Analysis of Irreversible Manufacturing Processes

P M V SubbaraoProfessor

Mechanical Engineering Department

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Second Law for A Generalized Manufacturing System

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Thermal pollution generated by a Manufacturing Process

Power Consumed by an irreversible Manufacturing System

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Vegetable Production System : Jagadishpr , Sonipat

Design : Krishi Vigyan Kendra ,Jagdishpur, Sonipat5KW design with 3.7KW Irrigation Pump

• Non-Renewable sources of petrol and diesel are not utilized • Whole system is noiseless and does not disturb the

surrounding with sound pollution • Water flowing through the turbine (partial pressure design II)

get oxygenated thereby effecting chemical and biological oxygen demands which have a bearing on self regeneration capacity of the soils [Pawlikewich]

• A pump with a high discharge head could be utilized with this turbines hence Water storage in upper reaches facilitate ground water recharge.

• The efficiency is the major player in power transmission and the water wheel is set to take on the costlier reaction turbines in its efficiency if it is properly worked on.

• The whole irrigation system costs around 700$ range.

ADVANTAGES OF IIT Delhi DESIGN

Effect of Planting methods on total irrigation time (hrs.) and yields of Cauliflower

and Pigeon pea (Quintals /ha) Crops Planting

methodIrrigations Nos.& (Time, hrs)/ I*

Water market Rates total irrigatime Irrigation time used (US$ )

AverageYields (Q/ha)

Value of Ferti use Irrigation the produce Water

Cauliflower

Raised beds

8 (3.0) $53 100 $1100 DAP<70% Drainage no other water ferti used

Flat 6 (5.5) $73 89 $990 20 kg/ha DAP ‘’ no other

Pigeon pea

Raised bed 4 (3.5) $47 223 $890 ‘’ ‘’

Flat 3(7.0) $31 200 $800 ‘’ ‘’

Preliminary results show that farmers using the micro turbine pumped water supplies stand to gain US$ 2.25 / hour of

pumping. Yhereby saving $53-73 in cauliflower and US$ 31-47 in pigeon

pea. Raised bed planting improved the value of the produce by 10

percent.

Efficient Reuse of Low Quality water linked to Micro Hydro

Irrigation charges @ $ 2.25 /h, amounts for savings as in cauliflower US$20/ha and pulse US$40/ ha on an average on the Whole Produce.{( KVK (HAU) , Sonepat,HARYANA,INDIA}

Penstock

Water Wheel

Main Shaft

Bush Bearing

Wooden Base

Grinder adjusting lever

Grinding Wheel

10” Pulley

12” Pulley

Gear Box Generator

Canal

Forbay

New Design

Workshop Powered by Pico-hydel Unit at Naya Gharat , Lacchiwala

Impact of System irreversibility on actual Power consumption

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The quantity H-TS is backbone of thermo-economic/ecological analysis and is referred to as the Gibbs free energy.

Thermo-economics/Thermo-ecology

• The quantity H-TS is known as the Gibbs free energy.

• In manufacturing system, a different quantity appears, H - T0S.

• The difference between this and the same quantity evaluated at the reference state is called flow exergy, B.

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• Exergy represents the maximum amount of work that could be extracted from a system as it is reversibly brought to equilibrium with a well-defined environmental reference state.

Exergy

• In general, the bulk-flow terms may include contributions that account for both the physical and chemical exergies.

• Hence = ph+ ch, as well as kinetic and potential exergy.

• The physical exergy is that portion of the exergy that can be extracted from a system by bringing a given state to the “restricted dead state” at a reference temperature and pressure (T0,p0).

• The chemical exergy contribution represents the additional available energy potential that can be extracted from the system at the restricted dead state by bringing the chemical potentials at that state (T0, p0) to equilibrium with its surroundings at the “ultimate dead state”.

Dead State

• Consider a quantity of mass that undergoes a steady-state process.

• With a given state for the mass entering the control volume, the reversible work will be a maximum when this mass leaves the control volume in equilibrium with the surroundings.

• This means that as the mass leaves the control volume, it must be at the pressure and temperature of the surroundings, be in chemical equilibrium with the surroundings, and have minimum potential energy and zero velocity.

Dead State

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Actual and Ideal Power Consumption in terms of Flow exergy

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Degree of Perfection

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