Experimental analysis of solar powered ventilation

750 views
715 views

Published on

0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total views
750
On SlideShare
0
From Embeds
0
Number of Embeds
1
Actions
Shares
0
Downloads
32
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide

Experimental analysis of solar powered ventilation

  1. 1. INTERNATIONALMechanical Engineering and Technology (IJMET), ISSN 0976 – International Journal of JOURNAL OF MECHANICAL ENGINEERING 6340(Print), ISSN 0976 – 6359(Online) Volume 3, Issue 3, Sep- Dec (2012) © IAEME AND TECHNOLOGY (IJMET)ISSN 0976 – 6340 (Print)ISSN 0976 – 6359 (Online) IJMETVolume 3, Issue 3, September - December (2012), pp. 471-482© IAEME: www.iaeme.com/ijmet.asp ©IAEMEJournal Impact Factor (2012): 3.8071 (Calculated by GISI)www.jifactor.com EXPERIMENTAL ANALYSIS OF SOLAR POWERED VENTILATION COUPLED WITH THERMO ELECTRIC GENERATOR ON UNROOFED PARKED VEHICLES Ganni Gowtham1, Ksitij Kumar2, S.S Charan3, K Manivannan4 1 (Vellore Institute of Technology, Vellore, India, ganni.gowtham14@gmail.com) 2 (Vellore Institute of Technology, Vellore, India, ksitiz52@yahoo.co.in) 3 (Vellore Institute of Technology, Vellore, India, samanchicharan@gmail.com) 4 (Professor, SMBS, Vellore Institute of Technology, Vellore, India, kmanivannan@vit.ac.in) ABSTRACT We have parked our vehicles in an open space under direct sunlight and observed the increase in vehicle’s interior temperature due to various means of heat transfer and greenhouse effect. We observed that, under hot weather conditions, vehicle’s interior temperature can rise by Twenty degrees or more in thirty minutes which is also a serious threat for children or pets left inside the vehicle. It is reported that in United States, about 38 children are dying every year in the vehicle because of rapid rise in vehicle’s interior temperature [6]. In some situations, where parking roofs are not present, vehicle has to be parked under direct sunlight most of the time. As a result, vehicle’s interior gets heated causing thermal discomfort to the driver and passengers inside the vehicle. Sometimes, Temperature rise in vehicle’s interior destroys the electronic gadgets left inside the vehicle. Our experiment aims at the study of providing ventilation by using renewable energy along with waste heat recovery from the vehicle. Solar panel along with a Thermo Electric Generator (TEG) is used which will generate sufficient power to run a DC Ventilator. Solar Panel and TEG powers the battery, the battery in turn powers the DC ventilator at constant voltage. The ventilator inhales fresh air from outside (i.e atmosphere) into the interior of vehicle and exhales hot air outside. Due to the mass transfer of hot air, the temperature inside the vehicle can be maintained at required level. Temperature sensors are used to measure the temperatures inside and outside the vehicle. Excess of power generated can be stored in the battery which can be used to power vehicle’s head lights and small scale appliances. Keywords – Thermo Electric Generator, Ventilation, ventilator, thermocouple, solar panel, waste heat recovery I. INTRODUCTION According to the data observed by the World Meteorological Organization, the sun irradiates the surface of the earth with at least 120 watts per square meter during daytime. The potential 471
  2. 2. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –6340(Print), ISSN 0976 – 6359(Online) Volume 3, Issue 3, Sep- Dec (2012) © IAEMEfor solar energy is huge. Recent technological advancements have enabled us to harness theelectrical energy produced by the solar radiation falling on earth. Many devices have beendeveloped like the photo voltaic cells that convert the sun’s energy into electrical potentialthat can power devices. Due to the recent developments in size, material, fabrication anddesign of PV panels they are easily accessible and portable. Solar powered vehicles havebeen powered by PV panels as well as devices like mobiles and laptops. Although solarenergy is abundant but methods to exploit it are limited and costly. Solar panels can bemounted on the roof of the vehicles to supply energy to recharge the batteries. I = IP – II – IScWhere:-I = current given as output (amperes)IP = current generated by photons (amperes)II = current through diode (amperes)ISc = current through shunt (amperes).The current can be governed by the voltage equation through the circuital elements. VH = I + I*RSWhere:-VH = voltage across both diode and resistor (volts)V = voltage at output terminals (volts)I = current as output (amperes).RS = resistance in series ( ).Thermo electric generator also known as TEG works on the principle of thermoelectric effectwhere direct conversion of temperature difference to electric potential takes place. It createsvoltage due to temperature difference on either sides of the conductor popularly known asSeeback effect.The voltage V obtained is derived from equation : V = ‫׬‬TT12 ቀSB ሺTሻ-SB ሺTሻቁ dT (1)Where:-SA = Seebeck coefficients of metals A as a function of temperatureSB = Seebeck coefficients of metals B as a function of temperatureT1 = temperatures of the junction 1(K)T2 = temperatures of the junction 2(K)One major applications of TEG in automotive industry is to recover waste heat from theexhaust of the engine. By placing a TEG at the exhaust of the vehicle we extract heat andconvert it into potential energy that can be used to power the electronics or recharge batteryof the car. Research in waste heat recovery is being carried out by BMW in their new energyefficient cars.The purpose of our experiment was to apply old model to develop a new approach forventilation in cars. The existing approach to supply ventilation required use of power fromcar battery which could easily drain the battery power. Our model coupled the use of a TEGwith solar panels to provide ventilation of the car without using car battery. We could use itwhile our car is parked as well as when the car is moving. 472
  3. 3. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –6340(Print), ISSN 0976 – 6359(Online) Volume 3, Issue 3, Sep- Dec (2012) © IAEME Sep II. PV SOLAR CELLSThe use of PV solar cell modules connected together I arrays of parallel and series circuits ll seenable current and voltage oriented dispo dispositions that allow capturing a distribution of theenergy generated at a DC level of 12V, 24V or 48V. PV conversion of solar energy intoelectricity is performed from semiconductor materials junctions that form layers of p and ndoped surfaces where photons coming from the sun overcome the photo-electronic band-gap ectronicgenerating an electron flux. The photoelectric effect is the base of such conversion.Applications on standard medium size energy generation are based on flat solar PV panellocated in house roofs, buildings and on the fields. In 1990 started [1] the use of solar energy tedpanels on the roof of small automobiles. Use of solar cells in vehicles had the goal to ful fill fullindividual requirements and comfort such as charging auxiliary batteries for air-conditioning, air-radio, charging GPS system, mobile phones or to maintain the temperature required inside the obilecabin, motor and air-conditioning for fast start. Total capacity of PV modules currently used conditioningis approximately 165-215 Watts, [2,3] though the limited surface available on the automobile 215roof is a constraint, as efficiency and capacity of cells improve, nominal power will increasegreatly and their use could soon be standardized. Fig1 indicates the PV used for theexperiment. Fig. 1 PV Solar Panel III. THERMOELECTRIC GENERATOR Thermoelectric generators (also called thermo generators) are devices which transform heat nerators(temperature differences) directly into electrical energy, using a phenomenon called the"Seebeck effect" (or "thermoelectric effect"). Their probable efficiencies are around 5-10%. 5One major applications of TEG in automotive industry is to recover waste heat from theexhaust of the engine. By placing a TEG at the exhaust of the vehicle we extract heat andconvert it into potential energy that can be used to power the electronics or recharge battery rechargeof the car. Research in waste heat recovery is being carried out by BMW in their new energyefficient cars. Fig2 shows Thermo electric generator 473
  4. 4. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –6340(Print), ISSN 0976 – 6359(Online) Volume 3, Issue 3, Sep- Dec (2012) © IAEME Sep Fig. 1 CAD Model of TEG IV. DETERMINATION OF TEMPERATURE INSIDE A PARKED CAR A Swift VDI car is used for experimentation. The following are the specifications of a car. ar Overall length 3760 mm Overall width 1690 mm Overall height 1530 mm Seating capacity 5 persons Colour White Glass type Tinted glass Location: VIT University (12° 55 N, 79° 11 E) Table 1 Observations Where: - Ti - Inside cabin temperature nside To - Ambient temperature ∆T - (Ti-To) Q - Amount of heat generated inside cabin Cp - Specific heat at constant pressure (1.005 KJ/Kg/°c) 474
  5. 5. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –6340(Print), ISSN 0976 – 6359(Online) Volume 3, Issue 3, Sep- Dec (2012) © IAEME 300 Heat Generated (kJ) 250 200 150 100 50 0 03:40 03:50 03:55 04:05 04:10 04:15 04:20 Time (s) Fig. 3 Graph for heat generated From the above analysis, it is clear that, within short span of one hour, the heat generatedinside cabin raises to 260 joules. To remove this heat, a ventilator or a cooling fan can beused V. SELECTION OF VENTILATORS Ventilator and ventilators provide air for ventilation and industrial process requirements.To decide the ventilator or cooling ventilators, one should know the parameters like staticpressure, maximum and minimum operating temperatures, rated power (operating voltageand current) [1,2] In enclosures and cabinets with highly efficient and sensitive electronic components heatcan also become a problem, especially with increasing packing density. Furthermore there isa risk that the service life of components, e.g. semi-conductors, might be reduced when themaximum operational temperature is exceeded. By using filter ventilator the generated heatin enclosures can effectively be eliminated and thus ensure trouble-free operation ofelectronic components. Using the following calculations to correctly assess the required filter ventilatorsperformance which are taken from an open internet source[6]. 1. Temperature differential Variations in temperature (e.g. day-night, summer-winter, climate zones) have to be takeninto account. Please enter the maximum temperature differential or determine the temperaturedifferential in the enclosure based on the desired interior temperature (Ti) and the expectedambient temperature (Tu): Maximum ambient temperature 42.5°c Maximum interior temperature 60°c Temperature differential 17.5K 2. Installed stray powerThe components installed in enclosures (e.g. transformers, relays, semi-conductors, bus bars,etc.) generate heat when in operation. This self-warming is described as stray power, powerloss or dissipation. In this case, it is power generated inside the cabin. Installed stray power 260W 475
  6. 6. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –6340(Print), ISSN 0976 – 6359(Online) Volume 3, Issue 3, Sep- Dec (2012) © IAEME Sep 3. Air constant The air constant f is determined by the altitude (above sea level) at the place of installation. It factors in decreasing barometric pressure and air density with increasing altitude. Altitude (above sea level) in meters 0 to 100 meters vel) Air Constant 3.1 m3/KWh 4. Calculation Required volume flow 21.17 cfmSo, the theoretical calculations show that around 22 cfm capacity should be used in cars. it’s o,safe if we use within the range of 30 30-40cfm. There are many ventilators and coolingventilator with the specified capacity and operating voltage and currents range between .7 and and .13 volts. Small ventilators of size 97x33mm (for example) can be installed as shown in thefigure 4 below.The source of heat penetration through car is the tinted glass windows. So, it can be placed fnear steering and at the top of roof. To run the ventilator or cooling ventilators, it’s better to ,go for green technology like usage of solar panels or waste heat recovery from exhaust gases. fromSo, here we can use combined system of solar panels and thermoelectric generators (TEGs)to harvest energy. Fig. 4 Placement of ventilator VI. IMPLEMENTATION OF VENTILATION SYSTEM As already observed, we are using ventilators to ventilate the car. To further optimize it, eand make it more efficient, it is necessary to control the power supplied to the ventilators,based on requirement. This power controller is necessary in a time like this, where ourconventional power sources are fast exh exhausting. [2, 3] Moreover a car runs on a battery, i.e.a fixed power source, on the move. So, it is necessary to optimize its consumption. The ideahere is to vary the power of ventilator, based on the temperature difference. A circuit which ventilator,shows a linear output with respect to input is chosen. The working of this circuit can arexplained using a simple block diagram. 476
  7. 7. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –6340(Print), ISSN 0976 – 6359(Online) Volume 3, Issue 3, Sep- Dec (2012) © IAEME Sep Fig. 5 Block Diagram VII. SIMULATION As one can see, the circuitry consists of two temperature sensors, one inside the car andanother outside the car. These sensors produce a voltage which is proportional to thetemperature of the surroundings. These two voltages are sent thru a differential amplifier,which gives the difference of the voltages. So, whenever the inside temperature and outsidetemperature are equal, the output of the differential amplifier would be zero. Otherwise, the emperatureoutput grows linearly with the temperature difference. This is sent through SCC block whichhas the ability to shift the voltage levels to required range, which is compatible as inputs fornext stage. And finally a “voltage controlled voltage source” controls the voltage to be givenout, hence controlling the power and rpm of the ventilators. Fig. 6 A simple amps based circuit We considered waste heat as first alternative. For this a thermo electric generator (TEG) alternative.can be used and its characteristics can be observed. An experiment was conducted on TEG ductedmodule HT 8-12-40 and the following reading is taken. Based on the study of existing 477
  8. 8. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –6340(Print), ISSN 0976 – 6359(Online) Volume 3, Issue 3, Sep- Dec (2012) © IAEMEsystems and project-relevant theories as well as different tests to evaluate the potential ofwaste heat recovery a thermoelectric system was developed. Unlike other approaches, that include a separate installation of the generator in the exhaustgas line, the concept of this work suggests the integration in the muffler of the vehicle.[4,5]The thermoelectric module as shown has many thermoelectric generators connected inseries with bimetallic strips inside to cut-off the modules from heat exchangers whenoperating temperatures of heat exchangers exceeds the operating temperatures of TEG’s. The following table represents the readings of thermoelectric generator of model numberHT8-12-40. Table 2 Readings are taken for one thermoelectric module 1 0.8 Voltage (V) 0.6 0.4 0.2 0 14.17 17.38 20.89 32.27 46.92 55.65 67.11 Temperature difference (°C) Fig. 7 Graph for temperature difference VIII. SOURCE CHARGING CIRCUIT As discussed earlier, these ventilators require power to run. Constant usage of power, whencar is parked can drain away the battery. So as an alternative solar power can be used. In herepower from solar panel is used to charge battery. A general solar charging circuit is used here.The figure below illustrates the circuit diagram. A voltage regulator LM317 is used here toprovide required voltage [6] to charge the batteries. Transistor here acts as a switching circuitwhich increases the efficiency when the output is finally taken through a low pass filter. 478
  9. 9. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –6340(Print), ISSN 0976 – 6359(Online) Volume 3, Issue 3, Sep Dec (2012) © IAEME Sep- Fig. 8 A general solar charging circuit used to charge batteriesThe solar panel charge the batteries, which prevents draining of them. As mentioned earlier ethis unit is producing a constant voltage of more than 12V, sufficient to charge the batteries.A similar circuitry can be used to harness power from TEG. But for this we need a lot ofTEGs connected in series which is highly expensive. The designed circuitry is implemented impleon a bread board. This circuitry was able to drive two cooling ventilator which are ventilators,estimated to consume a power of 4W. With a better MOSFET higher output power can bedelivered. Below photo illustrate the real time working of the circuitry. Fig. 9 Multimeter voltage reading g.In steady state, when the sensors are at equal temperatures the ventilator don’t run. The value“0.28” in the multimeter signifies that the temperature in the room is 28°C. The value “0.00”in the multimeter signifies that the temperature difference is zero. 479
  10. 10. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –6340(Print), ISSN 0976 – 6359(Online) Volume 3, Issue 3, Sep Dec (2012) © IAEME Sep- Fig. 10 shows temperature difference of 10°C between the two sensors.Now one of the sensor is heated using a lighter, the value “0.42” in multimeter in secondfigure indicates that the temperature of heated sensor reached 42°C.We can see that reachedventilators is running in this situation (figure 7). The value “0.10” in multimeter in the fourthfigure shows that there is a temperature difference of 10°C between the two sensors. After reaching a steady state, the temperature is back to normal and the ventilator slowsdown with drop in temperature and eventually stops without any external on/off switch. The following table indicates the variation of voltage and current with heat flux. The belowdata represents the voltage and current produced by solar panel of following specifications. Table 3 Readings for calculating output power The above data represents the voltage and current produced by solar panel of followingspecifications.Maximum power 10WMaximum power voltage (V) 17 VOpen circuit voltage (V) 21Maximum power current (A) 0.59 AmpsShort circuit current 0.62 AmpsMax system voltageage 1000V 480
  11. 11. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –6340(Print), ISSN 0976 – 6359(Online) Volume 3, Issue 3, Sep- Dec (2012) © IAEME 7.8 Pyranometer reading (No.) 7.6 7.4 7.2 7 6.8 6.6 19.23 18.97 19.25 19.2 Voltage produced (V) Fig 11 Graph for pyranometer reading IX. CALCULATIONS In the first part of the circuit, the temperature sensors provide a voltage governed by theequation Vo = (temperature in °Celsius)/100 Volts These voltage levels from the two sensors are subtracted in the next stage by a differentialamplifier circuit. The output voltage of differential amplifier is governed by Vo= (-Rf/R1)*(V1-V2) VoltsVo - Output from differential amplifierV1, V2 - Voltages from sensors one and twoRf, R1 - Resistors as mentioned in above simulation This output voltage is given as input to the VCVS. The behavior of VCVS are governed bythe equation R3/ (R2+R3) = V*Cmax/Vo The values of resistors and the output ranges are given below Rf = 1k R1 = 1k R3 = 10 R2 = 560Final output varies from 2V to 11V depending on the input temperature difference. X. CONCLUSIONS The interior of the car gets heated up when parked in sun. This is harmful for both livingand non-living things present inside the car. This project is an effort to bring down this heatby providing proper ventilation considering the draining effects of the car battery. A smartsystem to ventilate the car is designed and relevant prototype is implemented. This systemconsists of a ventilators placed at optimum positions and run with optimum power whichdepends on the temperature. A hybrid system which has a combination of both thermoelectricgenerators (TEG) and solar panel can be implemented as a source. The ventilation system can 481
  12. 12. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –6340(Print), ISSN 0976 – 6359(Online) Volume 3, Issue 3, Sep- Dec (2012) © IAEMEbe further improved by having ventilators which can rotate. They can recharge the battery ofthe car as well as power electronics of the car. However its demerits include added expenses to the car. Purchasing and installing solarpanel and a TEG would be expensive and add to the expense of the car. It will alsocomplicate the electronics of the car. If the system fails only a trained technician would beable to repair the fault. Added weight will complicate the vehicle dynamics as well as theergonomics of the car. Multiple units of the implemented prototype can be fitted inside the car to provideventilation effectively. According to our estimations 5-6 units of these prototypes can bringequal temperatures inside and outside the car, within 20 minutes. The output seemssatisfactory and reasonable. If it was economically possible, the energy from waste heat ofthe car would have been harvested. It is known that around 40% of energy from fossil fuels iswasted as heat in the exhaust gases. Even though solar energy is harvested effectively, wasteheat recovery must also be considered, as this energy would go waste if not made use of. Ifthermoelectric generators are used the hot side temperature can be maintained by exhaust gasfrom muffler and cold side temperature can be maintained by radiator cooling system. Thecombined system, we call it as hybrid system in modern vehicles can save fuel usage up to10%. Not only in automobiles, it can also be used in sailing ships which can save tons of fueland preserve the oil/coal reserves. The only problem with it is, to get considerable amount ofpower, investment should be higher and proper care should be taken for maintenance of TEGsetup. Further research has to be made to overcome these problems, we can expect goodboom for this. Anyways, considering the smart ventilation in automobiles, this hasremarkable advantages. ACKNOWLEDGEMENT We are deeply grateful to our advisor Dr E.Porpatam (SMBS-school), for his guidance,patience and support. We would like to thank our friends K.Vivek Shankar, B.Srinivas,L.Sree Harsha and committee members- Prof. Ram Mohan (TIFAC-school) and Prof. C.Ramesh Kumar (SMBS-school), for taking their precious time to consider our work. Weconsider ourselves very fortunate for being able to work with very considerate andencouraging people like them.REFERENCES[1] Goswami, Kreith and Kreider. Principles of Solar Energy. Taylor & Francis. Second Edition. 2000.[2] K. David Huang, Sheng-Chung Tzeng, Wei-Ping Ma, Ming-Fung Wu, in : Intelligent solar-powered automobile-ventilation system , Applied Energy Elsevier Vol. 141–154 (2005)[3] R. Saidur, H. H. Masjuki and M. Hasanuzzaman in : Performance of an improved solar car ventilator, International Journal of Mechanical and Materials Engineering (IJMME), Vol. 4 (2009), No. 1, 24 -34.[4] K. David Huang , Sheng-Chung Tzeng , Wei-Ping Ma ,Ming-Fung Wu “Intelligent solar-powered automobile-ventilation system,” in Applied Energy 80 (2005) 141–154[5] “Vehicle auxiliary power applications for solar cells”,I.F. Garner Solems S.A., France.[6] http:// www.stego.de an internet open source 482

×