MODELING AND CFD ANALYSIS OF RADIATOR BY USING NANO FLUIDS

Transcription

1 MODELING AND CFD ANALYSIS OF RADIATOR BY USING NANO FLUIDS 1 SUBBA REDDY.GANGIREDDY, 2 KISHORE KUMAR.B 1 PG Scholar, Department of MECH, Nalanda Institute of Technology, Kantepudi,Sattenapalli Dist.: Guntur,A.P, India,Pin: Id: subash318@gmail.com 2 HOD, Department of MECH, Nalanda Institute of Technology, Kantepudi,Sattenapalli Dist.:Guntur,A.P, India,Pin: Id: kishorekumarpsgtech@gmail.com Abstract Radiators are heat exchangersused to transfer thermal energy from one medium to another for the purpose of cooling and heating. The majority of radiators are constructed to function in automobiles, buildings, and electronics. The radiator is always a source of heat to its environment, although this may be for either the purpose of heating this environment, or for cooling the fluid or coolant supplied to it, as for engine cooling. Despite the name, most radiators transfer the bulk of their heat via convection. Automobile radiator main function is to cool the engine by passing the coolant through cylinder water jackets. The main objective of the project is to design a radiator and assign aluminum and copper materials to find out the better material for heat transfer. CFD analysis is carried out to find the heat transfer through the radiator. Designing of radiator is done in solid works 2014 premium software. And cfd analysis is carried out in solid works flow simulation tools. Introduction We know that in case of Internal Combustion engines, combustion of air and fuel takes place inside the engine cylinder and hot gases are generated. The temperature of gases will be around C. This is a very high temperature and may result into burning of oil film between the moving parts and may result into seizing or welding of the same. So, this temperature must be reduced to about C at which the engine will work most efficiently. Too much cooling is also not desirable since it reduces the thermal efficiency. So, the object of cooling system is to keep the engine running at its most efficient operating temperature. It is to be noted that the engine is quite inefficient when it is cold and hence the cooling system is designed in such a way that it prevents cooling when the engine is warming up and till it attains to maximum efficient operating temperature, then it starts cooling. It is also to be noted that: (a) About 20-25% of total heat generated is used for producing brake power (useful work). (b) Cooling system is designed to remove 30-35% of total heat. (c) Remaining heat is lost in friction and carried away by exhaust gases. Cooling System for engine A typical 4-cylinder vehicle cruising along the highway at around 50 miles per hour, will produce 4000 controlled explosions per minute inside the engine as the spark plugs ignite the fuel in each cylinder to propel the vehicle down the road. Obviously, these explosions produce an enormous amount of heat and, if not controlled, will destroy an engine in a matter of minutes. Controlling these high temperatures is the job of the cooling system. The modern cooling system has not changed much from the cooling systems in the model T back in the '20s.

2 Oh sure, it has become infinitely more reliable and efficient at doing its job, but the basic cooling system still consists of liquid coolant being circulated through the engine, then out to the radiator to be cooled by the air stream coming through the front grill of the vehicle. Today's cooling system must maintain the engine at a constant temperature whether the outside air temperature is 110 degrees Fahrenheit or 10 below zero. If the engine temperature is too low, fuel economy will suffer and emissions will rise. If the temperature is allowed to get too hot for too long, the engine will self-destruct WORKING OF COOLING SYSTEM Actually, there are two types of cooling systems found on motor vehicles: Liquid cooled and Air cooled. Air cooled engines are found on a few older cars, like the original Volkswagen Beetle, the Chevrolet Corvair and a few others. Many modern motorcycles still use air cooling, but for the most part, automobiles and trucks use liquid cooled systems and that is what this article will concentrate on. The cooling system is made up of the passages inside the engine block and heads, a water pump to circulate the coolant, a thermostat to control the temperature of the Cooling Systems in Automobiles & Cars 689 coolant, a radiator to cool the coolant, a radiator cap to control the pressure in the system, and some plumbing consisting of interconnecting hoses to transfer the coolant from the engine to radiator and also to the car's heater system where hot coolant is used to warm up the vehicle's interior on a cold day. A cooling system works by sending a liquid coolant through passages in the engine block and heads. As the coolant flows through these passages, it picks up heat from the engine. The heated fluid then makes its way through a rubber hose to the radiator in the front of the car. As it flows through the thin tubes in the radiator, the hot liquid is cooled by the air stream entering the engine compartment from the grill in front of the car. Once the fluid is cooled, it returns to the engine to absorb more heat. Fig:1 Radiator water pump has the job of keeping the fluid moving through this system of plumbing and hidden passages. A thermostat is placed between the engine and the radiator to make sure that the coolant stays above a certain preset temperature. If the coolant temperature falls below this temperature, the thermostat blocks the coolant flow to the radiator, forcing the fluid instead through a bypass directly back to the engine. The coolant will continue to circulate like this until it reaches the design temperature, at which point, the thermostat will open a valve and allow the coolant back through the radiator. Circulation The coolant follows a path that takes it from the water pump, through passages inside the engine block where it collects the heat produced by the cylinders. It then flows up to the cylinder head (or heads in a V type engine) where it collects more heat from the combustion chambers. It then flows out past the thermostat (if the thermostat is opened to allow the fluid to pass), through the upper radiator hose and into the radiator. The coolant flows through the thin flattened tubes that make up the core of the radiator and is cooled by the air flow through the radiator.

3 From there, it flows out of the radiator, through the lower radiator hose and back to the water pump. By this time, the coolant is cooled off and ready to collect more heat from the engine. The capacity of the system is engineered for the type and size of the engine and the work load that it is expected to undergo. Obviously, the cooling system for a larger, more powerful V8 engine in a heavy vehicle will need considerably more capacity then a compact car with a small 4-cylinder engine. On a large vehicle, the radiator is larger with many more tubes for the coolant to flow through. The radiator is also wider and taller to capture more air flow entering the vehicle from the grill in front. Antifreeze The coolant that courses through the engine and associated plumbing must be able to withstand temperatures well below zero without freezing. It must also be able to handle engine temperatures in excess of 250 degrees without boiling. A tall order for any fluid, but that is not all. The fluid must also contain rust inhibiters and a lubricant. The coolant in today's vehicles is a mixture of ethylene glycol (antifreeze) and water. The recommended ratio is fifty-fifty. In other words, one-part antifreeze and one-part water. This is the minimum recommended for use in automobile engines. Less antifreeze and the boiling point would be too low. In certain climates where the temperatures can go well below zero, it is permissible to have as much as 75% antifreeze and 25% water, but no more than that. Pure antifreeze will not work properly and can cause a boil over. CLASSIFICATION Types of cooling system in automobiles There are mainly two types of cooling systems: (a) Air cooled system, and (b) Water cooled system. Air Cooling System Air cooled system is generally used in small engines say up to kw and in aero plane engines. In this system fins or extended surfaces are provided on the cylinder walls, cylinder head, etc. Heat generated due to combustion in the engine cylinder will be conducted to the fins and when the air flows over the fins, heat will be dissipated to air. The amount of heat dissipated to air depends upon: (a) Amount of air flowing through the fins. b) Fin surface area. (c) Thermal conductivity of metal used for fins. Water cooling system In this method, cooling water jackets are provided around the cylinder, cylinder head, valve seats etc. The water when circulated through the jackets, it absorbs heat of combustion. This hot water will then be cooling in the radiator partially by a fan and partially by the flow developed by the forward motion of the vehicle. The cooled water is again re circulated through the water jackets Radiator It mainly consists of an upper tank and lower tank and between them is a core. The upper tank is connected to the water outlets from the engines jackets by a hose pipe and the lover tank is connected to the jacket inlet through water pump by means of hose pipes. There are 2-types of cores (a) Tubular (b) Cellular as shown. When the water is flowing down through the radiator core, it is cooled partially by the fan which blows air and partially by the air flow developed by the forward motion of the vehicle. As shown through water passages and air passages, water and air will be flowing for cooling purpose. It is to be noted that radiators are generally made out of

4 copper and brass and their joints are made by soldering. Fig 2 Radiator Basic Principleof Radiator Most internal combustion engines are fluid cooled using either air (a gaseous fluid) or a liquid coolant run through a heat exchanger (radiator) cooled by air. Marine engines and some stationary engines have ready access to a large volume of water at a suitable temperature. The water may be used directly to cool the engine, but often has sediment, which can clog coolant passages, or chemicals, such as salt, that can chemically damage the engine. Thus, engine coolant may be run through a heat exchanger that is cooled by the body of water. Most liquid-cooled engines use a mixture of water and chemicals such as antifreeze and rust inhibitors. The industry term for the antifreeze mixture is engine coolant. Some antifreezes use no water at all, instead using a liquid with different properties, such as propylene glycol or a combination of propylene glycol and ethylene glycol. Most "air-cooled" engines use some liquid oil cooling, to maintain acceptable temperatures for both critical engine parts and the oil itself. Most "liquidcooled" engines use some air cooling, with the intake stroke of air cooling the combustion chamber. An exception is Wankel engines, where some parts of the combustion chamber are never cooled by intake, requiring extra effort for successful operation. However, properties of the coolant (water, oil, or air) also affect cooling. As example, comparing water and oil as coolants, one gram of oil can absorb about 55% of the heat for the same rise in temperature (called the specific heat capacity). Oil has about 90% the density of water, so a given volume of oil can absorb only about 50% of the energy of the same volume of water. The thermal conductivity of water is about 4 times that of oil, which can aid heat transfer. The viscosity of oil can be ten times greater than water, increasing the energy required to pump oil for cooling, and reducing the net power output of the engine. Comparing air and water, air has vastly lower heat capacity per gram and per volume (4000) and less than a tenth the conductivity, but also much lower viscosity (about 200 times lower: Pa s for air vs Pa s for water). Continuing the calculation from two paragraphs above, air cooling needs ten times of the surface area, therefore the fins, and air needs 2000 times the flow velocity and thus are circulating air fan needs ten times the power of a recirculating water pump. Moving heat from the cylinder to a large surface area for air cooling can present problems such as difficulties manufacturing the shapes needed for good heat transfer and the space needed for free flow of a large volume of air. NANO FLUIDS A nanofluid is a fluid containing nanometer-sized particles, called Nanoparticles. These fluids are engineered colloidal suspensions of nanoparticles in a base fluid. TheNano particles used in nanofluids are typically made of metals, oxides, carbides, or carbon nanotubes. Common base fluids include water, ethylene glycol and oil. Nanofluids have novel properties that make them potentially useful in many applications in heat

5 transfer, including microelectronics, fuel cells, pharmaceutical processes, and hybrid-powered engines, engine cooling/vehicle thermal management, domestic refrigerator, chiller, heat exchanger, in grinding, machining and in boiler flue gas temperature reduction. They exhibit enhanced thermal conductivity and the convective heat transfer coefficient compared to the base fluid. [6] Knowledge of the rheological behavior of nanofluids is found to be very critical in deciding their suitability for convective heat transfer applications Nanofluids also have special acoustical properties and in ultrasonic fields display additional shear-wave reconversion of an incident compressional wave; the effect becomes more pronounced as concentration increases. In analysis such as computational fluid dynamics (CFD), nanofluids can be assumed to be single phase fluids. However, almost all of new academic papers use two-phase assumption. Classical theory of single phase fluids can be applied, where physical properties of nanofluid is taken as a function of properties of both constituents and their concentrations. An alternative approach simulates nanofluids using a two-component model. The spreading of a nanofluid droplet is enhanced by the solid-like ordering structure of nanoparticles assembled near the contact line by diffusion, which gives rise to a structural disjoining pressure in the vicinity of the contact line. However, such enhancement is not observed for small droplets with diameter of nanometer scale, because the wetting time scale is much smaller than the diffusion time scale. Applications Nanofluids are primarily used for their enhanced thermal properties as coolantsin heat transfer equipment such as heat exchangers, electronic cooling system (such as flat plate) and radiators. Heat transfer over flat plate has been analyzed by many researchers. However, they are also useful for their controlled optical properties. Graphene based nanofluid has been found to enhance Polymerase chain reaction efficiency. Nanofluids in solar collectorsis another application where nanofluids are employed for their tunable optical properties. SOLID WORKS Solid Works is mechanical design automation software that takes advantage of the familiar Microsoft Windows graphical user interface. It is an easy-to-learn tool which makes it possible for mechanical designers to quickly sketch ideas, experiment with features and dimensions, and produce models and detailed drawings. Introduction tosolidworks: Solidworks mechanical design automation software is a feature-based, parametric solid modeling design tool which advantage of the easy to learn windows TM graphical user interface. We can create fully associate 3-D solid models with or without while utilizing automatic or user defined relations to capture design intent. Parameters refer to constraints whose values determine the shape or geometry of the model or assembly. Parameters can be either numeric parameters, such as line lengths or circle diameters, or geometric parameters, such as tangent, parallel, concentric, horizontal or vertical, etc. Numeric parameters can be associated with each other through the use of relations, which allow them to capture design intent.

6 MODELING OF RADIATOR Boss Extrude Mirror Thin extrude Boss extrude on other side Fins dimensions for radiator fillet Cut extrude Final view of radiator Linear pattern

7 Four different view of radiator Other packages that can be added to Solid Works include Solid Works Motion and Solid Works Simulation. A fluid flow analysis using Flow Simulation involves a number of basic steps that are shown in the following flowchart in figure. Finite Element Analysis Finite Element Analysis (FEA) is a computer-based numerical technique for calculating the strength and behavior of engineering structures. It can be used to calculate deflection, stress, vibration, buckling behavior and many other phenomena. It also can be used to analyze either small or large-scale deflection under loading or applied displacement. It uses a numerical technique called the finite element method (FEM). CFD FLOW SIMULATION Computational fluid dynamics (CFD) is a branch of fluid mechanics that uses numerical analysis and data structures to solve and analyze problems that involve fluid flows. Computers are used to perform the calculations required to simulate the interaction of liquids and gases with surfaces defined By conditions. With high speed supercomputers, better solutions can beachieved. Ongoing research yields software thatimproves the accuracy and speed ofcomplexsimulation scenarios suchas transonicor turbulent flows. Initial experimentalvalidation of such software is performed using a windtunnelwith the final validation coming in full-scaletesting, e.g. flight tests. Solidworks Flow Simulation Introduction Solid Works Flow Simulation 2010 is a fluid flow analysis add-in package that is available for Solid Works in order to obtain solutions to the full Navier- Stokes equations that govern the motion of fluids. Fig: Flowchart for fluid flow analysis using Solid Works Flow Simulation CFD ANALYSIS OF RADIATOR General Settings CFD analysis Water as fluid Computational Domain

8 BOUNDARY CONDITIONS Inlet Inlet temperature as 80-degree C Results and counters Temperature Material Aluminum alloy Pressure Outlet Velocity Wall

9 TITANIUM OXIDE (TIO2) General Settings CFD analysis Velocity The boundary conditions are same for all the fluids which are selected. Results and counters Temperature ALUMINUM OXIDE (AL2O3) General Settings CFD analysis Fluid Properties of Al2O3 Pressure The boundary conditions are same for all the fluids which are selected. Results and counters Temperature

10 Pressure FOR TiO2 FOR Al2O3 Velocity RESULTS FOR WATER Fluid Inlet temperature Outlet temperature(c) (C) Water TIO AL2O Table: Results Table. Conclusion: Brief studies about radiators, types, working are done in this project. Studies about Nano fluids, applications are done. Modeling of Radiator is done by using solid works 2016 software. CFD analysis is performed on radiator by using solid works Flow simulation module. CFD analysis is performed on radiator by

11 selecting three different fluid i.e. one regular fluid water and two Nano fluid such as Titanium oxide (TIO2) and Aluminum oxide (Al2O3). Boundary conditions is provided as 80- degree C for inlet temperature of fluid, which will have cooled by radiator pipe and fins by means of convection process on ambient temperature of 25-degree C. Due to convection temperature of fluid flow inside radiator will decrease, values temperature, velocity and pressure of fluid after analysis are noted and tabulated. From result table, we can conclude that Nano fluids give better convection i.e. gives better cooling to engine compare to water. Aluminum oxide (Al2O3) gives best result compare to all fluid used for analysis. References 1.V.L.Bhimani,.P.P.Ratho and A.S.Sorathiya, Experimental study of heat transfer enhancement using water based nanofluids as a new coolant for car radiators.ijetae Vol.3, Issue 6,June Gaurav Sharma and Lal Kundan, Experimental investigation into thermal conductivity and viscocity of Al2O3 based engine coolant.ijrmet Vol. 3, Issue 6,MayOct Adnan M.Hussein, R.A.Bakar, K.Kadirgama,G.L.Ming Heat transfer augmentation for the car radiator by using nanofluid.mre, ISBN: doi. 4. Rahul A.Bhogare and B.S.Kotahwale A review on applications and challenges of nanofluids as coolant in automobile radiator International journal of scientific and research publications, volume 3,Issue 8, August 2013, ISSN Chavan D.K. and Tasgaonkar G.S. Study Analysis and Design of Automobile Radiator Proposed with Cad Drawing and Geometrical Model of the Fan IJMPERD ISSN , Vol 3, Issue 2, June 2013, Deepak Chintakayala and, Rajamanickam C.S. CFD analysis of fluid flow and heat transfer of an automotive radiator with nano fluid /13/$31.00@2013 IEEE. 7. NavidBozorgan, KomalaganKrishnakumar,NarimanBozorgan Numerical study on applications of CuO nanofluid in Automotive Diesel Engine Radiator Modern mechanical engineering 2012, 2, Paresh Machhar and FalgunAdroja Heat transfer enhancement of automobile radiator with TiO2 and water nanofluid International journal of engineering research and technology, ISSN , vol 2 Issue 5 may RavikanthS.Vajjha,DebendraK.Das, Praveen K Namburu Numerical study of fluid dynamic and heat transfer performance of Al2O3 and CuO nanofluids in the flat tubes of a radiator, International Journal of Heat and Fluid Flow 31 (2010) QijunYu, Anthony G. Straatman Brian Thompson Carbon-Foam finned tubes in air-water heat exchangers applied thermal engineering 26 (2006)