Pdf sintering technology for micro heat pipe with sintered wick. Aug 22, 2017 fluid flow inside a rectangular channel, that consisting of 6 pipes, in each pipe the fluid temperature is different, this tutorial will help to understand the flow physics as well as it will. Today, heat pipes are used in a variety of applications from space to handheld devices that fit in your pocket. Amir faghri department of mechanical engineering, university of connecticut, storrs, ct 06269, u. Singh the purpose of this research was to determine the optimal micro heat pipe mhp configuration on high performance heat spreaders. This expression relates the capillary radius of the interface and the hydraulic radius of the passage. Pdf heat transfer limitation of a micro heat pipe researchgate. Besides, some innovative ideas and novel micro flat heat pipe designs for particular applications are also documented along with comparisons and discussion on various crosssectional shapes and. Flanges can be added on the outer surface for easy integration with instruments or radiators the flange is an integral part of the extrusion. Numerical simulation of a cylindrical heat pipe and. Another drawback of excess fluid is peculiar to heat pipes in space, where in zero gravity the fluid can move about the vapour space, affecting the dynamics of the spacecraft. Web to pdf convert any web pages to highquality pdf. International journal of numerical methods for heat.
Refrigeration software for pipe sizing and heat load. Heat pipes rely on a temperature difference between the ends of the pipe, and cannot lower temperatures at either end below the ambient temperature hence they tend to equalize the temperature within the pipe. The heat pipe performance is predicted with evaporation models and the geometric design of heat pipe is optimized to achieve the maximum heat. In the short heat pipe extreme 34 length, this effect is nearly zero, so please consult with wakefieldvette engineers to find the right solution for your application. The capillarity of micro grooves with rectangular crosssection is studied theoretically and experimentally in this paper. Microminiature heat pipes and operating limitations. The heat pipe is simply inserted into the glass tube, held in place with high. An issue of concern with the recent densification of electrical components in integrated circuits is heat removal to avoid damage to the semiconductor structure.
Electronics cooling, high heat flux, micro flat heat pipe, modeling, novel designs, wick structure. As heat is applied to the pipe, the water will boil and turn to a gas, which then travels to the colder section of the heat pipe where it condenses back to a liquid. An experimental investigation of micro pulsating heat pipes. The ultimate goal was to reduce the spreading resistance and eliminate localized hot spots. Experimental investigation of coppergrooved micro heat pipes. A very small heat pipe that has a diameter between about 100 micrometers and 2 millimeters 0. Micro and miniature heat pipes electronic component. Ats engineering ebook advanced thermal solutions, inc. The heat pipes were nominally 81 mm in length, 10 mm. Experienced engineering consultants, with an extensive knowledge of the subject, design all of our products. Nov 01, 2004 mini micro heat pipes mhp and heat pipe spreaders hps, where the device is an integral part of the heat pipe.
Design calculation and heat transfer analysis of heat pipe. Individual heat pipe each individual heat pipe is independent, ensuring the utmost in reliability and performance. An experimental investigation of micro pulsating heat pipes mdpi. Flat heat pipes have been seriously considered and studied over the past 20 years as a solution for thermal management of these devices. In the mpu industry, while mpus with extreme heat generation are marketed for highend applications, powersaving type mpus with small heat generation have also been developed. In addition to the operational limitations of conventional heat pipes, micro heat pipes may be subject to the vapor continuum limitation, which may prevent micro heat pipes from operating under lower working temperatures. Some theoretical models capable to predict the effects of the thin film region on the evaporating and. Pdf micro flat heat pipes for microelectronics cooling.
Abstract liquid or gas flow through pipes or ducts is commonly used in heating and cooling applications and fluid distribution networks. Electronics cooling, high heat flux, micro flat heat pipe, modeling, novel designs, wick st ructure. Using darcys equation for twophase flows in porous media and laplaces capillary equation, a onedimensional model of a micro heat pipe is developed to investigate its thermal and fluidmechanical behaviors within its capillary limitation. It also provides a real life visual demonstration of. Loop heat pipe with coherent porous wick since the porous material used for current heat pipes is usually stochastic structure, it is hard to apply analytical or numerical methods for design optimization.
Micro heat pipe phenomena is often available in nature. Learn how to select a heat pipe working fluid in a given temperature range. Use pdf download to do whatever you like with pdf files on the web and regain control. The actual test results of heat pipe with different wick structure athorizontal and vertical gravity assist orientations.
Quality control includes individual testing and assembly of each heat pipe. Pdf the time of beginning of heat pipe science was near 40 years ago with first heat pipe definition and prediction of most simple cases. Nov 24, 20 wire sandwiched micro heat pipes part 1. Browse through our compatible pairs table, as well as recommended operating temperatures for heat pipes. Interaction between basic phenomena in heat pipes micro heat pipes micro heat pipes phenomena are often used in nature. Evaluation of convective heat transfer coefficient of air flowing through an inclined. It is the evaporation and condensing of the water that forms a pumping action to move the water and thus the heat along the pipe. Especially for micro applications there are micro heat pipes developed as for cooling the kernel of a cell phone down. The helmholtz free energy method is used to predict the capillarity as the groove is placed vertically and inserted the bottom end into the liquid.
Micro heat pipes are used to eliminate hot spots, reduce temperature gradients, and improve chip reliability. There exist flat plate and doubl e casing heat pipes, rigid and flexible heat pipes, as well as large and micro heat pipes. Php that exhibited trapezoidal microchannels that were 394 m in hydraulic diameter. A numerical study was conducted to analyze the heat and mass transfer in a micro heat pipe, with the thinfilm theory applied to the phase change at the liquidvapor interface. Prototype substrate heat pipe systems were fabricated using high temperature cofired ceramic alumina. U k based white rose software specialises in the research and development of engineering design software for the refrigeration industry. Design calculation and heat transfer analysis of heat pipe evacuated tube solar collector for water heating. In this, flat polymer based micro heat pipes were designed, fabricated and assessed for thermal. Micro heatpipe hereafter denoted as hp is capable of coping with this problem, and has been in practical use since 1995. Recent developments in heat pipe technology and applications. A numerical study on the heat and mass transfer of a micro. In this work, the development and technologies of micro heat pipe cooled reactor are overviewed.
To solve this problem, a microloop heat pipe with a flexible structure has been. Against this technological background, furukawa electric has been marketing heat sinks that incorporate micro heatpipes. Pdf capillarity of rectangular micro grooves and their. Heat pipes have a very important role in the thermal. Heat pipes, electronic cooling, wick structure, working fluids.
Lcp film with copper filled thermal vias and a microscale hybrid liquid. Fabrication, filling, sealing and testing of micro heat pipes except where reference is made to the work of others, the work described in this thesis is my own or was done in collaboration with my advisory committee. In this, flat polymer based micro heat pipes were designed, fabricated and assessed for. Based on the momentum conservation and laplaceyoung equations, an analytical expression for the minimum meniscus radius was derived and an expression for the maximum capillary heat transport limit in micro small heat pipes was obtained. It is found that longitudinal groove designs are crucial to increase the heat transport capacity of miniature heat pipes. At least one hollow metal body with a plurality of micro heat pipes embedded in the hollow metal body is used as a heat sink to remove heat from memory chips in a memory device. A loop heat pipe with coherent pores integrated to the heat source is considered as a calculation model in this paperfig. Heat pipes heat pipes how and where heat pipes work the dme heat pipe is a heat transfer device specifically designed for optimal performance in plastic injection moulds. The minimum meniscus radius and capillary heat transport.
If there is a deficiency of working fluid, the heat pipe may fail because of the inability of any artery to fill. An experimental investigation of micro pulsating heat pipes kaishing yang 1, yuchi cheng 2, mingshan jeng 1, kuohsiang chien 1, and. Circular heat pipe is the most popular from, since it is easy fabrication and low cost. For example, there is an analogy between micro heat pipe operation and functioning of a sweat gland. A compatible envelope must be selected for longterm operation. Control theory is introduced to quantify the thermal response of micro heat pipe. Heat pipe materials, working fluids, and compatibility. Micro heat pipe how is micro heat pipe abbreviated.
The high power level currently possible, on the order of 100wcm 2, together with the heat pipes being selfcontained and selfstarting make micro heat pipes an ideal heat transfer system. This work focuses on recent applications of heat pipes in electronics industry. Heat pipe engineering ebook advanced thermal solutions. R sekulib university of kentucky introduction a heat exchanger is a device that is used for transfer of thermal energy enthalpy between two or more fluids, between a solid surface and a fluid, or between solid particulates and a. Pdf an analytical expression for the heat transport capability of micro heat pipe is derived. Notice do not exceed the maximum soak temperature as indicated on the nameplate. Evaluation criteria are proposed to represent thermal response of micro heat pipe. Transient thermal performance analysis of micro heat pipes. Methodology to measure the heat pipe performance it is very important to achieve the top wall temperature profile.
Project description by means of knowledge about the theory of heat pipes, one is now able to carry out a basic calculation of a heat pipe. One end of the heat pipe is an evaporator, the opposite end is a condenser. Notice do not operate this heat pipe coil at conditions other than the design. The micro heat pipe cooled reactor, mainly consists of a reactor core, energy conversion system, shielding and heat removal system, is a new type reactor using heat pipes to cool the core. Optimal micro heat pipe configuration on high performance heat spreaders by seema s. Heat pipes are sealed vacuum vessels that are partially filled with a working fluid, typically water in electronic cooling, which serves as the heat transfer medium. The heat pipe envelope is made of copper in a myriad of shapes including cylindrical, rectangular, or any other enclosed geometry. Microfluidics is one of the extensive elaborated technologies in thermal and engineering fields due to its wide range of applications, such as micro heat exchangers, micro pdf 2. It has been shown that the operating limit of the micro heat pipe depends on the vapor continuum limitation. Opentype mini micro heat pipes are suggested in, as a system of thermal control of biological objects and drying technology. Research paper thermomechanical design and characterization of. Heat pipe science and technology, an international journal is encompassed on publishing i fundamental studies of heat and mass transfer in heat pipes and twophase thermosyphons, ii new streams of technology development, iii industrial innovation in elec. Hence, other than thermal design of the heat pipe, mechanical design of the. Heat pipes hardware m t l l i t b ith th i fmetal aluminum tube with grooves on the inner surface cold t ild extrusion grooves are filled with the working fluid water, ammonia, propylene, etc.
Advantages of heat pipes may reduce or eliminate the need fir reheat, allow cost effective manner to accommodate newventilation standards, requires no. Accordingly, furukawa electric has been marketing heat sinks that incorporate micro heat pipes since 1995. Heat pipes cantransfer much higher powers for a given temperature gradient than even the bestmetallic conductors. Study on thermal performance of microchannel separate heat. Heat pipes employ phase change to transfer thermal energy from one point to another by the vaporization and condensation of a working fluid or coolant. Fundamental study of heat pipe design for high heat flux source ryoji oinuma, frederick r. Micro heat pipe article about micro heat pipe by the. The heat pipes use an axially grooved wick structure and water as the working fluid. The heat pipe temperature reaches the water temperature in about 25 seconds, while the copper rod reaches just 30c after 200 seconds. For example there is an analogy between micro heat pipe operation and functioning of a sweat gland 3. The heat pipe is a very efficient means of transferring heat from within the evacuated tube to the water. Silicon is selected as the ideal material of micro heat pipes mhps. Use of heat pipe cooling systems in the electronics industry. If a chemical reaction is conducted inside a micro heat exchanger, the latter is also called a microreactor.
Two sibased micro pulsating heat pipes phps charged using hfe7100 were either. Bstract a detailed overview of heat pipes is presented in this paper, including a historical perspective, principles of operations, types of heat pipes, heat pipe. Micro heat pipe article about micro heat pipe by the free. The operating principles, heat transfer characteristics, and fabrication process of memsbased micro. A heat pipe is a heat transfer device that combines the principles of both thermal conductivity and phase transition to effectively transfer heat between two solid interfaces. The effects of various parameters are incorporated into the analysis. Thermomechanical design and characterization of flexible. However, in an actual application when a heat pipe is soldered or epoxied to the base of a heat sink, the effective thermal conductivity of the heat pipe may be.
Optimal micro heat pipe configuration on high performance. In the case of two fluidic flows, micro heat exchangers are usually classified by the orientation of the fluidic flows to another as cross flow or counter flow devices. Fluid flow and heat transfer analysis, ansys fluent tutorial. It consists of a vacuumtight copper tube containing a wick and a nontoxic working fluid. Micro and miniature heat pipes electronic component coolers. Heat pipe heat exchangers hphe, which are system level heat pipes, where the heat pipe is used to control temperature in equipment cabinets or systems. In order to improve the heat transfer performance of micro heat pipes, a new type of micro heat pipe gf with capillary wick, which is made of fibersintered grooves with an external diameter of. At the hot interface of a heat pipe a liquid in contact with a thermally conductive solid surface turns into a vapor by absorbing heat from. Heat pipe heat exchanger the des champs heat pipe heat exchanger provides sensible heat transfer between two airstreams using a counterflow configuration to maximize heat transfer and minimize pressure drop. This thesis does not include proprietary or classified information. The model described the liquid and vapor distributions, phase change rate, wall temperature, pressure drop, and heat transfer rate in a micro heat pipe under normal operation. Additional federal regulations may apply, and state regulations that are corollaries to the. Beginning with a definition of the problem, including the temperature. Considering a cylindrical heat pipe, a 2d axisymmetric model was constructed.
Collection of technical articles on heat pipes and. Heat pipe science and technology, an international journal is encompassed on publishing i fundamental studies of heat and mass transfer in heat pipes and twophase thermosyphons, ii new streams of technology development, iii industrial innovation in electronic thermal control, air conditioning, heating and cooling, aerospace thermal control. Haringx 10 modeled the bellow as the combination of annular plates connected by elastic cylinders and derived. Also the evaporator will have micro machine multiple layers to prevent boiling. When selecting the diameter and length of heat pipe it is important to consider the orientation with respect to gravity. Heat pipe is a capillary twophase heat transfer device. These envelopefluid pairs were determined by longterm life tests. Microelectromechanical systems mems based microheat pipes, as a novel heat pipe technology, is considered as one of the most promising options for thermal control applications in microelectronic circuits packaging, concentrated solar cells, infrared detectors, microfuel cells, etc.
Complete load capability colmac heat pipe coils are designed to handle virtually any heatingcooling load without the need for gravity assist. Pdf development, fabrication, and experimental study of. Heat pipes are one of the most efficient ways to move thermal energy from one point to another. Micro electromechanical systems mems based microheat pipes, as a novel heat pipe technology, is considered as one of the most promising options for thermal control applications in microelectronic circuits packaging, concentrated solar cells, infrared detectors, micro fuel cells, etc. Evaluation of convective heat transfer coefficient of air. Highperformance micro heat pipe by koji yamamoto, kenji nakamizo, hideaki kameoka 2 and kenichi namba 3 with greater electronic equipment speeds and higher performance, more heat is generated posing acute problems of heat dissipation. In the experiment, micro grooves are first constructed by the thick photoresist patterned by photolithography method and then. Micro heat pipes for cooling electronic devices were proposed in 83. The most important heat pipe design consideration is the amount of power theheat pipe is capable of transferring. Types of heat pipes thermosyphon leading edge rotating and revolving cryogenic pumped loop heat pipe flat plate micro heat pipes variable conductance capillary pumped loop heat pipe 16.
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