Air-cooling Device Research Articles

Transient Thermal Simulation of Liquid-Cooled 3-D Circuits

The 3-D integrated circuits (3-D ICs) are emerging as a viable solution to enhance the performance of many-core platforms. These architectures generate a high and rapidly changing thermal flux that makes conventional air-cooled devices more susceptible to overheating. Liquid cooling is an alternative that can improve dissipation and reduce thermal issues. Fast and accurate thermal models are needed to appropriately dimension the cooling system at design time. Several models have been proposed to study different designs, but generally with low simulation performance. In this paper, we present an efficient model of the transient thermal behavior of liquid-cooled 3-D ICs. This paper presents an approach with extremely low memory usage and advanced numerical methods to efficiently compute the transient temperature of 3-D ICs. Our experiments show the $100\times $ speedup versus the state-of-the-art models, while maintaining the same level of accuracy, and demonstrate the efficiency of liquid cooling to remove the heat from 3-D many-core platforms.

Hot Spot Cooling and Harvesting Central Processing Unit Waste Heat Using Thermoelectric Modules

The increasing integration of high performance processors and dense circuits in current computing devices has produced high heat flux in localized areas (hot spots), which limits their performance and reliability. To control the hot spots on a central processing unit (CPU), many researchers have focused on active cooling methods such as thermoelectric coolers (TECs) to avoid thermal emergencies. This paper presents optimized thermoelectric modules on top of the CPU combined with a conventional air-cooling device to reduce the core temperature and at the same time harvest waste heat energy generated by the CPU. To control the temperature of the cores, we attach small-sized TECs to the CPU and use thermoelectric generators (TEGs) placed on the rest of the CPU to convert waste heat energy into electricity. This study investigates design alternatives with an analytical model considering the nonuniform temperature distribution based on two-node thermal networks. The results indicate that we are able to attain more energy from the TEGs than energy consumption for running the TECs. In other words, we can allow the harvested heat energy to be reused to power other components and reduce cores temperature simultaneously. Overall, the idea of simultaneous core cooling and waste heat harvesting using thermoelectric modules on a CPU is a promising method to control the problem of heat generation and to reduce energy consumption in a computing device.

FEA technique of hot plate forming process using cell-typed die with cooling device

Hot plate forming using a cell-typed die is a process for forming a large thick plate with a spherical shape for the manufacture of a large spherical LNG tank. Cell-typed upper and lower dies made of a framework of steel plates fitted to make a grid pattern are used in this process, and an air-cooling device is separately installed inside the lower die. A finite element analysis (FEA) technique was developed, which included hot forming, air flow, cooling and thermal deformation analysis for the hot plate forming process using the cell-typed die. Further, the convective and interface heat transfer coefficients were used to reproduce analytically the effects of the cooling device in the hot plate forming analysis. A small-scale model test of the process was conducted to verify the FEA technique. The analysis results show that the curvature of the final plate agrees well with that of the designed experiment within a maximum relative error of 0.03% at the corner of the plate.

Cost-Efficient Hybrid Powertrain System with 48 V Network

Mission profiles show that a power of 12 kW in transient mode (20 s) is sufficient for hybrid functions. These rated powers are not compliant with a 12 V network. However, they are fully compliant with 48 V networks. Below 60 V, safety protections and insulated power networks are not required. In addition, with 48 V, the cell number of the storage unit is less than with 60 V. These improvements help to achieve a very low cost to CO2 ratio. For fast cost-effective vehicle integration, the first generation of the system is a belt driven architecture with standalone components. The electric motor replaces the conventional generator and is controlled by a standalone inverter supplied by a 48 V storage unit via an additional direct current (DC) network. Fixed transmission of the belt sets the maximum speed of the electric motor to 18,000 rpm. A specific belt tensioner was added to guarantee torque transmission over the full speed range. A 48 V/14 V DC/DC converter replaces the con ventional generator and supplies the standard 12 V power network. It provides 2.5 kW power with an efficiency of up to 96 %. Due to the limitations of the belt and Li-ion battery in cold conditions, a conventional starter and low voltage acid battery are retained. The 48 V electric motor covers the start/stop function without impacting the 12 V network. Hence, the electrical architecture, ➍, does not require a voltage stabilising system. Open image in new window ➍ System architecture of the hybrid concept The specifically developed air-cooled electric motor, with an efficiency of higher than 90 % throughout the operating range, provides 12 kW peak power and 55 Nm starting torque to optimise energy recovery. This definition is compliant with all mission profiles and helps to achieve CO2 targets. For the 48 V inverter driving the electric motor, a dedicated space vector control was developed to ensure accurate torque control. For the first generation, it is a standalone, air-cooled device operating in a voltage range between 35 and 60 V. The cost of the second generation hybrid architecture will be further reduced by removing wiring and EMC (electromagnetic compatibility) filters, combining the inverter with the electric motor and the DC/DC converter with the Li-ion battery. Further potential saving can be gained by removing the conventional starter and low voltage battery while adapting the belt drive for low temperature starting.

Energy performance of a lightweight opaque ventilated façade integrated with the HVAC system using saturated exhaust indoor air

The energetic performance of an integrated system basically consisting of an adiabatic humidifier, a lightweight mechanically ventilated opaque façade equipped with a direct evaporative air-cooling device, and an air-to-air heat exchanger for energy transfer from the outdoor airstream to the exhaust airstream leaving the air space, is analyzed numerically using an in-house-developed computer code. The minor energy consumptions with respect to a basic configuration consisting of a traditional closed cavity wall and a recovery equipment wherein energy is transferred from the outdoor air to the exhaust air extracted from within the building, are also calculated by introducing a cooling performance index and discussed in full details. A dimensional empirical correlation that expresses such cooling performance index as a function of the several independent variables considered is also proposed.

The effect of air cooling pain relief on protoporphyrin IX photobleaching and clinical efficacy during dermatological photodynamic therapy

Methyl aminolevulinate photodynamic therapy (MAL–PDT) is utilized to successfully treat licensed indications (e.g. actinic keratosis (AK), superficial basal cell carcinoma (sBCC) and Bowen’s disease (BD)) in the UK. Air cooling devices (ACD) are commonly utilized as a method of pain relief, however the effect of this on treatment outcome has never been extensively investigated. This non-randomized, retrospective observational controlled study investigated whether the application of the ACD limited photosensitiser (protoporphyrin IX – PpIX) photobleaching during irradiation and/or subsequent clinical outcome. Patients utilizing the ACD throughout treatment were observed to undergo significantly less PpIX photobleaching than the control group ( P < 0.001) and complete clinical clearances observed at 3 months were also reduced within the ACD group. Separate analysis of the different lesion types indicated that significantly less photobleaching occurred in AK lesions with ACD and all lesion types failed to fully utilize the accumulated PpIX when ACD was employed. The application of the ACD as pain relief during light irradiation therefore resulted in lower PpIX photobleaching which corresponded to a reduction in the efficacy of PDT treatment. Whilst the ACD is an effective method of dermatological PDT analgesia it should be utilized as sparingly as possible to minimize any deleterious effects on treatment outcome.

Performance of air cooled hydrogen storage device with external fins

Minimization of total weight is the major criterion in the design of a solid state hydrogen storage device for mobile or portable applications. The design should also address the requirements such as storage capacity, charge/discharge rates, space constraints, coolant temperature and hydrogen supply pressure. To achieve this, one should be able to reliably predict the dynamic performance of the storage device. In this paper, a parametric study of hydrogen sorption in an air-cooled annular cylindrical hydrogen storage device with external fins is reported. LaNi 5 , which has excellent hydrogen storage properties is used as the hydriding material. The influence of different geometric parameters such as hydride bed thickness and fin height, and operational parameters such as hydrogen supply pressure and cooling air temperature are studied. Copyright , Manchester University Press.

Selecting updated version of compressor station gas cooling system with due regard for equipment life cycle cost

An approach is proposed for selecting the most efficient updated (renovated) version of gas cooling system (GCS) based on concordance of energy and economic optimization results. This approach has been put into effect in optimizing the make-up and operation conditions of heat exchanging equipment in the course of its seasonal operation (efficiency criterion-energy cost) as well as in comparing GCS design versions with complete replacement of air cooling devices (ACD) and addition of new ACDs to the existing ones (efficiency criterion-life cycle cost). A general strategy is given for selecting the updated version of GCS of compressor stations (CS), and the characteristics of major Russian-and foreign-made ACDs are compared. An example of solution to problems of compressor stations of gas pipelines (diameter 1420 mm and operating pressure 7.45 MPa) lying under climatic conditions of the central zone of Russia is given.

Concurrent Use of a Handheld Forced Cold Air Device Minimizes Patient Discomfort during Fractional Photothermolysis

To assess the analgesic effect of a handheld forced cold air device during fractional photothermolysis. Twenty patients who were being treated with full-face fractional photothermolysis were asked to rate their pain level with and without the handheld air-cooling device. Pain was rated on a scale of 1 to 10, with 10 being the worst. Nineteen of 20 patients noted decreased pain with the addition of handheld cooling. The mean level of pain without air-cooling was 6.95 +/- 2.0. The mean level of discomfort with air cooling was 4.0 +/- 1.8. The mean decrease in pain with the addition of air-cooling was 2.9 +/- 1.8. The addition of a handheld forced cold air device to cool the skin before and after fractional photothermolysis treatment is an effective adjunctive analgesic modality.

Air Cooling Devices and Plate-and-Fin Heat Exchangers for Various Branches of Industry

Air Cooling Devices and Plate-and-Fin Heat Exchangers for Various Branches of Industry

Cold room air inhalation to abort cluster headaches: an exploratory study

Research has shown that inhalation of pure oxygen is effective in aborting cluster headache. This article advances the hypothesis that cooling is the critical ingredient behind the effectiveness of oxygen inhalation, rather than the oxygen concentration. To test this hypothesis, eight cluster headache participants used a device that delivered cooled room air as a means to abort headache attacks. Additionally, six of the subjects administered pure oxygen so that comparisons could be made to the air-cooling device. The proportion of cases in which subjects attained effective relief from cluster headache pain by use of the air-cooling device was significantly higher than the proportion of cases in which subjects did not attain effective relief from headache pain. There was no significant difference between the proportion of headaches relieved by oxygen and the proportion of headaches relieved by the air-cooling device. This study raises questions about the mechanisms of action of oxygen inhalation for treating cluster headache, and indicates that future clinical investigations into the use of cold room air for treating cluster headache pain are warranted.

MIXED CONVECTION IN A RECTANGULAR ENCLOSURE WITH DISCRETE HEAT SOURCES

A numerical study is carried out on mixed convective heat transfer in an enclosure. The discrete heat sources are embedded on a vertical board, which is situated on the bottom wall of an enclosure. An external airflow enters the enclosure through an opening in one vertical wall and exits from another opening in the opposite wall. This study simulates a practical system, such as air-cooled electronic devices with heated elements. Emphasis is placed on the influence of the governing parameters, such as Reynolds number, Re, buoyancy parameter, Gr/Re2, location of the heat sources, and the conductivity ratio, rk, on the thermal phenomenon in the enclosure. The coupled equations of the simulated model are solved numerically using the cubic spline collocation method. The computational results indicate that both the thermal field and the average Nusselt number (Nu) depend strongly on the governing parameters, position of the heat sources, as well as the property of the heat-source-embedded board.

$500,000 prize honors invention, innovation

The first winner of the $500,000 Lemelson-MIT Prize for excellence in invention and innovation is automotive engineer William J. Bolander of General Motors' Powertrain Division, Pontiac, Mich. Presented last week at a ceremony at the National Museum of American History in Washington, D.C., the prize is the largest U.S. award for invention and innovation. Underwritten by independent inventor Jerome H. Lemelson, of Nevada, the award is aimed at publicizing the contributions of U.S. inventors, elevating their status, and providing young Americans with inspirational role models. The program is administered by Massachusetts Institute of Technology. Bolander, 34, was honored for inventions that have improved car performance and passenger safety. For example, he helped develop the Cadillac Northstar's limp-home technology. If coolant is completely lost, this technology converts the engine to an air-cooled device that allows the car to limp home for service without damaging the engine. Another of his inventio...

Strong Eddy-Current Applications of Permanent Magnets

Small eddy-current brakes for kwh meters have a practically linear torque-speed characteristic, because the induced current increases proportionally to the low relative speed between eddy-current disk and magnetic poles. In bigger designs a considerable reaction of the induced-current field shifts the eddy-current paths in the direction of movement, so that the electrodynamic force between current and magnetic poles deviates from the linear relation, reaches a maximum at a critical speed, and decreases asymptotically to zero at infinite speed, whereas the dissipated power becomes a maximum. Some investigations were made into the behavior of permanent magnets with a water-cooled setup with p.m. rotor and an air-cooled device with p.m. stator, both of cylindrical shape with 11.8 in. effective diameter and an axial length of 5.5 in. and 6 in., respectively. Maximum torques of 410 ft-lb and 304 ft-lb were obtained. Pole pieces may sometimes increase the static flux, but do not always improve the dynamic behavior. The ideal solution might be obtained with a high-induction magnet without pole pieces, but the induction in available materials is limited by the demagnetizing effect on the free pole top. Possible applications could be found in a retarder for heavy trucks in mountainous districts and in a flexible coupling, slipping with decreasing torque when overloaded.

Outlook for the Air-Conditioning Industry

AIR CONDITIONING IS GROWING UP, and it is now pre/ paring to make its bid for the mass market. Considering the prolonged hot and humid weather that affected most of the country last summer and resulted in a sellout of virtually all types of air-cooling devices and airconditioning equipment by mid-July, it might be well to consider the indicated strong growth potentials for the infant air-conditioning industry and what it might mean to certain well-situated companies, especially since this is no longer a seasonal business.