Kelv Planck Statement of te Second aw It is imossible to construct an enge wic, oeratg a cycle, will roduce no oter effect tan te extraction of eat from a sgle reservoir and te erformance of an equivalent amount of work. Clausius Statement of te Second aw It is imossible to ave a system oeratg a cycle wic transfers eat from a cooler to a otter body witout work beg done on te system by te surroundgs Reversible eat Enge Reversible Refrigerator
Actual eat Enge
Actual Refrigeration Mace
Carnot Power Cycle Reversible constant temerature rocess Reversible adiabatic, rocess exansion, rocess, rocess eat transfer, Efficiency Desired Effect Required Inut cycle ork
Carnot Refrigeration Cycle Reversible constant temerature eat transfer, rocess, rocess Reversible adiabatic exansion, rocess rocess Coefficien t of Performance CP CP refrigerator eat um Desired Effect Required Inut ork out ork
NECMEN AMSPERIC ENGINE Ford Museum,Detroit, 760, strokes/m
NECMEN AMSPERIC ENGINE Ford Museum, 760 strokes/m atmoseric ressure F 7 stroke 5 sia steam 8 50 F water
NECMEN AMSPERIC ENGINE atmoseric ressure Ford Museum, 760 strokes/m 5 sia steam 8 F 7 stroke 50 F water A πr F A F d Power Power π 6 (.7 sia.8 sia) 9 lbs ( 7/) ft ft lb 5,68 stroke 765,000 ft lb/m,000 /ft lb/m strokes m 6 9 lbs 5,68 ft lb/ stroke 5 sia ( F) ft lb 765,000 m P or 7.5 kw 50 F (.8 sia) v m V v 6 /stroke strokes ft / strokes ft /6.6 m lb. lb/m
NECMEN AMSPERIC ENGINE atmoseric ressure Ford Museum, 760 strokes/m 5 sia steam F A F d m 8 F A πr π 6 (.7 sia.8 sia) 9 lbs ( 7/) ft ft lb Power 5,68 stroke 765,000 ft lb/m Power,000 /ft lb/m 7 stroke strokes m 50 F water 6 9 lbs 5,68 ft lb/ stroke ft lb 765,000 m P or 7.5 kw V 6 /stroke strokes ft strokes /6.6. lb/m v ft / m lb g 5 sia ( F) v05.5 BU/lb 80 F (.507 sia) l9.08 v @5, sia 50.5 BU/lbm @ 80 l m F 9.08 BU/lbm,759. BU/lbm 765,000 ftlb/m 778 ftlb/bu ( 9.008 BU/lb). lb/m 50.5 BU/lb 9. BU/m CYCE CYCE CARN l 9.BU/m,759. BU/lbm 6.% 80 0.% 60 +
Carnot Prciles. No enge oeratg between two eat reservoirs, eac avg a fixed temerature, can be more efficient tan a reversible enge oeratg between te same reservoirs. actual Carnot. All reversible enges oeratg between two eat reservoirs, eac avg its own fixed temerature, ave te same efficiency.. e efficiency of any reversible enge oeratg between two reservoirs is deendent of te nature of te workg fluid and deends only on te temerature of te reservoirs.. An absolute temerature scale can be defed a manner deendent of te termometric material.
FIGURE 5-7 Proof of te first Carnot rcile. Coyrigt e McGraw-ill Comanies, Inc. Permission required for reroduction or dislay. 5-5
function(, ) from enge scematics by identity, function(, ) f(, substitutg, ) f(, ) f(, ) f(, ) f(, ) ermodynamic emerature Scale f(, ) tis equation can be satisfied only if, l and l l l A reversibleenge (or a real enge corrected to reversibe)can be used to measure temerature difference. Second aw eat Enge ermodynamic emerature Scale
SECND A and ut and s s.66 i i.6 i substituti ng.66 Scale Range.66 Scale Range for, is meaasured, - absolute temeratures. emerature scales can be setu for any arbitrarily sleected scale 0 ot and Scale Range of degrees between ice and steam. ScaleRange, en a reversible enge (or a real enge correctable to reversible ) is run between ice and steam temeratures wit a constant eat s s i out i i i s For ice as Scale 0 00 i 7.5.66 Celsius 0 7.5 K For : : Celsius 00 80 Scale Scale less 80 i 9.68 K.66 Fareneigt 0 9.68 - Fareneigt 0 Scale Range Fareneig t Scale Range tan ice as Scale 0 59.68 K R
Carnot Cycle Performance ork CP ork CP ork - CP are, and Carnot efficiency e scale, temerature termodynamic absolute te Usg out CYCE REVERSIBE CARN EA PUMP CYCE REVERSIBE CARN REFRIGERA R CYCE REVERSIBE CARN ENGINE
alf te work of an enge oeratg between 800 C and 0 C is used to ower a refrigeration mace absorbg eat at C and rejectg 6,000 kj/r at C ow muc eat is sulied to te enge? CP eat um eat um eat enge out CP ea ea,556 out out tum l tum kj/r out eat um 6,000 kj/r.8 89..75 l 89. kj/kg 780 K.75 800 + 7.5 7.5 + 0 eat enge.8 800 C eat um eat enge eat um C 0 C C 6,000 kj/kg 5-6
.00 kg steam executes te followg cycle. e absolute ig temerature is twice te absolute low temerature and te net work outut is 5 kj. eat is rejected durg a ase cange from a vaor to a liquid. at is te rejection temerature? l out l l l 5 kj.5 l 5 kj 50 kj.5 out m 5 kj out 5 kj 7. kj/kg m.00 kg @ fg 7. fg 5 8.6. 7. 0 0.5 5 ( 7. - 8.6) ( 0.5-7.) 5. C fg.00 kg steam S
00 K 00 K wo Carnot enges oerate series at te same efficiency. e ig temerature enge receives eat at 00 K and te low temerature enge rejects eat at 00. at is te temerature between te enges? 00 00 l ( 00 ) 00 ( 00 00) 88.5 00 00 00 00 00 00 00 K.5 5-
Sce cycle l oneof l 0 may be deendent of l te caracteristics at, of a termodynamocroerty. l In First aw, cycle ( d ) 0 lead to te defitionof termodynamic roerty E + energy as a
Ideal Gas Carnot Cycle roerty reversible cycle like a beaves tis d 0 P ln R ln R n d Note R ln P R ln R ln P P or P P constant v for P R ln R ln P R ln R ln l net n n n n n net rocess, rocess Reversible adiabatic exansion,,rocess rocess Reversible constant temerature eat transfer,
An engeer roosed an attemted to imrove te efficiency of a ower cycle by transferrg eat from te available ig temerature source to am alternate iger temerature source usg a eat um. at do you tk of tis suggestion?, enge CP eat[um enge enge eatum Enge enge eat um, eat Pum eat um were enge enge eat um eat um tere is no net work ga wit reversible maces and tere would be a net loss wit real maces.,