industrial facilities to utilize off-peak electricity rates to charge the storage medium, subsequently discharging thermal energy during peak production hours. This load-shifting mechanism reduces operational expenditures and mitigates carbon footprints by enabling greater penetration of renewable electricity in thermal processes. The system’s scalability permits customization for varying thermal loads, making it suitable for both large-scale heavy industry and mid-sized manufacturing units.

Grid Stability and Peak Shaving

In broader grid applications, the thermal storage system functions as a flexible resource for peak shaving and frequency regulation. By converting electrical energy into thermal energy and vice versa, the system provides ancillary services that enhance grid resilience. During periods of high electrical demand, the stored thermal energy is rapidly converted back to electricity, reducing the need for costly peaker plants. Conversely, during periods of surplus generation, the system absorbs excess power, minimizing curtailment losses. This bidirectional energy flow supports the integration of variable renewable energy sources, facilitating a smoother transition toward a decarbonized energy mix. The operational flexibility of the system allows for rapid response times, comparable to battery energy storage systems (BESS), but with potentially longer duration storage capabilities.

Building HVAC and District Heating

The technology also finds application in building heating, ventilation, and air conditioning (HVAC) systems and district heating networks. In these contexts, the system stores thermal energy from renewable sources or waste heat recovery units, providing consistent temperature control for residential and commercial buildings. This application reduces reliance on fossil fuel-based boilers and electric resistance heating, thereby lowering greenhouse gas emissions and operational costs. The modular nature of the system allows for easy integration into existing infrastructure, enabling retrofitting of older buildings and expansion of district heating networks with minimal disruption. By optimizing thermal energy usage, the system contributes to enhanced energy efficiency and sustainability in the built environment.