Energy, Environment, and Industrial Development

Energy, Environment, and Industrial Development

Michael B. McElroyMichael B. McElroy

Lecture 11Lecture 11

March 13, 2006March 13, 2006

© Science A 52 FHA + MBM2

What was the maximum possible efficiency of the Newcomen engine (or more properly that of the Watt modification)? Consider a cylinder of length L, cross-section SConsider a cylinder of length L, cross-section S Suppose that the cylinder must be filled with steam Suppose that the cylinder must be filled with steam

to a pressure of 1 atmto a pressure of 1 atm First calculate the mass of HFirst calculate the mass of H22O corresponding to O corresponding to

this steamthis steam

The Perfect Gas Law: P = NRT The Perfect Gas Law: P = NRT

N = P/RT = 1atm / (8.31 J molN = P/RT = 1atm / (8.31 J mol-1-1KK-1 -1 * 373K) * 373K)

= 1.013x10= 1.013x1055 Pa / (8.31 J mol Pa / (8.31 J mol-1-1KK-1 -1 * 373K) * 373K)

= 32.68 mol/m= 32.68 mol/m33

Mass of HMass of H22O = N * L* S * 18g/mol = 588.23LS (gram)O = N * L* S * 18g/mol = 588.23LS (gram)


What was the maximum possible efficiency of the Newcomen engine (or more properly that of the Watt modification)? Then calculate heat required to produce this steamThen calculate heat required to produce this steam

Heat required = heat to raise water from 293K to 373K Heat required = heat to raise water from 293K to 373K + latent heat of evaporation + latent heat of evaporation

Q = (558.23LS)g * 4.8 J KQ = (558.23LS)g * 4.8 J K-1-1gg-1 -1 * (373-293)K + * (373-293)K + (588.23LS)g * 2500J/g (588.23LS)g * 2500J/g

= 1.56x10= 1.56x1066 LS (Joule) LS (Joule) Work done in one stroke of engineWork done in one stroke of engine

W = 1atm * S * L = 1.013x10W = 1atm * S * L = 1.013x1055 LS (Joule) LS (Joule) Efficiency = 1.013x10Efficiency = 1.013x1055 LS / (1.56x10 LS / (1.56x1066 LS) = 6.5% LS) = 6.5%


Calculate the energy required to raise 100 gallons Calculate the energy required to raise 100 gallons of water by 100 ft. of water by 100 ft.

E = mghE = mgh

m = density * volume m = density * volume

= 1 g/cm= 1 g/cm33 * 100 gallons * 3785 cm * 100 gallons * 3785 cm33/gallon/gallon

= 3.785x10= 3.785x1055 gram = 3.785x10 gram = 3.785x1022 kg kg

h = 100 ft = 100 ft * 0.305m/ft = 30.5 mh = 100 ft = 100 ft * 0.305m/ft = 30.5 m

E = 3.785x10E = 3.785x1022 kg * 9.8 m/s kg * 9.8 m/s22 * 30.5m * 30.5m

= 1.13x10= 1.13x1055 J J


Calculate the power required to raise 100 Calculate the power required to raise 100 gallons of water by 100 ft per minutegallons of water by 100 ft per minute

E = mgh = 1.13x10E = mgh = 1.13x1055 J J

power = 1.13x10power = 1.13x1055 J / min J / min

= 1.13x10= 1.13x1055 J / 60 sec J / 60 sec

= 1.89 x 10= 1.89 x 1033 W W

= 2.53 horse power = 2.53 horse power

(1 hp = 746 Watts)(1 hp = 746 Watts)


James Watt: Highlights of a Remarkable Life Born 19 January 1736, Greenock, Scotland, 25 miles Born 19 January 1736, Greenock, Scotland, 25 miles

from Glasgow.from Glasgow. Grandfather, Thomas Watt (1642-1734): “ professor Grandfather, Thomas Watt (1642-1734): “ professor

of mathematicks”. Taught navigation and surveying. of mathematicks”. Taught navigation and surveying. Father, James Watt (1698-1782), merchant, supplied Father, James Watt (1698-1782), merchant, supplied

nautical goods and mathematical instruments. nautical goods and mathematical instruments. Watt studied Mathematics (Euclid), Latin and Greek Watt studied Mathematics (Euclid), Latin and Greek

at Elementary and Secondary (Grammar) School. at Elementary and Secondary (Grammar) School. Worked in father’s workshop.Worked in father’s workshop.

Father ran into financial difficulties 1753-1754. Watt Father ran into financial difficulties 1753-1754. Watt moved to Glasgow to take up moved to Glasgow to take up apprenticeship as apprenticeship as instrument maker June 1774 (age 18). instrument maker June 1774 (age 18).


James Watt: Highlights of a Remarkable Life Worked with John Morgan, “philosophical instrument Worked with John Morgan, “philosophical instrument

maker”, expert on brass, in London.maker”, expert on brass, in London. June 1756, struck out on his own.June 1756, struck out on his own. Robert Dick, professor of natural philosophy arranged Robert Dick, professor of natural philosophy arranged

his first job, fixing a collection of astronomical his first job, fixing a collection of astronomical instruments bequeathed to Glasgow College, October, instruments bequeathed to Glasgow College, October, 1755 (age 19). Room to work in the College. 1755 (age 19). Room to work in the College.

Mathematical instrument maker to the University.Mathematical instrument maker to the University. Moved his tools to University July 1757 (age 21).Moved his tools to University July 1757 (age 21). Met John Robison (1739 – 1805) then an Met John Robison (1739 – 1805) then an

undergraduate who graduated in 1759, who later undergraduate who graduated in 1759, who later became professor of natural philosophy in 1774 in became professor of natural philosophy in 1774 in Edinburgh Edinburgh


James Watt: Highlights of a Remarkable Life Met Joseph Black, professor of anatomy and botany, Met Joseph Black, professor of anatomy and botany,

later professor of medicine. Long term associate.later professor of medicine. Long term associate. Partnership with merchant John Craig, October, 1759.Partnership with merchant John Craig, October, 1759. By 1764, Watt had 16 employees (age 28). By 1764, Watt had 16 employees (age 28).

Bankrolled by Craig.Bankrolled by Craig. Married his cousin, Margaret Miller, 1764.Married his cousin, Margaret Miller, 1764. James Watt Jr. born (1769 – 1848).James Watt Jr. born (1769 – 1848). Robison first planted idea of a steam carriage, 1759.Robison first planted idea of a steam carriage, 1759. Robison passed on books on steam from university Robison passed on books on steam from university

library.library. Watt measured relation between steam pressure and Watt measured relation between steam pressure and

temperature temperature


James Watt: Highlights of a Remarkable Life Began to work with model Newcomen engine 1764 Began to work with model Newcomen engine 1764

(age 28).(age 28). Measured heat capacities of wood, iron and copper. Measured heat capacities of wood, iron and copper.

Measured latent heat. Black’s influence.Measured latent heat. Black’s influence. April 1765, thought up idea of separate condenser April 1765, thought up idea of separate condenser

(age 29).(age 29). Watt admitted steam above piston. Valve connected Watt admitted steam above piston. Valve connected

above and below piston at bottom of stroke. above and below piston at bottom of stroke. Beginning of partnership with John Roebuck (1718 – Beginning of partnership with John Roebuck (1718 –

1794), former pupil of Black, successful industrialist. 1794), former pupil of Black, successful industrialist. Use of Roebuck’s Carron foundry and workshop at Use of Roebuck’s Carron foundry and workshop at Kinneil House. Kinneil House.

Worked on canals beginning 1767Worked on canals beginning 1767


James Watt: Highlights of a Remarkable Life Returned to work on engine 1768 completing a model Returned to work on engine 1768 completing a model

6 months later. Roebuck agrees to pay for patent in 6 months later. Roebuck agrees to pay for patent in return for “two thirds of the property of the inventions”. return for “two thirds of the property of the inventions”.

Met Dr. William Small, friend of Roebuck, first in Met Dr. William Small, friend of Roebuck, first in Birmingham in 1767. Franklin had introduced Small to Birmingham in 1767. Franklin had introduced Small to Matthew Boulton (1728 – 1809). Matthew Boulton (1728 – 1809).

Soho Works.Soho Works. Patent awarded 5 January 1769.Patent awarded 5 January 1769. Correspondence between Small and Watt. Watt Correspondence between Small and Watt. Watt

sought to draw Boulton into the Watt-Roebuck sought to draw Boulton into the Watt-Roebuck partnership. partnership.

Roebuck in financial trouble. Bankrupt. Transfer of Roebuck in financial trouble. Bankrupt. Transfer of interest in patent to Boulton May 1773 (Watt age 37) interest in patent to Boulton May 1773 (Watt age 37)


James Watt: Highlights of a Remarkable Life Wife dies 1773.Wife dies 1773. Watt, with James Hutton (1726 – 1779), moves to Watt, with James Hutton (1726 – 1779), moves to

Birmingham, May 1774. Birmingham, May 1774. Bill extending patent introduced in Parliament, February, Bill extending patent introduced in Parliament, February,

1775. In May, 1775, patent extended to 1800. 1775. In May, 1775, patent extended to 1800. John Wilkinson 91728 – 1808), iron master, casts 18 inch John Wilkinson 91728 – 1808), iron master, casts 18 inch

diameter cylinder, investing accurate boring machine. diameter cylinder, investing accurate boring machine. Wilkinson orders first engine.Wilkinson orders first engine.

Watt remarries July 1776 (age 40).Watt remarries July 1776 (age 40). William Murdock (1754 – 1819) joins firm 1777. Becomes William Murdock (1754 – 1819) joins firm 1777. Becomes

important on-site managerimportant on-site manager Difficulties in constructing engines. Difficulty in extracting Difficulties in constructing engines. Difficulty in extracting

payments. Financial stress payments. Financial stress


James Watt: Highlights of a Remarkable Life Boulton suggests developing rotary motion, 1781. Boulton suggests developing rotary motion, 1781.

Neglects to take out patent. Patent taken out by John Neglects to take out patent. Patent taken out by John Steed working for James Pickard Assertion that idea was Steed working for James Pickard Assertion that idea was stolen by Cartwright (later hanged!) . stolen by Cartwright (later hanged!) .

Watt patents five new methods of rotative motion Watt patents five new methods of rotative motion including sun-planet arrangement, 1781 (age 45).including sun-planet arrangement, 1781 (age 45).

Double action engine patented 1782.Double action engine patented 1782. Patented technique for using expansive action in 1782. Patented technique for using expansive action in 1782.

Had begun to work on this idea as early as 1769.Had begun to work on this idea as early as 1769. Many other inventions on the side: a copying machine; Many other inventions on the side: a copying machine;

drying machine for cloth; instrument for measuring drying machine for cloth; instrument for measuring specific gravity of liquids.specific gravity of liquids.

1782 patent also envisaged coupled engines 1782 patent also envisaged coupled engines


Work done as piston expands through a distance d

Let area of the piston be given by A.Let area of the piston be given by A.Assume pressure p acting from left; vacuum to the Assume pressure p acting from left; vacuum to the

rightrightWork done = (Force) (Distance)Work done = (Force) (Distance)

= (pA) d = pAd = p= (pA) d = pAd = pΔΔVVwhere where ΔΔV = volume of expansionV = volume of expansion


Thermodynamics ΔΔQ Q = = ΔΔE E + p + p ΔΔVV

Heat added increase in internal energy work doneHeat added increase in internal energy work done

ΔΔE = N CE = N Cvv ΔΔTT

Number of moles specific heat per moleNumber of moles specific heat per mole

ΔΔQ Q = N C= N Cvv ΔΔT + p T + p ΔΔVVSuppose expansion takes place without Suppose expansion takes place without

addition of heat addition of heat process is adiabatic process is adiabatic

N CN Cvv ΔΔT + p T + p ΔΔV = 0V = 0


Thermodynamics But But pV = NRTpV = NRT

constantTV

constantTV

constant)log(

constantloglog

5

2

v

v

C

R

C

R

v

v

v

TV

VC

RT

V

V

C

R

T

T

VV

NRTVpTNC

V

NRTp


Thermodynamics

decreases p increases, V As

)(

V)(

decreases T increases, V As

Vconst T

5

7

5

2

5

2

NRVconst

V

constNR

V

NRTp


James Watt: Highlights of a Remarkable Life 1783 Watt delivers a 700 lb. stamp hammer to 1783 Watt delivers a 700 lb. stamp hammer to

Wilkinson. Works a hammer raised 2 ft making up Wilkinson. Works a hammer raised 2 ft making up to 300 blows per minute.to 300 blows per minute.

1784 parallel motion patent – “one of the most 1784 parallel motion patent – “one of the most ingenious simple pieces of mechanism I have ingenious simple pieces of mechanism I have contrived”. contrived”.

1785 – Watt’s last patent. For improved methods 1785 – Watt’s last patent. For improved methods of constructing furnaces and fireplaces (age 49). of constructing furnaces and fireplaces (age 49).

The centrifugal governor was not invented by The centrifugal governor was not invented by Watt but was critical in ability to maintain a Watt but was critical in ability to maintain a uniform speeduniform speed


James Watt: Highlights of a Remarkable Life 1784 Watt and Boulton elected Fellows of the Royal Society 1784 Watt and Boulton elected Fellows of the Royal Society

of Edinburghof Edinburgh 1785 Watt and Boulton both elected as Fellows of the Royal 1785 Watt and Boulton both elected as Fellows of the Royal

Society of London (age 50)Society of London (age 50) Watt credited with developing the unit “horse power”. Watt credited with developing the unit “horse power”.

Savery believed that to have 1 horse work all the time, you Savery believed that to have 1 horse work all the time, you needed 3 horses. Watt claimed “average horse” could work needed 3 horses. Watt claimed “average horse” could work several hours raising 22,000 pounds one foot in one minute. several hours raising 22,000 pounds one foot in one minute. Defined 1 horse power as 33,000 ft. pounds per minuteDefined 1 horse power as 33,000 ft. pounds per minute

Original patent expires 1800. Transferred shares to sons, Original patent expires 1800. Transferred shares to sons, James Watt Jr., Matthew Robinson Boulton and Gregory James Watt Jr., Matthew Robinson Boulton and Gregory Watt. Gregory dies 1804. Firm continues successfully for 40 Watt. Gregory dies 1804. Firm continues successfully for 40 years until sons retired.years until sons retired.


James Watt: Highlights of a Remarkable Life Soho works, up to 1824, completed 1164 steam Soho works, up to 1824, completed 1164 steam

engines, nominal horsepower 25,945engines, nominal horsepower 25,945 Watt died August 19, 1819, age 83. Buried in the local Watt died August 19, 1819, age 83. Buried in the local

parish churchyard alongside Boulton. Joined later by parish churchyard alongside Boulton. Joined later by Murdoch. Murdoch.

Monument to Watt in Westminster Abbey. Statue by Monument to Watt in Westminster Abbey. Statue by Chantrey, inscription by Lord Brougham. Chantrey, inscription by Lord Brougham.



Watt as Scientist Was Watt first to identify the composition of water? Priestley Was Watt first to identify the composition of water? Priestley

proved that the weight of water deposited on sides of a proved that the weight of water deposited on sides of a vessel following reaction of oxygen and hydrogen is the vessel following reaction of oxygen and hydrogen is the same as the weight of the two gases. (Priestley is credited same as the weight of the two gases. (Priestley is credited with the discovery of oxygen)with the discovery of oxygen)

Watt’s Letter to Priestley, April 26, 1783Watt’s Letter to Priestley, April 26, 1783“ “ What are the products of your experiment? They are water, light What are the products of your experiment? They are water, light

and heat. Are we not, thence, authorized to conclude that and heat. Are we not, thence, authorized to conclude that water is a compound of the two gases, oxygen and water is a compound of the two gases, oxygen and hydrogen, deprived of a portion of their latent or elementary hydrogen, deprived of a portion of their latent or elementary heat; that oxygen is water deprived of its hydrogen but still heat; that oxygen is water deprived of its hydrogen but still united to its latent heat and light? If light be only a united to its latent heat and light? If light be only a modification of heat, or a simple circumstance of its modification of heat, or a simple circumstance of its manifestation, or a component part of hydrogen, oxygen gas manifestation, or a component part of hydrogen, oxygen gas will be water deprived of its hydrogen, but combined with will be water deprived of its hydrogen, but combined with latent heat.”latent heat.”

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Energy, Environment, and Industrial Development