Thermodynamic Systems - Assignment Example

Summary This papers involved a nomber of tasks dealing with thermodynamic systems. In the first taks involved defining thermodnamic systems and properties. This task also involved deriving expressions for various quantities which were then used in solving numeric quations of some systems. Task two involved finding solutions to numeric equations after using thermodynamic laws to prove the relationship  and  . In task three heat engine cycles were described and and numerical solutions were solved. Task four addressed efficiency while in task five the issue of improving engine performance was addressed. Task 6 involved engine power solutions while task 7 which was the last task gave looked at gantt chart and logbook. Task 1 C. At CSC Engineering, in an experiment, a quantity of air occupies 0.4 m3 at a pressure of 1 bar and a temperature of 16º C; undergoes a reversible polytropic process according to the law = constant until the volume is 0.1 m3. Using the above data and derieve expressions evaluate the following parameters of the polytropic process: I. the mass of the gas involved. II. the change in the internal energy. III. the value of Cv for the gas. IV. the new temperature. V. the workdone VI. The heat transfer during the process Assume that for air R = 0.287 kJ/kgK and Cp = 1.005 kJ/kgK D. If the above polytropic index is changed to 1.0 and 1.3,show what will be effects on all the above parameters. Also, compare and criticallyanalyse your results that are obtained for task 1C and 1D in your discussion. This provides evidence for M1& D1 Task1) D i) Gas characteristic law ii)  iii)    iv)    v)  vi)  kJ For index =1.3 i)  ii)    iv)    v)  vi)  kJ+51.35Kj = -17.07kJ Table 1: Results Summary Parameter n=0.2 n=1 n=1.3 m (kg) 0.48 0.48 0.48 cv 718 718 718 T2 (K) 381.34 289 438 u2-u1 ( kJ) 31.82 0 51.35 w ( kJ) -63.60 -114.98 -68.42 Q (kJ) -31.82 -114.98 -17.07 From the table it can be seen that in all the three cases there was negative heat exchange in the system, meaning that heat was ejected from the system. It can also be seen that all work was negative meaning that the work was directed into the system. At n=1 we have w=Q which is an indication that all the work done to the system was ejected out as heat. This in result resulted to the system gaining no internal energy. The system (n=1) was isothermal in that there was no change in temperature. Task 5 A. For the internal combustion engines investigate the following methods to improve engine performance. I. Supercharging II. Turbocharging III. Intercooling IV. Cooling system and V. Exhaust gas heat recovery systems This provides evidence for P 2.4 B. In no more than 10 slides, present the advantages and disadvantages of each methods used to improve the efficiency of internal combustion engines. This provides evidence for M3 Done in slides Task 6 Your company has decided to install a reconditioned piston engine into the pumping system as a backup to the existing engine. Regulations state that a bench test must be carried out on this engine prior to commissioning. The engine is a 4 cylinder, 4 stroke engine which gave the following results on a test bed: Shaft Speed N = 2550 rev/min Torque arm R = 0.4 m Net Brake Load F = 200 N Fuel consumption mf = 2.5 g/s Calorific value C.V.= 42 MJ/kg Area of indicator diagram Ad = 301 Pressure scale Sp = 81 kPa/mm Stroke L = 100 mm Bore D = 100 mm Base length of diagram Y = 59.9 mm. D. Determine the BrakeThermal, Indicated Thermal, and Mechanical efficiencies of the engine. This provides evidence for P2.3 D) Task 7 For the above tasks, a Gantt chart and logbook must be created, maintained and produced. You must think and plan carefully about the activities required in solving this assignment from initial research right through to final submission on time. This provides evidence for D2 Gantt chart Activity WEEK1 Week2 Week3 Task 1 Task 2 Task 3 Task 4 Task5 Task 6 Discussion This papers involved a number of tasks dealing with thermodynamic systems. In the first takes involved defining thermodnamic systems and properties. Through definition there is good foundation of understanding the entire subject of thermodynamics. By understanding the system , whether open, closed etc one is able to understand how to find solution to problem relating to the system. Task 1 also involved deriving expressions for various quantities which were then used in solving numeric quations of some systems. Through derivation of expression one is able to understand why some formulars are used in obtaining some solutions. Through derivation it is also easy for one to remember the expression because of the expressions being arrived at in a logical manner. It is through the derivation that it is realized that knowledge of mathematics is important in solving thermodynamics system questions. Task two involved finding solutions to numeric equations after using thermodynamic laws to prove the relationship  and  .This task helped in understanding the concept of internal energy, enthulpy and thermodynamic temperature scale whick is the Kelvin scale. In the process of deriving this equations one notices the interconnection of quantities. Apart from just mathematical manipulation one need understand the physical meaning of what is being dealt with. In task three heat engine cycles were described and and numerical solutions were solved. When dealing with the heat cycles one starts appreciating the whole concept of thermodynamic systems as solutions of real problem are being addressed. Learning about the cycle it was realized that in order to be able to solve any questions with regards to the cycles it is important that one be able to reprecent the cycle on a PV diagram and to be able to interpret what is happening phyically in the engine as you move along the PV diagram. The carnot cycle was found to be ideal cycle that is most efficient but may not be practical to attain (not unless in a laboratory set up). Task four addressed efficiency using the fact that the carnot cycle is the most efficient , then one is able to confirm if the claim of an engine manufacturer is true or falls. Where a manufacturer is giving figures that result to efficiency that is above that of carnot cycle for the same temperature levels, then the claim will be falls. It is not also possible to have an engine that attains the carnot cycle efficiency having seen that the cycle is an ideal cycle. A with regard to improving the performance of the engine a number of devices were discussed. The devices were seen to address performance by either manipulation of the extensive properties of the system by increasing the mass of material entering the combustion chamber for the case of supercharger and turbocharger. The other devices manipulated the intensive property by reducing the temperature of the material entering the combustion chamber as seen in the case of the intercooler. Task 6 involved engine power solutions while task 7 which was the last task gave looked at gantt chart and logbook. Read More