NEWCOMEN ATMOSPHERIC ENGINE

Transcription

1 NECMEN AMSPERIC ENGINE atmoseric ressure Ford Museum, 760 strokes/m F 7 stroke 5 sia steam 8 50 F water

2 NECMEN AMSPERIC ENGINE atmoseric ressure Ford Museum, 760 strokes/m 5 sia steam 8 F 50 F water 7 stroke assume 6 usabe 5 sia ( F) 80 F (.5075 sia) v F A F d m (.7 sia.5075 sia) 879.bs ( 6/) ft ft b strokes ft b Power ,0 stroke m m 67.0 ft b/m Power. P or 8.9 kw,000 /ft b/m steam V 6 strokes v 78 /ft 6,7 ft b/ stroke ft stroke 879.bs strokes m ft /6.97 b.5 b/m

3 Kev Panck Statement of te Second aw It is imossibe to construct an enge wic, oeratg a cyce, wi roduce no oter effect tan te extraction of eat from a sge reservoir and te erformance of an equivaent amount of work. Causius Statement of te Second aw It is imossibe to ave a system oeratg a cyce wic transfers eat from a cooer to a otter body witout work beg done on te system by te surroundgs Reversibe eat Enge Reversibe Refrigerator

4 Carnot Power Cyce Reversibe constant temerature eat transfer, rocess,rocess Reversibe adiabatic exansion, rocess, rocess Desired Effect Efficiency Required Inut CYCE

5 Carnot Refrigeration Cyce Reversibeconstant temerature eat transfer, rocess, rocess Reversibe adiabaticexansion, rocess, rocess Coefficien t of Performance Desired Effect Required Inut CP CP refrigerator eat um 5

6 Carnot Prcies. No enge oeratg between two eat reservoirs, eac avg a fixed temerature, can be more efficient tan a reversibe enge oeratg between te same reservoirs. actua Carnot. A reversibe enges oeratg between two eat reservoirs, eac avg its own fixed temerature, ave te same efficiency.. e efficiency of any reversibe enge oeratg between two reservoirs is deendent of te nature of te workg fuid and deends ony on te temerature of te reservoirs.. An absoute temerature scae can be defed a manner deendent of te termometric materia. 6

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8 8 ermodynamic emerature Scae and be satisfied ony if, can equation tis ) f(, ), f( ) f(, substitutg, by identity, f(, ) ), f( ) f(, from enge scematics ) function(, function(, )

9 SECND A and ut and s s.66 i i.6 i substitutg for.66 Scae Range.66 is meaasured, Scae Range, - absoute temeratures. emerature scaes can be setu for any arbitrariy seected scae 0 ot and ScaeRange of degrees between ice and steam. Scae Range, en a reversibeenge (or a rea enge correctabe to reversibe) is run between ice and steam temeratures wit a conatant eat s s i out i i i s For ice as Scae 0 00 i Cesius K For : : Cesius Scae Scae ess 80 i 9.68 K.66 Fareneigt Fareneigt 0 Scae Range Fareneig t Scae Range tan ice as Scae K R 9

10 0 Carnot Cyce Performance CP CP - e Carnot Efficiency and CP are, Usg te absoute termodynamic temerature scae, um eat refrigerator

11 NECMEN AMSPERIC ENGINE atmoseric ressure Ford Museum, 760 strokes/m m 5 sia steam F A F d V v 8 F (.7 sia.5075 sia) 879.bs ( 6/) ft 6 strokes 78 /ft 7 stroke 50 F water 6,7 ft b/ stroke ft b strokes ft b Power ,0 stroke m m 67.0 ft b/m Power. P or 8.9 kw,000 /ft b/m steam 879.bs m.5 b/m,8885 BU/m 67,0 ftb/m 778 ftb/bu ft strokes ft / b/m stroke m b 5 sia ( F) 50.7 BU/b 80 F (.5075 sia) 8.06 BU/b v ( 50.7 BU/b 8.06 BU/b ) 7.78 Btu/m CARN (~ tons/day coa ) %,87 50.% 60 +

12 af 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 suied to te enge? 800 C C 6,000 kj/kg eat enge eat um CP eat eat um um eat enge out out CP ea ea out,556 tum tum kj/r eat out um 6,000 kj/r kj/kg 780 K eat enge.8 eat um 0 C C 5-6

13 .00 kg steam executes te foowg cyce. e absoute ig temerature is twice te absoute ow temerature and te net work outut is 5 kj. eat is rejected durg a ase cange from a vaor to a iquid. at is te rejection temerature? 5 0 fg 5 m out fg out 5 kj 50 kj.5 5 kj 5 kj.00 kg abe vaues ( ) ( ) 5 kj abe vaues 7. kj/kg 5.09 C fg.00 kg steam S 50 kj 5 kj 5-7

14 Cyce efficiency is imroved wit an creased eat source temerature. at do you tk of usg a eat um to crease te ower cyce ig temerature?, η enge enge enge Enge enge eat um, eat Pum CP eat[um eatum eat um were enge enge eat um eat um tere is no net work ga wit reversibe maces and tere woud be a net oss wit rea maces., 5-9

15 00 K 00 K wo Carnot enges oerate series at te same efficiency. e ig temerature enge receives eat at 00 K and te ow temerature enge rejects eat at 00. at is te temerature between te enges? ( 00 ) 00 ( 00 00) K

16 Sce cyce may be deendent of at, one of te caracteristics of a 0 termodynamoc roerty. In First aw, cyce ( ) 0 ead to te defition of energy as a termodynamic roerty E + 6

17 7 roerty beaves tis reversibe cyce ike a d 0 P n R n R n d Note mr n P mr n mr n P P or P P constant v for P mr n mr n P mr n mr n net n n n n n net Idea Gas Carnot Cosed Cyce rocess, rocess Reversibe adiabatic exansion,,rocess rocess Reversibe constant temerature eat transfer,