The continuous increase in power density and overall energy consumption in modern data centers, primarily driven by artificial intelligence applications and high-performance computing workloads, has accelerated the adoption of advanced thermal management solutions. Liquid cooling systems (LCS) have become a prominent alternative to conventional air-based cooling approaches due to their higher heat removal efficiency, improved energy utilization, and suitability for high-density deployment scenarios. Despite these advantages, the practical implementation and long-term operational stability of liquid cooling systems remain key challenges, as such systems are vulnerable to multiple failure modes, including fluid leakage, material corrosion, particulate accumulation, and flow obstruction. This review systematically examines the technical methods and management strategies adopted to enhance the stability and reliability of liquid cooling systems in high-density data center environments. It provides a structured analysis of common failure mechanisms, with particular emphasis on their underlying causes and potential impacts on system performance and operational safety. In addition, the paper discusses water quality control strategies, material compatibility considerations, and structural design measures aimed at reducing leakage and corrosion risks. Real-time monitoring and early warning techniques, including sensor-based detection and data-driven diagnostics, are also reviewed as essential tools for maintaining stable system operation. Furthermore, the effectiveness of these solutions is evaluated through reported engineering practices, case studies, and experimental validation results. Finally, the importance of continuous monitoring, routine maintenance, and lifecycle management is emphasized, and future development directions for more robust, intelligent, and resilient liquid cooling systems are proposed to support the sustainable operation of next-generation data centers.

Two-phase flows have many important industrial applications, including in nuclear reactor coolant systems. Due to the density difference between the gas and liquid phases, buoyancy effects can have a significant impact on two-phase parameters, and thus the orientation of the flow is a major factor impacting system performance and safety. While recent work has greatly expanded the knowledge of horizontal and inclined flows, gaps still exist, especially regarding the relative motion between the two phases. There are few experiments in literature that measured both local liquid and gas velocity profiles, which are key to understanding and modeling the relative velocity. This work seeks to address this gap by performing experiments in horizontal air-water bubbly two-phase flow, specifically measuring the local gas and liquid velocities by means of a local four-sensor conductivity probe and Pitot-static probe, respectively. Eight fully developed conditions are measured and presented in the current work, with the trends in relative velocity analyzed. It was found that the relative velocity is negative throughout the pipe cross section when in a horizontal orientation. The relative velocity becomes more negative with increasing local void fraction, and remains negative as the void fraction approaches zero. With this newly established database, a model is then proposed to predict the relative velocity in horizontal bubbly flows, accounting for bubble wake interactions. The preliminary model is able to predict the void-weighted area-averaged relative velocity within 15%, and the local relative velocity with an average absolute percent difference of 38%, which is considered adequate given the experimental uncertainties.

With advancements in simulation technology, fluid–thermal interaction (FTI) has become a vital tool in machinery powertrain development. Traditional engine cooling systems, with mechanically coupled components like water pumps and fans, lack adaptive cooling control. Electronic cooling systems, however, use variable-speed components to enhance performance. Combining FTI simulations with intelligent optimization algorithms offers a novel approach to designing control strategies for these systems. This study establishes a multi-objective optimization model for pump and fan speed control in electronic cooling systems. Using MATLAB/Simulink 2018 and Fluent 2022R1, co-simulations were performed, and an elite-strategy-based NSGA-II algorithm was implemented. Different weights were assigned to optimization objectives based on engine performance requirements. The results provide fitted functions for heat exchange capacity and cylinder liner temperature versus flow rates, along with optimal solutions for a 65 kW engine under three weight configurations. These findings support control strategy design and demonstrate the integration of FTI with genetic algorithms.

The thermal stabilization and cooling systems for the time projection chamber (TPC) and electromagnetic calorimeter (ECAL) detectors of the multi-purpose detector (MPD) experiment at the NICA (Nuclotron-based Ion Collider fAcility) are based on a leakless water-cooling concept that ensures continuous operation under subatmospheric conditions. The implementation of such a system imposes stringent constraints on the hose materials responsible for coolant delivery, especially regarding their ability to resist radiation-induced activation, their long-term chemical stability against corrosion, and minimal gas diffusion under internal water pressure conditions of approximately 0.5 bar, and sufficient mechanical robustness and flexibility to allow for seamless integration within the MPD infrastructure. This research is dedicated to the evaluation and qualification of various types of flexible plastic hoses that are proposed to deliver distilled or deionized water to the cooling circuits of the TPC and ECAL detectors. Due to the proximity of these hoses to the TPC front-end electronics, they are expected to be exposed to neutron radiation levels approaching 1011 neutrons/cm2 at 1 MeV over the projected operational duration of the MPD experiment, which spans an estimated 10 years. To emulate this cumulative neutron exposure under controlled conditions, the candidate hose materials were irradiated using neutron fluences of F1 = 109 n/cm2, F2 = 1010 n/cm2, F3 = 1011 n/cm2, and F4 = 1012 n/cm2. The effects of irradiation were systematically assessed using Raman spectroscopy for molecular structural changes, mechanical tensile testing for changes in strength and elasticity, and gas permeability evaluations to measure performance degradation related to leak tightness. These empirical results were complemented with multiphysics simulations conducted using COMSOL to analyze the thermal distribution and fluid dynamics within the selected hose materials under realistic operational conditions. Based on the collective findings from the experimental and simulation studies, reinforced polyvinyl chloride was identified as the most suitable candidate for long-term use in the MPD thermal stabilization and cooling subsystems.

Investigation of Waste Heat Recovery from a 4E Perspective: Performance of Combined Cooling, Heating, and Power Systems with Various Prime Movers for Residential Applications

In thermal power plants, Vapour Absorption Machines (VAMs) are conventionally operated using Auxiliary Pressure Reducing and Desuperheating Station (APRDS) steam, resulting in losses of high-grade energy and condensate. Simultaneously, turbine gland steam drain during self gland-sealing operation is continuously discharged to the condenser to maintain required inlet temperatures, leading to additional waste of recoverable thermal energy. This study presents a Kaizenbased modification in which the turbine gland steam drain is utilized as the driving heat source for a 300 TR Vapour Absorption Machine, integrated with a condensate recovery system. The proposed system effectively harnesses low-grade waste steam for refrigeration, reduces dependence on APRDS steam, and enables condensate reuse. Integration of DCS-based control, protective interlocks, and real-time monitoring ensured safe and reliable operation. Implementation results demonstrate a coal saving of approximately 6 tons per day, along with reductions in CO₂ emissions, ash generation, and DM water consumption. The study confirms that turbine gland steam drain utilization offers a practical and sustainable approach for waste heat recovery in thermal power plants

Cooling systems play a vital role in maintaining optimal operating conditions in modern data centers (DCs). Efficient control of cold source groups, such as chillers and air handling units, is essential for reducing energy consumption while ensuring temperature stability. This research introduces a novel data-driven approach to optimize the control strategy for cold source groups in DCs by leveraging extensive real-time monitoring data. The control problem is formulated as an energy cost minimization task subject to strict temperature constraints. Addressing these issues, this research proposes an end-to-end group control algorithm based on deep reinforcement learning (DRL). The research suggests a new algorithm called Artificial Gorilla Troops Optimizer-driven Controlled Deep Q-Network (AGTO-CDQN) for dynamically coordinating the operation of multiple cold source units. The research involves collecting both historical and real-time data from DC sensors, including temperature readings, power consumption of cooling units, and server workloads. Experimental results demonstrate that AGTO-CDQN considerably increases the power savings above 15% for IT power consumption, cooling power consumption, total power consumption, and average zone air temperature. These findings highlight the approach’s potential for practical deployment in energy-efficient DC cooling management.

The temperature-induced efficiency loss of 0.4% to 0.5% for every °C above 25 °C alongside the inherent variability in solar irradiance, poses a critical challenge to the efficiency and stability of Photovoltaic (PV) modules. This study addresses this limitation by developing and analyzing an Integrated Photovoltaic Thermal-Thermoelectric Cooler (PV/T–TEC) system designed for robust thermal management and enhanced energy yield. The proposed system utilizes a synergistic hybrid cooling mechanism: a passive PV/T air collector for bulk heat dissipation from the PV panel's rear surface, coupled with an active Thermoelectric Cooler (TEC) for precise temperature stabilization. The electrical energy flow is managed by a DC–DC Boost Converter employing a PID controller, with a focus on input disturbance rejection, ensuring the TEC operates at an optimal, stable power point.Simulation and performance analysis demonstrate the significant advantages of this hybridized approach. The PV/T air collector was confirmed as the primary thermal component, achieving a peak heat dissipation QEmit approximately 7.5 times greater than the TEC-only configuration. This strategic pre-cooling successfully stabilizes the TEC's hot-side temperature, enabling the TEC to operate with a low operational temperature differential ∆T and resulting in an exceptionally high calculated Effective System Coefficient of Performance COP peaking at 14.5. The system maintains a stable operating point during peak solar radiation, maximizing the Net Electrical Power Gain. In conclusion, the integration of passive PV/T cooling, active TEC cooling, and a PID-enabled DC–DC Boost Converter provides an exceptionally efficient and stable solution for PV thermal management. The research strongly supports the efficacy of this hybrid system for significantly improving the overall energy efficiency and sustainability of solar energy applications.

Problem. Mild hybrid vehicles are a good compromise in terms of price-quality ratio among hybrid vehicles. To reduce the cost and weight, as well as to increase the efficiency of recuperation of a mild hybrid vehicle, a new algorithm for the operation of the power plant engines in the city traffic mode is proposed. In the proposed vehicle, movement with an electric drive and a stopped ICE is replaced by uniform movement at a relatively low speed (40-50 km/h) on an asphalt road without a noticeable rise. The ICE idle mode is also excluded due to the start-stop system. Starting from a standstill and accelerating must be done on the ICE. In this driving mode, the service recuperative braking mode of the electric motor-generator is of great importance, in which a sufficient electrical load of the traction electric motor operating in the generator mode is important. The small capacity of the traction battery of the mild hybrid vehicle and the relatively high speed of regenerative service braking quickly lead to low efficiency of electric braking due to the reduced charging current of the low-capacity traction battery. Goal. The aim of the work is to increase the efficiency of regenerative braking. Methodology It is shown that in this case sufficient deceleration during regenerative braking will be achieved by connecting an active three-phase load for alternating current to the electric motor-generator. Results. An improved regenerative braking of a mild hybrid vehicle is considered. Excess recuperation energy is proposed for heating the internal combustion engine coolant. A theoretical justification is considered for why an active three-phase load of the electric motor-generator with heating elements in the internal combustion engine cooling system is required. A practical implementation of the technical solution is given, for which an electrical circuit of the recuperation system and a basic electrical circuit of the current control unit are developed. Originality. This study provides a comprehensive solution to the technical proposal in the patent. Practical value. The results of this study are of value to mild hybrid vehicle developers. The knowledge gained contributes to the optimization of the regenerative braking process. This study supports the broader goal of accelerating the adoption of mild hybrid vehicles.

The interest in the IRIS (International Reactor Innovative and Secure) reactor is revived by today's popularity of small modular reactors. The IRIS reactor project, led by Westinghouse Electric Corporation, was active in the first decade of the 21st century. Different groups of institutions such as nuclear manufacturers, academic institutions, national laboratories, etc. from 10 countries around the world participated in the IRIS team. IRIS is an integral, modular, medium sized (1000 MWt) pressurized water reactor. The IRIS reactor pressure vessel houses, beside the reactor core, also other major reactor coolant system components such as the pressurizer, reactor coolant pumps and steam generators. The lack of large pipes ensures high safety of the IRIS power plant and eliminates many causes of major accidents. This principle is known as “safety-by-design” approach. Polytechnic of Milan and the University of Zagreb were leading institutions in performing safety analyses for the IRIS reactor. The explicit coupling of RELAP5 and GOTHIC codes has been set up to cover the sequence of most probable LOCA transient events. This was necessary because the reactor vessel and the containment, once when the LOCA is initiated, become one hydraulic system with strong interaction. They exchange mass and energy which affects both systems in short time period and therefore cannot be treated separately as in a conservative analysis of a classic PWR nuclear power plant. In addition, the ASYST code model was recently developed to cover possible severe accident sequences. The core heat structures were replaced with SCDAP components to simulate core degradation. A couple of different GOTHIC models were developed to represent various arrangements of passive safety systems. A steady state analysis was performed to confirm the applicability of the IRIS numerical model in the safety analyses.

A Very rapid population growth has resulted in fossil energy being gradually depleted and environmental pollution getting worse. So far, burning fossil fuels has produced about 40% of global carbon dioxide (CO2) emissions, which are considered a major source of greenhouse gases. The Internal Combustion Engine (ICE) has become the main power source for cars, trucks, locomotives, and ships. In ordinary diesel engines, less than 45% of the fuel energy can be converted into useful work output from the crankshaft, and the remaining energy is largely lost through exhaust gases and jacket water. One way that can be done is to utilize the waste from the internal combustion engine (ICE). This method uses the Organic Rankine Cycle (ORC) system by utilizing the wasted heat generated by the Diesel engine when operating, through the engine coolant coming out of the engine gap (water jacket) to the radiator. In this study, the study focused on the exergy analysis of each component in the ORC system integrated in the diesel engine cooling unit which was simulated using Aspen Plus software. The analytical method used in this study is the exergy method with variations in ambient temperature of 20oC, 21oC, 22oC, 23oC, 24oC, 25oC, 26oC, 27 oC, and 28 oC using the working fluid R141B. The results showed that the greatest exergy destruction was found in the components of the pump, evaporator, and turbine.

This paper presents the structural design and supporting analysis for the Microreactor Applications Research Validation and Evaluation (MARVEL) primary coolant system (PCS) using the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code Section III, Division 5, rules. MARVEL is a liquid metal–cooled microreactor intended to provide experimental capabilities for the rapid testing and development of microreactor technologies. The PCS utilizes high-temperature sodium-potassium liquid metal as the primary coolant and operates at a design temperature of 570°C, necessitating the consideration of creep-related failure mechanisms. The base metal for the PCS is 316H stainless steel, and the weldments are made with a 16-8-2 filler. The design approach incorporates the current base code rules along with ASME code cases N-924, N-861, and N-862 to address primary load, ratcheting, and creep-fatigue evaluations, respectively. The reactor’s operation involves complex thermal and mechanical interactions due to natural convective flow and differential thermal expansion between components. This paper discusses the structural engineering challenges encountered, such as managing thermal stresses in the distribution plenum and guard vessel, and outlines the strategies implemented to meet the code requirements, including design modifications and operational constraints.

This study examines the applicability of solar energy for cooling in the tropical climate and focuses on the performance assessment of a modular solar-powered cooling system (MSPCS), integrated with a DC-Remote monitoring and control (RMC) system, installed on a 10 m³ cooling chamber for the storage of fruits and vegetables. The RMC capability to stabilise the MSPCS operation was assessed through real-time monitoring and control of system parameters, including temperature and relative humidity, water chiller temperature, and DC voltage utilisation by the components. This was achieved by connecting sensors for monitoring via an internet-enabled data box linked to a PC dashboard. The system cooling performance was assessed by measuring chamber temperature, humidity, voltage consumption and weight loss of the stored produce. The results demonstrated effective tracking/control of the system parameters and enhanced activation of components to stabilize the operation of the entire cooling system at temperature of (8.40 ±0.455a °C), relative humidity of (88.91 ±1.571 %) inside the cooling chamber, the water chiller temperature at (2.75 ±1.25 °C) and system voltage (25.61±0.033 V) at no-load and loading conditions. The integration of the DC-RMC system significantly enhanced both the cooling chamber's thermal performance and the overall voltage efficiency of the system, resulting in 20% physiological weight loss and a delay in ripening by 10 days for stored tomatoes in the solar cold room as against 75 % and 7 days, respectively from the ambient over 14 days. of storage.

The University of Wisconsin (UW) is part of a team supporting General Atomics Electromagnetic Systems (GA-EMS) in its development of a 100-MWth gas-cooled fast modular reactor. In particular, the FMR uses the reactor vessel cooling system (RVCS) to passively remove the decay heat from the reactor pressure vessel. UW has developed an RVCS test facility for the GA-EMS modular high-temperature gas-cooled reactor and has performed past experiments to demonstrate its performance. This RVCS facility has been updated, and we have performed a series of repeatability tests under ISO (International Organization for Standardization) 17025 standards to validate the existing data set and our previous work. In addition, the UW team has developed a MELCOR model of the UW RVCS facility to analyze these tests and to simulate the two-phase natural circulation flow. This paper presents the recent tests and associated analyses that demonstrate good agreement with the data, except for the larger flow oscillation. The effects of the heat loss in the loop and the water tank pressurization were investigated, but no significant impact was shown. The detailed investigation revealed that the MELCOR simulation results in a higher void fraction (10% to 70%) compared to the experiments (5% to 40%) and an earlier start of flashing. We hypothesize that the water needs to be superheated to flash in the UW RVCS facility due to the slightly colder pipe structures with heat loss.

Modeling and Thermal-hydraulics Characteristics Analysis of sCO2/LiPb Dual Function Blanket Auxiliary Cooling System

Organic-cooled reactor concepts offer potential advantages over traditional light water reactors, including operation at elevated temperatures and reduced pressures. However, radiation-induced degradation of organic coolants remains a critical concern requiring thorough investigation. This study examines the effects of gamma irradiation (1-MGy dose) on Dowtherm A (27% biphenyl, 73% diphenyl ether) under varying atmospheric conditions (ambient air versus argon) and temperatures (room temperature versus 250°C). Chemical characterization using Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy (UV-Vis), and gas chromatography-mass spectrometry revealed the formation of higher molecular weight byproducts, including terphenyls and quaterphenyls, along with notable biphenyl degradation. Physical property measurements using differential scanning calorimetry, rheometry, and thermal conductivity analysis demonstrated significant changes in the thermophysical properties, including decreased heat capacity and viscosity, with increased thermal conductivity observed under argon irradiation conditions. Pronounced photodarkening occurred in all the irradiated samples, with atmospheric conditions significantly influencing degradation pathways. UV-Vis analysis indicated that oxygen presence during irradiation suppresses certain chromophoric species formation. These findings provide crucial insights into radiation-induced degradation mechanisms and their impact on coolant performance, informing future organic coolant system design and optimization strategies for advanced reactor applications.

The radiant heating and cooling (RHC) system is one of the important air-conditioning methods that simultaneously achieves indoor thermal comfort and building energy efficiency. It is characterized by utilizing low-grade energy sources to provide low-temperature heating and high-temperature cooling, playing a significant role in promoting the development of green and low-carbon buildings. This study firstly introduces the typical heat transfer calculation methods of the RHC system and analyzes the surface heat transfer coefficients of radiant heating and cooling. Subsequently, the factors affecting the thermal performance of the RHC system are discussed from two aspects: relevant physical property parameters and flow channel structures. Finally, the control strategies of RHC systems are summarized to address issues such as condensation, overheating, and long response times. And several conclusive findings are presented that are worthy of further investigation in the future.

This study presents an experimental methodology for assessing the thermal behavior of high-power Chip-On-Board (COB) light-emitting diodes (LEDs) using infrared thermography, integrated with a novel compact forced-convection cooling device. The thermal performance was evaluated under varying power inputs and flow rates, revealing the system's ability to maintain LED junction temperatures below critical thresholds. Thermographic imaging enabled the spatially resolved temperature analysis of the LED surface under both natural and forced convection regimes. The proposed cooling device was specifically designed for compact integration, featuring a radial inlet/outlet configuration that minimizes space while maximizing heat dissipation efficiency. The simulation results generated were validated against experimental data, ensuring the reliability of the proposed cooling approach. This work demonstrates a feasible and replicable method for thermal management characterization in solid-state lighting applications, providing a scalable solution for integration in confined environments, such as LED luminaires, smart lighting systems, or embedded electronic modules.

The effect of amplitude and presence of suspended particles on the cavitation damage caused by truck engine coolants was investigated using an ultrasonic test rig. Two factors were tested against a reference fresh coolant with 50% ethylene glycol in water sonicated at 100% amplitude (50 µm): 50% probe vibration amplitude, and an addition of boron nitride (BN) particles (1,5 g/L, median size 0,2 µm). Additionally, their influence on the damage mechanisms of two materials – a spheroidal graphite iron (SGI) and a ferritic stainless steel (EN 1.4016)- was studied. Sample mass loss measurements and surface damage images revealed that SGI is more damaged than 1.4016 due to the removal of free graphite nodules from the SGI surface. A 50% amplitude led to a strong reduction in mass loss for both materials, but the effect was stronger for SGI due to the drastic offsetting of graphite removal. For 1.4016, the reduction was noticeable but became less significant once late stages of testing were reached, likely due to the buildup of damage as deformation and subsurface cracking. BN particles led to an exceptional mass loss reduction for both materials and at all times throughout the test. This occurred with qualitative changes to the damage mechanisms, shifting from a combination of overload, plastic deformation and low-cycle fatigue to a high-cycle fatigue regime exclusively, indicating that BN powders can reduce the cavitation impact load enough to prevent localized yielding. The findings corroborate the remarkable potential of suspended particles as viable solutions to reduce cavitation damage.

Optimization and Thermal Performance Parameters of Novel Hybrid Automotive Cooling System Designed for Modern Hybrid Electric Vehicles