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**Introduction To Thermodynamics**

ERT 206/4 Thermodynamics CHAPTER 1 Introduction To Thermodynamics Miss. Rahimah Bt. Othman

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**COURSE OUTCOME 1 CO1) Chapter 1: Introduction to Thermodynamics**

Identify and analyze scope, dimensions and units, measure of amount or size, force, temperature, pressure, work, energy and heat. 2. Chapter 2: The First Law and Other Basic Concepts 3. Chapter 3: Volumetric properties of pure fluids 4. Chapter 4: Heat effects 5. Chapter 5: Second law of thermodynamics 6. Chapter 6: Thermodynamics properties of fluids

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**THERMODYNAMICS: Definition**

(from the Greek θέρμη therme, meaning "heat“ and δύναμις, dynamis, meaning "power") - is the study of energy conversion between heat and mechanical work, and subsequently the macroscopic variables such as temperature, volume and pressure. THERMO = HEAT AND TEMPERATURE DYNAMICS = MOTION

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**THERMODYNAMICS: Definition**

* Initially, thermodynamics is the study of the flow of heat to produce mechanical energy that could be used for locomotive; - after that is used for steam engines, turbines, pumps, air conditioners etc. * Because such equipment also used in chemical/ bioprocess plant, it is also important for those engineers to learn the fundamental of such equipment.

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**THERMODYNAMICS: Example**

The production of chemicals, polymers, pharmaceuticals and other biological materials, and oil and gas processing, all involve chemical or biochemical reaction that produce a mixture of reaction product. (e.g:Production of acetic acid from ethanol using Acetobacter aceti bacteria) These must be separated from the mixture and purified to result in product of societal, commercial, or medicinal value. These is the area where thermodynamics plays a central role in bioprocess eng. Separation processes, e.g. distillation are designed based on information from thermodynamics

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**Measures of amount or size**

Thermodynamics Dimensions and Units Measures of amount or size Force Temperature Pressure Work Energy Heat

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**Measures of amount or size**

Thermodynamics Dimensions and Units Measures of amount or size Force Temperature Pressure Work Energy Heat

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Dimensions and Units Dimension is recognize through our sensory perceptions and not definable without the definition of arbitrary scales of measure, divided into specific units of size. The units have been set by international agreement, and are codified as the International System of Units (SI). Note: See Table 1.1 for Prefixes (eg: deca, hecto, kilo, etc.) of SI units. (eg: 1 cm = 10-2 m, 1 kg = 103 g)

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**Measures of amount or size**

Thermodynamics Dimensions and Units Measures of amount or size Force Temperature Pressure Work Energy Heat

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**Measures of amount or size**

Three measures of amount or size are in common use: Mass, m ; Number of moles, n ; Total volume, Vt Mass, m divided by the molar mass M (molecular weight) to yield number of moles; Total volume, divided by the mass or number of moles of the system to yield specific or molar volume. or Specific volume: or Molar volume: or

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**Measures of amount or size**

Thermodynamics Dimensions and Units Measures of amount or size Force Temperature Pressure Work Energy Heat

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**Metric engineering system units**

Force SI unit Metric engineering system units Newton (N) Kilogram force (kgf) F = ma * Note : The kilogram force is equivalent to N

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**Force Example 1.1 With a = g, Newton’s law is : F = mg. Hence;**

An astronaut weighs 730 N in Houston, Texas, where the local acceleration of gravity is g = ms-2. What are the astronaut’s mass and weight on the moon, where g = 1.67 ms-2. Solution With a = g, Newton’s law is : F = mg. Hence; Because the newton N has the unit kg m s-2, This mass of the astronaut is independent f location, but weight depends on the local acceleration of gravity. Thus on the moon the astronaut’s weight is;

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**Measures of amount or size**

Thermodynamics Dimensions and Units Measures of amount or size Force Temperature Pressure Work Energy Heat

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Temperature Temperature is commonly measured with liquid-in-glass thermometers, wherein the liquid expands when heated.

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**Measures of amount or size**

Thermodynamics Dimensions and Units Measures of amount or size Force Temperature Pressure Work Energy Heat

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**Metric engineering system units**

Pressure The pressure P exerted by a fluid on a surface is defined as the normal force exerted by the fluid per unit area of the surface. SI unit Metric engineering system units Pascal (Pa) Kilogram force per square centimeter (kgf cm-2) The primary standard for pressure measurement is the dead-weight gauge in which a known force is balanced by a fluid pressure acting on a known area.

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Force Example 1.2 A dead-weight gauge with a 1 cm diameter piston is used to measure pressures very accurately. In a particular instance a mass of 6.14 kg (including piston and pan) brings it into balance. If the local acceleration of gravity is 8.82 ms-2, what is the gauge pressure being measured? If the barometric pressure is 748 Torr, what is the absolute pressure? Solution The force exerted by gravity on the piston, pan and weights is The absolute pressure is therefore;

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Force Example 1.3 At 27oC ( K) the reading on a manometer filled with mercury is 60.5 cm. The local acceleration of gravity is ms-2. To what pressure does this height of mercury correspond? Solution Recall the equation in the preceding text, P = hρg. At 27 oC ( K) the density of mercury is g cm-3. Then,

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**Measures of amount or size**

Thermodynamics Dimensions and Units Measures of amount or size Force Temperature Pressure Work Energy Heat

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Work Work, W is performed whenever a force acts through a distance. * Note: The minus sign ‘-’ the volume change is positive, and the minus sign is required to make the work negative.

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**Measures of amount or size**

Thermodynamics Dimensions and Units Measures of amount or size Force Temperature Pressure Work Energy Heat

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THANK YOU

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**TUTORIAL 1 - QUESTIONS Problems : 1.3, 1.4, 1.11, 1.14, 1.22**

Reference Book: Smith, J.M., Van Ness, H.C. and Abbort, M.M., Introduction to Chemical Engineering Thermodynamics, Seventh Edition, McGraw-Hill, 2005.

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