Instrumentation for control system 2

Control System 2 Instrumentation for Control System

Title: The Radiator System for Vehicle

Member of Group: MOHD ZHARIF BIN OTHMAN [2006874765] HAIRI ANWAR BIN AMINUDDIN [2006874852] AHMAD AZKA BIN HJ MOHD ZAIN [2006686484]

Group: EEB6R1 Lecturer’s Name: EN. ADIZUL AHMAD

Title: The Radiator System for Vehicle 1.0

Introduction

Inside the car's engine, fuel is constantly burning. A lot of the heat from this combustion goes right out the exhaust system, but some of it soaks into the engine, heating it up. The engine runs best when its coolant is about 200 degrees Fahrenheit (93 degrees Celsius). At this temperature:  



The combustion chamber is hot enough to completely vaporize the fuel, providing better combustion and reducing emissions. The oil used to lubricate the engine has a lower viscosity (it is thinner), so the engine parts move more freely and the engine wastes less power moving its own components around. Metal parts wear less.

Although gasoline engines have improved a lot, they are still not very efficient at turning chemical energy into mechanical power. Most of the energy in the gasoline (perhaps 70%) is converted into heat, and it is the job of the cooling system to take care of that heat. In fact, the cooling system on a car driving down the freeway dissipates enough heat to heat two averagesized houses! The primary job of the cooling system is to keep the engine from overheating by transferring this heat to the air, but the cooling system also has several other important jobs[1]. The car engine runs best at a fairly high temperature. When the engine is cold, components wear out faster, and the engine is less efficient and emits more pollution. So another important job of the cooling system is to allow the engine to heat up as quickly as possible, and then to keep the engine at a constant temperature. The radiator system is one of the main systems in the car.

Figure 1: The whole system of radiator for vehicle

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Schematic Diagram

Figure 2: 2: The schematic of the cooling of the vehicle 3.0

Block Diagram Input Element Initial Temperature Process Element Radiator System

Water Pump

Head Cooling

Output Element Block Cooling

Thermostate Control Element

Figure 3:: The block diagram of the cooling of the vehicle

Constant Temperature

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Principle of Operation

There are four elements involve in this radiator system. There are consists of control elements, process elements, input and output elements. 4.1 Input Element Once the car engine start, the initial temperature will be determined. The cooling system on liquid-cooled cars circulates a fluid through pipes and passageways in the engine. As this liquid passes through the hot engine it absorbs heat, cooling the engine. After the fluid leaves the engine, it passes through a heat exchanger, or radiator, which transfers the heat from the fluid to the air blowing through the exchanger. 4.2 Process Element 4.2.1 Plumbing The cooling system in car has a lot of plumbing. The process to cool down the engine start with the pump sends the fluid into the engine block, where it makes its way through passages in the engine around the cylinders. Then it returns through the cylinder head of the engine. The thermostat is located where the fluid leaves the engine. The plumbing around the thermostat sends the fluid back to the pump directly if the thermostat is closed. If it is open, the fluid goes through the radiator first and then back to the pump. There is also a separate circuit for the heating system. This circuit takes fluid from the cylinder head and passes it through a heater core and then back to the pump.

4.2.2 Fluid Cars operate in a wide variety of temperatures, from well below freezing to well over 100 F (38 C). So whatever fluid is used to cool the engine has to have a very low freezing point, a high boiling point, and it has to have the capacity to hold a lot of heat. Water is one of the most effective fluids for holding heat, but water freezes at too high a temperature to be used in car engines. The fluid that most cars use is a mixture of water and ethylene glycol (C2H6O2), also known as antifreeze. By adding ethylene glycol to water, the boiling and freezing points are improved significantly. Pure Water Freezing Point Boiling Point

0 C / 32 F

50/50 70/30 C2H6O2/Water C2H6O2/Water -37 C / -35 F

-55 C / -67 F

100 C / 212 F 106 C / 223 F

113 C / 235 F

Table 1: The different temperature between pure water and antifreeze water

The temperature of the coolant can sometimes reach 250 to 275 F (121 to 135 C). Even with ethylene glycol added, these temperatures would boil the coolant, so something additional must be done to raise its boiling point. The cooling system uses pressure to further raise the boiling point of the coolant. Just as the boiling temperature of water is higher in a pressure cooker, the boiling temperature of coolant is higher if you pressurize the system. Most cars have a pressure limit of 14 to 15 pounds per square inch (psi), which raises the boiling point another 45 F (25 C) so the coolant can withstand the high temperatures. Antifreeze also contains additives to resist corrosion.

4.2.3 Water Pump A water pump is a simple device that will keep the coolant moving as long as the engine is running. It is usually mounted on the front of the engine and turns whenever the engine is running. The water pump is driven by the engine through one of the following. The water pump moves the water from the engine to the thermostat assembly. If the thermostat is open, the water passes through the radiator and back into the engine. Whether the thermostat is open or closed, the pump also circulates water through the heater core and back into the engine.

Figure 4: The Water Pump

4.3 Control Element 4.3.1 Thermostat

Figure 5: 5 The Thermostat The thermostat's main job is to allow the engine to heat up quickly, and then to keep the engine at a constant temperature. It does this by regulating the amount of water that goes through the radiator. At low temperatures, the outlet to the radiator is compl completely blocked -alll of the coolant is circulated back through the engine. The thermostat in a vehicle regulates the flow of coolant throughout the system. This is important for two reasons. First, it controls the amount of coolant moving through the cooling cooling system to help keep the vehicle’s engine from overheating. And second, it controls the flow in such a way that the operating temperature is kept within a narrow margin. The vehicle’s engine operates at peak efficiency within this narrow band of temperature temperat regulation [3]. Once the temperature of the coolant rises to between 180 and 195 F (82 - 91 C), the thermostat starts to open, allowing fluid to flow through the radiator. By the time the coolant reaches 200 to 218 F (93 - 103 C), the thermostat is open ope all the way. The secret of the thermostat lies in the small cylinder located on the engine engine-side of the device. This cylinder is filled with a wax that begins to melt at around 180 F (different thermostats open at different temperatures, but 180 F is a common common one). A rod connected to the valve presses into this wax. When the wax melts, it expands significantly, pushing the rod out of the cylinder and opening the valve. This same technique is used in automatic openers for greenhouse vents and skylights. In these devices, the wax melts at a lower temperature.

4.3.2 Radiator Fan Mounted on the back of the radiator on the side closest to the engine is one or two electric fans inside a housing that is designed to protect fingers and to direct the air flow. These fans are there to keep the air flow going through the radiator while the vehicle is going slow or is stopped with the engine running. If thes these fans stopped working, every time you came to a stop, the engine temperature would begin rising. On older systems, the fan was connected to the front of the water pump and would spin whenever the engine was running because it was driven by a fan belt ins instead of an electric motor. In these cases, if a driver would notice the engine begin to run hot in stop and go driving, the driver might put the car in neutral and rev the engine to turn the fan faster which helped cool the engine. Racing the engine on a car with a malfunctioning electric fan would only make things worse because you are producing more heat in the radiator with no fan to cool it off. The electric fans are controlled by the vehicle's computer. A temperature sensor monitors engine temperature temperature and sends this information to the computer. The computer determines if the fan should be turned on and actuates the fan relay if additional air flow through the radiator is necessary. If the car has air conditioning, there is an additional radiator mounted in front of the normal radiator. This "radiator" is called the air conditioner condenser, which also needs to be cooled by the air flow entering the engine compartment. You can find out more about the air conditioning condenser by going to our article on Automotive Air Conditioning. As long as the air conditioning is turned on, the system will keep the fan running, even if the engine is not running hot. This is because if there is no air flow through the air conditioning condenser, the air conditioner will not be able to cool the air entering the interior

Figure 5: Radiator fan

4.3.3 Radiator A radiator is a type of heat exchanger. The radiator's main function is to transfer the heat generated in the engine to the surrounding atmosphere. It contains a large quantity of small water passage tubes and interconnecting fins, and as hot water passes through the tubes, some of the heat is radiated into the air passing between the tubes. A secondary purpose of the radiator is to provide storage for the needed volume of water required to cool the engine in question. Most modern cars use aluminum radiators. These radiators are made by brazing thin aluminum fins to flattened aluminum tubes. The coolant flows from the inlet to the outlet through many tubes mounted in a parallel arrangement. The fins conduct the heat from the tubes and transfer it to the air flowing through the radiator. The tubes sometimes have a type of fin inserted into them called a turbulator, which increases the turbulence of the fluid flowing through the tubes. If the fluid flowed very smoothly through the tubes, only the fluid actually touching the tubes would be cooled directly. The amount of heat transferred to the tubes from the fluid running through them depends on the difference in temperature between the tube and the fluid touching it. So if the fluid that is in contact with the tube cools down quickly, less heat will be transferred. By creating turbulence inside the tube, all of the fluid mixes together, keeping the temperature of the fluid touching the tubes up so that more heat can be extracted, and all of the fluid inside the tube is used effectively.

Figure 6: Radiator

4.3.4 Heater Core The hot coolant is also used to provide heat to the interior of the vehicle when needed. This is a simple and straight forward system that includes a heater core, which looks like a small version of a radiator, connected to the cooling system with a pair of rubber hoses. One hose brings hot coolant from the water pump to the heater core and the other hose returns the coolant to the top of the engine. There is usually a heater control valve in one of the hoses to block the flow of coolant into the heater core when maximum air conditioning is called for. A fan, called a blower, draws air through the heater core and directs it through the heater ducts to the interior of the car. Temperature of the heat is regulated by a blend door that mixes cool outside air, or sometimes air conditioned air with the heated air coming through the heater core. This blend door allows you to control the temperature of the air coming into the interior. Other doors allow you to direct the warm air through the ducts on the floor, or, the defroster ducts at the base of the windshield, and the air conditioning ducts located in the instrument panel.

Figure 7: heater core

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Objective of Control

Once the engine operates, the heat will be produced. Then, the temperature will increase due to combustion in the engine block. The chemical energy will be converted into mechanical energy. The thermostat is a component to control the coolant that circulated around the block engine. The heat from the engine block will be spread and transfer to the coolant [2]. The radiator’s function here is to remove the heat in the water to the air. The temperature of the water will be maintained at the constant temperature.

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Conclusion As a conclusion, we know that radiator is the closed system. The operation is clearly explained in this report. The temperature is expected to be constant in order to maintain the operation of the engine. The combustion will produce and spread more heat. If the cooling system is not there, the engine will not functioning properly.

7.0

References [1] http://auto.howstuffworks.com/cooling-system.htm [2] http://www.car-stuff.com/radiator.htm [3] http://www.streetdirectory.net.my/travel_guide/12348. html