Chemical Engineering Thermodynamics - I

Instructors:

Dr. Lalit Pandey Dr. Amit Kumar Dr. S. Gumma

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L T P C

CL 203 (2-1-0-6)

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Thermodynamics

• What is thermodynamics? Thermo + Dynamics (Heat) (Motion) Flow of heat

“the science of energy and its transformations”

Born in 19th Century to increase the efficiency of

steam engine, which concerts heat to work.

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Newcomen (1663-1729) invented the first successful

reciprocating steam engine in 1712

Used to pump water out of mines and driving water wheels. Mine depth increased allowing to new coal reserves.

Importance of thermodynamics

enables one to derive relationships that quantitatively describe the nature of the conversion of energy from one form into another

calculation of hear and work requirements for chemical or physical processes

can be used to predict the equilibrium state of a system as well as direction of change in a system not at equilibrium

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Limitations of thermodynamics

• Do not predict the rates of chemical or physical

processes

Rate α (Driving Force, Resistance)

• Do not predict Microscopic (molecular) mechanism

of chemical or physical processes

(Knowledge of microscopic behavior of matter can be useful

in determination of thermodynamic properties )

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Applications of Thermodynamics

Steam generators,

refrigeration and air conditioning,

internal-combustion engines,

steam and gas turbines,

steam power plants,

regulate and maintain internal temperature in a wide range of ambient conditions in living beings,

capture and direct heat from deep within the earth, to supplement our energy needs.

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How to define a real problem?

• Identification of a particular body of matter as the focus of attention

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System Region in which

process occur

Boundary Real/Imaginary Fixed /Flexible

Surroundings Interacts with

system

Thermodynamic state is defined by properties i.e. temperature, pressure and composition

Properties depend on fundamental dimensions of science i.e. l, t, T, m

Temperature • Degree of hotness

t˚C = T K – 273.15

t˚F= T R – 459.67

Absolute zero (0 K), Ice point (0 ˚C ), Stream point (100 ˚C)

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Pressure

• Normal force exerted per unit area of the surface [Unit: N m-2 (Pascal, Pa); 1 bar = 105 Pa]

1 atm = 101325 Pa or 101.325 kPa or 760 mmHg

absolute P = gauge P + atm P

Work, Heat and Energy

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Internal Energy

Kinetic, KE Potential, PE

Energy = Microscopic form + Macroscopic form

Work (Force)

Heat (Temperature)

Transfer of Energy