engel Boles Thermodynamics Thermodynamics An Engineering Approach Third Edition Yunus A. engel Michael A. Boles Third Edition WCB/McGraw-Hill WCB/McGraw-Hill The The McGraw-Hill McGraw-Hill Companies, Companies, Inc.,1998 Inc.,1998
1 CHAPTER engel Boles Thermodynamics Basic Concepts of Thermodynamics Third Edition WCB/McGraw-Hill The McGraw-Hill Companies, Inc.,1998 What is thermodynamics? The study of thermodynamics is concerned with ways energy is stored within a body and how energy transformations, which involve heat and work, may take place.
Approaches to studying thermodynamics Macroscopic (Classical thermodynamics) engel Boles Thermodynamics study large number of particles (molecules) that make up the substance in question does not require knowledge of the behavior of individual molecules Microscopic (Statistical thermodynamics) concerned within behavior of individual particles (molecules) study average behavior of large groups of individual particles Third Edition WCB/McGraw-Hill The McGraw-Hill Companies, Inc.,1998
1-1 Applications of Thermodynamics engel Boles Thermodynamics The human body Air-conditioning systems Car radiators Airplanes Power plants Refrigeration systems Third Edition
WCB/McGraw-Hill The McGraw-Hill Companies, Inc.,1998 Thermodynamic Systems Thermodynamic System quantity of matter or a region of space chosen for study Boundary real or imaginary layer that separates the system from its surroundings Surroundings physical space outside the system boundary Types of Systems Closed Open engel Boles Thermodynamics Third Edition
WCB/McGraw-Hill The McGraw-Hill Companies, Inc.,1998 1-2 Closed Systems (fixed masses) Energy, not mass, crosses closed-system boundaries (Fig. 1-13) engel Boles Thermodynamics Third Edition WCB/McGraw-Hill The McGraw-Hill Companies, Inc.,1998 1-3 Closed System with Moving Boundry
engel Boles Thermodynamics Third Edition WCB/McGraw-Hill The McGraw-Hill Companies, Inc.,1998 1-4 Open Systems (Control Volumes) Mass and Energy Cross Control Volume Boundaries engel Boles Thermodynamics Third Edition WCB/McGraw-Hill The McGraw-Hill Companies, Inc.,1998
Isolated System engel Boles Closed system where no heat or work (energy) may cross the system boundary typically a collection of the a main system (or several systems) and its surroundings is considered an isolated system Thermodynamics Isolated system boundary work system heat Surr 1 Surr 2 mass
Surr 3 Third Edition WCB/McGraw-Hill The McGraw-Hill Companies, Inc.,1998 Total Energy of a System engel Boles Thermodynamics Sum of all forms of energy (i.e., thermal, mechanical, kinetic, potential, electrical, magnetic, chemical, and nuclear) that can exist in a system For systems we typically deal with in this course, sum of internal, kinetic, and potential energies E = U + KE + PE E = Total energy of system U = internal energy
KE = kinetic energy = mV2/2 PE = potential energy = mgz Third Edition WCB/McGraw-Hill The McGraw-Hill Companies, Inc.,1998 1-5 Systems Internal Energy Systems Internal Energy = Sum of Microscopic Energies (Fig. 1-19) engel Boles Thermodynamics Third Edition WCB/McGraw-Hill The McGraw-Hill Companies, Inc.,1998
Properties engel Boles Thermodynamics Any characteristic of a system in equilibrium is called a property. Types of properties Extensive properties - vary directly with the size of the system Examples: volume, mass, total energy Intensive properties - are independent of the size of the system Examples: temperature, pressure, color Extensive properties per unit mass are intensive properties. specific volume v = Volume/Mass = V/m density = Mass/Volume = m/V Third Edition WCB/McGraw-Hill
The McGraw-Hill Companies, Inc.,1998 State & Equilibrium engel Boles Thermodynamics State of a system system that is not undergoing any change all properties of system are known & are not changing if one property changes then the state of the system changes Thermodynamic equilibrium equilibrium - state of balance A system is in equilibrium if it maintains thermal (uniform temperature), mechanical (uniform pressure), phase (mass of two phases), and chemical equilibrium Third Edition
WCB/McGraw-Hill The McGraw-Hill Companies, Inc.,1998 Processes & Paths engel Boles Thermodynamics Process when a system changes from one equilibrium state to another one some special processes: isobaric process - constant pressure process isothermal process - constant temperature process isochoric process - constant volume process isentropic process
- constant entropy (Chap. 6) process Path series of states which a system passes through during a process Third Edition WCB/McGraw-Hill The McGraw-Hill Companies, Inc.,1998 1-7 Compression Process engel Boles Thermodynamics Third Edition WCB/McGraw-Hill The McGraw-Hill Companies, Inc.,1998
1-6 engel Boles Quasi-Equilibrium Processes System remains practically in equilibrium at all times Thermodynamics Easier to analyze (equations of state can apply) Work-producing devices deliver the most work Work-consuming devices consume the least amount of work Third Edition WCB/McGraw-Hill The McGraw-Hill Companies, Inc.,1998
State Postulate & Cycles engel Boles Thermodynamics State Postulate The thermodynamic state of a simple compressible substance is completely specified by two independent intensive properties. Cycles A process (or a series of connected processes) with identical end states P 2 Process B
Process 1 A V Third Edition WCB/McGraw-Hill The McGraw-Hill Companies, Inc.,1998
