Nandyputra’s Weblog


nanofluids
March 1, 2008, 3:29 pm
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Heat transfer enhancement of nanofluids in car radiator Nandy Putra,  Syahrial MaulanaHeat Transfer LaboratoryDepartment of Mechanical Engineering, University of IndonesiaKampus Baru UI Depok JakartaEmail: nandyputra@eng.ui.ac.id  Keywords: Nanofluids, Heat Transfer Enhancement, Nanoparticles, Forced Convection  Improvement of the thermal properties of energy transmission fluids may become a trick of augmenting heat transfer. An innovative way of improving the thermal properties of fluids is to suspend solid particles in nanometer diameter in the fluids. These fluids are called nanofluids. They are dispersions of nanoparticles in liquids that are permanently suspended by Brownian motion. Some researchers tried to suspend nanoparticles into fluids to form high effective heat transfer fluids. They showed that this new fluid has a great potential to meet the increased demand of heat removal in heat transfer technology. In order to use nanofluids as applicative and commercial fluids, further advanced research in forced convection mechanism of these fluids must be conducted. The measurement of forced convective coefficient on nanofluids is carried out by using car radiator in cross flow arrangement. Water-based nanofluids containing Al2O3 nano particles 1% and 4% have been investigated. The result shows the enhancement of heat transfer convective coefficient compared to the base fluids: 31-48% for 1% particles concentration and 52-79% for 4% particles concentration. The rate of increase of enhancement shows a dramatic increase with elevated temperature (50-70oC).



paper vaksin
February 17, 2008, 11:57 am
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Design, Manufacturing and Testing of Portable Vaccine Carrier Box Employing Thermoelectric and Heat Pipe Nandy PutraHeat Transfer LaboratoryDepartment of  Mechanical Engineering, University of IndonesiaKampus Baru UI Depok JakartaEmail: nandyputra@eng.ui.ac.id    


Abstract Vaccination is a highly effective method and cheap tool of preventing certain infectious diseases. Routine immunization programs protect most of the world’s children from a number of infectious diseases that previously claimed millions of lives each year. There are many practical problems impeding vaccine delivery especially to keep up the cold chain system which means for storing and transporting vaccines in a potent state from the manufacturer to the person being immunized in certain temperature 2-8 oC. The development of solid state thermoelectric cooling system has permitted packages to be developed that are capable for many applications where environmental concern, size, weight, performance and noise are at issue. In this paper, the development of Vaccine carrier box is described. The combination between thermoelectric and heat pipe are used for the cooling system in the developed vaccine carrier box. The position of heat pipe as a heat sink on hot side of thermoelectric can enhance the thermoelectric performance. The minimum temperature in the cabin of Vaccine Carrier Box reached -10oC which indicated that the designed vaccine carrier box can maintain the vaccine in desired temperature. Keywords: Thermoelectric, Heat Pipe, Vaccine Carrier Box, Introduction  There are many infectious diseases that can result in the death or disability of infants and young children. Some of the most dangerous of these are poliomyelitis, measles, diphtheria, whooping cough, tetanus, tuberculosis, hepatitis B, and mumps. These diseases can all be prevented by immunization. Immunization is achieved by the administration of a vaccine, produced from an attenuated, inactivated or killed form of the virus or bacteria. A vaccine is normally injected, or in some cases may be given orally. The vaccine will provoke the development of antibodies in the infant, who thus acquires immunity without suffering the disease.Vaccination is a highly effective method and cheap tool of preventing certain infectious diseases. For the individual, and for society in terms of public health, prevention is better and more cost-effective than cure. Vaccines are generally very safe and adverse reactions are uncommon. Routine immunization programmes protect most of the world’s children from a number of infectious diseases that previously claimed millions of lives each year.Some Countries used Vaccination Week in their countries to mount a major campaign to immunize children in indigenous communities. Health workers and volunteers in countries joined forces to make sure vaccines reached their targets, from urban neighborhoods to the remotest rural zones. The cold chain system is a means for storing and transporting vaccines in a potent state from the manufacturer to the person being immunized. This is a very important component of an immunization program, since all vaccines lose potency over time, especially if exposed to heat, and in addition, some also lose their potency when frozen. It is obviously pointless to immunize with impotent vaccine, and efforts to reach extremely high levels of immunization coverage will be useless if the vaccine being administered has insufficient potency to give the necessary protection. WHO guidelines and manufacturers’ vaccine labels state that vaccines should be stored at temperatures between 2°C and 8°C and should not be used if thought to have been frozen [1].There are many practical problems impeding vaccine delivery. Delivering vaccines to patients requires functioning freezers and refrigerators (which in turn require a constant supply of energy); good roads and reliable transport to move the vaccines from port to clinic; clinics with access to people who need to be immunized; parents who know the value of vaccination; trained medical staff to deliver the dose; and sterile syringes. Attention to maintaining correct temperatures during storage and transport of vaccine is thus a major task for health workers.Cooling Systems employing the thermoelectric module are commonly less efficient than conventional cooling systems but do represent the most direct way of using electricity to pump heat. A schematic sketch of a thermoelectric module is shown in Fig. 1. It is built of a number of pair of n- and p-type semiconductor materials, connected electrically in series and thermally in parallel and covered between two ceramic plates, which make the cold and the hot surfaces of the module. This Thermoelectric module has been applied in numerous applications [2,3,4,5], range from simple food and beverage coolers for picnic to extremely sophisticated temperature control systems in missiles and space vehicles, including military, biotechnology, medical, industrial, consumer, scientific/laboratory, electronics cooler and telecommunications organizations. The development of solid state cooling system to form thermoelectric module has permitted small commercial packages to be developed that are capable of precise temperature control in a variety applications where environmental concern, size, weight, performance, and noise are at issue.   Figure 1. Thermoelectric Module The thermoelectric module is an unique solid state heat pump because its direction of heat-pumping is fully reversible. When a DC current flows through a thermoelectric couples, one of the surface will be cooled whilst the other is heated depend on the polarity of the current. If the polarity of the DC power supply is changed, it causes heat to be pumped in the opposite direction––a cooler can then become a heater. The amount of heat that can be removed by the hot side depends on the cooling load and the electrical power input and the efficiency of thermoelectric as well. A single stage thermoelectric module is capable to of producing temperature difference up to 67oC, [6]. For higher temperature differences, multi-stage (cascade) thermoelectric modules are considered to apply [7].Fig. 2. Basic components of a thermoelectric cooling system A Thermoelectric cooling systems normally consists of three basic components, there are the thermoelectric module itself, the heat sink at the hot side of the module and the cold sink component at the cold side of the module, as shown in Fig. 2. Any thermoelectric module has maximum temperature difference between hot side and cold side depends on number of junctions and stages of thermoelectric. To have optimal temperature difference which is the key factor for cooling system in thermoelectric module, the waste heat from the hot side must be rejected as much as possible to the ambient either by natural or forced convection. Normally thermoelectric coolers (TECs) require heat sinks on the hot side of thermoelectric module in order to dissipate the energy generated or absorbed at the hot side, usually used heat sink fan which can conduct heat transfer through convection. The box or the compartment to be cooled may be in direct contact with the cold ceramic plate of the thermoelectric module, but in order to have  effective heat transfer or cooling in the compartment, thermoelectric module require also cold sink. The use of thermoelectric module has progressed, but not as much as it was expected, because it has the lower COP than conventional cooling system. In order to have better COP, the dissipation of heating provided by the thermoelectric module in a little surface should be attended, therefore design or selection of a heat sink on the hot side is significant and crucial factor affecting the overall performance of a thermoelectric system. The heat sink should be designed to minimize the thermal resistance as small as possible. D Astrain et. al [8] used  thermosyphon with phase change which could increased the coefficient of performance up to 32%. Chein et. al [9] proposed micro channel heat sink to reduce both thermal resistance and size. The Enhancement heat transfer or to minimize thermal resistance between thermoelectric module and heat sink fan devices may be employed heat pipes. Heat pipes [10] are devices with a very high thermal conductivity and typically consist of a sealed hollow tube with an internal wick. The advantage of using heat pipes over conventional methods is that large quantities of heat can be transported through a small cross-sectional area over a considerable distance with no additional power input to the system. Numerous investigations have been made to obtain the thermal performance, ensure efficient and reliable operation of heat pipe [11,12]. The schematic of heat pipe can be seen in Fig. 3. The pipe contains a relatively small quantity of a “working fluid” or coolant such as water, ethanol, methanol, or with new fluids which is called nanofluids [13]. When heat is absorbed on one end of the pipe (evaporator), the working fluid will evaporate and the vapour pressure inside the cavity of the heat pipe will increase and then vapour moves to the condensing end where the excess vapour condenses, releases its latent heat, and warms the cool end of the pipe. The condensed working fluid then returned to the hot end of the pipe. In the case of vertically-oriented heat pipes the fluid may be flowed by the force of gravity. In the case of heat pipes containing wicks, the fluid is returned by capillary action.This heat pipe could be attached on the hot side of the thermoelectric module to absorb more waste heat and then to be dissipated to the ambient air by forced air.  Figure 3.  Structure of Heat Pipe The aim of the present study is development a Vaccine Carrier Box for carrying vaccine to remote rural zone based on thermoelectric module and to investigate the thermal performance and effectiveness of heat pipe for heat dissipation of the hot side of thermoelectric module. Prototype of Vaccine Carrier BoxDetails of developed Vaccine Carrier Box in this research are shown in Fig. 4. The Vaccine Carrier Box consists of a vaccine compartment (40 mm x 40 mm x 38 mm)…, thermoelectric „, heat pipe ƒ, heat sink fan‚ and temperature controller †. The thermoelectric can be operated only in a certain temperature difference range between the cold and hot side depending on the input electric current, and to maintain the temperature difference within the operating range. In the prototype, two commercially 40 X 40 mm thermoelectric modules were sandwiched and connected electrically in series. This way was chosen in order to have higher temperature difference between hot side and cold side of the thermoelectric module and gives larger COP [12]. A metallic space block made of aluminum was positioned between the cold side of the thermoelectric modules and the cold side heat sink. To minimize the thermal contacts between the thermoelectric module and cold sink, a thin film of silicon thermal paste were used.  Figure 4.  Prototype of Vaccine Carrier Box Thermoelectric module requires a heat sink on the hot side to reject heat away from thermoelectric. To obtain the best performance of the vaccine carrier box, the thermoelectric cooler must be designed with heat sink thermal resistance as small as possible. The commercial heat pipe was mounted on the hot side of thermoelectric to release more heat and to keep at the certain temperature on that surface. Fins made of aluminum were attached on condensation side of heat pipe horizontally then a small fan was mounted directly on the fins to provide forced air convection to the hot side heat sink of heat pipe. The size of fan is 50 X 50 X 20 mm a specified air flow is 20 CFM and a power input 1 Watt.  Thermal insulating Polyurethane foam is used for inhibiting the backflow of heat that may occurs when operating at or below the dew point or humid condition. The thickness of insulation was 30 mm. The Vaccine Carrier is equipped with a temperature control not only to maintain the setting temperature but also to reduce energy supply when the setting temperature has been reached. Test Methodology Since the intention of the research was to examine the potential use of heat pipe with thermoelectric, the prototype of Vaccine Carrier Box has been built and tested with, and without heat pipe, in order to know the effect of the heat pipe on the COP of the thermoelectric cooling system when we replace the finned heat sink with heat pipe. The purpose was also to know the performance of cooling system when we give the cooling load inside the cabin of vaccine carrier box. For this reason, tests were also carried out with 4 ampoules (40 ml), to investigate its effect on the performance of the thermoelectric cooling system. Figure 6 illustrates the schematic of the experimental setup used for testing performance of Vaccine Carrier Box(2).  Fig. 5 Experimental Set-up The temperatures were measured at various positions, including the cold and hot side  of the thermoelectric, condenser section of the heat pipe-embedded fins heat sink system, the interior of  vaccine cabinet, and the ambient air. Type-K thermocouples (11) were used and all thermocouples connected to data acquisition card (12) and can be monitored through the PC (13). The overall accuracy of temperature sensor is 0.5 oC. DC power supply (9 & 10) was used to supply electrical energy input to the thermoelectric module and fan. The input power (voltage and current) are recorded from its LCD display.  Result and Discussion  The impact of using a heat pipe embedded fins heat sink fan to enhance the heat transfer from vaccine carrier box was tested. The results of these tests are presented in Figs. 6–8. Fig. 6 shows the variation of the temperatures at several positions of thermocouple such as on the cabin, cold side and hot side of the thermoelectric modules, condenser of heat pipe and ambient temperature. In this test, no heat load was located inside the cabin and 12 Volt and 2 Amp DC current was supplied for thermoelectric. The ambient temperature during experiment was constant 30 oC. The beginning of measurement showed that all thermocouples were 30oC, then the temperature on the cold side of thermoelectric and in the cabin drops rapidly until minimum temperature was reached. There were -10oC and -14oC for cabin temperature and cold side temperature respectively. The temperature on the hot side of thermoelectric or on the evaporator of heat pipe jumped to be 45oC in short time, while the average temperature on the condenser side of heat pipe was 37oC.   From the measurement it found that the desire temperature for life temperature of vaccine 2-8oC can be reached after 5 minute of operation. The temperature measurements showed similar tendency like result from Chatterjee et.al 2003[14]. Fig. 6. Temperature Distribution             Figure 7 shows the measurements of cabin temperature with different conditions. When the cooling system only used thermoelectric and heat sink fan on the hot side of thermoelectric, temperature in the cabin drops fast similar like system with thermoelectric and heat pipe but the minimum temperature of the cabin that can be reached is only -4oC while if the heat pipe is applied, cabin temperature reached -10oC. When the 4 ampoules (40 ml) are stored in the cabin, where the combination of thermoelectric and heat pipe were applied, at the initial stage, the most of the cooling energy is absorbed by the ampoules and therefore the temperature in the cabin drops more slowly than when without ampoules. After 60 minutes, the cabin temperature reached below 0oC and after several times the cabin temperature reached – 7oC.  It should be noted here, the measurements started from room temperature. In the practice, this vaccine carrier box use for maintaining the cold chain of vaccines where temperature of vaccines are already between 2-8oC, it means the cooling load of vaccine carrier box is so small, therefore the developed vaccine carrier box does not need more time to reach desired temperature.In fact, using heat sink fan on the hot side thermoelectric is quite enough to keep vaccines in desire temperature, more advantages will be earned by utilizing heat pipe, such as the consumption of electric energy can be reduced, the capacity of box can be enlarged, and the vaccine carrier box can be used for vaccines that should be maintained below 0oC. Those are a major advantage of utilizing heat pipe compared with a conventional heat sink. Fig. 7  Cabin’s Temperature with different condition In the thermoelectric module, the temperature difference between hot and cold side is the important parameter. Every type of thermoelectric module has each maximum temperature difference. To have maximum temperature difference between hot and cold side, the produced heat in hot side of thermoelectric must be rejected as much as possible.  A comparison of the difference temperature between hot side and cold side of the thermoelectric cooling systems with and without ampoules and with heat sink fan are presented in Fig. 8. For all conditions the difference temperature between hot and cold side increased rapidly until the maximum possible temperature difference across thermoelectric is reached. The maximum temperature difference between hot side and cold side was 59oC under condition where the heat pipe is applied. When a conventional heat sink is used on the hot side, the temperature difference between hot and cold side was only 50oC.While results from Riffat et. al 2006 [3] stated only 38 oC difference temperature with temperature ambient 20oC.The placement of heat pipe on the hot side of thermoelectric module showed improvement of the performance of thermoelectric module. It can enhance temperature difference between hot and cold side 9 oC higher than only used heat sink fan. The developed vaccine carrier box has 21 oC higher difference temperature than the results from Riffat et. al 2006 [3], this effect maybe from the two sandwiched  thermoelectric modules and type of heat pipe that were applied  in vaccine carrier box.  Fig. 8. Difference Temperature between hot and cold side of thermoelectric ConclusionVaccine Carrier Box described above is an important device to guarantee the cold chain of vaccine in order to ensure the full potency of essential vaccines. A Vaccine Carrier Box device based on thermoelectric and heat pipe, has been designed, manufactured, and tested which allows distributing the heat flow of the hot side of a thermoelectric module. The enhancement of cooling performance could be achieved by using heat pipe to improve heat transfer on the hot side of thermoelectric. The achieved minimum temperature in the cabin is 40oC under the ambient temperature.  AcknowledgementsThe authors would like to thank Hibah Bersaing DIKTI RI 2007 for funding this project. References [1]   www.who.org, Download 20th March 2007[2]   S. B. Riffat and Xiaoli Ma, Thermoelectrics: a review of present and potential applications, Applied Thermal Engineering, Volume 23, Issue 8, June 2003, Pages 913-935[3]   S.B. Riffat, S.A. Omer and Xiaoli Ma, A novel thermoelectric refrigeration system employing heat pipes and a phase change material: an experimental investigation, Renewable Energy, Volume 23, Issue 2, June 2001, Pages 313-323[4]   T. Hara, H. Azuma, H. Shimizu, H. Obora and S. Sato, Cooling performance of solar cell driven thermoelectric cooling prototype headgear, Applied Thermal Engineering 18 (1998) 1159–1169[5]   Nihal Fatma Güler and Rait Ahiska, Design and testing of a microprocessor-controlled portable thermoelectric medical cooling kit, Applied Thermal Engineering, Volume 22, Issue 11, August 2002, Pages 1271-1276[6]   www.melcor.com, Download 10th January 2007[7]   Jincan Chen a,Yinghui Zhou a ,Hongjie Wang a ,Jin T.Wang, Comparison of the optimal performance of single-and two-stage thermoelectric refrigeration systems,Applied Energy 73 (2002) pp. 285 –298[8]   D. Astrain, J. G. Vián and M. Domínguez,  Increase of COP in the thermoelectric refrigeration by the optimization of heat dissipation
Applied Thermal EngineeringVolume 23, Issue 17December 2003Pages 2183-2200
[9]   Reiyu Chein and Yehong Chen, Performances of thermoelectric cooler integrated with microchannel heat sinks, International Journal of RefrigerationVolume 28, Issue 6September 2005Pages 828-839[10]  Faghri A. Heat pipe science and technology. Taylor & Francis, 1995.[11]  Leonard L. Vasiliev, Heat pipes in modern heat exchangers,Applied Thermal Engineering, Volume 25, Issue 1, January 2005, Pages 1-19[12]  Mostafa A. Abd El-Baky and Mousa M. Mohamed,  Heat pipe heat exchanger for heat recovery in air conditioning Applied Thermal EngineeringVolume 27, Issue 4March 2007Pages 795-801[13]     Shung – Wen Kang, Wei-Chiang Wei, Sheng-Hong Tsai and Shih-Yu Yang, Experimental investigation of silver nano-fluid on heat pipe thermal performance, Applied Thermal Engineering, Volume 26, Issues 17-18, December 2006, pp. 2377-2382[14]  S. Chatterjee and K. G. Pandey, Thermoelectric cold-chain chests for storing /transporting vaccines in remote regions, Applied EnergyVolume 76, Issue 4December 2003, pp. 415-433     



Vaccine Carrier Box
January 7, 2008, 4:36 pm
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Nandy mau berapa paper lagi kamu tulis? dan cuman untuk jadi KUM dan disimpan di lemari??? pertama sich bingung maksud teguran yang disampaikan oleh Prof. Raldi pada saat ngobrol santai. Bukannya setelah pulang Doktor memang harus terus meneliti dan menulis. Padahal ilmu yang saya bawa dari Jerman, sesuatu yang baru untuk dikembagkan di Dunia apalagi di Indonesia yakni mengenai Nanofluid…orang bilang nano teknologi…kedengarannya susah banget dan canggih. Dari topik itu saya punya 6 Jurnal International dan beberapa jurnal nasional dan paper-paper prosiding. Memang bener Prof Ral, itu karya cuman jadi tulisan yang tersusun rapi di lemari saya dan lumanyan mendokrak pengumpulan KUM yang totalnay 667 sudah dekat menuju Prof. yang jumlahnya 850. Tapi apa iya hasil penelitian hanya jadi penghias lemari buku?? Lalu apa manfaat langsung untuk bangsa ini dan masyarakat??? kayakanya nol dech.  Saya mulai sadar (tapi masih ragu-ragu juga) dan mulai mengarahkan penelitian menjadi produk jadi yang bermanfaat. Saya mulai membuat Vaccine Carrier Box bermesin Elemen Peltier, nanti saya cerita khusus mengenai Elemen Peltier. Elemen ini saya geluti sejak belajar di Jerman thn 98. Alhamdulillah penelitian ini dapat dukungan dana dari Hibah bersaing selama dua tahun dan Produk ini jadi serta siap diluncurkan ke pasaran. Kehandalan produk ini adalah hemat energi, non CFC, ringan, portable. dan yg teramat penting mampu menjadi Cold chain vaksin di temperatur 2-8 derajat. Alat ini bisa digunakan untuk membawa vaksin ke pelosok pedalaman.



Mulai nulis di Blog
November 24, 2007, 2:30 pm
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24 nov 07 mulai coba menulis apa aja yg saya mau di web blog, dulu pernah punya blog di salah satu blog, tapi udah lupa passwordnya. Pengen coba konsisten menulis yang ringan-ringan mungkin nanti ada gunanya sepuluh tahun kemudian…biar katrok (kata om tukul). Kadang-kadang kalo nggak bisa tidur, dan malas baca buku atau majalah, acara tv membosankan, baca koran di internet juga males, nulis di blog bisa jadi alternative. Menulis apa yang dilakukan seharian di kantor atau kejadian-kejadian yang menarik. Mudah-mudahan nggak panas-panas tahi ayam. Keinginan buat blog di sini, karena melihat blognya prof koestoer yang udah move ke wordpress.com, yang jadi inget lagi dan pengen coba lagi. (jkt,24.11.07, 21.30 WIB)



Hello world!
November 24, 2007, 2:21 pm
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