Cooling Device Research Articles

A Numerical Study on Microgap-Based Focal Brain Cooling Device to Mitigate Hotspot for the Treatment of Epileptic Seizure

Abstract Epilepsy is a common chronic neurological disorder characterized by abnormally excessive and synchronized brain cell activities causing seizures. For proper functioning of the brain, epilepsy should be diagnosed with existing treatments such as medication therapy, lorazepam, benzodiazepine drug intake, and surgery. However, 30–40% of people continue to have a seizure because of the available treatments. So, the focal brain cooling device (FBC) is a new alternative cooling method in which affected brain tissue is cooled to suppress unprovoked seizures. The present numerical study investigates the cooling effectiveness by adding three different structured titanium micro pin fins in the existing base model. A finite volume-based software fluent-15.0 is used to perform transient heat transfer analysis and flow hydrodynamics. The numerical results obtained show that the temperature distribution is found and more uniform and diamond-structured micro pin fin takes less than 7 min to reach below 15 °C, which is desirable to diminish the high-frequency and high-amplitude epileptic discharges.

Study on Performance of the Thermoelectric Cooling Device with Novel Subchannel Finned Heat Sink

The thermoelectric refrigeration system is an application of the Peltier effect, and good refrigeration performance is dependent on effective heat dissipation performance. To enhance the cooling performance of the thermoelectric system, this paper designs a new type of finned heat sink, which does not change the overall size of the thermoelectric system. The performance of the refrigeration system under the new fin is tested by experiments under various conditions. During the experiment, the cooling wind speed, the temperature of the hot and cold side of the TEC, the power consumption of the fan, and other parameters were directly recorded through the measuring instrument. The results show that the use of new finned heat sinks can improve the COP of the thermoelectric refrigeration system. Within the scope of the study, the thermal resistance of the new fins can be reduced by 42.6%, and the system COP value can be increased by 22.8%. In addition, increasing the cooling wind speed can further reduce the cold side temperature. Within the research range, the lowest temperature can reach −8.25 °C, but the power consumed by the fan is 166% of that of the conventional fin heat sink refrigeration device.

MnP Films with Desired Magnetic, Magnetocaloric, and Thermoelectric Properties for a Perspective Magneto‐Thermo‐Electric Cooling Device

A new magneto‐thermo‐electric cooling device (MTECD) comprising a central magnetocaloric (MC) material (e.g., Gd) sandwiched by two thermoelectric (TE) materials (e.g., MnP) is proposed. The presence of the TE materials in the MTECD guides the heat flow direction and enhances heat pulsation. In this case, the usage of a ferromagnetic TE material that combines large TE with small MC properties within a similar temperature region can enhance the magnetic flux density and heat exchange efficiency. Herein, it is shown that MnP nanorod‐structured films with desired magnetic, MC, and TE properties are very promising for use in MTECDs. The films are grown on Si substrates at 300, 400, and 500 °C using molecular beam epitaxy. The 400 °C sample shows a desired TE and MC combination. A large power factor of 24.06 μW m−1 K−2 is achieved at room temperature. In this temperature region, the film exhibits a small MC effect (−ΔSM ≈0.64 J kg−1 K and ΔTad ≈0.3 K at μ0H = 2 T) but ferromagnetism that gives rise to the enhanced MC effect of the central MC material. These properties can enable the MTECD to operate at high frequency.

Abstract 10771: Avoidance of Lethal Isotherm Formation in Esophageal Tissue with an Active Cooling Device Under High-Power, Short-Duration Ablation

Introduction: Atrioesophageal fistula (AEF) is a severe complication of left atrial ablation for the treatment of atrial fibrillation. Thermal injury is the proposed mechanism, and a potential pathway occurs through exceeding the lethal isotherm of esophageal tissue in contact with the left atrial posterior wall. Active cooling with a novel cooling device has been shown to significantly reduce thermal injury, with no AEFs encountered after more than 4200 treatments worldwide. We aimed to evaluate the effects of active cooling when specifically using newer high-power short-duration (HPSD) ablation settings to further estimate the protective mechanisms of this novel approach to reduce serious injury. Hypothesis: Active cooling may preclude attainment of a lethal isotherm in esophageal tissue under HPSD ablation. Methods: We developed a model of the left atrium and esophagus, and simulated radiofrequency (RF) ablation of the left atrium under HPSD settings. Tissue thickness was set to typical posterior-wall parameters (Figure). Power settings were evaluated at 50 W for 10 seconds, and 90 W for 4 seconds. Active cooling was set to a typical 4 °C coolant temperature. Lethal isotherm temperature was taken as 50 °C. Results: In both scenarios of HPSD ablation, the peak esophageal mucosal temperature reached 39° C in control conditions, using no active cooling. With active cooling in place, peak temperatures remained below 11 °C (Figure). Peak temperatures at the epi-esophageal region of esophageal tissue exceeded the lethal isotherm of 50 °C in control conditions, but remained at or below the lethal isotherm with active cooling in place. Conclusions: Based on our mathematical modeling, esophageal cooling significantly reduced temperature rise and prevented the achievement of temperatures thought to be lethal to esophageal tissue. This finding may offer a mechanistic rationale for the absence of serious esophageal injury encountered to date using this approach.

Engine Cooling Device of New Energy Vehicle

With the environmental pollution and the shortage of oil resources becoming more and more serious, the development and application of new energy vehicles have attracted more and more attention. Engine is an important part of new energy vehicles, and its performance has a great impact on the vehicle. Compared with traditional industrial motors, new energy vehicle engines have higher requirements on power density, and the improvement of power density poses new challenges to the design of motor cooling system. The purpose of this paper is to study the engine cooling device of new energy vehicles and improve the overall performance of the vehicle. The main research content of this paper is to lay a foundation for the theoretical basis of the engine cooling device, elaborate the working principle of the motor cooling system and the loss of the motor in operation. Then, the heat dissipation system of permanent magnet synchronous motor based on heat pipe is studied experimentally. Aiming at the problem of only considering the temperature rise and ignoring the pressure loss in the flow channel design, a flow channel design method considering the motor temperature rise and the flow channel pressure loss is proposed, and the motor flow channel is optimized. The test results show that the maximum temperature rise at the end is close to 16.56 °C, which is in good agreement with the simulation results. It shows that the heat pipe based heat dissipation system can effectively reduce the temperature rise of motor winding, which provides a new idea for the heat dissipation design of permanent magnet synchronous motor

Simple and Low-Cost Footstep Energy-Recover Barocaloric Heating and Cooling Device.

In this work, we design, build, and test one of the very first barocaloric devices. The here presented device can recover the energy generated by an individual’s footstep and transform it into barocaloric heating and/or cooling. Accordingly, we present an innovative device that can provide eco-friendly and gas-free heating/cooling. Moreover, we test the device by measuring a new barocaloric organic polymer that exhibits a large adiabatic temperature change of ~2.9 K under the application of 380 bar. These results pave the way towards novel and more advanced barocaloric technologies and provide a simple and low-cost device to explore new barocaloric materials.

Investigating the Efficacy of a Canine Rabies Vaccine Following Storage Outside of the Cold-Chain in a Passive Cooling Device.

Background: Thermostable vaccines greatly improved the reach and impact of large-scale programmes to eliminate infectious diseases such as smallpox, polio, and rinderpest. A study from 2015 demonstrated that the potency of the Nobivac® Rabies vaccine was not impacted following experimental storage at 30°C for 3 months. Whether the vaccine would remain efficacious following storage under more natural, fluctuating temperature conditions remains unknown. We carried out a randomised controlled non-inferiority trial to compare serological responses in dogs following vaccination with doses stored under cold chain conditions with those stored within a locally made Passive Cooling Device (“Zeepot”) under fluctuating temperature conditions.Materials and Methods: Nobivac® Rabies vaccine was stored under either cold-chain conditions or within the Zeepot for 2 months. Daily ambient temperatures and temperatures within the Zeepot were recorded every 3 h. Following storage, 412 domestic dogs were randomly assigned to receive either cold-chain or Zeepot stored Nobivac® Rabies vaccine. Baseline and day 28-post vaccination blood samples were collected. Serological analysis using the Fluorescent Antibody Virus Neutralisation assay was carried out with a threshold of 0.5 IU/ml to determine seroconversion. In addition, the impact of dog Body Condition Score, sex, and age on seroconversion was examined.Results: The serological response of dogs vaccinated using Nobivac® Rabies vaccine stored within the Zeepot was not inferior to the response of dogs vaccinated using cold-chain stored vaccine (z = 1.1, df = 313, p-value = 0.25). Indeed, the 28-day post-vaccination group geometric mean titre was 1.8 and 2.0 IU/ml for cold-chain vs. non-cold-chain storage, respectively. Moreover, the percentage of dogs that seroconverted in each arm was almost identical (85%). There was a positive linear trend between Body Condition Score (O.R. 2.2, 95% CI: 1.1–5.1) and seroconversion, suggesting dogs of poor condition may not respond as expected to vaccination.Conclusions: Our study demonstrated the potency of Nobivac® Rabies vaccine is not impacted following storage under elevated fluctuating temperatures within a Zeepot. These results have potentially exciting applications for scaling up mass dog vaccination programmes in low-and-middle income countries, particularly for hard-to-reach populations with limited access to power and cold-chain vaccine storage.

Design and Research of Grinder Cooling Device Used for Mechanical Numerical Control Machining

This paper introduces design method and working principle of grinder cooling device for mechanical numerical control machining. By analyzing the problems of grinder cooling in mechanical numerical control machining, technical solutions for the problems, model construction and specific implementation pattern are proposed. Compared with the traditional cooling device, this device is simple to use, uniform in cooling, and has better coolant cooling effect. While cooling, it removes a part of metal chips and impurities, avoidingadverse effect on accuracy of the machined surface, whichprovides important guidance for production practice.

Thermal Analysis of a MEMS-Based Self-Adaptive Microfluidic Cooling Device.

This study presents a thermal analysis of a temperature-driven microfluidic cell through a nonlinear self-adaptive micro valve that provides the mechanisms for the system to maintain a given critical temperature in an efficient way. For the description of the dynamics of the microfluidic cell, a system of two ordinary differential equations subjected to a nonlinear boundary condition, which describes the behavior of the valve, is proposed. The solution of the model, for determined conditions, shows the strong nonlinearity between the overall thermal resistance of the device and the heat flux dissipated due to the action of the thermostatic valve, obtaining a variable thermal resistance from 1.6 × 10−5 to 2.0 × 10−4 Km2/W. In addition, a stability analysis of the temperature-driven microfluidic cell is presented. The stability of the device is essential for its proper functioning and thus, to prevent its oscillating behavior. Therefore, this work focuses on assessing the range of design parameters of the self-adaptive micro valve to produce a stable behavior for the entire system. The stability analysis was performed by studying the linear perturbation around the stationary solution, with the model solved for various heat flows, flow rates, and critical temperatures. Finally, a map of the design parameters space, which specifies the region with asymptotic stability, was found. In this map, the critical temperature (temperature at which the valve initiates the buckling) plays and important role.

Modeling and Performance Optimization of Double-Resonance Electronic Cooling Device with Three Electron Reservoirs

Abstract In this paper, a new model of the three-electron reservoir energy selective electronic cooling device applying double-resonance energy filters is proposed by using finite time thermodynamics. The analytical formulas of the main performance parameters for the double-resonance three-electron reservoir cooling device are derived. The optimal cooling load and coefficient of performance of the cooling device varying with major structure design parameters are explored and the optimal operation regions are further determined. Moreover, detailed analyses are conducted to reveal the influences of center energy level difference, chemical potential difference, energy level width, energy spacing and the phonon transmission induced heat leakage on the optimal performance characteristics of the cooling device. Finally, a performance comparison is made between the double-resonance and single-resonance three-electron reservoir electronic cooling devices. It is shown that through reasonable structure design, the optimal performance characteristics of the double-resonance device can be controlled to be much higher than those of the single-resonance cooling device.

Thermal Management: Electrostatic Actuating Double‐Unit Electrocaloric Cooling Device with High Efficiency (Adv. Energy Mater. 13/2021)

In article number 2003771, Rujun Ma and co-workers report a highly efficient double-unit solid-state refrigeration device based on two-layer modified electrocaloric polymer stacks actuated by electrostatic forces. The availability and the high-efficiency of the device for cooling the central processing unit provides a unique option for thermal management of microcircuits in the future.

히트파이프를 이용한 항공전자장비용 냉각장치 열전달 성능 연구

항공전자장비의 고성능화가 요구됨에 따라 전자소자의 방열설계는 중요한 요소가 되어가고 있다. 특히 전자소자의 발열량을 제어하지 못할 경우 온도가 상승하여 운용 중 성능저하 및 영구적 손상이 발생할 수 있다. 본 연구에서는 항공전자장비의 방열을 위한 냉각장치를 제작하여 해석과 시험을 통해 비교하였다. 냉각장치 열전달부를 히트파이프, 알루미늄, 구리를 이용하였으며 시험 결과, 히트파이프의 최고온도가 142.3°C로 나타나 알루미늄 대비 18.0°C 낮았고, 구리 대비 12.7°C 낮았다. 온도 편차는 알루미늄 대비 27.2°C, 구리 대비 17.0°C 가량 낮게 나타나 히트파이프의 열전달 성능이 가장 우수한 것을 확인하였으며, 작동 유체의 안정성을 검증하였다.

Multifunctional Cantilevers as Working Elements in Solid-State Cooling Devices

Despite the challenges of practical implementation, electrocaloric (EC) cooling remains a promising technology because of its good scalability and high efficiency. Here, we investigate the feasibility of an EC cooling device that couples the EC and electromechanical (EM) responses of a highly functionally, efficient, lead magnesium niobate ceramic material. We fabricated multifunctional cantilevers from this material and characterized their electrical, EM and EC properties. Two active cantilevers were stacked in a cascade structure, forming a proof-of-concept device, which was then analyzed in detail. The cooling effect was lower than the EC effect of the material itself, mainly due to the poor solid-to-solid heat transfer. However, we show that the use of ethylene glycol in the thermal contact area can significantly reduce the contact resistance, thereby improving the heat transfer. Although this solution is most likely impractical from the design point of view, the results clearly show that in this and similar cooling devices, a non-destructive, surface-modification method, with the same effectiveness as that of ethylene glycol, will have to be developed to reduce the thermal contact resistance. We hope this study will motivate the further development of multifunctional cooling devices.

Zero Energy Consumption Motor Cooling Device Based on Vortex Tube Effect

In the daily operation of the industry, due to the long-term operation of machinery, the motor load is too large, resulting in motor overheating. In this paper, a kind of large-scale machine tool is designed, which uses the energy wasted in the non-working state of the large-scale machine tool to convert kinetic energy into air energy to produce compressed air with larger compressibility. Then, the compressed gas is sent to the special vortex tube. By using the structural characteristics of the vortex tube device, the cooling gas with lower temperature can be generated, which can rapidly cool the motor and improve the motor operation. The efficiency and the service life of the motor reduce the probability of motor failure in the actual production process.

Electrostatic Actuating Double‐Unit Electrocaloric Cooling Device with High Efficiency

AbstractCompact solid‐state refrigeration systems that offer a high specific cooling power and a high coefficient of performance (COP) are desirable in a wide range of applications where efficient and localized heat transfer is required. Here, a double‐unit electrocaloric (EC) polymer‐based refrigeration device with high intrinsic thermodynamic efficiency is demonstrated using a flexible EC polymer film with improved performance by doping plasticizer and an electrostatic actuation mechanism. The double‐unit refrigeration device achieves a large temperature span of 4.8 K, which is 71% higher than that of the single‐unit device. A specific cooling power of 3.6 W g−1 and a maximum COP of 8.3 for the cooling device are produced. The surface temperature of a central processing unit (CPU) cooled by an active EC device is 22.4 K lower than that of the CPU cooled in air. The highly efficient and compact EC cooling device demonstrated here not only leapfrogs the performance of existing solid‐state cooling technologies, but also brings solid state cooling closer to reality for a variety of practical applications that require compact or mechanically flexible refrigeration.

Ergogenic and Physiological Outcomes Derived From a Novel Skin Cooling Device.

Gray, WD, Jett, DM, Cocco, AR, Vanhoover, AC, Colborn, CE, Pantalos, GM, Stumbo, J, Quesada, PM, and Caruso, JF. Ergogenic and physiological outcomes derived from a novel skin cooling device. J Strength Cond Res 35(2): 391-403, 2021-Our study's purpose assessed a cooling headband's ergogenic and physiological impacts. Subjects (15 women and 13 men) completed six visits; the final 3 entailed rowing workouts with the following treatment conditions: no head cooling (NoHC), intermittent head cooling during exercise (HCex), and intermittent head cooling during exercise and post-exercise recovery (HCex&post). Data collection occurred at the following times (a) pre-exercise and post-warm-up, (b) between stages of up to eight 2-minute bouts, and (c) at 5, 10, 15, and 20 minutes post-exercise. In addition to distance rowed, thermal, cardiovascular, perceptual, and metabolic measurements were obtained. Results included a small yet significant intertreatment difference (HCex, HCex&post > NoHC) for distance rowed. Our cardiovascular and metabolic indices exhibited sex and time differences but likely did not contribute to the ergogenic effect. Yet, left hand temperatures (LHT) exhibited significant 2-way and 3-way interactions that were the likely source of the ergogenic effect. Auditory canal temperature (AUDT) results suggest the head is sensitive to heat increases, yet LHT data show headband use evoked significantly greater temperature increases at the hand's palmar surface, indicative of heat transfer. We conclude, and our practical applications suggest, the headband's ergogenic effect was manifested by cold-induced vasodilation at the hand's palmar surface, rather than heat losses through the head.

립이 있는 2차원 슬롯 형상의 가스터빈 입구측 케이싱 막냉각 장치 막냉각 특성에 대한 수치적 연구

립이 있는 2차원 슬롯에 대해 분사비 0.2~1.5 범위에서 슬롯 형상의 변화가 막냉각 효율, 누셀트수에 미치는 영향을 수치 해석으로 연구하였다. 형상 변수로 립의 두께, 분사구-슬롯 면적비 및 분사 각도를 선정하였다. 립 두께의 증가는 낮은 분사비에서 막냉각 효율의 감소를 야기하는 반면, 높은 분사비에서 막냉각 효율을 증가시키는 요인임을 확인하였다. 립의 두께 및 분사구-슬롯 면적비의 증가에 따라 누셀트 수가 감소함을 확인하였다.

Optimal Design of Neuroprotective Focal Brain Cooling Device Using Surrogate Model Approach

Focal brain cooling (FBC) is a treatment for refractory epilepsy to suppress epileptic discharges from an epileptic focus. Our wearable FBC system under development consists of a recirculating coolant apparatus and a battery located extracorporeally, and a cooling device made of titanium with water channels inside which is embedded in the skull. An optimal channel design of the cooling device is needed to cool the brain efficiently. Although clinical and animal studies are required to design the cooling device, the number of experiments should be reduced, and finite element (FE) simulation be utilized instead. However, trial-and-error simulations impose a heavy computational burden. One option to deal with this problem is to use surrogate modeling, which is a data-driven approach that mimics the behavior of simulation models with a low computational burden. We optimized the channel structure by combining the surrogate model approach and non-dominated sorting genetic algorithm II (NSGA-II), which is a multi-objective optimization algorithm. The objective was to design a cooling device that simultaneously achieves high cooling performance and low pressure drop since low pressure loss contributes to miniaturization and energy saving of the recirculating apparatus. The optimization result showed that pressure loss was reduced by 28.7% in comparison with the design variables determined through experiments without deteriorating the cooling performance.

ANN for Solar-Assisted Adsorption Cooling Device Performance Prediction with PCM as Thermal Energy Storage

The paper deals with use of an artificial neural network for predicting the performance or efficiency of a single bed solar-assisted adsorption cooling (SAC) device with activated carbon-ethanol as adsorbent-adsorbate pair. A single bed harmonize with PCM as an energy storage system has been developed and tested according to the weather conditions (Latitude-8.890 N, Longitude-76.610 E) of Kollam, Kerala. The cooling system features an adsorbent bed, condenser, evaporator, expansion valve and two storage tanks. In this system, the second storage tank has been used for the storing phase change material (PCM) which acts as the latent heat storage device so that the system can be used during night time also. The usage of PCM for thermal energy storage will help to boost the adsorption refrigeration system performance. The 35kg PCM mass has been used for storing solar energy 6.5MJ during the day time for four hours and is used to improve the adsorption cooling system working time by two hours during the night time. The system has been designed for cooling of six litres of water from 30oC to 5oC within one hour. The cooling system produces a refrigeration effect of 4500kJ in each operating cycle with a coefficient of performance (COP) 0.413 and specific cooling power of 26W/s-kg. It is suggested that the Artificial Neural Network be used to predict or forecast the system’s COP and SCP. The Levenberg-Marquardt (LM), Scaled Conjugate Gradient (SCG) and Pola-Ribiere Conjugate Gradient (CG) backpropagation algorithm has been used to evaluate and determine the best approach for predicting the efficiency of the adsorption cooling system. The analysis shows that the findings obtained from ANN are well in line with the result of experiments.

Controlling Human Rabies: The Development of an Effective, Inexpensive and Locally Made Passive Cooling Device for Storing Thermotolerant Animal Rabies Vaccines.

Thermotolerant vaccines greatly improved the reach and impact of large-scale vaccination programs to eliminate diseases such as smallpox, polio and rinderpest. A recent study demonstrated that the potency of the Nobivac® Canine Rabies vaccine was not impacted following experimental storage at 30 °C for three months. We conducted a study to develop a passive cooling device (PCD) that could store thermotolerant vaccines under fluctuating subambient temperatures. Through a participatory process with local communities in Northern Tanzania, we developed innovative PCD designs for local manufacture. A series of field experiments were then carried out to evaluate the effectiveness of five PCDs for vaccine storage under varying climatic conditions. Following iterative improvement, a final prototype “Zeepot Clay” was developed at the cost of US$11 per unit. During a further field-testing phase over a 12-month period, the internal temperature of the device remained below 26 °C, despite ambient temperatures exceeding 42 °C. Our study thus demonstrated that locally designed PCDs have utility for storing thermotolerant rabies vaccines at subambient temperatures. These results have application for the scaling up of mass dog vaccination programs in low-and-middle income countries, particularly for hard-to-reach populations with limited access to power and cold-chain vaccine storage.