Fundamentals and Laws of Thermodynamics - Essay Example

THERMODYNAMICS By Name Course Instructor Institution City/State Date Thermodynamics Task One Closed and open systems In open systems, Balmer (2010, p.33) posits that matter can flow into as well as out of the system boundaries. With the view to the open systems, an raise in the system’s internal energy is the same as the increased energy to the system through the flowing of the matter as well as heating, less the amount of energy that that the matter losses while flowing out as the work performed by the system. Therefore, an open system can be described as a system where there matter and energy are exchanged freely with its surroundings. For example, when a person uses an open saucepan to boil water on a gas stove, the matter and energy are transferred through steam to the surroundings. In this case, the saucepan can be considered as an open system since it facilitates the transfer of both matter and energy. In the closed system, Balmer (2010, p.33) asserts that transferring mass into or out of the system boundaries is impossible. After combustion, heat transfer happens through system boundary, but the transfer of mass does not happen either way. For example, when a lid is placed on the saucepan, the transfer of matter can no longer happen since the matter is prevented by the lid from entering and leaving the saucepan. However, energy can be transferred from the saucepan. Intensive and Extensive Properties An extensive property can be defined as the property which relies on the system’s extent (or size), such as volume. When solid cube’s edges lengths are increased, the volume would definitely increase. Mass is also an extensive property, which increases with the length of the system. According to Balmer (2010), examples of extensive property inlcudeExamples of extensive properties include energy, momentum, electrical charge, and so forth. On the other hand, the intensive property is a property that does not rely on the size of the system. Some of the intensive properties include an object’s hardness, refractive index, temperature, pressure as well as density. Two property rule The two property rule states that the pure substance state of a certain mass could be specified in two independent properties, without effects because of elastic deformation, motion, gravity, electricity, and so forth. According to Swati and Venkanna (2010, p.324), when a substance mode of energy storage is just one; its state can adequately be defined by two independent properties (for particular mass). Considering a gas having a mass m, for instance, enclosed in the cylinder, the initial state is given as initial volume as well as pressure, V1 and p1 in that order. Likewise, the final state is given as final volume and pressure, V2 and p2 correspondingly. This specification of gas states connotes that every other property of state 2 or state could be established from the given volume and pressure data (Swati & Venkanna, 2010, p.324). Isochoric process The isochoric process, according to Venkanna and Swati (2011, p.332) occurs when the volume is constant; that is to say, the work done by the system is zero. For the simple two-dimensional system, any heat energy transferred externally into the system is taken in as internal energy. The process can be explained by heating a closed tin that has only air. Evidently, the tin will start expanding since the internal energy gained by the gas is the change that will take place, as demonstrated by the increase in pressure as well as temperature. In this case, the system is considered to be dynamically insulated by the environment’s rigid boundary. Isobaric process An isobaric process according to Venkanna and Swati (2011, p.332) happens when pressure is held constant. This can be demonstrated by a cylinder’s movable piston, with the intention that the pressure in the cylinder remains at the atmospheric pressure even if it has been secluded from the atmosphere. That is to say; the system is connected dynamically to a constant-pressure reservoir through a movable boundary. The work done through this process is: Isothermal process The isothermal process as mentioned by Venkanna and Swati 2011, p.333) happens when the temperature is held constant. This can be evidenced by a system immersed in a big bath where the temperature is constant. In this case, the work done by the system is transferred to the bath, but the temperature would remain constant. Idea gas can be achieved through;  .    Adiabatic process Venkanna and Swati (2011, p.334), describes the adiabatic process as the one whereby there is no subtraction or addition of energy from the system through cooling or heating. The system is considered to be thermally insulated from the surrounding environment while its boundary acts as the thermal insulator. Task 3 Carnot Cycle According to Venkanna and Swati (2011, p.93), a Carnot cycle as demonstrated in figure one has four processes: two isothermal reversible legs as well as two adiabatic reversible legs. This system can be considered as a chamber that is filled with ideal gas and enclosed by a piston. Figure One: The Carnot Cycle As mentioned earlier, the Carnot cycle involves four processes: in the first stage, the system is at state a, at temperature T2 and it comes into contact with the heat reservoir, which according to Venkanna and Swati (2011, p.93) is a solid or liquid mass. The mass is adequately large to ensure that there is no significant change of temperature when heat is transferred into the system. In the second stage, the system at state b is insulated thermally and later allowed to expand to state c. At the time of expansion, the temperature reduces to T1. In the third process, the system comes into contact with the heat reservoir at c, at temperature T1. Later, it is compressed towards state d and in the process heat, Q1 is rejected. In the last stage, the system is adiabatically compressed back into state a. Therefore the thermal efficiency of Carnot Cycle is given by: Otto Cycle Venkanna and Swati (2011, p.102) describe Otto cycle as processes set mainly utilised by spark-ignition engines. In this case, the spark-ignition engine ingests the air and fuel mixture, then it compresses to facilitate reaction; hence, adding heat effectively by means of chemical energy conversion into thermal energy. The combustion products are expanded expand the combustion products, and then e) eject the combustion products and before being ejected to be replaced with a new charge of air and fuel. As demonstrated by figure two, the Otto cycle involves five processes: (i) intake stroke (the engine ingest air and gasoline vapour); (ii) Compression stroke (pressure and temperature are increased); (iii) Combustion (sparking occurs and volume is held constant); (iv) power stroke (expansion happens); and (v) exhaust stroke (the gas escapes after the valve opens). This is demonstrated in figure two. Figure Two: the Otto Cycle The thermal efficiency of Otto Cycle is given by: Diesel cycle The Diesel cycle has been described by Venkanna and Swati (2011, p.111) as a compression ignition engine, whereby at high pressure, the fuel is sprayed into the cylinder after the compression completion, and ignition happens without a spark. The cycle is demonstrated by figure three, and it can operate efficiently with a higher compression ratio as compared to the Otto cycle since there is no fuel auto-ignition risk because air is compressed only. Even though Otto cycle efficiency is higher than that of Diesel cycle, operating the Diesel engine to higher compression ratio is possible; therefore, the Diesel engine is inclined to have high efficiency than Otto cycle when operating both at compression ratios that can be realised practically. Figure 3: The Diesel cycle Basically, the Diesel cycle thermal efficiency is given by:           Dual cycle Dual Cycle as mentioned by Venkanna and Swati (2011, p.123) is a combination of Diesel cycle as well as Otto cycle. Heat in this cycle is partly absorbed at V= Constant and partly at a P=Constant. The dual cycle, as demonstrated by figure four has two reversible isentropic or adiabatic, a constant pressure and two constant volume processes. Figure Four: Dual Cycle the Dual cycle efficiency of this cycle is given by, Joules or Brayton cycle The Brayton cycle depicts the gas turbine engine operation, and the cycle involves four processes, as demonstrated by figure five. Stage one involves quasi-static, adiabatic compression in the compressor as well as the inlet. Stage two and three involves fuel combustion at constant pressure and quasi-static, adiabatic expansion in the exhaust nozzle and turbine, respectively. The last process involves cooling air at constant pressure back into the initial condition. Figure 5: the Brayton cycle The Brayton cycle thermal efficiency is given by: Task 4 The second law of thermodynamics as cited by Moran et al. (2010, p.249) states that processes happen in a particular direction and energy have both quantity and quality. Basically, the Second Law of Thermodynamics is associated with the energy’s quality stating that while transforming or transferring energy, more of it become wasted. According to this law, any isolated system is naturally inclined to degenerate into a state that is more disordered. This law is commonly utilised to determine the theoretical performance limits of engineering systems like refrigerators and heat engines. It is also utilised to predict the chemical reactions’ completion level. According to Moran et al. (2010), this law is closely related to the perfection concept. Actually, the law defines the thermodynamic processes’ perfection and can be utilised for quantifying the perfection level of the thermodynamic processes and indicate the direction for effectively getting rid of imperfections. According to the second law, because of the entropy increase, it is impossible to convert heat into work devoid of generating waste heat. In view of this, the Carnot Efficiency can be described as theoretical maximum efficiency that could be achieved by the heat engine between cold as well as hot reservoirs with temperatures TL and TH. The Carnot Efficiency is given by: On the other hand, the Second Law Efficiency can be described as the measure of the amount of Carnot (theoretical maximum) that can be achieved. In this case, the system’s thermal efficiency is compared to the maximum possible efficiency. Therefore, the Second Law efficiency is normally between the First Law and Carnot efficiencies. According to Serway and Jewett (2013, p.654), a fundamental limit is placed by the second law of thermodynamics on all heat engines’ thermal efficiency. Whereas the first law of thermodynamics spells out that it is impossible to gain more energy from a cyclic process through work than the energy used, the second law states that it is impossible to break even since a lot of energy must be placed in, at increased temperature, as compared to the net amount of energy achieved through work. Task 5 Supercharging As mentioned by Sen et al. (2015, p.2), the engine’s power output rely on the indicated amount of air per unit time, the air’s utilisation level as well as the engine’s thermal efficiency. For engine speed to increase, the need for robust and rigid engine arises because of the increasing inertia loads. Therefore, supercharging is the process of increasing the density of inlet air, and it is normally utilised to improve the engine’s power output. Basically, this is achieved by supplying air at a higher pressure as compared to the pressure that the engine aspirates atmospheric air naturally through a supercharger. A supercharger is a device that boosts pressure. The engine’s power output could be improved by increasing the engine’s thermal efficiency. The objectives of supercharging are to increase the engine’s power output as well as to compensate for the power loss because of altitude. The Schematic diagram of the supercharging system is exhibited in figure six. Figure Six: Supercharging System adopted from Krajniuk (2010, p.320) study Turbocharging A turbocharger can be described as special supercharger whereby the gas turbine is utilised with the objective of increasing the pressure of air-fuel mixture or air supplied to the engine. Normally, the kinetic energy of the engine’s exhaust gases is used to power turbochargers. In a turbocharger, the compressor and a gas turbine are coupled together and keyed into a similar shaft. Therefore, every the turbine is rotating, the compressor is subsequently operated. Turbocharging allows for the increase of the engine’s power and reduces specific consumption of fuel oil, since scavenge, thermal and mechanical efficiencies are improved because of utilisation of exhaust gases, increased air supply as well as fewer cylinders. Furthermore, there is a reduction of thermal loading. Figure seven shows a schematic diagram of Turbocharging system. Figure Seven: Turbocharging system Intercooling According to Mifdal et al. (2015, p.49), an intercooler can be described as a mechanical device utilised for cooling fluid, which includes gases or liquids, in-between the multi-stage heating process. The intercooler is normally installed somewhere in air path between the motor and the turbo/supercharger. Importantly, the intercooler is important because it increases the induction system efficiency through reduction of induction air heat that the turbocharger or supercharger generates. Figure eight shows a schematic diagram of Intercooling system. Figure Eight: Intercooling System Cooling Systems Cooling systems are normally integrated into IC engine so as to dissipate heat in the cylinder body in order to protect the cylinder material from the failure of the cylinder material. Basically, large temperature differences attributed to overheating could result in engine components’ distortion because of the set up thermal stresses. A cooling system removes approximately 30 percent of the heat generated during the process of combustion. It removes the heat swiftly when the engine is hot. The cooling system can be divided into the water-cooling system as well as Air cooling system. Figure nine shows a schematic diagram of a cooling system. Figure Nine: Radiator Cooling System Exhaust Gas Heat Recovery Systems According to Jadhao and Thombare (2014), the exhaust gas heat recovery system consists of an exhaust gas economiser that has sections for transferring heat, which includes a section for preheating, evaporating, as well as a superheating. The system also includes a feed water heater, a steam separation drum, and a mixed pressure turbine. The system turns the exhaust pipe’s thermal losses into energy. Figure ten shows a schematic diagram of the exhaust gas heat recovery system. Figure Ten: Exhaust Gas Heat Recovery System References Balmer, R.T., 2010. Modern Engineering Thermodynamics. Cambridge, Massachusetts: Academic Press. Jadhao, J.S. & Thombare, D.G., 2014. Review on Exhaust Gas Heat Recovery for I.C. Engine. International Journal of Engineering and Innovative Technology, vol. 2, no. 2, pp.93-100. Krajniuk, A., 2010. Development of supercharging systems of internal combustion engines with the cascade pressure exchanger. ТЕКА Кom. Mot. i Energ. Roln, vol. 10, pp.303-10. Mifdal, M.Y.A., M.H.Nuraida, Norzalina, O. & Shamil4, A.H., 2015. Turbo Intercooler Cooling System. International Journal of Engineering Science Invention, vol. 4, no. 1, pp.49-56. Moran, M.J., Shapiro, H.N., Boettner, D.D. & Bailey, M.B., 2010. Fundamentals of Engineering Thermodynamics. New York: John Wiley & Sons. Sen, P.K., Jaiswal, R. & Bohidar, S.K., 2015. PERFORMANCE ANALYSIS OF SUPERCHARGING. International Journal of Advance Research In Science And Engineering, vol. 4, no. 1, pp.1-9. Serway, R.A. & Jewett, J.W., 2013. Physics for Scientists and Engineers with Modern Physics. New York: Cengage Learning. Swati, B.V. & Venkanna, 2010. Cambridge, Massachusetts, United States. New Delhi: PHI Learning Pvt. Ltd. Venkanna, B.K. & Swati, B.V., 2011. Applied Thermodynamics. New Delhi: PHI Learning Pvt. Ltd. Read More