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The Comparison for Different Type of Drive Mechanism for Small Solar Stirling Engine 500 W in Thailand.
 

The Comparison for Different Type of Drive Mechanism for Small Solar Stirling Engine 500 W in Thailand.

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The Comparison for Different Type of Drive Mechanism for Small Solar Stirling Engine 500 W in Thailand. ISEC 2007

The Comparison for Different Type of Drive Mechanism for Small Solar Stirling Engine 500 W in Thailand. ISEC 2007

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    The Comparison for Different Type of Drive Mechanism for Small Solar Stirling Engine 500 W in Thailand. The Comparison for Different Type of Drive Mechanism for Small Solar Stirling Engine 500 W in Thailand. Document Transcript

    • The Comparison for Different Type of Drive Mechanism for Small Solar Stirling Engine 500 W in Thailand. Eng’r. Suravut, Snidvongs*1 and Dr. Sirinuch, Chindaruksa*2 *1 Vice President, Asian Renewable Energy Development and Promotion Foundation, Bangkok, 10400, Thailand , airscan@cscoms.com, PhD Students, School of Renewable Energy Technology (SERT), Naresuan University, Pitsanulok, THAILAND. *2 Physic Department, Faculty of Science, Naraesuan University, Pitsanulok, THAILAND.Abstract The Author tries to develop the Drive Mechanism A purpose of this research is to compare the for Stirling engine which has the lowest friction. Thisdifferent type of drive mechanism for Small Gamma may cause to increase the performance of the StirlingType Solar Stirling Engine. This system was direct engine up to 30 %.equipped with asynchronous motor, 500 W, as In this research the author will compare 3 differentgenerator. There are three type of daisy chain drive mechanism Stirling engines, with the samemechanism to compare, Gear drive, Swash Plate Drive condition, four cylinders, power piston diameter,Type I (Whisper Tech), Swash Plate Drive Type II displacement diameter, regenerator, pressure, cooler,(Rotary Drive). This system will compare in term of generator, heat exchanger, and stroke. The Daisycost, performance, and efficiency. Chain Drive Mechanism has three different types, Gear Drive, Swash Plate Drive Type I (Whisper Tech),1. Introduction Swash Plate Drive Type II (Rotary Drive). It will compare cost of manufacture, performance, The Author had found out from his past and efficiency.experience of Stirling Engine experiments. Theperformance of the Stirling engine depend on the fluid 2. Engine Specificationtype, pressure, efficiency of heater tube, efficiency ofcooler tube, efficiency of regenerator and friction etc. The Stirling Steele engine was redesigned byFriction is the most critical for Stirling engine. The enlarges. The power piston size changes from 22 mmmore friction in the system it will be less power output. to 48 mm, Stroke from 25 mm to 40 mm, and VolumeIf we can reduce the friction of the engine it will from 37.6 cc to 289.4 cc. The power changed from 20increase the efficiency of the Stirling engine greatly. W at 20 psi Air to 215 W at 20 psi Air. The engine Insolation in Thailand is varying between in 450 specifications shown in Table 1.to 550 W/m2 daily whole year round, and the average The piston sets of this engine was linked withvalue is at 550 W/m2 daily over the year. Friction of three different type daisy chain drive mechanism, GearStirling engine may not have direct effect to the Drive, Swash Plate Drive Type I (Whisper Tech),insolation, but if the Stirling engine has less friction, Swash Plate Drive Type II (Rotary Drive). As theStirling engine will require less power to overcome the engine has less crank case along with a simpler crank.friction and could produce more power output. This It permits for a more cost effective engine towill gain the performance of the Stirling engine up. manufacture. Building four cylinders instead of singleThus, with medium insolation as Thailand, Stirling cylinder units has several strong advantages such asengine could perform better. easy starting, good balance, smooth running even at Lot of researchers tries to improve the efficiency very low speeds, increased heater and cooler surfaceof the heater tube, cooler tube, regenerator, and seal to area, and good low end torque.adopt higher pressure. All of these reach to maximum Since this Stirling engine is a closed cycle device,criterion already but to reduce the friction of the it runs very quiet. It also has no cam shaft, lifters, pushengine still far away. Stirling engine friction may come rods, valves, spring, intake or exhaust manifold,from Power Piston Seal, Connecting Rod Seal, Shaft complex spark ignition or carburetor. [1]Seal, Displacer Seal, and Type of Drive Mechanicaletc.Copyright© 2007 by the Japan Society of MechanicalEngineers. All rights reserved. 1
    • Table 1 Engine Specification bearing system. The rotation, Clock-wise or counter Type Gamma clock-wise, can be done by adjust a little phase angle, Acting Double positive or negative, different. Working Gas Air Max. Expansion space gas 650 C (+/- 5 C) 2.2 Swash Plate Type 1 Drive Mechanisms temp The four pistons gamma type Stirling engine, are Compression space gas temp 40 – 50 C (+/- 5 daisy chained together with Whisper Tech C) Technology, Swash Plate, Figure 2. [2] This is done by Ambient Temperature 40 C (+/-5 C) driving the displacer via linear drive rods which are Thermal Efficiency 60 % attached to the top of power pistons. The rods pass Power Control Variable Pressure through a sealed bulkhead and the displacer cylinders No. of Cylinders 4 are ported to power piston cylinders that are phased Means Pressure 0.5 MPa behind them 90°. This allows an engine that only requires one crank through per piston where other Maximum Pressure 1 Mpa Stirling engine requires two. Bore, mm. 48 This engine was replace bronze bushing sealed Stroke, mm. 40 bulkhead as guide bearing with rubber seal, and Engine Displacement, cc. 72 x 4 replace the Mitter gear with Whisper Tech Speed, rpm 500 - 1200 Technology, Swash Plate. This could call Positive Cooling type Ethyl glycol Swash plate. It also added more bearing and universal Mechanical Output Power 215 W @ 20 psi joint. The rotation, Clock-wise or counter clock-wise, Mechanical Output Power 550 W @ 60 psi can be done by adjust a little phase angle, positive or Heat Source, Electric Heater 700 W x 4 negative, different.Source : By Author2. Drive mechanism2.1 Gear Drive Mechanisms Figure 2 Swash Plate Type 1 Souce : By Author Figure 1 Gear Drive Mechanism Source : By author 2.3 Swash Plate Type 2 Drive Mechanisms The four pistons gamma type Stirling engine, are The four pistons gamma type Stirling engine, are daisy chained together with Rotary Air Compressordaisy chained together with Mitter gear, Figure 1. This Swash Plate, Figure 3. [3] This is done by driving theis done by driving the displacer via linear drive rods displacer via linear drive rods which are attached to thewhich are attached to the top of power pistons. The top of power pistons. The rods pass through a sealedrods pass through a sealed bulkhead and the displacer bulkhead and the displacer cylinders are ported tocylinders are ported to power piston cylinders that are power piston cylinders that are phased behind themphased behind them 90°. This allows an engine that 90°. This allows an engine that only requires one crankonly requires one crank through per piston where other through per piston where other Stirling engine requiresStirling engine requires two. two. This engine still has the same bronze bush sealed The ideal of this engine mechanism was comebulkhead as original designed. But at the Mitter gear from Rotary Air condition. The bronze bushing sealedinstead using of bronze bushing it was changed to bulkhead was replaced with guide bearing with rubber 2
    • seal, and replace the Mitter gear with Rotary Drum. Table 2 PerformanceThis could call Negative Swash plate. It also added Gear Drive, Figure 4more bearing and universal joint. The rotation, Clock- Friction @ 1800 RPM (W) 8.9wise or counter clock-wise, can be done by adjust a Cost USD 950.00little phase angle, positive or negative, different. Mean Time Between Fail (hrs) 2,500 How to make Easy Maintenance Time (hrs) 150 Torque (N-m) 8 Carnot Eff. % 60 Thermal Eff. % 28 Mechanical Eff. % 44 Easy to start (Count as 10) 7 Swash Plate Drive Type I, Figure 5 Friction @ 1800 RPM (W) 7.6 Cost USD 1500.00 Mean Time Between Fail (hrs) 15,000 How to make Accurate Maintenance Time (hrs) 2,500 Torque (N-m) 9.8 Carnot Eff. % 60 Thermal Eff. % 29 Mechanical Eff. % 56 Easy to start (Count as 10) 8 Figure 3 Swash Plate Type 2 (Rotary) Souce : By Author Swash Plate Drive Type II, Figure 6 Friction @ 1800 RPM (W) 6.13. How to test Cost USD 1280.00 Friction test, Use DC motor, Minertia Encoder Mean Time Between Fail (hrs) 18,000Motor 200 W torque 3.5 N-m, direct connects to the How to make Very Accurateshaft of the Stirling engine without load and Power Maintenance Time (hrs) 3,500piston connected. Supply the motor with DC power, Torque (N-m) 10.2measure volt and current every 100 RPM until reach to Carnot Eff. % 60maximum 1,800 RPM. Stop measurement. Thermal Eff. % 30 Connect Power piston, Displacer Cylinder, Mechanical Eff. % 58Connecting rof, all other components. Release pressure Easy to start (Count as 10) 9value of Stirling engine to atmospheric pressure. Source : By AuthorSupply the motor with DC power, measure volt andcurrent every 100 RPM until reach to maximum 1,800RPM. Stop measurement. Gear Drive Friction Test Power test, connect Stirling Engine with Torque 12indicator. Supply AC volt to Electric Heater, supply 10Air up to 0.5 MPa measure Torque, Temperature,Power. 84. Results 6 Table 2 shown the performance of each type of V 4 Amechanism, Gear Drive, Swash Plate Type I, Swash Wplate Type II. This performance from the experiment at 2AREF laboratory, Bangkok, Thailand. 0 500 700 900 1100 1300 1500 1700 1900 RPM Figure 4 Daisy Chain Gear Drive Mechanism, Friction Test Source : By Author 3
    • accurate workmanship to make but it operates quite. Swash Plate Friction Test As the parts are precision it helps the maintenance time 12 increase up to 15,000 hrs. 10 As the weight of swash plate is in balance so it creates less vibration. This type of Drive Mechanism 8 had lot of parts and complicates to make. The cost to make this system is quite high. The friction is about 6 7.6 W. The engine torque 9.8 N-m is quite good. Carnot efficiency is 60 %. Thermal Efficiency is 29 % 4 V and Mechanical Efficiency is 56 %. The friction test A shown as Figure 5. 2 W The Swash Plate Drive Mechanism Type 2 (Rotary Drive), all piston rods install with guide - bearing on both side to reduce the friction. This type of 500 700 900 1100 1300 1500 1700 1900 Mechanism needs very accurate workmanship to make. It is very quite during the operation. The StirlingFigure 5 Daisy Chain Wisper Tech Swash Plate, engine can be rotate clockwise or counter clockwise byFriction Test adjust a little phase angle, positive or negative,Source : By Author different. The maintenance time are high, 18,000 hrs. As the weight of Rotary drum is in balance so this Rotary Drive Friction Test type of mechanism create much lower vibration than other system. This type of Drive Mechanism has fewer 12 parts than Daisy Chain Gear Drive but complicate to 10 make. The cost of the system is medium high. The friction is about 6.1 W. The engine torque 10.2 N-m is V quite good. Carnot efficiency is 60 %. Thermal 8 A Efficiency is 30 % and Mechanical Efficiency is 58 %. 6 W The friction test shown as Figure 6. The Swash Plate Drive Type I (Whisper Tech) can 4 be improved mechanical efficiency 27 % from Gear Drive Mechanism. The Swash Plate Drive Type II 2 (Negative Rotary) can be improved mechanical - efficiency 31 %. 500 700 900 1100 1300 1500 1700 1900 Some modification may improve better efficiency, such as weight of linkage arm, weight of piston, typeFigure 6 Daisy Chain Rotary, Friction Test of piston seal. Source : By Author Friction of Stirling engine may not have direct effect to the insolation, but if the Stirling engine has5. Conclusions less friction, Stirling engine will require less power to overcome the friction. This will gain the performance All three Daisy Drive Mechanisms work well in of the Stirling engine up. Thus, with mediumthe test bench. All Stirling engine can be rotate Clock- insolation as Thailand, average 550 W/m2 daily,wise or counter clock-wise by adjust a little phase Stirling engine could perform better.angle, positive or negative, different. The Gear Drive Mechanism is easy to make but ACKNOWLEDGMENTSvery noisy during the operation. As the weight of gear This research was prepared by Mr. Suravutnot easy to balance so this type of mechanism can SNIDVONGS, Vice President, Asian Renewablecreate a lot of vibration. This type of Mechanism is the Energy Development and Promotion Foundation, EITcheapest one to make. The maintenance time too low, member, a PhD Student, School of Renewable Energy150 hrs as the screw holding the bearing, and axial Technology, Naraesuan University, Pitsanulok,shaft always loose from vibration. The friction is Thailand. The author would like to acknowledge theabout 8.9 W. The engine torque 8 N-m is quite good. assistance and guidance of Asian Renewable EnergyCarnot efficiency is 60 %. Thermal Efficiency is 28 % Development and Promotion Foundation Dr. Sub.Lt.and Mechanical Efficiency is 44 %. The friction test Prapas Limpabandhu Deputy Minister of Foreignshown as Figure 4. Affair, Mr. Sutas AROONPAIROJ and staffs, the All piston rod of Swash Plate Drive Mechanism Engineering Institute of Thailand members whowas installed with guide bearing on both sides to provided a critical review of this research through itsreduce friction. This type of Mechanism needs various stages, including Asist. Prof. Dr. Sirinuch, 4
    • Chindaruksa, Physic Department, Faculty of ScienceNaraesuan University, as Advisor, Dr. Vichit,Yamboonrung, Assoc. Prof. Dr. WattanapongRakwichien, Asist. Prof. Dr. MathaneeSanugansermsri, as Co-Advisor and the NaraesuanUniversity Staffs, Pitsanulok, Thailand. Especially theDon Bosco Technical School staffs for theirfabrication and construction work on the prototype.Finally, the author would like to thank the numerousindustries to provide information for this research.References[1]. The Stirling Steele engine, Ronald J. Steele, 1994.[2]. Development of Stirling Engine Generator, Whisper Tech, 2006[3]. Mitsubishi Air-condition Swash Plate, Rotary compressor, 2004. 5