International Journal of Engineering and Advanced Technology (IJEAT) ISSN: 2249 – 8958, Volume-2, Issue-4, April 2013 Cooling Systems in Automobiles & Cars Gogineni. Prudhvi, Gada.Vinay, G.Suresh Babu Abstract: Most internal combustion engines are fluid cooled What the cooling system does for an engine. using either air (a gaseous fluid) or a liquid coolant run through a heat exchanger (radiator) cooled by air. 1. Although gasoline engines have improved a lot, they In air cooling system, heat is carried away by the air flowing are still not very efficient at turning chemical energy over and around the cylinder. Here fins are cast on the cylinder into mechanical power. head and cylinder barrel which provide additional conductive 2. Most of the energy in the gasoline (perhaps 70%) is and radiating surface. In water-cooling system of cooling engines, the cylinder walls and heads are provided with jacket converted into heat, and it is the job of the cooling through which the cooling liquid can circulate. system to take care of that heat. In fact, the cooling An internal combustion engine produces power byburning fuel system on a car driving down the freeway dissipates within the cylinders; therefore, it is oftenreferred to as a "heat enough heat to heat two average-sized houses! engine." However, only about25% of the heat is converted to 3. The primary job of the cooling system is to keep the useful power. Whathappens to the remaining 75 percent? Thirty engine from overheating by transferring this heat to the to thirtyfive percent of the heat produced in the air, but the cooling system also has several other combustionchambers by the burning fuel are dissipated by important jobs. thecooling system along with the lubrication and 4. The engine in your car runs best at a fairly high fuelsystems. Forty to forty- five percent of the heatproduced passes out with the exhaust gases. If this heatwere not removed temperature. quickly, overheating and extensive 5. When the engine is cold, components wear out faster, damage would result. Valves would burn and warp,lubricating and the engine is less efficient and emits more oil would break down, pistons and bearingwould overheat and pollution. seize, and the engine would soonstop.The necessity for cooling 6. So another important job of the cooling system is to may be emphasized byconsidering the total heat developed by an allow the engine to heat up as quickly as possible, and ordinary six-cylinder engine. then to keep the engine at a constant temperature. I. INTRODUCTION What is a Cooling System? We know that in case of Internal Combustion engines, A typical 4 cylinder vehicle cruising along the highway at combustion of air and fuel takes place inside the engine around 50 miles per hour, will produce 4000 controlled cylinder and hot gases are generated. The temperature of explosions per minute inside the engine as the spark plugs gases will be around 2300-2500°C. This is a very high ignite the fuel in each cylinder to propel the vehicle down temperature and may result into burning of oil film between the road. Obviously, these explosions produce an enormous the moving parts and may result into seizing or welding of amount of heat and, if not controlled, will destroy an engine the same. in a matter of minutes. Controlling these high temperatures So, this temperature must be reduced to about 150-200°C at is the job of the cooling system. which the engine will work most efficiently. Too much The modern cooling system has not changed much from the cooling is also not desirable since it reduces the thermal cooling systems in the model T back in the '20s. Oh sure, it efficiency. So, the object of cooling system is to keep the has become infinitely more reliable and efficient at doing it's engine running at its most efficient operating temperature. job, but the basic cooling system still consists of liquid It is to be noted that the engine is quite inefficient when it is coolant being circulated through the engine, then out to the cold and hence the cooling system is designed in such a way radiator to be cooled by the air stream coming through the that it prevents cooling when the engine is warming up and front grill of the vehicle. till it attains to maximum efficient operating temperature, Today's cooling system must maintain the engine at a then it starts cooling. constant temperature whether the outside air temperature is It is also to be noted that : 110 degrees Fahrenheit or 10 below zero. If the engine (a) About 20-25% of total heat generated is used for temperature is too low, fuel economy will suffer and producing brake power (useful work). emissions will rise. If the temperature is allowed to get too (b) Cooling system is designed to remove 30-35% of total hot for too long, the engine will self destruct. heat. (c) Remaining heat is lost in friction and carried away by How Does a Cooling System Work? exhaust gases. 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. Manuscript received April, 2013. The cooling system is made up of the passages inside the Gogineni. Prudhvi, KL University, Guntur (A.P.), India Gada.Vinay, KL University, Guntur (A.P.), India engine block and heads, a water pump to circulate the G.Suresh Babu, KL University, Guntur (A.P.), India coolant, a thermostat to control the temperature of the 688 Cooling Systems in Automobiles & Cars coolant, a radiator to cool the coolant, a radiator cap to Antifreeze control the pressure in the system, and some plumbing The coolant that courses through the engine and associated consisting of interconnecting hoses to transfer the coolant plumbing must be able to withstand temperatures well from the engine to radiator and below zero without freezing. It must also be able to handle also to the car's heater system where hot coolant is used to engine temperatures in excess of 250 degrees without warm up the vehicle's interior on a cold day. boiling. A tall order for any fluid, but that is not all. The A cooling system works by sending a liquid coolant through fluid must also contain rust inhibiters and a lubricant. passages in the engine block and heads. As the coolant The coolant in today's vehicles is a mixture of ethylene flows through these passages, it picks up heat from the glycol (antifreeze) and water. The recommended ratio is engine. The heated fluid then makes its way through a fifty-fifty. In other words, one part antifreeze and one part rubber hose to the radiator in the front of the car. As it water. This is the minimum recommended for use in flows through the thin tubes in the radiator, the hot liquid is automobile engines. Less antifreeze and the boiling point cooled by the air stream entering the engine compartment would be too low. In certain climates where the from the grill in front of the car. Once the fluid is cooled, it temperatures can go well below zero, it is permissible to returns to the engine to absorb more heat. The water pump have as much as 75% antifreeze and 25% water, but no has the job of keeping the fluid moving through this system more than that. Pure antifreeze will not work properly and of plumbing and hidden passages. can cause a boil over. II. TYPES OF COOLING SYSTEMS There are mainly two types of cooling systems : (a) Air cooled system, and (b) Water cooled system. Introduction to air cooling: Turbo cooling have been adopted for IC-engines at least since 1975 by I Kalmar and J Antal for Nox reduction in CI- engines. Engineers from SWRI contributed in the same subject between 1990-1991 with adress to M Shahed and RH Thring in the ”Clean Diesel Project” Volvo Truck also performed a MSc thesis work carried out by Jan Wiman in 1991. A thermostat is placed between the engine and the radiator to make sure that the coolant stays above a certain preset III. AIR COOLING SYSTEM temperature. If the coolant temperature falls below this Air cooled system is generally used in small engines say up temperature, the thermostat blocks the coolant flow to the to 15-20 kW and in aero plane engines. In this system fins or radiator, forcing the fluid instead through a bypass directly extended surfaces are provided on the cylinder walls, back to the engine. The coolant will continue to circulate cylinder head, etc. Heat generated due to combustion in the like this until it reaches the design temperature, at which engine cylinder will be conducted to the fins and when the point, the thermostat will open a valve and allow the coolant air flows over the fins, heat will be dissipated to air. back through the radiator. The amount of heat dissipated to air depends upon : Circulation (a) Amount of air flowing through the fins.b) Fin surface The coolant follows a path that takes it from the water area. pump, through passages inside the engine block where it (c) Thermal conductivity of metal used for fins. collects the heat produced by the cylinders. It then flows up to the cylinder head (or heads in a V type engine) where it Advantages of Air Cooled System collects more heat from the combustion chambers.