The utilization of exhaust waste heat is now well known and the basic of many combined cooling, heating, and power installations. Heat recovery from automotive engines has been predominantly for turbo-charging or others such as cabin heating, thermoelectric, and air conditioning. The exhaust gases from such installations represent a significant amount of thermal energy that traditionally has been used for combined heat and power applications. This paper explores the theoretical performance and simulation of natural aspirated spark ignition engine model of 1.6 L, which is occupied with waste heat recovery mechanism (WHRM). Mathematical model and simulation test results suggest that the concept is PFI thermodynamically feasible and could significantly enhance system performance depending on the load applied on the engine. However, the experimental test should be conducted to validate the simulation results as for scalability and reliability that require further investigation

Herawan, Safarudin Gazali

Ismail, Ahmad Faris

Rohhaizan, Abdul Hakim

English

Universiti Teknikal Malaysia Melaka (UTeM) Repository

SAFARUDIN GAZALI HERAWAN ABDUL HAKlM ROHHAIZAN AHMAD FARlS ISMAIL 0000098135 1 Waste heat recovery from the exhaust of natural aspirated engine / Safarudin Gazali Herawan, Abdul Hakim Rohhaizan, Ahmad Faris Ismail. I WASTE HEAT RECOVERY FROM THE EXHAUST OF NATURAL ASPIRATED ENGINE I UNlVERSlTl TEKNIKAL MALAYSIA MELAKA WASTE HEAT FUCCOVERY FROM THE EXHAUST OF NATURAL ASPIRATED ENGINE Safarudin Gazali ~era\van""*, Abdul Hakim ~ohhaizan'~ and Ahmad Faris ~ s m a i l ~ ' ~  '3 Fakulti Kejuruteraan Mekanikal, Universiti Teknikal Malaysia Melaka, Melaka, Malaysia, "mail: safarudin@utem.edu.my, "mail: ake31nz@gmail.com Kulliyyah of Engineering, International Islamic University Malaysia, Gombak, Malaysia. 'Email: faris@iium.edu.my Abstract-The utilization of exhaust waste heat is now well known and the basic of many combined cooling, heating, and power installations. Heat recovery from automotive engines has been predominantly for  turbo-charging or others such as enbin heating, thermoelectric, and air conditioning. The exhaust gases from such instsllations represent a significant amount of thermal energy that traditionally has been used for combined heat and power applications. This paper explores the theoretical performance and simulation of natural aspirated sparlc ignition engine model of 1.6 L, which is occupied with waste heat recovery mechanism (WHRM). Mathematical model and simulation test results suggest that the concept is PFI thermodynamically feasible and could significantly enliance Figure 2: Efticieney of Gasoline and Diesel Engines [7] system performance depending on the load applied on the engine. However, the experimental test should be conducted to validate the simulation results as  for scalability and reliability that require further investig a t '  ion. Key~uor(ls-Waste heat recovery; Natural aspirated engine; Turbo-system. The number of motor vehicles on the globally roads and the number of miles driven by those vehicles continue to grow, resulting in increased air pollution, increased petroleum consumption, and increased reliance on the sources of petroleum. To overcome these trends, new vehicle technologies must be introduced to achieve better fuel economy without increasing harmful emissions. For internal combustion engine (ICE) in most typical gasoline fuelled vehicles, it is well known that only approximately 25% of the fuel energy is utilized for vehicle in rotating the wlieels and accessories [I I]. As shown in Fig. I and Fig. 2, the remainder of the fuel energy is lost in the form of waste heat in the exhaust and coolant, as well as friction and parasitic losses [ I  I]. Figure I. Typical energy path in gasoline helled Internal Combustion Engine Vehicle [I  I ]  Since the electric loads in a vehicle is increasing due to improvements of comfort, driving performance and power transmission, it is interesting to utilize the wasted energy by developing a heat recovery mechanism of exhaust gas from internal combustion engine. It has been identified by 141 that the temperature of exhaust gas varies depending on the engine load and engine speed as shown in Fig. 3.  From the figure, it can be seen that significant amounts of energy that would normally be lost via engine exhausts can be recovered into electrical energy. Theoretically, the engine exhaust gas can be harnessed to supply an extra power source for vehicles and result in lower fuel consumption, greater efficiency and an overall reduction in greenhouse gases. Figurc 3. Temperature of Eslraust Gas [4] The aim of this research is to create waste heat recovery mechanism that can produce power generation system that can be used for electrical purposes such as air conditioning, power steering, or other electrical/electronic device in automotive vehicle. A. Ctrrrent sttidy on waste heat recovely 111. RESULTS AND DISCUSS~ON The main points of this section can be highlighted as follows: 1. Most of the proposed works for waste heat recovery is using diesel engine since the gas exhaust is in the high temperature, the compression ratio is high, the higher mass flow rate of air, and higher load compared to spark ignition engine [6, 81. 2. Most of tlie current methods of recovery of waste heat are reported in literatures using turbocharger, thermoelectric, turbocompound, absorption air conditioning system [2,9, 101. 3. Only few proposed work using spark ignition engine for this purpose. It might be the problems as mentioned above are difficult to recover the waste heat, and also can generate knocking and reduce the engine performance [I, 31. These motivate 11s to investigate a heat recovely mechanism from exhaust gas using natural aspirated spark ignition engine for additional power in automotive vehicle. In this work, a novel waste heat recovery mechanism for auxiliary power unit in automotive vehicle is proposed. By using a model of spark ignition engine equipped with waste heat recovery mechanism (WHRM), the power produced of WHRM can be determined. The methodology research of this work is based on the modeling and simulation, tlieri validated by the experimental works and continued with the data learning method to propose tlie optimum validation of the results. The simulation is done in simulink Matlab. All tlie conditions of simulation work and experimental work are in the free load condition with neutral position of transmission engine. In this simulation, all the sub systems in the engine model are simulated in each sub system model and integrated every sub system to another to achieve the desirable results. These simulation resdts are obtained fi-om the mathematics model of spark ignition engine equipped with WHRM and validated with discrete analogue data fiom the experimental work. The whole sub system model is shown in Fig. 4. Below, the result of simulation is obtained. The pressure and temperature exhaust with increasing engine speed are shown in Fig. 5 and Fig. 6. These simulation results are obtained from the engine model and validated with discrete analogue data from the experimental work. Fignrc 5. Pressure Eshaust vs Engine Speed .fir1 1. 1 I -m3 , . . s - , - ~ - - _ r  l-.-.r_l-L-.r_lr_lr_l"r_lr_lL" L. L ' i - rm .L.3] : .?LO ? . 2x0 iirx 5?.>? <.LC  PIC:,;* ::,.< .!; ,7 . 1;iglrre 6. Teinpenture Eshaust vs Engine Speed It is clearly shown in Fig. 5 that pressure fiom exhaust manifold is increasing with increasing engine speed. Since tlie engine is a natural aspirated spark-ignition (SI) engine, the pressure exhaust is lower than SI turbocharger engine [7] and diesel engine [5]. The reasons are the ST turbocharger engine has higher pressure boost in intake manifold resulting a higher pressure exhaust, and for diesel engine, the pressure ratio is more higher than a natural aspirated SI engine. Fig. 6 shows the temperature from eshaust manifold with increasing engine speed. The temperature exhaust will increase when the engine speed is increasing. However, these temperatures are slightly lower compared to diesel engine [4]. At the 0% engine load of diesel engine, the temperature of exhaust is higher than the simulation results, nevertheless at 6000 rpm of engine speed, both of the temperatures of exhaust are almost same. Based on the simulation results of temperature from exl~aust manifold and exit temperature fiom WHRM, tlie power produced and torque by waste heat recovery mechanism (WHRM) can be determined by the model of modified turbocharger model. The exit temperature from WHRM is validated with discrete analogue data from the experimental work. . I Figurc 4. Simulation of Engine model and WHRM As shown in Fig. 7, the power will raise when the engine speed is increasing. When applying the normal driving, the engine speed is around 1500 up to 3500 rpm, WHRM can produce the power from 1 up to 4 kW. This kind of energy is significant enough to be recovered for an auxiliary power in automotive vehicle. Figure 7. Power Produced by WHRM vs Engine Speed The torque generated by WHRM can be observed in Fig. 8 with increasing engine speed. The simulation results of torque can be obtained based on power produced by WHRM and WHRM shaft speed. The speed of shaft WHRM, which is shown in Fig. 8, is validated wit11 discrete analogue data from the experimental work. ::i..-, . .,. . . . - r .I..-.- ^L i-.s --.. 2 .. . . ... . - i.. _.! 1 . . I  " 0  . r.:,, i3...! v:.+: i<.,j ,:>.?I E!.!,.,, ..rt !s:,,,-, Figure 8. WI-IRM Speed vs Engine Spced As shown in Fig. 9, the torque generated by WHRM will raise when the engine speed raise. At 4000 rpm, the torque is at the maximum value, and remains constant with increasing engine speed. The WHRM torque is very important parameter to determine the sufficient power and torque for running the generator/alternator. The maxinium torque of WHRM is 4.5 Nm at 4000 rpm. This figure shows that the torque is not sufficient to drive the alternator based on Fig. 8. Therefore, it is not comply when tlie pulley of WHRM is coupled with the Pulley of alternator by 1 to 1 ratio. To overcome the problem with regards to insufficient torque to drive the alternator, the speed of alternator shaft should be reduced. In this way, the torque applied on alternator shaft can be increased. By changing the pulley ratio between WHRM pulley and alternator pulley such as %, 1 6 ,  %, 1/5, and 1/6, the alternator speed and the torque are summarized in Fig. 10 and Fig. 11, respectively. - .  -1; 1 : :I' j il.... j .>,, - 2  I c " 3 .  5 t.j.,> : r.lr*> - ," Dn.)..t ':i-?r-; tl!m, Figure 9. WHRM Torque vs Engine Spced It is clearly shown that the smaller ratio can reduce the alternator speed and the same time, can increase the torque. For ratio of %, 1/3, and I/4 as shown in Fig. I I ,  the torques are not sufficient to overcome requirement of minimum torque of the product to drive the alternator. Therefore, tlie ratio of 1/5 and 116 are pass the requirement of minimum torque of the product. However, to gain more output current, the alternator shaft speed should be higher. Since the ratio of 1/5 has a higher alternator speed compared to 1/6, therefore, the ratio of 1/5 is the optimum choice to use for running the alternator. j loo00 - + 2x Pulley WHRM m 3 x  Pullav WHRM I I I 1000 2000 3000 4000 5000 6000 1 1 Engine Speed (rpm) i Figure 10. Allemator Speed vs Engine Speed for 5 Different Pulley Ratio / A3xPullw WHRM .I- t X4xPulley WHRM i I 0 -1 . _ _ J :  - 11000 2000 3000 4000 5000 6000 1 I -- Alternator Speed (rprn) 1 Figure I I .  Alternator Torque vs Engine Spced for 5 Different Pulley Ratio and Product Fig. I2 and Fig. 13 show the current that generated by alternator for 115 ratio and 116 ratio, respectively. While, Fig. 14 and Fig. 15 show the power output by alternator for 115 ratio and 1/6 ratio, respectively. It is clearly shown that the ratio of 1/5 can generate higher current as well as power compared to the ratio of 116. The reason is the 115 ratio has higher alternator shaft speed than 116 ratio. Even though, the torque of 116 ratio is higher than 115 ratio. d I: cg!. K :  ,2 d31.  I I ! LJ I. i I $, J : :  .; 2 :  ! < : ,  +;*, ei:.,,:4 Er., .e "5 .>,a :,,?..A Figurc 12. Current outp"t vs Engine Speed for 115 ratio c - _ _ l i - . A  i I%<!:lr !'M .93 : 4'0.. jifl i Y 6  -9.63 F,?;r,. 'i-.,d .,>lf. Figurc 13. Currcnt output vs Engine Speed for I16 ratio : , '  .L :$'>? .3?:-c :-I.>. I . :cc 2 ,  2 : >  &:cc b;xr Z;eJ x*(tr.l Figurc 14. Power oulput vs Engine Speed for IR ratio .-.z ,. -. [------ 5.1 -" _--. - :<z, i -._._- .. .- 4 - - :A:,? . -.- *- # g 5.a ._.- 3 .3:cl " ,.,i r \-.; rL. : r<Gt :t,v L i 1 ,, *, , i C . ) -. t : " _ i l i - . - .  . ' I  = a  '~yn L ~ G  : =c-o ? ;re-! Et,!r** < ~ . + Z J  (,I.?.; Figurc 15. Powver output vs Engine Speed for I16 ntio By using Fig. 14, which is an optimum choice for the system, the power output can be recovered is around 200 W up to 1600 W. In the normal driving, the engine speed is around I500 up to 3500 rpm, this system can produce the power up to 1.2 IcW. IV. CONCLUSIONS The simulation work of waste heat recoverv mechanism for an auxiliarv Dower unit in automotive vehicle has . . been presented. It is shown by the siinulation that waste heat from exhaust gas can be recovered. The results show the output power is not so huge, however the condition on experimental work and simulation work are on the fiee engine load. Therefore by applying the engine load, the results of output power will become greater. [I] Boatto, P., Boccaletti, C., Cerri, G., and Malvicino. C., Internal Combustion Engine Waste I-leat Potential for an Autoniotive Absorption Systen~ of Air Conditioning. Part I :  Test on tlic Eslianst Systeni of a Spark-Ignition Engine, Proc. Insr~i. ~bfecli. D~grs rrol. 21 4 Part D, IMecltE 2000. [2] Bumby. J. R., Spooner, E. S., Carter, J., Tctinant, H., Mego, G. G., Dellora, G., Gstreiti, W., Sutter, H., and Wagner, J.. Electrical hlac/iincs for Use in Electrica/ly Assisted T~rrbocl~argers, The Institution oFElectrical Engineers, 2004. [3] Darlington, T. E. and Frank, A. A., Exlia~~st Gas Driven Generator with Altitude Compensation for Battery Dominant Hybrid Electric Vehicles, SAE Trclrnical Paper Series, SAE International, 2003. [4] Eder. A. and Crane, D., Syste~ii Architecture of Thermoelectric Wastc Heat Recovery. Proceedings of /Ile 2005 DEER Conjcrerrce, A11g11sf 25-27. C/~icago. IL, 2005. [5] Han, S. B.. Lee, N. H., and Lec. S., A Study on tlic Unsteady Temperature Field of Combustion Cliamber Wall in a Turbocharger Gasoline Engine, KShIE Jorrrnal, vol. 10, no. 4, pp. 5 18 - 525. 1996. [GI Katrasnik, T.. Medica, V., and Trenc, F., Analysis of the Dynamic Response Improvement of a Turbocharger Diesel Engine Driven Alternating Current Generating Set. Diergy Conversion anrl d~lanagen1enf46.2838 -2855,2005. [7] LaGnndeur, J.. Crane, D. and Eder, A., Vehicle Fuel Eco~iomy Improvement Througl~ Thermoelectric Waste Heat Recovery. Proceedings of f l~e  2005 DEER Cot,/eretrce. clrrgzrst 25-27. Clticogo, IL. 2005. [8] Talbi, M., and Agnew, B., Energy Recovery fro111 Dicsel Engine Exhaust Gases for Performance Enliwcement and Air conditioning, Applied Tllcrtnal Engineering 22, 693 - 702, 2002. [9] Talom, H. L.. and Beyene, A., Heat Recovery fro111 Automotive Engine, Applied 771er11tal Engineering (Article in press). 2008. [lo] Yang F., and Yuan, X., and Lin, G., Waste Meat Recovery using Heat Pipe Heat Exchanger for Heating Automobile using Exhaust Gas, Applied Tl~ertnal Engineering 23, 367 - 372, 2003. [I I] Yang, J., Potential Applications of Thermoelectric Waste Meat Recovery in tlie Automotive Industry, 2005 lnter~rationul Col7jieretice on T~~ert~ioelecf~ics. IEEE, 2005. 

Waste Heat Recovery From The Exhaust Of Natural Aspirated Engine

http://eprints.utem.edu.my/id/eprint/20112/1/WASTE%20HEAT%20RECOVERY%20FROM%20THE%20EXHAUST%20OF%20NATURAL%20ASPIRATED%20ENGINE-SAFARUDIN%20GAZALI-MAK%2000341%20RAF.pdf

Waste Heat Recovery From The Exhaust Of Natural Aspirated Engine

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