Introduction:
Thermodynamics is an exciting and fascinating subject that deals with energy,which is essential for sustenance of life, and thermodynamics h as long been an essential part of engineering curricula all over the world .It has a broad application area ranging from microscopic organism to common household appliance ,transportation vehicle ,power generation systems ,and even philosophy .This Course material contains sufficient materials for two sequential courses in thermodynamics . Objectives
This course material is intended for use as a test book by undergraduate engineering en gineering students in their sophomore, and as a reference book for practicing engineers. The objective of this text are . To cover the basic principles of thermodynamics. !. To present a wealth of real world engineering examples to give students a feel for how thermodynamics is applied in engineering practice . ". To develop an intuitive understanding of thermodynamics by emphasi#ing the physics and physical arguments. It is our hope that this book, through its careful explanations of concepts and its use of numerous practical examples and figures, helps students de velop the necessary skills to bridge the gap between knowledge and the confidence to properly apply kn owledge.
Unit – I Overview of Unit -01
This unit consists of seven lesson of teaching, in the first lesson we will study $asic of Thermodynamics, %acroscopic and microscopic approach .and its definitions, .In the second lesson we will study system types with pictorial representation, introduction to properties. In third lesson we will study &roperties i.e intensive and extensive properties with examples in addition to that we study the definition of state, path and process. In fourth lesson we study thermodynamic equilibrium, types of equilibrium with examples .In fifth lesson we study about 'iathermia wall, (uasi)static
process and some basic definition to solve the numerical problems like specific volume, pressure, temperature* +eroth law of thermodynamics etc. In sixth lesson we study study Temperature scale factor conversion like ahrenheit to Celsius and Celsius to ahrenheit and few -umerical problems were solved .In seventh lesson we study about %easurements and internal fixed points. Objective of Unit -01
t the end of this unit we shall understand that/ $asic concepts about the Thermodynamics pplication of Thermodynamics with examples Cycles, 0quilibrium and their types with examples and sketches Temperature scale factor conversion and its utility in engineering science ew numerical problems in 1niversity aspects.
Lesson -01
1.1 BASIC CONC!"S AN# #$INI"IONS Objective:
t the end of lesson you shall understand that The 2tatistical thermodynamics and classical thermodynamics are different based on the requirements the type can be chosen. The temperature and its fixing with numerical problems. nd how the classification and definitions are varying in equilibrium, equilibrium, cycle with examples. In overall you will be able to through about what is thermodynamics how it plays its vital role . Introduction:
In this lesson you will be able to solve the numerical problems in energy conversion and, in internal fix points. %ore o ver you will get thorough knowledge in $asic thermodynamics.
1.1 "%er&od'n(&ics:-
process and some basic definition to solve the numerical problems like specific volume, pressure, temperature* +eroth law of thermodynamics etc. In sixth lesson we study study Temperature scale factor conversion like ahrenheit to Celsius and Celsius to ahrenheit and few -umerical problems were solved .In seventh lesson we study about %easurements and internal fixed points. Objective of Unit -01
t the end of this unit we shall understand that/ $asic concepts about the Thermodynamics pplication of Thermodynamics with examples Cycles, 0quilibrium and their types with examples and sketches Temperature scale factor conversion and its utility in engineering science ew numerical problems in 1niversity aspects.
Lesson -01
1.1 BASIC CONC!"S AN# #$INI"IONS Objective:
t the end of lesson you shall understand that The 2tatistical thermodynamics and classical thermodynamics are different based on the requirements the type can be chosen. The temperature and its fixing with numerical problems. nd how the classification and definitions are varying in equilibrium, equilibrium, cycle with examples. In overall you will be able to through about what is thermodynamics how it plays its vital role . Introduction:
In this lesson you will be able to solve the numerical problems in energy conversion and, in internal fix points. %ore o ver you will get thorough knowledge in $asic thermodynamics.
1.1 "%er&od'n(&ics:-
It can be defined as the science which deals with the relation between heat, work and properties of the system.
P, V, T,
W Q
A))*ic(tions:
'esigning work producing machine 3 4eat engine, 2team engine, 5as Turbine 'esigning work bsorbing machine 3 6efrigerator, ir compressor -o work transfer systems
) boiler, condenser, and furnace.
7here no work is transferred, the Thermodynamic problem involve the use of heat to produce the change in state or the transfer of mass mass with a chemical reaction, reaction, as in the combustion of a fuel. It is the science dealing with energy and its transformation. 0nergy can be viewed as ability to cause the change the name thermodynamics is derived from greek word 8Therm9 means heat and 8dynamics9 means power, which is the most descriptive of the earlier efforts to convert heat into po wer.
1.+ ,(crosco)ic (nd &icrosco)ic ())ro(c%:
,(crosco ,(crosco)ic )ic ())ro( ())ro(c%: c%:
In the the stud study y of the the ther thermo mody dynam namic icss one can can adop adoptt two two
different different approaches approaches namely macroscopic macroscopic and microscopic. microscopic. In macroscopic macroscopic approach approach
suppose a certain amount of gas is trapped in a container, one can measure the volume occupied occupied by the gas by measuring measuring the diameter diameter and height of the cylinder. cylinder. The pressure pressure exerted exerted by the gas by measuring measuring the diameter diameter and height of the cylinder. cylinder. The pressure pressure exerted exerted by the gas can be measured with the help help of pressure pressure gauge and its temperatu temperature re can be measured with the help of thermometer. Then the state of the gas can be described by specifying the pressure, volume and temperature. The values of these variables which can be measured very easily. Thus in macroscopic macroscopic approach.
. The structure of the matter is not considered.
!. :nly a few variables are used to describe the state of the matter under consideration
". The The value valuess of the the vari variab able less used used to descr describ ibee the the stat statee of the the matt matter er are are easi easily ly measurable. In classical thermodynamics, we adopt macroscopic approach.
,icrosco)ic ,icrosco)ic ())ro(c%: ())ro(c%:
In micros microscopi copicc approach approach a same same gas can be conside considered red as
consisting of a large number of small particles each of which moves at random with independent velocity. The state of each particle can be specified in terms terms of position position co) ordinates ;xi, yi, yi, #i< and the momentum component ;&xi, &yi, &#i<. If we consider a gas occupying a volume of cm" at ambient ambient temperatur temperaturee and pressure. pressure. The number number of particles present in it is of the order of = != and the same number of position co)ordinate and momentum momentum components components are required required to specify the state state of the gas. t a particular particular instant each particle has a definite position velocity and energy and these characteristics change very frequently due to collision between the particles.
The overall behavior of the gas or matter is then predicted by the statistical averaging the behavior of the individual particles. particles. 2o, thus in microscopic approach.
. a large number of variables are required for complete specification of the state of the matter under consideration.
!. The variables choose to describe the state of the matter cannot be measured easily and preciously. ". knowledge of structure of matter under consideration is essential. In statistical thermodynamics, we adopt microscopic approach.
S'ste&:
2ystem or thermodynamic system is defined as a quality of matter or a region in space upon which attention is concentrated in the analysis of a problem.
Surroundin:
The mass ;matter< or a region outside the system is called surrounding or everything external to the system is called surrounding.
Bound(r':
The real or imaginary surface that separates the system from its surrounding is called the boundary. The boundary of a system can be fixed or movable.
Note: The boundary is a contact surface sheared by both system and surrounding. The
boundary has #ero thickness and thus it can neither contain any mass nor occupy any volume in space.
2ystem and its surrounding forms universe
2ystem
1niverse
$oundary
2urrounding
2ystem and surroundings from &iston cylinder arrangement
Boundary system
2urrounding
Surrounding Su&&er': 4ere we learnt the Classical and statistical thermodynamics and their explanation. 7e studied how the system is classified and what are surroundings and boundaries.
Lesson-0+ Objective:
t the end of the lesson you shall understand that 2ystems are being considered to study about the energy transformation Isolated system has fixed mass and energy
&roperties are required to mention about the characteristics of the 2ystem Introduction:
In this lesson you will study about system, and its types with examples. >ou will get introduction about properties and its lists with units.
1. "%ree c*(ssific(tions of s'ste&:
;a< Closed 2ystem ;b< :pen 2ystem ;c< Isolated 2ystem.
/( C*osed s'ste& /Contro* &(ss: Closed system is a identifiable collection of matter
on which attaintion is focused during thermodynamic analysis of problem. closed system consists of fixed amount of mass and no mass can cross its boundary i.e., no mass can enter or leave a closed system.
C%(r(cteristics of ( c*osed s'ste& bound(r':
. The si#e, shape and orientation of a system, boundary with respect to a stationary observer can change.
!. %aterial ;mass< cannot cross the system boundary either or both direction.
". There can be heat and ? or work interaction across the system boundary.
&iston
%ass ;-o<
5as
$oundary
0nergy ;>es<
nother view of cylinder
Q
W
b O)en s'ste& /contro* vo*u&e: :pen system or control volume is an identifiable
#one in space on which attaint ion is focused during thermodynamic analysis of problem. :pen system is a properly selected region in a space for thermodynamic analysis of problem.
0g/ 7ater heater.
4ot 7ater
%ass ;>es<
0nergy ;yes<
Cold 7ater
Control surface ;boundary<
m
In case of piston cylinder arrangements
m
C%(r(cteristics of Contro* s'ste&:
. There is no change in the si#e, shape and orientation with respect to the stationary observer.
!. There can be material flow ;mass< across the control surface in either or both the direction.
". There can be heat and? or work interaction across the control surface or system boundary.
/c Iso*(ted S'ste&: The isolated system is one in which there is no interaction between
system and the surrounding it is of fixed mass and energy. nd there is no mass or energy transfer across the system boundary.
!ro)ert':
property of a system is an observable, measurable or calculatedly
characteristic of a system. thermodynamic property refers to the characteristic which can be used to describe the condition or state of the system. The salient aspect of the thermodynamic property are/
. It is measurable characteristics describing a system and helps to distinguish one system from other.
!. It has a definite unique value when the system is in particular state.
". It is dependent only on the state of the system, it does not depend on @path or route of the system follower to attain that particular state. (&)*e:
&ressure ;&<, temperature ;t, T<, Aolume ;A<, energy ;0<, enthalpy ;4<, entropy ;2<, density ;∫ <, specific heat ;Cv, Cp<.
2pecific volume ;v<, specific energy ;e<, specific enthalpy ;h<, specific entropy ;s<.
Su&&er':
7e learnt about the systems and its classification and examples, properties and their lists with units. Lesson-0
Objective:
t the end of the lesson you will be able to understand Intensive * 0xtensive properties with examples. 2tate, point, path and process and indication in sketches. Cyclic and non cyclic process Introduction:
In this lesson we will study about the Intensive and 0xtensive properties, and point, path and process definition which are necessary for this lesson. we study about Cyclic and non Cyclic process
1.2 ."')es of t%er&od'n(&ic )ro)erties: /( Intensive !ro)ert'. /b tensive !ro)ert'.
/( Intensive !ro)ert': nything comes per kg is an intensive property.
Intensive properties are those that are independent of si#e of system or independent of mass. 0x/ 2pecific heat, specific volume, pressure, temperature, density, specific energy, specific enthalpy, specific entropy. Note: ny property comes with specific is an intensive property. /b tensive !ro)ert': 0xtensive properties are depending on si#e or extent of the
system or mass of the system. 0x/ Aolume, energy, enthalpy, entropy. St(te: The condition of the system at any given instant is called its state
2tate of system is nothing but the totality of the properties of the system.
It is the complete description of a system in terms of its properties.
St(te di(r(&:
it is a diagram on Cartesian co)ordinate with any two independent
properties being marked on x)y axis that represents the state of the system at any given instant.
>
↑ A
v!
!
↓
v
B p!
p
p→
* ! are state points.
St(te !oint:
This is a point in a state diagram showing the condition of the system at any given instant in terms of two properties B and >.
!(t%: &ath is a line joining the successive state points on a state diagram during a
change of state.
!rocess: 7hen a path is completely specified the change of state is called a process. To
describe a process one should specify the initial and final states of the process, as well as the path it follows and the interaction with the surrounding.
C'c*ic !rocess:
In a cyclic process the initial and final state point after a certain
happenings are the same.
In other words after system being subjected to a cyclic process would experience no change in any property.
Non-C'c*ic )rocess: system is said to be execute a non)cyclic process if its initial and
final points are not the same after happening. Su&&er':
7e learnt the Intensive * 0xtensive properties with examples. 2tate, point, path and process and indication in sketches. Cyclic and non)cyclic process.
Lesson -02 Objective:
t the end of the lesson you shall understand that 2tudy of Thermodynamic equilibrium gives vast knowledge about other equilibrium like %echanical , chemical ,Thermal equ ilibrium. 1nderstanding aboutTypes of 0quilibrium or stability Criteria. Introduction:
In this lesson, we will be studying about various equilibrium involving in thermodynamics. we will understand about Types of 0quilibrium of 2tability Criteria.
1.3."%er&od'n(&ic 4ui*ibriu&:
Thermodynamics deals with equilibrium states. The word equilibrium implies the state of balance. In an equilibrium states there are no unbalanced potential with the system.
;:r<
system is said to be in thermodynamic equilibrium if no change in any of its properties occurs when it is isolated from its surrounding.
In such a case there would be no unbalanced force, no temperature gradient and no chemical reaction or transfer of materials from one part of system to another .part such as diffusion.
1. ,ec%(nic(* 4ui*ibriu&:
system is said to be in mechanical equilibrium when there is no unbalanced force within the system and also between system and the surrounding.
If any unbalanced force exists either of the system alone or both the system and the surrounding will undergo a change of state till mechanical equilibrium is reached.
+. C%e&ic(* 4ui*ibriu&:
If there is no chemical reaction or transfer of matter from one part of the system to another such as diffusion.
The system is said to be exist in a state of chemical
equilibrium.
. "%er&(* 4ui*ibriu&:
system is said to be in thermal equilibrium if its temperature is uniform with in the system and that is equal to the temperature of surrounding during a process.
In other words a system is said to be in thermal equilibrium if there is no change in any of its properties occurred. (usi)static process is also called reversible process it is also nothing but successions of equilibrium state.
"')es of 4ui*ibriu& or st(bi*it' Criteri(:
The equilibrium states of the system can be classified as/
. 2table 0quilibrium/
+. Neutr(* 4ui*ibriu&:
. Unst(b*e 4ui*ibriu&:
2. ,et( st(b*e 4ui*ibriu&:
7hen it is communicated with the surrounding through a diathermicwall.
Su&&er':
0quilibrium study in thermodynamics is very important for solving the numerical problems. 2tability theory gives more information about the involvement about the equilibrium in stability theory.
Lesson-03 Objective:
t the end of the lesson you will answer 'iathermic wall is suitable for heat transfer (uasistatic process with equilibrium state &roperties of the system with its units +eroth law of thermodynamics dealing of Thermal equilibrium
#i(t%er&ic 5(**: It is one which when brought between a system and its surrounding
allows only heat transfer across it, but no work transfer.
0quality of force ;pressure< is in mechanical equ ilibrium.
0quality of temperature is in thermal equilibrium.
0quality of chemical potential is in chemical equilibrium.
1.6.7usi – st(tic )rocess or 7usi-e4ui*ibriu& )rocess:
7hen a process proceeds in such a manner that the system remains infinitesimally closed to an equilibrium state at all times, it is called a (usi)static or (usi)equilibrium process.
(usi)equilibrium process can be viewed as sufficiently slow process, that allows the system to adjust itself internally so that properties in one part of system do not change any faster than those at other parts.
↑
↑
&
&
!
!
A→
A→
(usi 3 static process
-on 3 (usi static process.
Units (nd #i&ensions:
Units: There are seven basic units are there/
. Dength
)
meter
m
!. %ass
)
Eilogram
Eg
". Time
)
2econd
2
F. 0lectric Current
)
mpere
G. Duminous intensity
)
Candela
Cd
H. Temperature
)
Eelvin
E
. mount of substance
)
mole
mol
1. $orce:
∝ m
∝ a J ma J kg m ? sec!
J-
+. !ressure:
& J F
A
N
m!
;&a<
E&a %&a
bsolute pressure J 5auge pressure K tmospheric pressure
;&abs J &g K &atm<
7here, tmospheric pressure J =." E&a.
J .=" bar
bar J =G &a
If negative gauge pressure is there then,
bsolute pressure J atmospheric pressure ) Aacuum pressure
&abs J & atm 3 & Aacuum
. 5or8 or %e(t or ner':
7ork J orce × displacement
J - × m J -m
JL
2. "or4ue:
Torque J orce × &erpendicular distance
J - × m
J -m J L
3. !ower: The rate of doing work.
&ower J J J 7 ;watt<
s
6. #'n(&ic 9iscosit':
µ J Ns
m
!
;- 3 sec?m!<
/ J Eg ) m
J
sec !/
sec m !/
Kg m − sec
. S)ecific %e(t:
J Kg E
J o Kg C
;. "%er&(* Conductivit':
; E < J W
mK
W
m oC
<. =e(t tr(nsfer Co-efficient: /%:
W
!
m K
W ! m C o
1..>erot% *(w of "%er&od'n(&ics:
It is the basic law of thermodynamics. It states that two systems on thermal equilibrium if they are separately in thermal equilibrium with the third system.
/Or
In other words, if body one is thermal equilibrium with body three with separately and body two in thermal equilibrium with body three with separately. Then body one and two are also in thermal equilibrium with each other.
The #eroth law of thermodynamics provides basis for the temperature measurement. The temperature measuring device ;Thermometer< junctions as the third body and compares the unknown temperature with the temperature of the system at a known thermal level ;reference temperature<.
"e&)er(ture:
Temperature is an important hot and cooled body is measured by using thermometer. The temperature is known to bring about certain changes in system for e.g.
. 7ith increase in temperature volume of fluid increases.
!. 6esistance of an electrical resistance increases.
". Dength of metallic rod increases and so on.
'epending upon its made of operation thermometer reads changes in certain property and the change is the related to temperature through certain calibration done using the concept of #eroth law of thermodynamics and by reference datum points ;fixed points<
property or characteristics which changes in value as a function of temperature is called thermometric property and the corresponding substance is known as thermometric substance.
Su&&(r'
rom this lesson the important +eroth law and some important properties which are related with thermodynamics were studied. The Types of equilibrium and (uasistatic process also covered. Lesson-06 Objective:
t the end of the lesson you will understand 7hat is thermometer how it is used in 6eal life and 6*' %easurement of temperature and temperature scale Temperature conversion and few problems related to it Introduction:
The thermometer, and its uses in thermal industry will be studied and its related problems of conversion from ahrenheit to Celsius vice versa .7e will be studying about %easurement of temperature and its scale.
1.;."%er&o&eter:
Thermometer may be defined as the act of measuring temperature with accuracy and precision.
,ost Co&&on*' used t%er&o&eters:
. %ercury in glass thermometer. ;which measures the change in volume of mercury with change in temperature<.
!. 6esistance thermometer ;which measures the change in resistance with change in temperature<.
". Thermocouple ;which measures the e.m.f generated at the junction of two dissimilar metals<.
F. Ideal gas thermometer or gas thermometer which measures the change in volume at constant pressure as in the case of constant pressure thermometer<
;:r<
;%easures the change in pressure
at constant volume in a constant volume gas
thermometer.
1.<.,e(sure&ent of te&)er(ture or te&)er(ture sc(*e:
quantitative measure of temperature of the system requires reference to some datum plane or reference conditions or fixed points. $efore MGF there were two fixed points one is ice point and another one is steam point. Det temperature represented at this states be ti and ts corresponding to ice point and stem point. nd their thermometric properties be xi and xs respectively. Considering linear Co)relation.
T J ax K b
$etween temperature t and thermometric property 2.
t ice point ti J axi K b
)))))))))))))))) ;<
t steam point ts J axs K b
))))))))))))))) ;!<
2olving ;< and ;!<
aJ
t s
− t i
x s
− xi
b J ti )
t s
− t i
x s
− xi
xi
t J ti K ;ts 3 ti<
x − x x − x i
s
i
Centir(de Sc(*e:
t ice point,
Ti J =oC
nd at stem point,
Ts J ==oC
x − x ∴ toC J == x − x i
s
i
$(%ren%eit Sc(*e:
t ice point
Ti J "!o
To J "! K ;N=<
x − x x − x i
s
6elation between oC and o.
; x − xi < ; x s
− xi <
o
J
t C ==
i
o
o
t J "! K ;N=<
t C ==
to J "! K .N toC.
. new temperature scale in o - is designed with free#ing point at ==o - and boiling point at F==o -. 0stablish a co)relation between oC and o - and o.
2olution/
5iven at ice point
Ti J ==o -
nd at steam point
Ts J F==o -
7e know,
T J ti K ;ts 3 ti<
x − x x − x i
s
To - J ti K ;ts 3 ti<
i
x − x x − x i
s
i
x − x x − x i
To - J ti K "==
s
To - J == K "==
i
x − x x − x i
s
o
t N
− ==
"==
J
x − x x − x i
s
i
i
)))))))))))))))))) ;<
7e also, know
ToC J ==
x − x x − x i
s
i
))))))))))))))) ;!<
Comparing ;< and ;!< we get
o
− == J "=/ =/
t N
o
t C = /= /
to - J ;"toC K ==<
)))))))))))))) ;"<
7e know
To J "! K .N toC o
t F
− "!
.N
J toC
))))))))))))) ;F<
2ubstituting the value of toC from ;F< in ;"< we get
o
T - J " × o
t F
− "!
.N
K ==
=.H
o
o
t - J
t F
− "!
=.H
K ==.
!. Two thermometers one oC and other o are immersed in a fluid. fter the thermometer reaches equilibrium with the fluids, it is noted that both the thermometer indicate the same numerical value. ind the identical numerical value.
2olution/
7e know,
To J "! K .N toC
-ow if m is the point where both the readings are same.
m J "! K . N m
)
"! J ;.N 3 < m
mJ
−"! =.N
J ) F=.
Therefore at 3 F= the both thermometer reads equals.
". temperature T on thermometric scale is defined in terms of property & by a relation T J a log e & K b.
7here a and b are constants, the temperature at ice point and steam points are = oC and ==oC respectively. The instrument gives values of & as .NH and H.N at ice and steam point respectively evaluate temperature corresponding to a reading of & J !.G.
2olution/
5iven/
&i J .NH
&s J H.N & J !.G
Ti J =
ts J ==
tJO
ti J a loge&i K b
ts J a loge &s K b
aJ
− t i loge Ps − loge Pi
b J ti )
t s
− t i × loge&i loge Ps − loge Pi t s
== − =
a J log H.N J .=G e
.NH ==
b J = )
H.N × loge ;.NH< .NH
loge
J ) F.NH
T J a loge & K b
J .G × loge ;!.G< 3 F.NH
J !!.NoC
T J !!.NoC.
Su&&(r':
In this lesson we studied about the thermometer and temperature scale conversion by solving numerical problems.
Lesson-0 Objective:
t the end of this last lesson we will be familiar with 4ow gas temperature being measured by Thermometer 4ow to solve the problems with respect to ahrenheit and Celsius Introduction:
In this chapter the gas temperature how its calculated by converting in to Celsius and ahrenheit and temperature points are calculated.
1.10.,et%od in use (fter 1<32:
2ince after MGF only one fixed point has been in use, that is the triple point of water, the state at which ice, liquid, water and water vapour co)exist in equilibrium. The temperature at which this state exist is arbitrarily assigned to a value of !". H E. Temperature at triple point.
T J ax
Ttp J =.HoC J ! ".H E and thermodynamic property at that stage is Btp.
Ttp J aBtp
T tp
aJ
X tp
TJ
T tp X tp
B
?(s "%er&o&eter:
Ide(* (s te&)er(ture:
P
T T tP
T T tP
J
P tP
J P lim →= tP
P P tP
J ."HH
:xygen
air
P P tP
nitrogen
= mm &t&
&rove that
ToE J toC K !" .H
T T a
J ."HH
Tt& ≈ Ti
T s T i
J ."HH ))))))))))) ;<
Ts 3 Ti J ==oC
==o C + T i
T i
)))))))))))))))) ;!<
J ."HH
==oC K Ti J ."HH Ti
== ."HH
J Ti J !".!! E ≈ !" E
Ts J "" E
ToE J !" K ==
x − x x − x i
s
i
o
− !" J =/ =/
t K
o
t C = /= /
toE J toC J !"
Convert arehait scale into absolute scale ;6ankine
T s T i
J ."HH ))))))))))) M<
Ts 3 Ti J N= )))))))))) ;!<
."HH Ti 3 Ti J N=
Ti J
N= =."HH
J FM.N=
Ts J H.N=
To6 J FM.N= K N=
x − x x − x i
s
o
t R
− FM.N= J / N/ =/
o
i
− "! / N/ =/
t F
to6 J to K FGM.N=.
. new temperature scale in o - is designed with free#ing point ;ice point< at ==o - and boiling point at F==o -. 0stablish Co)relation between its absolute unit and o -.
2olution/
T s T i
J ."HH
ti o - J == at ice point.
ti o - J F== at steam point
to - J == K "==
x − x x − x i
s
i
Ts 3 Ti J "==
))))))))))))) ;<
."HH Ti 3 Ti J "==
))))))))))) ;<
"==
Ti J
=."HH
J NM.H %
Ts J M.H ≈ M %
x − x x − x
To% J NM K "==
o
t M
− NM
"==
o
J
i
s
t N
to% J to - K M
i
−==
"==
F. The e.m.f in a thermocouple with test junction at toC on gas thermometer scale and reference junction at ice point is given by
e J =.! t 3 G × =)F t! mA
The mill voltmeter is calibrated at ice point and steam point. 7hat will this thermometer reads in a place where gas thermometer reads G=oC.
2olution/
2ystem Ice point 2team point 5as
$y mercury T J =oC T J ==oC T J G=oC
T J ti K
ε
Thermo couple = ==oC GN.""
= G N.G
ε − ε i ;ts 3 ti< − ε ε s i ε G
T J ==
TJ
== G
ε
t J GN.""oC.
". 6esistance thermometer at room temperature shows G
Ω and its kept equilibrium with
another system whose temperature is to be measured. resistance F= Ω and it obey, the expression. 6 J 6 = ; K
$y the time it is showing
∝t<.
Take room temperature to
be !GoC where 6 o is resistance at =oC. 'etermine the temperature of the system ∝ J =.!F.
2olution/
6 J 6 o ; K ∝t<
G Ω J 6 o ; K =.!F × !GoC<
6 o J !.F Ω
F= Ω J !.F Ω ; K =.!F t<
N.HM
−
=.!F
J t J ".oC.
1.11.Intern(tion(* fied )oints:
These are all reproducible temperature usually phase change temperatures of certain substances. They are not measured by using any thermometer but are assigned to a certain value which are universally accepted their primary purpose is to serve as standard or reference temperature in calibrating thermometer in various temperatures.
The following is the list of temperatures, fixed points and the temperature shown in oC.
. :xygen ; boiling point temperature< ;)N!.MoC<
!. Triple point of water ) =.=oC
". -ormal boiling point of water 3 ==oC.
F. -ormal boiling point of sulphur 3 FFF.HoC
G. -ormal boiling point of ntimony 3 H"=.GoC
H. -ormal $.&. of silver 3 MH=.NoC
. -ormal $.&. of 5old 3 =H."oC. Su&&(r':
In this last lesson we studied about the Internal fixed points and gas temperature measuring by thermometer and we solved few problems .
7US"ION BAN@
.'efine 0ngineering thermodynamics. 5ive applications of it. !.2tate +eroth law of thermodynamics ".7hat is thermometer list most commonly used thermometer F.7hat is international fixed pointsO4ow it is being fixedO G.0xplain %easurement of temperature or temperature scale.
"utori(* )rob*e&s:
. In =" sir Ijack -ewton proposed a linear temperature scale for which he choose the ice point and human point temperature as the two fixed point and assigned numerical values of =o2 and ==o2 respectively. If the human body temperature is in centigrade "HoC. :btain the relation between -ewton scale and oC.; ns/ Tos J !. toC ,
ToC J =."H to -.<
!. ahrenheit, Celsius thermometer both immersed in fluid. numerically twice that of centigrade reading.
ahrenheit reading
7hat is temperature of fluid
expressed as o6 and oE.;ns/or o J !oC ,TJ FFH. 6,<
".
The e.m.f in a thermocouple is =A when the test junction is at =oC ;ice point< and ! A when it is at steam point. ind the temperature of the system when e.m.f is "A. 1se the relation.; ns/ t J H.!GoC.<
Universit' 7uestions
)rob*e&s:
. The readings T and T$ of two Celsius thermometers and $ agree at ice point !
and steam point. $ut else where are related by equation t J D K %t$ K - t B .7here, D.%.- are constant. 7hen both thermometer are immersed in a system of fluid. registers oC while $ registers =oC. 'etermine the reading on when $ registers ".FoC. ii. 7hich thermometer is correct.; AT1)-ov !==< !. The Temperature t on a certain Celsius thermometric scale is given by means of a property through a relation t J a ln p K b 7here a and b are constants and p is the property of the fluid .If at the ice point and steam points the values of pare found to be F and != respectively,7hat will be temperature reading corresponding to a reading of p J H;AT1 'ec =N ? Lan =M < ". The resistance of the windings in a certain motor is found to be N= :hms at room temperature ; !G=P < .7hen operating at full load,1nder steady state conditions,the motor is switched off and the resistance of the windings immediately measured again ,is found to be MN= ohms.The windings are made of copper whose resistance at temperature tP C is given by 6 t J 6 = @ K =.=="M" t Q 7hen 6 = is the resistance at = P C .ind the temperature attained by the coil during full load.; AT1)Lune ?Luly =N< "%eor':
F.%ention the Characteristics of a thermodynamic &roperty ;'ec =N? Lan =M <
G.'ifferentiate between the following with suitable examples ; Lune?Luly !==N< i. 2ystem and control volume ii.Intensive and 0xtensive &roperties iii.&ath and &oint function H.'efine the following ; Lune?Luly !==N < i.Thermodynamic state ii.(uasi)2tatic &rocess
