Electric Power Generation from Heat Energy Using Thermo Electric Generator and Single Ended Primary Induction Converter
Manivasagam Rajendran*, S.P. Richard
Department of Electrical and Electronics Engineering, K. Ramakrishnan College of Engineering,
Samayapuram, Trichy-621112.
*Corresponding Author E-mail: manivasagammn3@gmail.com
ABSTRACT:
The objective of this paper is to utilize the waste heat energy being generated in automobiles. It involves the trapping of heat energy being generated from the vehicles, such as silencers in bikes and converts the waste heat to electrical energy which can be used for many appliances. Thermoelectric Generator (TEG) which works on Seebeck effect. In this paper, SEPIC is designed and implemented to overcome this problem. The electric potential produced in thermoelectric generator is boosted by the SEPIC thereby increasing or decreasing the magnitude of voltage, required for charging battery without reversing the polarity of the supply. The waste heat can be utilized efficiently, which will be clean and green and can also be applied for both the industrial purposes and domestic purposes. The improved performance parameters are constant voltage and current, efficiency is high and low ripple with desired output voltage.
KEYWORDS: Seebeck effect, Thermoelectric Generator (TEG), Buck converter ,Boost converter,
Buck-Boost converter
1. INTRODUCTION:
This paper mainly concentrates on the effective production of electric energy from the waste heat energy available from the source. For this purpose we are using TEG, with auxiliary circuits like SEPIC and few other circuits. We can also directly use the output of TEG to power loads but the major problem is the cost of implementation of TEG[1].
· Increases the efficiency
· Reduces the ripple and maintain the constant current and voltage
· By using SEPIC it gives the non- inverted output and better voltage profile
2. LITRATURE SURVEY
“Modelling and Simulation of thermo Electrical Generator with MPPT” Abdelhakim, Korhan Kayisli et al., This paper presents modelling, simulation, and control of the power generation of a thermoelectric generator (TEG) using Matlab/Simulink. To get the aim of maximizing the power from the TEG, an MPPT controller based on sliding mode control (SMC) was implemented on a boost DC/DC converter, to ensure that the TEG operated at its peak power whatever the truthful function of the MPPT method, an HZ-20 module feeding a resistor through a chopper was used[1].
3. PROPOSED SYSTEM
3.1 EXISTING SYSTEM
TEG uses the heat to generate electric power that can be given to a battery for storage. But the main drawback is that that the converter used is only a buck or boost or buck-boost converter only. The major disadvantage that the converter gives inverted output and no absolute zero voltage when the source is cut off [2].
Figure.1 Block Diagram of Existing System
The above block diagram shows that the TEG is connected to the boost converter. Then the boost converter is given trigger pulse through MOSFET driver. The control is done by the PIC micro controller the LCD display is also connected to PIC for the display of the output voltage. A 12V battery is connected to the output of the boost converter to store the energy output given [3].
To overcomes the disadvantage of the existing system. We are using the single ended primary inductor converter. Also we are designing the circuit in such a way that it can be used with any source, the only condition is that there must be a temperature more than 80C.The main purpose of using SEPIC is that it does the work of buck boost and equal value of output to that of the input. It gives non- inverted output and better voltage profile can be obtained [4].
Figure.2 Block Diagram of proposed system
The heat from the source is converted to electric power by the thermoelectric generator (TEG). Depending upon the value of the temperature the value of the output voltage differs. To get a constant voltage without fluctuation. We use the single ended primary inductor converter. The PIC microcontroller is used for the control of the circuit. It gives the trigger pulse for the MOSFET in the SEPIC. The SEPIC bucks or boost according to the set voltage then the battery is connected the output. Then the DC load is connected and for the AC voltage the inverter is used.
For the purpose of comparison the output voltage of the TEG is given to the PIC micro controller. The LCD display is used to display the set voltage and the output voltage of the SEPIC. The LCD is 16*2 display device and is connected with the PIC micro controller. The PWM is pulse width modulator is used to provide ON and OFF pulse for the MOSFET Drive which in turn will provide the pulse to the switch in the SEPIC, for its operation.
When the TEG is kept near the source of heat then the starts to heat up and hence the voltage starts to develop. The voltage developed is completely based on the temperature obtained from the source. To get a steady state temperature we use the SEPIC. The main control for the circuit is the PIC micro controller. The PIC is given a separate power supply for its working. Also the output of the TEG is given to the controller. The main purpose of using the PIC micro controller is that it’s low cost and satisfies the basic requirements. The PIC is further connected to the following components.
The PIC provides the switching pulse to the SEPIC, through the MOSFET Drive circuit. The MOSFET dive consist of both the pnp and npn transistors. The PWM gives the pulse for the MOSFET Drive circuit. For better accuracy the square wave PWM is used. Then the SEPIC works according to the input trigger given and the set voltage. The POT is used to set the voltage instead of the a keypad because of the reason that POT has easy operation. The range of voltage set can be from 1V to 60V for the SEPIC.
The output of the SEPIC is then given to a DC load. Depending upon the interest of the user the DC load can be a battery or any load like dc motor etc. We have connected a battery of 12V with the output of the SEPIC. Then a DC load is connected with the battery. For domestic purpose the AC supply is the mist needed one. So to obtain the AC supply form DC we are using an inverter to convert the DC into AC supply. The any AC load can be connected to the inverter based upon the capacity of the particular inverter. The advantage of the MOSFET Drive circuit is that is has a high switching speed. The battery used can vary in capacity based upon the needs or demand of the user.
4. THE SINGLE-ENDED PRIMARY-INDUCTOR CONVERTER
Figure.3 SEPIC circuit diagram
The series inductor L1 operates.
When the switching period of the S1 switch, the ON time is greater than the OFF time the boost operation occurs [5].
The parallel inductor L2 operates.
When the OFF time of the switching pulse is greater than the ON time of the pulse then the buck that is the step-down operation occurs.
There is a freewheeling diode in circuit helps to stop the supply following back to the main circuit [6].
Figure. 4 Buck converter circuit diagram.
Figure. 5 Boost converter circuit diagram
5. PERIPHERAL INTERFACE CONTROLLER
Table 1 Specification of PIC
|
DEVICE |
PROGRAM FLASH |
DATA MEMORY |
DATA EEPROM |
|
PIC 16F877 |
8K |
368 Bytes |
256 Bytes |
6. THERMO ELECTRIC GENERATORS
Thermoelectric generators are also called Seebeck generators.TEG converts heat (temperature differences) directly into electrical energy, using a form of thermoelectric effect [7-9].
Figure. 6 Structure of TEG
SEEBECK EFFECT
The Seebeck effect is a phenomenon in which a temperature difference between two dissimilar electrical conductors or semiconductors produces a voltage difference between the two substances [10-12].
Figure.7 Seebeck effect
Figure. 8 Equivalent circuit diagram
Figure.9 TEG Dimension in millimeters
Figure.10 Snapshot specification of TEG
The advantages are
Constant current and voltage
Efficiency is high and Low ripple
Recycles the waste heat.
It has a wide scalability.
Running cost is low.
The disadvantages are
Initial cost is high [9].
Table 2 Specification of TEG
|
Hot side temperature (οC) |
300 |
|
Cold side temperature (οC) |
30 |
|
Open circuit voltage (V) |
8.4 |
|
Matched load resistance (ohms) |
1.2 |
|
Matched load output voltage (V) |
4.2 |
|
Matched load output current (A) |
3.4 |
|
Matched load output power (W) |
14.6 |
Figure. 11 Kit photo
1. TEG:
We are connecting two TEG in series to increase the voltage. TEG is connected to the SEPIC. It converts heat directly into electrical energy, using thermoelectric effect. It produces constant voltage and current with high efficiency.
It is the important component for our project. It is connected with the TEG and the PIC micro controller. The output of the SEPIC is connected to a battery of 12V DC. It is type of converter that allows electrical voltage at its output to be greater than, less than, or equal to that at its input.
The POT is used in to set the voltage PIC micro controller for control of SEPIC. PIC has the LCD display connected to it, it is a16*12 display that displays both the set voltage and the output of SEPIC voltage. It uses flash memory for program storage.
The bridge rectifier is used to connect AC to DC and a transformer steps down the input 250V to 12V AC, 5VAC. Then the 5V supply is given to the PIC micro controller and the 12V supply is given to the SEPIC.
The inverter is connected with the battery and it converts the 12V DC into 230V AC. The load upto 60watts can be connected to this prototype.
For AC, a CFL is connected to the inverter which is 12watts lamp. For DC, a 12V DC and 12A DC fan is connected directly to the battery.
OUTPUT
The output of the TEG is given to the SEPIC. The voltage is set in the SEPIC as per the user requirement using control signal from the microcontroller. POT is used for setting the voltage in PIC micro controller. We are setting 12V for the output, to charge the battery of 12V DC. DC load can be connected to the battery or directly to the SEPIC based upon the available waste heat. We are also connecting AC load to the SEPIC through an inverter.
Waste heat from the sources such as an iron box, bike silencer, in industrial boiler. For prototype we are using iron box as our source. The TEG hot side is kept over the iron box. As the temperature of the TEG increases, the voltage generation starts. The TEG produces some voltage, that voltage is given to the SEPIC, then the SEPIC gives the preset voltage at the output. SEPIC works in buck or boost mode depending upon the input voltage and preset voltage given.
8. CONCLUSION:
This paper contributes improvement of the already existing project with a better voltage and current control with improved efficiency. Gives a easier implementation according to the need. To get a improved voltage, we just need to connect more number of TEG. The main advantage of this paper is its scalability. Because when we increase the number of TEG there is no need to change any other component. Only the inverter design changes depending upon the needs of the customer or the user. Also the operation of the circuit is also simple and easy to understand. Depending upon the energy available and the power required the battery can be chosen.
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Received on 21.01.2020 Accepted on 19.02.2020 ©A&V Publications all right reserved Research J. Engineering and Tech. 2020;11(1):01-09. DOI: 10.5958/2321-581X.2020.00001.X |
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