High Temperature Heat Research Articles

Optimization of reversible heat pumps utilizing waste heat from electric power plants

Abstract Current global climate targets aim to decarbonize all energy sectors. In the power generation sector, the increasing presence of Renewable Energy Sources (RES) has changed the role of Combined Cycle Gas Turbine (CCGT) power plants. They are becoming systems that need to provide more flexibility to the grid through ancillary and balancing services or reserve capacity. At the same time, urgent action is needed to significantly reduce the carbon intensity of the heating sector, a major contributor to greenhouse gas emissions. Using the low-exergy waste heat from water-cooled CCGT condensers as a thermal source for vapor compression heat pumps serves two purposes. Firstly, it improves the economic viability of CCGT plants, which is crucial for ensuring the security of the electricity supply. Secondly, the heat produced provides a low-carbon alternative to conventional gas-fired boilers or less efficient air-source heat pumps. This study evaluates the potential for recovering thermal energy from seawater cooling at the condenser of the 794 MWel CCGT plant in Vado Ligure operated by Tirreno Power. A high-temperature heat pump using R600 as the working fluid is proposed. Seawater is an advantageous heat source, and integration into the power plant site allows the heat pump to be operated at a lower cost than the retail price of electricity. To assess economic and environmental performance, the case study focuses on the new Vado Ligure sports hall. This involves sizing the heat pump and analysing its impact, managing both heating and cooling demand using the same reverse cycle heat pumps.

Integration of hydrogen for decarbonisation: the possible contribution in “Hard-to-Abate” Sectors

Abstract The energy transition requires significant efforts to decarbonize hard-to-abate sectors. These sectors pose substantial challenges due to their high energy demands and reliance on fossil fuels, necessitating a comprehensive strategy. Hydrogen emerges as a helpful element, through its use as a feedstock, process agent, and alternative fuel for high-temperature heat. Its use in hard-to-abate sectors, such as steel and chemical industries, offers promising low-carbon alternatives, particularly in processes like direct reduction of iron (DRI). This paper aims to provide a critical analysis and framework to better organize and address the varied challenges and activities related to hydrogen utilization in these sectors.

Thermally conductive, mechanically robust alumina-incorporated polyurethane films prepared by ultraviolet light curing

Abstract The development of heat dissipating composite materials for electronic systems can be expedited using alumina particles as modifiable polymer-matrix fillers. However, these composites are difficult to synthesize given the tradeoffs between thermal conductivity, insulating characteristics, and conduciveness to processing. To that end, the present study is focused on synthesizing environmentally friendly polyurethane films that could be cured by ultraviolet light within minutes, without requiring high-temperature heat treatment. Through the optimization of alumina modification, hybridization of thermally conductive fillers, filler content, and stirring time on the thermal conductivity of the polyurethane composites, this study improves the process for sustainability, low-cost, and convenient preparation. The experimental results confirmed that the use of surface modification and hybrid fillers is effective for enhancing the thermal conductivity, with the value of the polyurethane integrated with 50 wt% Al2O3 and 5 wt% Al2O3–poly (catechol/polyamine) being 76.40 wt% higher than that of pure PU (0.44 W/mK). Additionally, the use of hybrid fillers resulted in superior mechanical and thermal properties (such as tensile strain, tensile strength, thermal expansion coefficient, and temperature resistance) compared with those of pure PU and films incorporated with only a single filler.

Incorporation of SnSe2/SnO2 heterostructures in carbon nanotubes for excellent lithium storage performance

As a new type of negative electrode material, tin-based material exhibits a high theoretical capacity. However, tin-based anode materials always undergo severe volume change upon alloying reaction during lithium insertion and extraction, which leads to the pulverization of the active materials and poor electrochemical performance, seriously hampering its practical application. In this work, oxygen-containing group functionalized carbon nanotubes (FCNTs) were facilely obtained, and the three-dimensional crosslinked SnSe2-SnO2@FCNTs multiphase materials were prepared by solvothermal and high-temperature heat treatment. The formation of Sn-O-C bonds from oxygen-containing functional groups of FCNTs combined with Sn can promote the electric connection and integrity of the composites. The implanted defects in FCNTs can not only be beneficial to anchoring SnO2 and SnSe2 nanoparticles, but also helpful to the penetration of Li+ ions into the electrodes from electrolyte. In addition, the large Fermi energy difference between SnSe2 and SnO2 nanoparticles results in the formation of a built-in electric field at the interface of the multiphase materials, accelerating the diffusion of ions. The smaller size of the multiphase materials leads to significant pseudocapacitive behavior, which facilitates the highly reversible surface/interface adsorption. Under the multiple effects of FCNTs, SnSe2, and SnO2, the SnSe2-SnO2@FCNTs multiphase materials exhibited excellent electrochemical performance. At a current density of 0.1 A·g−1, a discharge specific capacity of 898.0 mA h·g−1 was achieved. When the current density was increased to 2 A·g−1, it still exhibited a discharge specific capacity of 443.9 mA h·g−1. After a long charge/discharge cycling at 1 A·g−1 over 450 cycles, it still showed a specific capacity of ∼ 400 mA h·g−1. This work significantly demonstrated the enhanced Li-storage performance of SnSe2-SnO2 heterostructures incorporated in the functionalized multi-walled CNTs. This opens a new way to synthesize advanced tin-based materials as high-performance anodes for high-energy density lithium-ion batteries.

Electrification or Hydrogen? The Challenge of Decarbonizing Industrial (High-Temperature) Process Heat

The decarbonization of industrial process heat is one of the bigger challenges of the global energy transition. Process heating accounts for about 20% of final energy demand in Germany, and the situation is similar in other industrialized nations around the globe. Process heating is indispensable in the manufacturing processes of products and materials encountered every day, ranging from food, beverages, paper and textiles, to metals, ceramics, glass and cement. At the same time, process heating is also responsible for significant greenhouse gas emissions, as it is heavily dependent on fossil fuels such as natural gas and coal. Thus, process heating needs to be decarbonized. This review article explores the challenges of decarbonizing industrial process heat and then discusses two of the most promising options, the use of electric heating technologies and the substitution of fossil fuels with low-carbon hydrogen, in more detail. Both energy carriers have their specific benefits and drawbacks that have to be considered in the context of industrial decarbonization, but also in terms of necessary energy infrastructures. The focus is on high-temperature process heat (>400 °C) in energy-intensive basic materials industries, with examples from the metal and glass industries. Given the heterogeneity of industrial process heating, both electricity and hydrogen will likely be the most prominent energy carriers for decarbonized high-temperature process heat, each with their respective advantages and disadvantages.

Characteristic analysis and performance optimization of a transcritical CO2 heat pump for high-temperature heating: An experimental study

Based on the improved experiment, a study on the characterization and optimization of transcritical CO2 heat pumps for high-temperature heating is conducted through the combined analysis perspective of thermal quality and heat capacity, as well as the proposed indicator. The result shows that: In the heat transfer process of the gas cooler, the thermal quality of CO2 is closely related to the variation of discharge pressure and compression ratio, and the temperature rise of water shows a corresponding three stages; An increase in the heating temperature (th) requires a higher level of thermal quality on the CO2 side, which exacerbates the heat capacity mismatch in the gas cooler; The elevated compressor speed (ncom) can effectively alleviate this mismatch, but an excessive ncom can instead cause a reduction in system COP; In the study, the COP of the system is improved by up to 26.12 % by optimizing the throttle opening benchmark, and it is further enhanced by up to 19.91 % through the synergistic control strategy optimization; Consequently, the optimized COP can be obtained 2.204 when the required th is 100 °C; Furthermore, the introduction of IHX significantly benefits the high-temperature heating performance of the system and the COP lifting studied ranges 3.70%–14.12 %.

Numerical study of a copper oxide-based thermochemical heat storage system

A multi-physics model is developed to investigate the performance of high-temperature thermochemical heat storage using the redox looping cycle of CuO/Cu2O. The model involved flow in free and porous domains, heat transfer in the CuO pellet-packed porous domain (i.e., convection between fluid and pellets, conduction and radiation among pellets), and the endothermic/exothermic reaction. The reaction rate was estimated using a non-parametric kinetic approach which depends on temperature and extent of the reaction. The model was validated within <10 % error margin by the experimental measurements of the temperature inside the reactor and the molar fraction of O2 at the reactor outlet. The validated model is used to determine the temperature variation and reaction evolution in the pellet-packed domain. In the end, parameter studies were implemented, including inlet mass flow rate, reduction temperature, and oxidation temperature. It was found that a large inlet mass flow brings about a high output temperature, and the reaction runs faster with the larger inlet mass flow. Similarly, increasing the furnace temperature during the reduction process (reduction temperature) also increases the output temperature and accelerates the reaction. In contrast, increasing the furnace temperature during the oxidation process (oxidation temperature) only slightly affected the reaction in the present case. This model could provide useful insights into reactor design, scale-up, and operating conditions to improve the energy storage system performance.

The Role of Low-Carbon Fuels and Carbon Capture in Decarbonizing the U.S. Clinker Manufacturing for Cement Production: CO2 Emissions Reduction Potentials

Low-carbon fuels, feedstocks, and energy sources can play a vital role in the decarbonization of clinker production in cement manufacturing. Fuel switching with renewable natural gas, green hydrogen, and biomass can provide a low-carbon energy source for the high-temperature process heat during the pyroprocessing steps of clinker production. However, up to 60% of CO2 emissions from clinker production are attributable to process-related CO2 emissions, which will need the simultaneous implementation of other decarbonization technologies, such as carbon capture. To evaluate the potential of fuel switching and carbon capture technologies in decarbonizing the cement industry, a study of the facility-level CO2 emissions is necessary. This study evaluates the potential for using a single low-carbon fuel as an energy source in clinker production for cement manufacturing compared to conventional clinker production (which uses a range of fuel mixes). In addition, conventional carbon capture (operated with natural gas-based steam for solvent regeneration) and electrified carbon capture configurations were designed and assessed for net-zero emission targets. Carbon emissions reductions with and without biogenic emissions credits were analyzed to ascertain their impact on the overall carbon accounting. Results show that carbon emissions intensity of cement can vary from 571 to 784 kgCO2eq/metric ton of cement without carbon capture and from 166.33 to 438.66 kgCO2eq/metric ton of cement with carbon capture. We find that when biogenic carbon credits are considered, cement production with a sustainably grown biomass as fuel source coupled with conventional carbon capture can lead to a net-negative emission cement (−271 kgCO2eq/metric ton of cement), outperforming an electrified capture design (35 kgCO2eq/metric ton of cement). The carbon accounting for the Scope 1, 2, and biogenic emissions conducted in this study is aimed at helping researchers and industry partners in the cement and concrete sector make an informed decision on the choice of fuel and decarbonization strategy to adopt.

Numerical simulation of transient thermal stresses in medium- and high-temperature latent heat storage systems with different fins: Incorporation of experimental stress cracking

Latent heat storage systems play an essential role in energy applications by improving the utilization efficiency and increasing the system flexibility. In this study, a pilot-scale medium-to-high-temperature latent heat storage system was constructed, and experimental heat storage tests were conducted. The temperature distribution of the experimental system was verified through numerical simulations that coupled the physical fields of the fluids, heat transfer, and solid mechanics. Also, the changing dynamic behavior of the stresses in the heat storage process related to the experiments was carefully studied. It was discovered that there were stress concentrations where the heat exchanger tubes touched the casing, with the highest level being over 370.00 MPa. Experimental stress rupture of the shell occurred in the horizontally arranged heat-exchange tubes, whereas vertically arranged tubes significantly reduced the stress at the contact surfaces by 24.70 % according to simulations. Simulation studies on various influencing factors indicated a more significant impact of spiral fins on the system stress. Increasing the preheating temperature by 30 °C reduced stress on the front surface by 109.67 MPa; each 20 °C increase in heating temperature raised the stress by 223.30 MPa, whereas the effect of heat transfer fluid speed was minimal. Regarding the heat-exchange tube dimensions, increasing the height increased the tube body stress by 25.74 MPa, whereas increasing the thickness reduced the stress by 24.20 %. This study comprehensively analyzed the stress dynamics and mitigation strategies of the high-temperature latent heat storage system under various conditions, emphasizing the importance of heat-exchange tube orientation, temperature control, and fin design for optimizing system performance and durability.

High-Temperature SHS Heat Insulators Based on Pre-Activated Mineral Raw Materials

In this paper, the results of the technological combustion of SHS heat insulators based on mineral origins are presented. It is shown that after mechanochemical treatment of minerals—diatomite—the kinetic characteristics of the combustion process change, providing targeted formation of the phase composition, structure, and properties of the SHS composite. A positive effect of using various modifiers during the MCT of diatomite—the activation of the combustion process—was established. The selection of modifiers provides an increase in the strength of the synthesized SHS composites as a result of the formation of aluminate compounds in the synthesis products, and a decrease in thermal conductivity to 0.157 W/m*K due to the formation of the ultraporous structure of the samples.

Numerical study on carbon emissions and economics of a high temperature heat pump system for an industrial process

Research to achieve net-zero is actively being carried out. In industrial processes, large amounts of carbon are emitted to product thermal energy, and there is a growing interest in electrification technologies to reduce this. While electric heaters and heat pumps are representative technologies for electrification, research to determine which technologies can economically contribute to carbon reduction is necessary. In this study, transient model for a heat pump and thermal energy storage (TES) was developed, and the CO2 emissions and economic feasibility were analyzed. When coupled with photovoltaic power and battery energy storage (BESS), it was found that the heat pump can reduce CO2 emissions more economically than electric heater. Transient analysis was performed for the case of coupling TES with heat pump instead of BESS and it was found that CO2 emissions vary from 276 to 231 g/kWhth with and without the TES, respectively. When combining the heat pump and photovoltaic system with TES or BESS, the nominal levelized cost of heat to reach the same level of CO2 emissions is 11.6 % higher for the BESS-coupled system. Up to certain level of CO2 emissions, the TES-coupled system is economically viable, but minimum emissions can be achieved with the BESS-coupled system.

Effect of membrane filtration and direct steam injection on mildly refined rapeseed protein solubility, air-water interfacial and foaming properties

Rapeseed is an upcoming source of alternative proteins and extensive processing is necessary to utilise these proteins as functional ingredients. A risk here is the potential alteration of proteins upon processing, such as aggregation, thus affecting final ingredient's functional properties. Therefore, we aim to evaluate processing methods that are considered ‘mild’ for the proteins to retain native proteins with good techno-functionality. We evaluate the impact of two upcoming processes: 1) membrane filtration (5 kDa) to remove small solutes and 2) short but high-temperature heating using direct steam injection (DSI, 4 s at 115 °C) to ensure microbial safety. These extracts were studied for their protein composition, size and hydrophobicity. We, for instance, show the presence of cruciferin and napin in the extracts, which are the two main rapeseed protein families. Membrane filtration was suitable to remove phenols and non-protein solutes (e.g. carbohydrates and minerals), thereby increasing the protein content of the protein powders from 45.1 to 63.4% (w/w). DSI led to about three times lower protein solubility (from ∼44% to ∼16%) due to aggregation. These aggregates were mainly formed by cruciferin proteins, while napins remained soluble. As a result, the soluble napin proteins dominated the air-water interface and foam stabilisation. At the same time, cruciferin proteins were more dominant in the non-heated extracts, as they were in a soluble non-aggregated state. We showed an improved foamability of about 10% after heating but a 30–40% decrease in foam stability. A final finding was the impact of non-protein solutes, which vastly decreased the interfacial stiffness, leading to substantially less stable foams compared to membrane-filtered samples. In this work, we demonstrate how crucial processing steps, such as heating and filtration, impact (protein) composition, molecular and functional properties, which are crucial insights in designing protein extraction processes to obtain functional protein ingredients.

Analysis of the CO2 + C2Cl4 mixture in high temperature heat pumps: Experimental thermal stability, liquid densities and cycle simulations

Transcritical heat pumps working with CO2-based mixtures with a low-volatility dopant are found to achieve good performances in thermally integrated heat pumps, especially when sensible heat sources and heat sinks are considered. This paper introduces in literature tetrachloroethylene, C2Cl4, as CO2-dopant for the mixture to be adopted as working fluid in high temperature heat pumps. To calibrate the thermodynamic model used in the cycle simulations, an experimental characterization on the mixture is proposed: liquid densities of the mixtures are measured, in a wide range of concentration, optimizing the binary interaction parameter of the Peng Robinson equation of state. Moreover, the thermal stability of pure C2Cl4 is experimentally evaluated, identifying the maximum allowable compressor outlet temperature between 200 °C and 250 °C, with a decomposition rate below 1 %/year if the fluid is kept at temperatures around 200 °C. Then, the potentialities of this very high temperature heat pump are assessed in spray dryer applications: a coefficient of performance around 3.38 is obtained for a conventional spray dryer plant, corresponding to 73 % of second law efficiency, considering an air flow heated from ambient temperature to 200 °C as the sink, while cooling the sensible heat source, available at 76 °C, below 30 °C. As term of comparison, the same system adopting propane, instead of the CO2 + C2Cl4 mixture, would achieve a coefficient of performance and second law efficiency of 2.94 and 64 %, respectively.

Dissolution of Primary Carbides and Formation and Healing of Kirkendall Voids in Bearing Steel under Pulsed Electric Current

The alloying elements in 8Cr4Mo4V bearing steel tend to form large primary carbides with carbon, which not only causes element segregation but also becomes the primary source of fatigue crack initiation, thereby decreasing the material's usability and machinability. Owing to the excellent thermal stability of primary carbides, traditional homogenization annealing requires high temperatures, which is both time‐ and energy‐intensive. Excessively high heat treatment temperatures can also result in “overburning” of the sample. Herein, primary carbides are rapidly dissolved at low temperatures using pulsed electric current treatment. The additional free energy introduced by the pulsed electric current lowers the thermodynamic barrier for carbide dissolution. During the second‐phase dissolution process, the unbalanced diffusion of elements may cause the formation of Kirkendall voids. Due to the difference in electrical conductivity between the voids and the matrix, the pulsed electric current generates thermal compressive stress on the voids, promoting rapid atom migration to these voids and accelerating their healing. This pulse‐current treatment technology offers a novel method for the rapid dissolution of carbides in alloys at low temperatures and for the rapid healing of related voids.

The Joint Use of a Phase Heat Accumulator and a Compressor Heat Pump

This article presents an example of the joint use of a compressor heat pump that uses propane as a natural, ecological thermodynamic medium and a phase heat accumulator that uses paraffin as a medium. Special attention has been paid to the solidification process of the phase change material, and a simple theoretical model of the solidification of this material has been proposed. Thermodynamic balance calculations were carried out for the compressor heat pump and the phase heat accumulator. This paper presents a theoretical analysis of two examples of heating using a compressor heat pump, implementing the Linde cycle for the refrigerant R290 (propane): high-temperature heating at a temperature of 80 °C and low-temperature (surface) heating at a temperature of 60 °C, with the same unit heat output of 0.376 kW taken from the lower-temperature heat source of each evaporator. This heat is generated by the solidification of the PCM. The compressor power is 77 W in the first case and 40 W in the second. The energy efficiency coefficients of the compressor heat pump for the proposed combination of a phase heat accumulator and compressor heat pump are 5.98 and 10.40. The joint use of a heat accumulator and a heat pump presented in this paper can be used in applications for the heating of domestic water or water for space heating.

Porous Monolithic Perovskite Structures for High-Temperature Thermochemical Heat Storage in Concentrated Solar Power (CSP) Plants and Renewable Electrification of Industrial Processes

A novel approach towards thermal energy storage of surplus renewable energy (RE) is introduced via a hybrid thermochemical/sensible heat storage concept implemented with the aid of porous structures made of redox metal oxides, capable of reversible reduction/oxidation upon heating/cooling in direct contact with air, accompanied, respectively, by endothermic/ exothermic heat effects and demonstrating fully reversible dimensional changes under cyclic operation. The proposed modular storage units can be heated during the day to a level exceeding the metal oxide’s reduction onset temperature either by hot air streams from air-operated Concentrated Solar Power (CSP) tower plants or via surplus/cheap RE-electricity from photovoltaics, wind, or other renewable sources (“charging”/energy storage step). When this RE sources become non-available or upon demand, the fully charged system can transfer its energy to a controlled airflow that passes through the porous oxide block and initiates the exothermic oxidation of the reduced metal oxide. Thus, a hot air stream is produced which can be used to provide electricity or exploitable heat for industrial processes. The present work elaborates on the operating principles and the potential application of this concept and reports progress in the preparation and shaping of reticulated porous ceramics (RPCs also known as “ceramic foams”) from CaMnO3-based perovskite compositions and their preliminary testing with respect to cyclic reduction-oxidation.

Efficient Computation of Radiative Heat Recovery from Porous Ceramic Monoliths for Efficient Solar Thermochemical Fuel Production

Solar thermochemical hydrogen (STCH) produced by heat-driven water-splitting is a promising route for producing green hydrogen and other zero-emission synfuels. However, the efficiency of STCH must be dramatically increased for it to make an impact on decarbonization efforts. We have previously presented a novel Reactor Train System (RTS) for significantly increasing the efficiency of STCH by employing heat recovery from the redox material and efficient gas exchange processes. In this paper we present a higher-fidelity model for the RTS that accommodates the slow heat diffusion through the STCH redox material. For this purpose, a novel method is introduced for transient modelling of radiative heat in participating media. This method, called GREENER: Generalized Radiation Exchange Factors and Net Radiation, combines the accuracy of Monte Carlo Ray Tracing with the low computational cost of the P1 or Rosseland diffusion approximations. Along with STCH, GREENER has application for modelling volumetric solar receivers, high temperature heat recovery systems like heat exchangers and regenerators, and packed bed reactors. Using the GREENER method, the RTS counterflow radiative heat exchanger is shown to achieve heat recovery effectiveness greater than 70%. The performance of non-uniform porous redox morphologies is evaluated, and high-performing configurations are identified.

A Review on the Effect of Wood Surface Modification on Paint Film Adhesion Properties

Wood surface treatment aims to improve or reduce the surface activity of wood by physical treatment, chemical treatment, biological activation treatment or other methods to achieve the purpose of surface modification. After wood surface modification, the paint film adhesion performance, gluing performance, surface wettability, surface free energy and surface visual properties would be affected. This article aims to explore the effects of different modification methods on the adhesion of wood coating films. Modification of the wood surface significantly improves the adhesion properties of the paint film, thereby extending the service life of the coating. Research showed that physical external force modification improved the hydrophilicity and wettability of wood by changing its surface structure and texture, thus enhancing the adhesion of the coating. Additionally, high-temperature heat treatment modification reduced the risk of coating cracking and peeling by eliminating stress and moisture within the wood. Chemical impregnation modification utilized the different properties of organic and inorganic substances to improve the stability and durability of wood. Organic impregnation effectively filled the wood cell wall and increased its density, while inorganic impregnation enhanced the adhesion of the coating by forming stable chemical bonds. Composite modification methods combined the advantages of the above technologies and significantly improved the comprehensive properties of wood through multiple modification treatments, showing superior adhesion and durability. Comprehensive analysis indicated that selecting the appropriate modification method was key for different wood types and application environments.

Numerical investigation of high temperature heat pump integrated hybrid cooling system

Over 67 % of the energy demand within the pharmaceutical and semiconductor industries is for their cleanrooms, driven by stringent temperature and humidity control requirements. Despite high energy usage, heating, ventilation, and air-conditioning (HVAC) units consisting of conventional vapor compression systems (CVCS) are favoured for their simplicity. Hybrid cooling systems (HCS) offer potential efficiency gains by separating latent and sensible loads. Still, reliance on fossil-fuel-fired or electric heaters to regenerate the desiccant makes it energy intensive and reduces CO2 mitigation benefits. This study explores high-temperature heat pumps to simultaneously cool process air and heat regeneration air, thereby using multiple benefits. Heat pumps with condensing temperatures of 80 °C, 90 °C, and 120 °C and an ejector-enhanced trans-critical CO2 heat pump were compared with CVCS and HCS. The 120-bu and CO2HP configurations demonstrated a system COP of 2.94 and 3.22, respectively, surpassing CVCS, which has a system COP of 1.44. These setups achieved CO2 emission reduction of 51 % and 55.2 %, compared to CVCS, respectively.

Synthesis and tunable luminescence properties of SrY₂O₄:Dy³⁺ phosphors

In this study, SrY₂O₄:Dy³⁺ phosphors were synthesized using the solid-state reaction method and evaluated after heat treatment at 1300 °C for 5 h. XRD analysis confirmed the orthorhombic structure of SrY₂O₄ with residual Y₂O₃ present. The addition of Dy³⁺ ions caused lattice expansion, impacting grain size and crystallinity. SEM images showed that the phosphor particles had irregular shapes with minimal size variation, although they tended to agglomerate due to high-temperature heat treatment. Optical analysis revealed significant absorption and emission peaks, with a strong excitation band in the 200–306 nm range and prominent sharp peaks in the 306–480 nm range, particularly at a 0.5 mol% doping concentration. Emission spectra indicated the highest intensity at 0.5 mol% Dy³⁺ concentration, with intensity decreasing due to concentration quenching at higher levels. Thermal stability tests showed peak emission intensity at 70 °C, with stability maintained up to 190 °C before notable thermal quenching. Chromaticity coordinates remained within the warm white region at both temperatures. This study provides detailed insights into the effects of Dy³⁺ doping on the structural, optical, and thermal properties of SrY₂O₄ phosphors. Compared to previous studies on rare-earth-doped SrY₂O₄ phosphors, this work is the first to systematically explore the substitution of Y³⁺ ions with Dy³⁺ ions until full replacement. The study not only confirmed that the highest emission intensity occurs at 0.5 mol% Dy³⁺ concentration, but also demonstrated that Dy³⁺-doped SrY₂O₄ phosphors exhibit excellent thermal stability, with emission stability maintained below 150 °C. These findings expand the potential applications of Dy³⁺-doped SrY₂O₄ phosphors, particularly in high-temperature environments and solid-state lighting.