Basic Concepts of Thermodynamics: Types of Systems, Properties, and Equilibrium, Assignments of Thermodynamics

Download Basic Concepts of Thermodynamics: Types of Systems, Properties, and Equilibrium and more Assignments Thermodynamics in PDF only on Docsity! Faculty of Engineering Thermodynamics 1 Course code: MPE 101 Sheet 1: Basic Concepts of Thermodynamics 1. What are the types of thermodynamic system? A system is defined as a quantity of matter or a region in space chosen for study. The mass or region outside the system is called the surroundings. The real or imaginary surface that separates the system from its surroundings is called the boundary. The boundary of a system can be fixed or movable. There are three types of systems in thermodynamics: open, closed, and isolated. An open system can exchange both energy and matter with its surroundings. A closed system, on the other hand, can exchange only energy with its surroundings, not matter. An isolated system is one that cannot exchange either matter or energy with its surroundings. 2. What is the difference between intensive and extensive properties? Intensive properties do not depend on the size/mass (extent) of the system, but extensive properties do. 3. A can of soft drink at room temperature is put into the refrigerator so that it will cool. Would you model the can of soft drink as a closed system or as an open system? Explain. A can of soft drink should be analyzed as a closed system since no mass is crossing the boundaries of the system. 4. A large fraction of the thermal energy generated in the engine of a car is rejected to the air by the radiator through the circulating water. Should the radiator be analyzed as a closed system or as an open system? Explain. Faculty of Engineering Thermodynamics 1 Course code: MPE 101 Sheet 1: Basic Concepts of Thermodynamics The radiator should be analyzed as an open system since mass is crossing the boundaries of the system. 5. Define state, process and cycle. State: The condition of the system described by specifying values of some state variables and state parameters. Process: The change of system from one state to other state. Cycle: The thermodynamic cycle consists of two or more than two processes such that the state of the system returns to its original state after the series of processes. 6. Define the zeroth law of thermodynamics. The zeroth law of thermodynamics states that if two bodies are each in thermal equilibrium with some third body, then they are also in equilibrium with each other. 7. Determine the types of thermodynamic equilibrium, realize each one. When the state variables do not change with time and space is called thermodynamic equilibrium. It is of three types: 1. Thermal equilibrium if the temperature is the same throughout the entire system, 2. Mechanical equilibrium if there is no change in pressure at any point of the system with time, 3. phase equilibrium when the mass of each phase reaches an equilibrium level and stays there. and 4. Chemical equilibrium if its chemical composition does not change with time. 8. A 3-kg plastic tank that has a volume of 0.2 m3 is filled with liquid water. Assuming the density of water is 1000 kg/m3, determine the weight of the combined system. Faculty of Engineering Thermodynamics 1 Course code: MPE 101 Sheet 1: Basic Concepts of Thermodynamics 13. The absolute pressure in water at a depth of 9 m is read to be 185 kPa. Determine (a) the local atmospheric pressure and (b) the absolute pressure at a depth of 5 m in a liquid whose specific gravity is 0.85 at the same location. 14. The lower half of a 6-m-high cylindrical container is filled with water (ρ= 1000 kg/m3) and the upper half with oil that has a specific gravity of 0.85. Determine the pressure difference between the top and bottom of the cylinder. Faculty of Engineering Thermodynamics 1 Course code: MPE 101 Sheet 1: Basic Concepts of Thermodynamics 15. Both a gage and a manometer are attached to a gas tank to measure its pressure. If the reading on the pressure gage is 80 kPa, determine the distance between the two fluid levels of the manometer if the fluid is (a) mercury (ρ = 13,600 kg/m3) or (b) water (ρ =1000 kg/m3). Faculty of Engineering Thermodynamics 1 Course code: MPE 101 Sheet 1: Basic Concepts of Thermodynamics 16. A gas is contained in a vertical, frictionless piston cylinder device. The piston has a mass of 3.2 kg and a cross-sectional area of 35 cm2. A compressed spring above the piston exerts a force of 150 N on the piston. If the atmospheric pressure is 95 kPa, determine the pressure inside the cylinder.