SUMMARY OF BASICCONCEPTS OF THE RMODYNAMICS

SUMMARY

In this chapter, the basic concepts of thermodynamics are introduced and discussed.

A system of fixed mass is called a closed system, or control mass, and a system that involves mass transfer across its boundaries is called an open system, or control volume. The mass-dependent properties of a system are called extensive properties and the others intensive properties. Density is mass per unit volume, and specific volume is volume per unit mass. The sum of all forms of energy of a system is called total energy, which is considered to consist of internal, kinetic, and potential energies. Internal energy represents the molecular energy of a system and may exist in sensible, latent, chemical, and nuclear forms.

A system is said to be in thermodynamic equilibrium if it maintains thermal, mechanical, phase, and chemical equilibrium. Any change from one state to another is called a process. A process with identical end states is called a cycle. During a quasi-static or quasi-equilibrium process, the system remains practically in equilibrium at all times. The state of a simple, compressible system is completely specified by two independent, intensive properties.

The zeroth law of thermodynamics states that two bodies are in thermal equilibrium if both have the same temperature read- ing even if they are not in contact.

The temperature scales used in the SI and the English system today are the Celsius scale and the Fahrenheit scale, respectively. They are related to absolute temperature scales by

BASICCONCEPTS OF  THE RMODYNAMICS-0092

The magnitudes of each division of 1 K and 1°C are identical, and so are the magnitudes of each division of 1 R and 1°F. Therefore,

BASICCONCEPTS OF  THE RMODYNAMICS-0093

Force exerted by a fluid per unit area is called pressure, and its unit is the pascal, 1 Pa = 1 N/m2. The pressure relative to absolute vacuum is called the absolute pressure, and the differ- ence between the absolute pressure and the local atmospheric pressure is called the gage pressure. Pressures below atmo- spheric pressure are called vacuum pressures. The absolute, gage, and vacuum pressures are related by

BASICCONCEPTS OF  THE RMODYNAMICS-0094

Small to moderate pressure differences are measured by a manometer. The pressure in a fluid remains constant in the horizontal direction. Pascal’s principle states that the pressure applied to a confined fluid increases the pressure throughout by the same amount. The atmospheric pressure is measured by a barometer and is given by

BASICCONCEPTS OF  THE RMODYNAMICS-0095

Related posts:

Pumps:Pumps in series switched to meet demand
Engineering Data:Graphical symbols for pneumatic systems and components
Compressed Air Transmission and Treatment:Pressure gauges and indicators.
Compressed Air Transmission and Treatment:Solid contaminants
THE COMPRESSOR:AIR RECEIVERS
Multiple use systems:Multiple material handling and Air supply control.
Design procedures:Logic diagram for system design
Control components in a hydraulic system:Open and closed center hydraulic circuits.
Control components in a hydraulic system:Flow control valves.
Hydraulic fluids.
Sequencing Applications:Pneumatic limit switches
INTRODUCTION AND OVERVIE:THERMODYNAMICS
ENTROPY:ISENTROPIC EFFICIENCIES OF STEADY-FLOW DEVICES
INTRODUCTION TO FLUID MECHANICS:THE NO-SLIP CONDITION
HEAT EXCHANGERS:THE EFFECTIVENESS–NTU METHOD

Leave a comment

Your email address will not be published. Required fields are marked *