Air Heat Sink Research Articles

Experimental investigation of a PV/T system containing a TEG section between water-based heat exchanger and air-based heat sink

The negative impact of temperature on PV power generation has led to the implementation of new cooling techniques globally to enhance the annual performance of PV systems. This study proposes a novel arrangement of Photovoltaic/Thermal-Thermoelectric generator PV/T-TEG integrated system that uses water and air cooling to enhance the performance of PV modules in warm regions. The system applies TEGs between the water heat exchanger and the air heatsink, instead of between the PV module and the cooling fluid. This avoids the non-uniform cooling associated with direct TEG connection to the PV backside. The proposed system was tested in four different climates in Iran and compared with PV-TEG and alone-PV systems. The results showed that the proposed system reduced the PV surface temperature by 23%, increased the electrical output power by more than 15%, and improved the PV electrical efficiency by about 3%. The average total energy efficiency was 55.6% and the maximum thermal efficiency was about 20%. These values were satisfactory for the non-concentrated TEG-based PV/T system in all analyzed climates.

Numerical and experimental investigation on the mechanism of synchronous trailing cold air heat sink in eliminating the deformation during laser welding SUS301L thin sheet

In order to control and eliminate the welding induced welding deformation of thin stainless steel a laser welding method assisted by a new type of synchronous trailing cold air heat sink is first proposed in this paper. This kind of heat sink is obtained by using vortex tube compressed air refrigeration (VTCAR), which is safe, of low cost and easy to be implemented compared with other commonly used heat sinks such as argon-water mixture, liquid nitrogen, etc. Then, a thermo-elastic-plastic multi physical field coupling numerical model of laser welding with a cold air heat sink located at the rear of laser beam is established, and the effects of the places where the VTCAR heat sink is exerted and heat sink parameters including the heat sink strength and the distance between the heat sink and the laser beam on the welding induced welding deformation are numerically studied. Such two cases as the heat sink is located on the top and bottom surface of the sample respectively are considered. The simulation results show that the cold source exerted on the top surface has the more significant effect than that on the bottom surface under the same heat sink parameters, and the position of heat sink, exactly speaking, the distance between the cold source and the laser beam, has a decisive effect on reducing welding induced buckling. The smaller the distance, the smaller the welding induced buckling. At the heat sink strength of 200 ml and the distance of 5 mm, the equivalent residual stress decreases by 8.09%, and the maximum welding induced deformation decreases by 31.62%. Thirdly, experiments of laser welding with a synchronous trailing VTCAR heat sink are carried out onSUS301L thin sheet. It can be seen that the specimen appears a saddle shape after welding. The coordinate values of the points on the outer plane of the post weld specimen are measured by three coordinates measuring machine, from which the actual welding deformation can be obtained. Both the specimen shape and the measured welding deformation value are in good agreement with the simulation results based on the large deformation theory, which verifies the correctness and the accuracy of the above simulation model. Finally, the mechanism of the synchronous trailing VTCAR heat sink in eliminating the deformation is discussed by inherent strain theory. In the cooling stage during laser welding, the heat sink not only reduces the temperature field of the base metal near the weld, but also makes the typical comet characteristics at the tail of the weld pool disappear and become a flat temperature profile, which effectively reduces the temperature gradient in the weld area and weakens the longitudinal tensile plastic strain of the weld specimens, and eventually reduces Tendon force and the welding inherent strain. There is a high consistency between Tendon force and the welding deformation, so Tendon force can be taken as the basis for evaluating the welding induced welding deformation.

Topology optimization of heat sink based on variable density method

A topology optimization method based on the variable density method is used to optimize the design of the forced convection air heat sink structure, with minimum pressure drop as the optimization objective and heat transfer performance as the constraint, using a two-layer 2D model instead of the traditional 3D model. The technique of changing the interpolation parameters is introduced in the optimization process to effectively avoid the formation of blocking structures in the optimization. The optimized heat sink effectively enhances the heat transfer performance. Compared with the straight fin heat sink, the average temperature of the topology optimized heat sink decreases by 5.76%, indicating a lower temperature with the same pump power. This new type of heat sink contributes to energy saving and emission reduction.

Design of thermoelectric devices for extracting foreign objects from the human body by freezing

Objectives.The purpose of the article is to consider the designs of thermoelectric devices (TEC) for extracting foreign objects (IO) from the human body by freezing with various options for removing heat from the hot junctions of the thermoelectric module (TEM).Method. Modifications of thermoelectric devices are described for extracting the IO from the human body by freezing it to a special probe. Their technical design differs in the way of heat removal from the TEM hot junctions, for which air heat removal, melting working substances and preliminary cooling of the radiator are used. The basic relationships for calculating the technical means intended for the removal of heat from the hot junctions of the TEM are presented.Result. The graphs of the dependence of the temperature change of the TEM hot junctions in time are obtained for different values of its heat output when using an air heat removal system and the time of complete penetration of various working substances used in the device.Conclusion. The data obtained show that for the operating conditions of the TEC, the temperature of the hot junctions of the TEM with an air heat sink does not go beyond the permissible limits. With a module power of 8 W, 12 W and 16 W, the temperature of the hot junctions of thermoelements stabilizes rather quickly and takes the value of 308 K, 313 K and 318 K. maintaining their stable temperature is most preferred is nickel nitrate, less - elaidic acid and paraffin. Calculations of the design of a device with a pre-cooled radiator system also show the efficiency of heat removal from the hot junctions of the TEM for the duration of the entire procedure for removing the IO from the human body.

CFD Numerical Modelling of a PV–TEG Hybrid System Cooled by Air Heat Sink Coupled with a Single-Phase Inverter

This study presents full transient, three-dimensional numerical models of a PV–TEG hybrid module coupled with single-phase inverter by co-simulation. The influence of factors, such as wind speed, solar radiation intensity, or ambient temperature on the PV–TEG system, was also examined. The numerical model was implemented using Ansys software which accounted the phenomena of Thomson, Seebeck, and Joule’s heat place on the TEG system. Furthermore, its impact on total electrical efficiency was studied. The heat transfer surface of the passive heat sink and forced air circulation positively affected the total heat transfer, and therefore helped to maintain the electrical efficiency at a higher level. Simulation of the single-phase inverter with a PV–TEG system allows the determination of the power characteristics of the system in real time. The results of the study presented may provide a basis for performance optimization of a practical PV–TEG-inverter hybrid system co-design.

3D-ICE 3.0: Efficient Nonlinear MPSoC Thermal Simulation With Pluggable Heat Sink Models

The increasing power density in modern high-performance multiprocessor System-on-Chip (MPSoC) is fueling a revolution in thermal management. On the one hand, thermal phenomena are becoming a critical concern, making accurate and efficient simulation a necessity. On the other hand, a variety of physically heterogeneous solutions is coming into play: liquid, evaporative, thermoelectric cooling, and more. A new generation of simulators, with unprecedented flexibility, is thus required. In this article, we present 3D-ICE 3.0, the first thermal simulator to allow for accurate nonlinear descriptions of complex and physically heterogeneous heat dissipation systems, while preserving the efficiency of latest compact modeling frameworks at the silicon die level. 3D-ICE 3.0 allows designers to extend the thermal simulator with new heat sink models while simplifying the time-consuming step of model validation. The support for nonlinear dynamic models is included, for instance, to accurately represent variable coolant flows. Our results present validated models of a commercial water heat sink and an air heat sink plus fan that achieve an average error below 1 °C and simulate, respectively, up to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3\times $ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$12\times $ </tex-math></inline-formula> faster than the real physical phenomena.

Analysis and comparison of potential power and thermal management systems for high-speed aircraft with an optimization method

• An advanced PTMS with an indirect regenerative air cycle is analyzed. • A comparison based on minimum fuel weight penalty optimization is proposed. • Optimal matching of the PTMS and flight mission is achieved at Mach 1-4.4. • The PTMS with a ram air bleed mode is suitable for Mach 3.4–4.4 cruise aircraft. Under the dual effects of aerodynamic heating and high-power electronic equipment heating, the heat sink and power demand of advanced high-speed aircraft have been exponentially rising, which seriously restricts the aircraft performance. To improve system cooling and power supply performance and reduce engine performance loss, a power and thermal management system (PTMS) with high performance, low energy consumption, and light weight urgently needs to be developed. In this paper, three modes of a potential PTMS with different heat sinks and bleed air sources are further discussed to analyze and compare the optimal matching with the flight mission at Mach 1–4.4. The equivalent mass method is used to uniformly assess the costs of the fixed weight, bleed, resistance, etc. as a function of the fuel weight penalty, which is chosen as the optimization objective. The optimization variables consist of the compressor outlet temperature, cooling air flow rate, and fan duct heat exchanger structure size. The results show that the intermediate-stage bleed air and fan duct heat sink are more suitable when the Mach number is less than 2, but the ram air bleed is highly suitable for flight missions at a high Mach number. Especially at Mach 3.4–4.4, the ram air bleed mode can respond to the cooling and power demands with a simple architecture.

Enhancing a solar panel cooling system using an air heat sink with different fin configurations

The temperature of a solar panel is an important parameter, which influences its performance and efficiency. Thus, development of solar panel cooling systems represents a new face of technology that may be used to improve power generation. Here, the reduction of solar panel temperature using an air-cooled heat sinks is studied numerically. The design of the heat sink comprises rectangular fins and rectangular fins with holes, made from a material with high thermal conductivity. The cooling efficiency is studied for different configurations of the heat sink, which are obtained by changing the fin numbers and hole distances. The numerical model is realized, using ANSYS-Fluent software, for a steady state whereby the ambient temperature is 25–35 °C, for different heat flux values. Increasing the number of fins and holes decreases the panel temperature. The reduction of panel temperature with fins is 50% compared to solar panels without fins.

Experimental and numerical investigation of a mini channel forced air heat sink designed by topology optimization

This work presents a method of designing an air heat sink with forced convection by topology optimization. Both pressure drop and heat transfer performances are evaluated. To reduce computational cost, a 2D two-layer model is first developed and implemented in COMSOL Multiphysics to represent three-dimension fully conjugate heat transfer modeling. It has been shown to be accurate in temperature field prediction and able to capture trends of pressure drop variation. Through a multi-stage optimization process, a non-conventional fin structure is created. The optimized structure is then manufactured and experimentally validated. Compared to a conventional straight channel heat sink, the topology optimized heat sink can achieve lower junction temperatures with the same pumping power or requires lower pumping powers for maintaining the same junction temperature. Furthermore, full 3D numerical analysis by ANSYS Fluent is performed to study the detailed characteristics of the topology optimized heat sink. It shows that the non-conventional layout of the fins introduces strong mixing effect, continuous boundary layer interruption and local high speeds, which all contribute to heat transfer enhancement.

Experimental and numerical investigation of a hybrid PCM–air heat sink

The present work deals with a combined device in which the heat may be both absorbed by a phase-change material (PCM) and dissipated to the ambient air. Accordingly, the heat sink, made of aluminum 6061, has compartments where the PCM (eicosane C20H42) is stored and fins exposed to the air. The experiments are performed in both room- and elevated-temperature environment. A simplified thermal model, based on a two-dimensional enthalpy formulation for the PCM, is developed for a conservative estimation of temperature evolution. The results, presented in terms of base temperature (experimental and numerical) and PCM melt fraction (predicted), show a fairly good agreement between the experiments and simulations. Also shown are some findings obtained using a more complex model, which accounts for convection in the melt. A dimensional analysis yields the melt fraction and Nusselt number as functions of the Fourier and modified Stefan numbers. It also addresses the relative contributions of latent/sensible accumulation and heat transfer to the air. The dimensionless curves for latent-heat-based accumulation rate are rather similar in various cases. On the other hand, it is found that the share of sensible-heat-based accumulation rate tends to increase when the heat input increases.

Packaging of High Power UV-LED Modules on Ceramic and Aluminum Substrates

An LED module consisting of 98 UV-LEDs with an emission wavelength of 395 nm placed on a ceramic substrate of 211 mm2 is presented. The module is cooled by a forced air heat sink as well as a high performance microstructured water cooler to lower the thermal resistance. For high thermal conductance a liquid metal as the thermal interface material between substrate and heat sink is used. With the forced air heat sink a maximum irradiance of 27.3 W/cm2 at a forward current of 700 mA and 220 W electrical input power was achieved. The microstructured water cooler enabled an almost doubling of the electrical input power (430 W) while maintaining the chip's maximum temperature. For a reduction of the module's thermal resistance a thick film process for aluminum sheet metal substrates was developed. A prototype LED module with 25 UV-LED chips on an area of 54 mm2 achieved a maximum optical power density of 31.6 W/cm2 at a forward current of 900 mA using a forced air heat sink. For an improved cooling of the LED chips a chip-on-heat sink-technology with embedded water cooling channels is developed to eliminate the thermal interface between substrate and heat sink.

Heat Dissipation of Printed Circuit Board by the High Thermal Conductivity of Photo-Imageable Solder Resist

Thermal management issues with IC packages have been growing as electronic systems have become smaller with a higher functionality. Since the high junction temperature of IC packages induces the low performance and malfunction of electronic systems, the thermal dissipation capability of electronics is important for stable electrical performance and electro-mechanical reliability. However, the conventional cooling methods that depend on air flow path and heat sink structure is not sufficient to meet the growing thermal requirements of IC packages. Since there is limit on conventional design, such as optimization air flow path and heat sink structure, to dissipate more heat through an exhaust fan system. The main purpose of the present research is to reduce the junction temperature of the IC package by using a Printed Circuit Board (PCB) coated with new Photo-imageable Solder Resist (PSR) that has high thermal conductivity. The thermal conductivity of the newly developed PSR is about five times as high as that of the conventional PSR for PCB(0.23∼0.25W/m·K). The PCB was prepared by the EIA/JEDEC standard, JESD51-7. Experimental and finite element analyses were performed to investigate the effect of SR on thermal dissipation capability. The experimental and FE results show that the high thermal conductivity of PSR can reduce the steady-status regulator surface temperature by about 3∼8K as an air flow conditions around PCB. Also, the high thermal conductivity of SR is more effective under a low air heat transfer coefficient condition. Therefore, it is believed that an improved heat transfer with a PSR of high thermal conductivity should provide stable electrical performance for the IC package.

Heat dissipation effect of Al plate embedded substrate in network system

Decreasing junction temperature in an IC package is required for stable electrical performance and electro-mechanical reliability of network communication system in today’s market. Much effort to decrease the junction temperature is already done. Since it is critical to increase both speed and mass of information transmission, reducing junction temperature needs to be optimized for better electrical performance of IC packages. So, it is necessary to develop more advanced methods to reduce the temperature. Because there is limit on conventional design, such as optimization air flow path and heat sink structure, to dissipate more heat through an exhaust fan system. This paper presents that an Al plate embedded network substrate to decrease the junction temperature of an IC package by experimental and finite element analysis. Results show that good heat dissipation can be enhanced by the Al plate embedded network substrate. It is believed that such network substrate decreases the junction temperature of IC package. FE analysis and experimental results show that an Al plate embedded substrate can reduce the steady-status temperature by about 4–8 °C with an exhaust fan running. Also temperature distribution on the surface of substrate is more equally than that of a conventional substrate by high heat conductivity of Al plate. Thus, it is possible that an Al plate embedded substrate works well with stable electrical performance with low junction temperature in an IC package communication system.

Self-Cooling Cavity Burs for Surgical Drills

In a self-cooled drill, an especially designed bur is used to transport heat generated at the cutting edge into the handpiece, where it is dissipated into an air heat sink. The bur contains a sealed cavity partially filled with water, which transports heat via the principle of rotating heat pipe technology. The heat transport capability of burs fitted out as rotating heat pipes was established. A conceptual design for a representative bur was prepared, based on surgical drill sculpting criteria. It appears that a self-cooled surgical drill for sculpting can limit bone temperatures below levels for the initiation of thermal damage in bone, nerve, and brain tissue, without the need to employ an externally applied coolant.

Plate fins with variable thickness and height for air-cooled electronic modules

This paper shows that the hot spot temperature of an electronic module with finned air heat sink can be reduced by allowing the fin thickness and height to increase in the flow direction x. The hot spot temperature decreases by about 15% if the thickness of a plate fin with constant height increases as x 0.42 .The decrease is approximately 30% if the height of a constant-thickness plate fin increases as. x, i.e. if the fin shape is almost like a triangle when viewed from the side. In addition to lowering the hot spot temperature, the fin thickness and height variations recommended by this study lead to considerably more uniform temperature distributions on the module surface on which the fins are installed.

Forced air heat sink with new enhanced fins.

A forced-air-cooled heat sink with new enhanced fins was developed. The fin has many perforations and is bent to form a trapezoidal shape. The fin was enhanced in heat transfer by a breathing effect, a phenomenon by which the fluid is injected and sucked through the trapezoidal perforated fins. The thermal conductance of the heat sink at the same pumping power was about 1.6 times that of a similar heat sink with conventional plain fins, and also about 3 times at the same Reynolds number. A heat sink with the new enhanced fins designed for practical use was also shown.

Narrow Channel Forced Air Heat Sink

The heat transfer between the coolant anti the heat sink contributes a significant fraction of the thermal resistance of a package. It has been widely recognized that the heat transfer can be increased by increasing the area of the heat sink in contact with the coolant, and therefore the use of fins is common. However it has not been generally recognized that for laminar flow in confined channels, the heat transfer coefficient is inversely proportional to the width of the channel. Narrow channel forced air heat sinks have been designed, built, and tested. Three different channel widths, 5, 10, and 25 mils, were investigated. The design of the sinks permit integrated circuits (IC's) on 1/2 in centers and printed circuit (PC) boards on I in centers. The measured values of individual heat sinks with 30 I/min air flow are 5.5, 3.7, and 3.4°C/W for 25,10, and 5 mil channel widths, respectively. These values are in good agreement with calculated values. A 16 chip package with chips on 1/2 in centers was assembled utilizing 10 mil channel width heat sinks. A plenum fitted over the sinks supplied air to each of the sinks from a single source. The measured values of thermal resistance of the four center dies were between 5.3 and 5.9°C/W. If the chips are mounted directly on the sink instead of on the alumina substrate, the thermal resistance would be reduced by about 2°C/W.