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Enhancement of Heat Transfer Rate in Heat Exchanger Using Nanofluids

Enhancement of Heat Transfer Rate in Heat Exchanger Using Nanofluids

A very low Nano fluid concentration was used as the first Nano heat transfer experiment. An increase in heat transfer rate is observed at any given flow rate. The plot of mass flow rate vs. heat transfer rate is shown in Fig.3. There is an improvement in heat flow rate due to the addition of nanoparticles even at very low concentrations. For example at a mass flow rate of 0.005 kg/s, a 5.5% increase in heat transfer rate is observed.

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Analysis of a Heat Pipe to Obtain Maximum Heat Transfer Rate

Analysis of a Heat Pipe to Obtain Maximum Heat Transfer Rate

Maximum heat transfer rate is an important parameter in heat pipe performance. In the present study the maximum heat transfer rate has been calculated by using C++ program for the different operating temperature of a particular heat pipe dimension. For this purpose the selected fluids is water. Taking the dimension as constant and varying the temperature, the maximum heat transfer rate has been calculated.

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Influence of Viscosity of nanofluids on heat transfer Rate

Influence of Viscosity of nanofluids on heat transfer Rate

Any type of nanoparticles mixed with bases fluid is called nanofluid. Nanofluid sometimes called an emulsion. Nanofluids are having several advantages. Due to nano size particles, pressure losses during flow will be less. Higher thermal conductivity of nano particles will increase the heat transfer rate. Successful employment of nanofluid will lead to lighter and smaller heat exchanger. There will be a drastic change in the properties of the base fluid after introducing suspending nanofluids. Heat transfer rate increases due to large surface area of the nano particles in the base fluid. Nanofluids are most suitable for rapid heating and cooling systems.

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Enhancement of Heat Transfer Rate using Nano Fluid in Heat Exchanger

Enhancement of Heat Transfer Rate using Nano Fluid in Heat Exchanger

A heat exchanger is a device used for affecting the process of heat exchange between two fluids that are at two different temperatures. Heat exchangers are useful in engineering process like those in refrigeration and air conditioning systems, power systems, food processing systems, chemical reactors and space or aeronautical applications. In heat exchangers the temperature of each fluid changes as it passes through the exchanger and hence the temperature of the dividing wall between the fluids also changes along the length of the exchanger. Heat exchangers are designed to deliver a certain heat transfer rate for a certain specified condition of flow rates and temperatures. Shell and tube heat exchangers are used when a process requires large amounts of fluid to be heated or cooled, is suited for higher pressure applications. Nano particles research is gaining increasing interest due to their unique properties, such as increased thermal conductivity, toughness and ductility, increased hardness and strength of metals and alloys, luminescent efficiency of semiconductors, formability of ceramics. In order to enhance the heat transfer rate of the heat exchanger, a new category of fluids are used along with the conventional fluids like water, those fluids are called as nano fluids. Nano fluids are those fluids which exhibit significantly novel properties when compared to conventional fluids. Nano fluids are suspensions containing particles that are less than 100nm and have a bulk solids thermal conductivity of orders of magnitude higher than the base fluids.

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Thermal Performance Analysis of IC Engine Fins

Thermal Performance Analysis of IC Engine Fins

1.1 FINS:In study of heat transfer, a fin is a surface that it is extends from an object to increase the rate of heat transfer. Fin act as the important part that help to reduce the distribution of overheat by the engine block. In Many thermal applications heat has to be removed from a small area to the surrounding (or) Environment to maintain it in a steady state condition.

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Effect of Aluminum Fin on the performance of Stratified Chambers Gas to Gas Heat Exchanger with Porous Medium

Effect of Aluminum Fin on the performance of Stratified Chambers Gas to Gas Heat Exchanger with Porous Medium

through a partially filled pipe with porous material. The results showed that the location of the porous medium affects the performance of the composite pipe, the thermal conductivity ratio has a considerable effect on the heat transfer enhancement in case 1 for all porous thicknesses. While, in case 2, its effect on the enhanced heat transfer is more obvious at higher porous thicknesses. Guo, Shi Zhang, and Rong [6] investigated numerically the enhancement of the heat transfer for fluid flow in pipe partially filled with porous medium. The results show that changing the thickness of porous medium affect the rate of heat transfer and flow resistance, small effect of porosity on temperature and flow field ( other parameters were fixed) and at the same parameter values, pipe partially filled with porous media enchanted the rate of heat transfer effect comparing with blank pipe. Aziz, Kundu, and Bhanja [7] investigated numerically the rate of heat transfer on fixed and moving porous fin material by studying the temperature distribution, optimum design parameters and efficiency of the moving porous fin. The investigation shows that the results of both decomposition method and finite difference method approach with each other and the moving porous fin better than fixed ones in the rate of heat transfer. Mehrizi, Farhadi, Sedighi, and Delavar [8] studied the extent of enhancement of the heat transfer at a ventilated porous media plate heat exchanger by using method of Boltzmann which was designed by square cavity with thermal insulated inlet and outlet and three fins with constant hot temperature. The study shows that the rate of heat transfer enhanced due to adding porous medium to the heat exchanger, at high Reynolds number, the porous medium has high effect in Nusselt number, the position of the fin affects sensibly on Nusselt number

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Numerical Investigation on Solar Collectors by Using Finite Element Aanalysis

Numerical Investigation on Solar Collectors by Using Finite Element Aanalysis

By observing the CFD analysis the pressure drop & velocity values are more for water fluid at solar parabolic trough collectors compared with flat plate collector. The more heat transfer rate at fluid water. By observing the thermal analysis Heat flux value is less for steel material than aluminum and copper material at solar collectors and Heat flux value is more for copper material than aluminum and steel material at solar absorber

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Heat transfer enhancement of double pipe heat exchanger with FDM delta-channel winglet inserts

Heat transfer enhancement of double pipe heat exchanger with FDM delta-channel winglet inserts

Abstract - For the enhancement in performance of the heat exchanger, it is decided to increase the turbulence and intermixing of flow of hot fluid inside the hot fluid pipe by means of specially design delta winglets that will be placed within the inner tube and these winglets are produced by the 3-d printing process .The winglet serve dual purpose namely- one to increase the surface area and other to improve the interaction between particles and thereby increasing the heat transfer. In this work, 3-D printed delta winglet holder used in Inline, 5 degree inclined and 10degree inclined staggered position in double pipe heat exchanger. It is observed that heat transfer rate of the 10 degree inclined configuration of counter flow is better than that of parallel flow configuration. The thermal analysis shows that the maximum heat flux is 31.80W/mm². The increased heat transfer rate can be attributed to higher turbulence and closer interaction of the working fluids. This is achieved with the complex design of delta winglet to create turbulence. The comparative results also displayed in the paper.

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Review on Experimental and Numerical Analysis of Heat Transfer and Friction Factor using Almond Dimple in Rectangular Duct

Review on Experimental and Numerical Analysis of Heat Transfer and Friction Factor using Almond Dimple in Rectangular Duct

Heat transfer can be defined as the exchange of thermal energy between physical systems. The rate of heat transfer is dependent on the properties of the intervening medium and temperatures of the systems through which the heat is transferred. The three basic fundamental modes of heat transfer are conduction, convection and radiation. Heat transfer is a process by which a system changes its internal energy. Hence it plays a vital role in applications of the First Law of Thermodynamics. Conduction is also known as diffusion. The direction of heat transfer is from a region of high temperature to another region of lower temperature, and is governed by the Second Law of Thermodynamics. Heat transfer changes the internal of the systems from which and to which the energy is transferred. Heat transfer occur in a direction that increases the entropy of the collection of systems. When all involved bodies and the surroundings reach the same temperature, thermal equilibrium is achieved. Thermal expansion is the tendency of matter to change in volume in response to a change in temperature.

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CFD Analysis of Heat Transfer Enhancement in Heat Exchangers using Nanofluids

CFD Analysis of Heat Transfer Enhancement in Heat Exchangers using Nanofluids

different techniques have been used. One of the advanced techniques among them is suspension of nanoparticle in the base fluids as water, ethylene glycol, oil. In last few years so many research has been done for enhancing the heat transfer rate like inserting baffles, twisted tapes, brushes, etc. This leads to increase in weight of heat exchangers and also cost of manufacturing. The worldwide researchers are making hard efforts to find out suitable alternatives for heat exchangers with different geometry and varying parameters which effects on performance of heat exchanger. Now days Nano fluid has become blessings for researchers. Nano fluid increases the heat transfer rate when suspended in base fluids water, ethylene glycol. With the fast track development of nanotechnology, particles of nanometer size are used for enhancing heat transfer rate are called Nano fluids. This work is focused on study of heat transfer rate enhancement at low concentration.

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REVIEW ON HEAT TRANSFER ENHANCEMENT IN HEAT EXCHANGER WITH ROTATING TWISTED INSERTS

REVIEW ON HEAT TRANSFER ENHANCEMENT IN HEAT EXCHANGER WITH ROTATING TWISTED INSERTS

The heat exchangers have many applications in the industry. Its performance depends on its design, heat transfer rate, type of medium, pressure drop etc. Its heat transfer rate can be increased my changing the fluid stream inside the heat exchanger. It is done by placing the obstacle in the flow called as insert. Heat transfer rate can be enhanced by using different methods. Those are as follows: 1)Active Techniques: These techniques are more complicated for the design and use point of view. It requires external power source to enhance the heat transfer rate. It has limited application due to requirement of external power source. 3) Passive Techniques: These techniques use surface of geometrical modifications to the flow channel by incorporating inserts or additional devices. This technique does not require any external power; rather they use power form system itself. Ultimately leads into a rise in fluid pressure drop. This method gives higher heat transfer rate as compared with the extended surface. 4) Compound Techniques: It is a hybrid method where both active and passive techniques are combined to increase the heat transfer rate. As this method uses passive technique since it doesn’t require any external power source. Due to this advantage it is widely used in the industries. 5)Extended Surface: They provide effective heat transfer enlargement. The new research led to modify the fin surface that also tends to improve the heat transfer coefficient. 6)Treated surface: These are the heat transfer surfaces which have thin alteration on their finish or coating.

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Thermoelectric Generators for Automotive Waste Heat Recovery Systems Part I: Numerical Modeling and Baseline Model Analysis

Thermoelectric Generators for Automotive Waste Heat Recovery Systems Part I: Numerical Modeling and Baseline Model Analysis

The electrical power generation is observed to be a strong function of flow rate and inlet exhaust temperature. The implications of varying inlet con- ditions could be very severe if proper conditioning of output power is not carried out. The ZT value of high-temperature skutterudites decreases consid- erably along the flow direction due to decreasing DT and temperatures at the hot-side junction. The thermoelectric modules close to the inlet are exposed to much higher gas temperatures and hence generate higher electrical power output per unit area. By optimizing the fin spacing and thick- ness, the heat transfer rate can be enhanced con- 0

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Numerical Study of Corrugation on Performance of Double Pipe Heat Exchanger

Numerical Study of Corrugation on Performance of Double Pipe Heat Exchanger

Variation of heat transfer rate with Q Reynolds number are shown in figure 5.5 and it is observed that for all the cases heat transfer rate increases as Reynolds number increases and it is maximum in outer corrugated tube for all values of Reynolds number. Variation of h with Reynold number are as shown in Fig 5.3. As seen from the figure h increases as Re increases. At low Reynold.no h of internally corrugated tube is higher as compared to externally corrugated tube and plain tube but at high Reynold number it is lesser than the other two.

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Numerical Study of Corrugation on Performance of Double Pipe Heat Exchanger

Numerical Study of Corrugation on Performance of Double Pipe Heat Exchanger

Variation of heat transfer rate with Q Reynolds number are shown in figure 5.5 and it is observed that for all the cases heat transfer rate increases as Reynolds number increases and it is maximum in outer corrugated tube for all values of Reynolds number. Variation of h with Reynold number are as shown in Fig 5.3. As seen from the figure h increases as Re increases. At low Reynold.no h of internally corrugated tube is higher as compared to externally corrugated tube and plain tube but at high Reynold number it is lesser than the other two.

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CFD Analysis of Heat Transfer Enhancement in Heat Exchangers using Nanofluids

CFD Analysis of Heat Transfer Enhancement in Heat Exchangers using Nanofluids

Thermal conductivity can be defined as amount of heat transferred through unit thickness of material in a direction normal to a surface of unit area. Thermal conductivity refers to the amount/speed of heat transmitted through a material. Heat transfer occurs at a higher rate across materials of high thermal conductivity than those of low thermal conductivity. Thermal conductivity of nanofluid is determined by following equation,

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EFFECT OF WATER VOLUME ON A THERMOELECTRIC COOLER BOX PERFORMANCE

EFFECT OF WATER VOLUME ON A THERMOELECTRIC COOLER BOX PERFORMANCE

Due to rapid demand on the thermoelectric cooler box, an investigation concerning the effect of water volume on a thermoelectric cooler box performance and its COP has been conducted. The aim of this study is to know the performance and the COP of the cooler box with water volume variations. The conduction heat transfer rate flowing from the ambient to the cooler box space is discussed deeply as this type of heat transfer rate is seldom to be elucidated in the published literature and it can be the dominant of the heat load when there is no water volume inside the cooler box. The cooler box size was 390 mm x 320 mm x 530 mm and the water volume variations employed were ranging from 0 to 4500 ml. The power used was of approximately 51.27 W. The results indicate that increasing the water volume raises the cooler box space temperature and the COP but decreases the conduction heat transfer rate. At 0 ml water volume, the conduction heat transfer rate increases and it gets constant, while at higher water volumes the COP decreases with the time. The effect of the water volume on the heat transfer rate of the air is negligible but it is significant on the total heat transfer and conduction heat transfer.

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Experimental  Investigation Of Heat Transfer In Heat Exchanger Using Different Geometry Of Inserts  A Review

Experimental Investigation Of Heat Transfer In Heat Exchanger Using Different Geometry Of Inserts A Review

Ahmet Tandiroglu studied effect of the flow geometry parameters on transient forced convection heat transfer for turbulent flow in circular tube with baffle inserts. The characteristic parameter of the tubes was different range of pitch to inlet diameter ratio H/D=1, 2, 3and the baffle orientation angle β=45 0 , 90 0 and 180 0 . Air was used as working fluid in the range of Reynolds number 3000 to 20,000. It was varied different geometrical parameter such as baffle spacing H and the baffle orientation angel β. It was conclude that the tubes with baffle inserts give higher heat transfer rate than smooth tube. The time averaged Nusselt number increases with increasing Reynolds number. The rate of pressure drop increases with increasing Reynolds number for transient flow conditions but decreases with increasing Reynolds number for the steady state flow conditions. The rate of average pressure drop in the baffle inserted tubes for transient flow conditions was higher than that of steady state flow conditions.

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64-CPWTR model. Wong et al. [3]

64-CPWTR model. Wong et al. [3]

Equations (23) to (26) are solved by an in-house USTREAM code developed by the third named author to obtain the three-dimensional numerical heat transfer results. In order to check if the numerical results are reliable, an insulated sphere is analyzed to determine how many cells are needed to obtain a satisfactory result. It was found that a model of an insulated sphere, which consists of 26600 cells, gave a satisfactory solution of heat transfer rate within ±0.01% compared with that from exact analytic solution. Therefore, in the case of analyzing an insulated oblate spheroid, the numerical solutions obtained by the model with same number of cells can be expected to be highly accurate.

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EXPERIMENTAL STUDY OF THE PERFORATED RECTANGULAR FINS BY NATURAL CONVECTION

EXPERIMENTAL STUDY OF THE PERFORATED RECTANGULAR FINS BY NATURAL CONVECTION

A. M. &, the other. Treats the natural convection heat transfer from perforated fins. The temperature distribution was examined for an array of rectangular fins (15 fins) with uniform cross-sectional area(100x270 mm) embedded with different vertical body perforations that extend through the fin thickness. The patterns of perforations include 18 circular perforations (holes). Experiments were carried out in an experimental facility that was specifically design and constructed for this purpose. The heat transfer rate and the coefficient of heat transfer increases with perforation diameter increased.

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Passive Heat Transfer Augmentation Methods in a Circular Tube: A Review

Passive Heat Transfer Augmentation Methods in a Circular Tube: A Review

The Passive heat transfer augmentation methods does not need any external power input. In the convective heat transfer, one of the ways to enhance heat transfer rate is to increase the effective surface area and residence time of the heat transfer fluids. By Using, this technique causes the swirl in the bulk of the fluids and disturbs the actual boundary layers, which increase effective surface area, residence time and simultaneously heat transfer coefficient increases in an existing system. Methods generally used are, extended surface, displaced enhancements devices, rough surfaces surface tension devices, Inserts requires additional arrangements to make to fluid flow which enhance and augment the heat transfer. The types of inserts are twisted tape, wire coils, ribs, baffles, plates, helical screw insert, mesh inserts, convergent – divergent conical rings, conical rings etc. Twisted tapes are the metallic strips twisted using some of the suitable techniques as per the required shape and dimension, which are inserted in the flow to enhance the heat transfer. The twisted tape inserts are most suitable and widely used in heat exchangers to enhance the heat transfer. Twisted tape inserts increase heat transfer rates with less friction factor. The use of twisted tapes in a tube gives simple passive technique for enhancing the convective heat transfer by making swirl into the heavy flow which disrupting the boundary layer at the tube surface due to rapidly changes in the surface geometry. Which means to say that such type of tapes induce turbulence and swirl flow which induces inside the boundary layer and which gives better results of heat transfer coefficient and Nusselt number due to the changes in geometry of twisted tape inserts. Simultaneously, the pressure drop inside the tube will be increases when using twisted-tape as an insert. For this a many researchers have been done by experimentally and numerically to investigate the desired design to achieve the better thermal performance with less frictional losses. The heat transfer enhancement of twisted tapes inserts depends on the Pitch In addition, twist ratio.

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