USE OF EXHAUST GASES IN PISTON INTERNAL COMBUSTION ENGINE BY IMPLEMENTATION OF THE STIRLIG CYCLE

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1 0. medzinárodná vedecká konferenci Riešenie krízových situácií v špecifickom prostredí, Fkult bezpečnostného inžinierstv ŽU, Žilin, máj 05 USE OF EXHAUS GASES IN PISON INERNAL COBUSION ENGINE BY IPLEENAION OF HE SIRLIG CYCLE Detelin Vsilev *) ABSRAC he improvement of the fuel economy of the piston internl combustion engine is lwys question of present interest. One wy of solving it is the use the energy of the exhust gses. he scope of the study is test of n engine, which is set of four-cycle piston internl combustion engine nd n engine connected to its shft, operting ccording to the Stirling cycle nd using the het of exhust gses of piston internl combustion engine. Key words: internl combustion engine, Stirling engine, fuel economy. ABSRAK Zlepšenie spotreby pliv piestového spľovcieho motor je stále ktuáln tém. Jeden zo spôsobov riešeni spočív vo využívní energie z výfukových plynov. Predmetom príspevku je test motor tvoreného štvordobým piestovým spľovcím motorom motorom pripojeným k jeho hrideľu, prcujúcim podľ Stirlingovho cyklu, z použiti tepl z výfukových plynov piestového spľovcieho motor. Kľúčové slová: spľovcí motor, Stirlingov motor, spotreb pliv. INRODUCION here re mny plnts in literture tht uses the energy of the exhust gses of the piston internl combustion engine (ICE). All of them improve fuel economy to certin degree. here re plnts tht operte ccording to the Rnkine cycle with stem turbine nd there re plnts with gs turbine. All these plnts hve the disdvntge tht the vne nd plte mchines re externl to the piston engine combustion, which is precondition for incresing the therml nd mechnicl losses. he speed of the gs nd stem turbines is ten to * Detelin Vsilev, Assoc. Prof., PhD, odor Kbleshkov University of rnsport, 58 Geo ilev Str., Sofi, Bulgri, tel.: , mobile tel.: , dvsilev@vtu.bg 707

2 twenty times higher thn tht of the piston engine, which is why optiml collbortion occurs only in the clcultion mode or in very nrrow working rnge round it. hese shortcomings cn be voided to some extent, if the energy of the exhust gses is used in cycle of Stirling, s the cylinders of the internl combustion engine nd the Stirling cylinders re combined into single housing with common crnkshft. he scheme of such combined engine is shown on Fig.. HEADING he combustion engine is double-cylinder, four-tct engine, where both cylinders move synchronously, but their work is out of phse t he knee of the Stirling cylinder 3 is dephsed to the knees of the engines t +5 0, nd tht of the Stirling cylinder - t -5 0, where the ngle between them is r3 Н O Р Н C E 3 r C E Н O Р Н r r r 3 Figure he exhust gses from the internl combustion engine pss successively through the two het-exchnge groups, ech of which consists of heter H, regenertor R nd cooler O, nd then come out into the tmosphere. he spces bove the pistons of both Stirling cylinders re interconnected through the upper het exchnger. Subpiston spces re similrly connected through the lower het exchnger. hus both Stirling pistons form the hot volume E nd cold volume C. For defining the verge torque nd the effective power of the internl combustion engine the methodology given in [] shll be pplied. he inertil force of the movement of crnkshft group is locted by the sttement: cos sin sin P j Rm j cos, () sin sin 708

3 where m j is the reduced mss of the j piston, R nd L respectively the lengths of the R knee nd the connecting rod,, the ngle of the rottion of the knee, ω the L ngle speed. he gs force is defined pplying the sme procedure [] using the indictor digrm from Fig.. he imported quntity of het Q is determined by the expression: Q g ц H u, () where g ц is the fuel portion of the cycle, nd H u - the lower specific het of fuel combustion. he pressures in specific points of the indictor chrt types hve the expression: k pc cp, (3) k nq yk py cp, () V p b k b k k V n knk nk Q y k k c p V Q yz c k kp V where с is fctor, which determines the losses during compression, k is the fctor of 5 V the dibtic, p 0,9.0 P, Vc compression rtio, n distribution coefficient of imported het, y fctor, which determines the losses during the combustion t constnt volume, b chrcterizes the losses during relese. At the so determined pressure p г, the gs force is determined by the following expression: D Pг p г. (6) he totl force cting on the crnk mechnism is defined s the mount of the gs nd the inerti forces: k, (5) Q =Q' +Q'' P P г P j. (7) he torque of the one-cylinder engine is determined by the expression: sin rcsin sin P R. (8) sin he torque of the two-cylinder engine is determined by the expression: ( 0 ) ( 360). (9) he verge torque of the internl combustion engine is determined by the expression: p p y p c p Q' c Vc y Vz Q'' z L t V Figure dq=0 b Q V 709

4 , ср. (0) 70 And the effective power of ICE is:, ср N е 0,8. () 000 Here the coefficient 0,8 gives the therml nd mechnicl losses. o determine the pressure in the Stirling sector it is ssumed tht the working substnce in the Stirling groups is n idel gs with constnt mss. Further the following indexes re plced: for prmeters ssocited with the hot volume - index E, for those ssocited with the cold volume index C nd for those ssocited with the ded - index D. We come to the expression for the totl mss of the working substnce: m me mc md. () king into ccount the eqution of the condition the expression () shll be modified like tht: p V E VC VD m, (3) R E C D where p is the pressure in the system, nd with V nd Т the respective volumes nd tempertures re mrked. If the temperture in the ded volume is the verge of the two tempertures E C D, then from (3) for the pressure in the system looks like tht: mr p. () VE VC V D E C E C he mss of the working substnce does not chnge nd is equl to its mss t the beginning, when occupying the mximum volume Vmx by the initil vlues of the p0vmx temperture Т 0 nd the pressure р 0, i.e. m. hus, the finl expression for the R0 pressure in the cylinder Stirling tkes the form: Vmx p p0. (5) V E VC V D 0 E C E C he vlues of the hot nd cold volumes re determined by the expressions: DE DC VE xe nd VC xc, (6) where D E nd D C re the dimeters of the respective pistons, nd x E nd x C re their displcements. For determining the displcements of the pistons of the 3 th nd th cylinder the following expressions re vlid: x E R cos sin nd 70

5 x C R cos sin. (7) he totl volume is determined by the expression: V VE VC VD. (8) king into ccount the lredy determined prmeters the pressures in the upper prt of the Stirling group (dephsed by +5 0 from the first piston) nd in the lower prt of the group (dephsed by -5 0 from the first piston) cn be determined by (5). hus for ech of the pistons the gs forces from bove nd below shll be determined ccording to the expressions: up D up P p down D down Г nd P p Г. (9) he inertion force for ech stirlig piston is determined by (), tking into ccount the respective dephsing (for the 3 th cylinder with +5 0, nd for th with ). he totl force cting on the crnk mechnism for the Stirling cylinder is defined s the mount of the gs nd inerti forces: up down up down P, 3 PГ,3 PГ,3 Pj,3 nd P, PГ, PГ, Pj, (0) he torque for ech cylinder Stirling is determined by expressions: sin rcsin sin 3 P,3R () sin nd sin rcsin sin P,R. () sin he cumultive torque of the Stirling group is determined by the expression: 3 3. (3) hus the verge torque of the engine of Stirling is determined: 3 3, ср () 70 nd the effective power of the engine of Stirling: 3 3, ср N е 0,75. (5) 000 Here the coefficient 0,75 mrks the therml nd mechnicl losses in this sector. he totl torque of the combined engine is defined by summing up the expressions (9) nd (3): 3. (6) he verge torque is defined s:, ср, (7) 70 7

6 while the totl effective power is equl to:, ср N e 0,8. (8) 000 he totl efficiency coefficient of this combined engine is obtined s rtio between the totl effective power nd the power tht would result from imported het Q. his power is determined by the expression: Qi N, 000 (9) where i= is the number of cylinders of the internl combustion engine. he shre of the processed energy from Stirling group, which is obtined from the exhust gses, is: 3 N е стир.. (30) N 3 From (8) nd (9) the totl efficiency coefficient of the combined engine is obtined: N e N. (3) Figure 3 he bove described methodology is pplied by determining the torque of specific two-cylinder four-cycle internl combustion engine nd two-cylinder Stirling group by the following numericl vlues of the prmeters tht re formed on the grounds of the diesel engine D3900: k=,33 y=0,95 ε=6 D=0,098[m ] n=0,5 V =0, [m 3 ] c=0,8 z=0,95 m j =[kg] R=0,0635[m] b=0,95 hrough the conducted numericl study the chrcteristics of lterntion of the torques of the ICE ccording to (9) (with the dotted line) re found (shown on fig. 3) of the Stirling group ccording to (3) (with the light line) of the totl torque of the combined engine (6) (with the solid line). he totl effective power of the combined 3 engine is N e =39,55 kw, nd only of the Stirling group - N е =,9 kw. he shre of the processed energy by the Stirling group is стир. = 0,3, nd overll efficiency of the combined engine is η = 0,508. 7

7 3 CONCLUSION We could drw the conclusion tht the built in this mnner combined engine uses effectively the fuel energy nd relizes good overll performnce rte. BIBLIOGRAPHY [] Vsilev D., utfchiev., ethodology for determining cting on the crnkhft forces nd moments, XXI Interntionl Scientific Conference "RANSPOR 03", echnics, trnsport, communictions, p., copy 3, prt, 03., ISSN 3-383, VII-3 9 (in Bulgrin), [] utfchiev., hermodynmic Fundmentls of Internl Combustion Engines, onogrph, Sofi, 0(in Bulgrin). Článok recenzovli dvj nezávislí recenzenti. 73

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