International Journal of Technology Management and Information System (IJTMIS) eISSN: 2710-6268 [Vol. 1 No. 2 December 2019]
Journal website: http://myjms.mohe.gov.my/index.php/ijtmis
COMPARATIVE STUDY OF THERMAL ENERGY HARVESTING USING THERMOELECTRIC GENERATOR
(TEG) ON HOME APPLIANCES
N. Saudin1*, M. A. Bermawi2, M. A. Mohamed3, N. Jamel4 and C. L. Wooi5
1 2 4 5 School of Electrical Systems Engineering, Universiti Malaysia Perlis, Kangar, MALAYSIA
3 Faculty of Engineering Technology, Universiti Malaysia Perlis, Kangar, MALAYSIA
*Corresponding author: [email protected]
Article Information:
Article history:
Received date : 12 October 2019 Revised date : 23 November 2019 Accepted date : 6 December 2019 Published date : 16 December 2019
To cite this document:
Saudin, N., Bermawi, M., Jamel, N., &
Wooi, C. (2019). COMPARATIVE STUDY OF THERMAL ENERGY HARVESTING USING
THERMOELECTRIC GENERATOR (TEG) ON HOME APPLIANCES.
International Journal Of Technology Management And Information System, 1(2), 1-9.
Abstract: Thermal energy harvesting is one of the processes of collecting energy from the ambient environment and converting it to electricity. Currently, the concept of utilising surrounding sources that comes in the means of vibration, heat, radio waves, light, and motion has become more attractive. Many researchers have developed methods to produce electricity from these different kinds of energy sources. This project investigates the capability of thermal energy of wasted heat produced by home appliances be harvested as renewable energy and the method to convert the thermal energy into electrical energy using a thermoelectric generator (TEG). This paper presents a comparison of the output voltage harvested from various heat-producing appliances such as refrigerator, rice cooker, notebook, television and water heater. The data is measured using single TEG and two TEGs connected in series to increase the output. An ultralow voltage step-up converter (LTC3108) boosts the energy harvested from the TEGs to up to 5 volts.
Keywords: Renewable Energy, Thermal Energy, Thermoelectric Generator.
1. Introduction
In terms of physics, energy is the ability to do work. The human body has the energy that helps to do activities such as walking, running, jumping or even turning on machine operations. The energy stored in the body is known as potential energy, while the movement of the human is kinetic energy. Energy comes in several forms such as kinetic, potential, mechanical, chemical, thermal, electrical, gravitational, radiant, and sound.
Many home appliances could release waste heat whenever it is in use. The source of waste heat comprises hot combustion gases in the atmosphere, hot products and heat exchanges of hot items, for examples, heater, rice cooker, refrigerator, washing machine and other electronic devices. The waste heat temperature is the key to determining thermal energy harvesting (Aimable &
Middleton, n.d.). To obtain heat transfer, and harvest thermal energy, waste heat as the source must have a higher temperature than the heat sink. The magnitude of the temperature difference between the heat source and the heat sink is essential for the thermal power harvesting process. Higher waste heat temperature increases the energy that can be harvested. Hence, this project aims to analyse the potential of harvesting the wasted heat energy emitted from home appliances by a thermoelectric generator.
2. Literature Review 2.1 Energy Harvesting
Energy harvesting is defined as energy scavenging or power harvesting, in which it is a process that captures a small amount of energy that will be lost as heat, light, sound, vibration or movement. The energy source for energy harvesters is called βambient energyβ, which is present as ambient background and freely available. The main task of an energy harvesting device is converting the captured ambient energy into electrical energy and in the next step powers consumer electronics, wireless sensor nodes, implantable biosensors, military equipment and many more (Ahmed & Kakkar, 2017; Chao, 2016; Mehraeen, Jagannathan, & Corzine, 2010; Morelli, 1996).
Energy harvesting is so important because it can improve efficiency and produce new technology in the future. Energy harvesting also has the potential to replace batteries for small, low power electronic devices. There are many different energy sources that can be used for the conversion in Figure 1, such as:
β’ Light energy (solar energy from sunlight) (Luo, Peng, Wang, & Zheng, 2018)
β’ Thermal energy (human body) (Goudar, Ren, Brochu, Potkonjak, & Pei, 2014)
β’ Radio frequency energy (electromagnetic spectrum, antennas) (Biswas et al., 2018)
β’ Kinetic energy (motion, vibration, rotation, linear movement) (Beker, Zorlu, GΓΆksu, &
KΓΌlah, 2013)
β’
Figure 1: Ambient energy source and corresponding harvesting technologies (Yen Kheng Tan (PhD, SrMIEEE), 2009).
Thermal energy can be converted into electrical energy. One method of conversion is through a phenomenon called the Seebeck effect. Thermoelectric generator (TEG) creates DC power when there is a different temperature on each side of the TEG. The DC voltage can be boosted to provide power to any low-powered devices. Figure 2 shows the power generation mechanism of TEG.
Figure 2: Thermoelectric generator consists on n-doped and p-doped semiconductors with different Seebeck coefficient.
2.2 Thermal Energy Harvesting
From all the energy harvesting methods mention above, thermal energy harvesting has the most abundance source inside a house. Most of the main appliances like rice cooker, fridge and television produce heat as waste during operation. It is suitable for thermal energy harvesting.
Thermoelectric generator (TEG) is the main component in this project. The function of this thermoelectric generator is to convert waste heat from home appliances into electricity.
The difference between the heat radiated from the home appliances and the ambience temperature,
βπ, is affecting the electromotive force generated by the TEG. The output voltage is derive using equation (1) (Kubov, Dymytrov, & Kubova, 2016)
π½πππ = βπβπ (1)
where π is the Seebeck coefficient and βπ is the temperature difference on the two sides of the TEG element. Large temperature gradient is needed to produce high output at a minimum of 20 mV before it can be converted by LTC3108.
2.3 Power Generation using Thermoelectric Generator
Heat flux is converted into electric energy through Seebeck effect. The DC voltage generated is small due to low temperature gradient. The voltage is not enough to power any electronic device hence the need to convert the small voltage using ultralow voltage converter and manager (LTC3108).
The potential of thermoelectric generation has been investigated for quite sometimes (Morelli, 1996) and it continue to emerge. Some interesting development is the design for automobile battery charging (Solanki et al., 2018). Other noticeable research is the harvesting of electrical energy from body heat which shows that a good Vout of 4.4 V can be achieved (Jurkans, Blums, &
Gornevs, 2018).
2.4 Thermoelectric Module
Thermoelectric module (TE), also known as the thermoelectric cooler or Peltier module are components that contain electrical semiconductor materials that operate as small heat pumps or transfer heat from one side to another. This component is made from bismuth telluride (Bi2Te3), an electrical semiconductor material that is an excellent thermoelectric material operates as a heat exchanger.
There are two sides of the TE module, which are the hot side and cold side. When changing the polarity (plus or minus) of DC voltage, the TE module may be a reversed will be caused in the opposite direction of heat. Thus, the TE module can use both heating and cooling for temperature control applications. TE module can be used for an electrical generation because it can generate a current when having a temperature difference across the module.
3. Problem Statement
Waste heat generated in almost electrical devices in the house. There are about 20% to 50% of the energy in the environment is waste heat (Mohd Zul Waqar B. Mohd Tohid et al., 2018). This heat exists through several factors such as object heating, machine operation, mechanical processes and friction forces of electrical devices. The rated power of each home appliances will influence the heat energy released. The thermoelectric device can convert this thermal energy into electrical energy. The energy that produced reacts as a DC voltage input. The low-power electronic devices can utilise the harvested energy as a source of power. However, each appliance releases a different amount of heat. Therefore, a study has to be done to determine the potential of harvesting waste heat from the appliances.
4. Methodology
4.1 Project Development
Figure 3 shows a block diagram of the thermal energy harvesting process. There are four main parts, which are home appliances, TEG, LTC3108 and load. Five home appliances which are the rice cooker, refrigerator, water heater, laptop and television are chosen as the primary source of thermal energy. The DC voltage generated by the TEGs is converted using LTC3108.
Figure 3: The block diagram of the thermal energy harvesting
4.2 Circuit Construction
The hot surface of thermoelectric generator was placed on the most level surface of the home appliances to maximize the contact for heat transfer. There are two different configurations of the TEGs as shown in Figure 4 below. The first circuit consist only a single TEG and the second circuit use two TEGs connected in series. Ammeter and voltmeter are connected appropriately for data measurement.
Figure 4: TEGs configuration for thermal energy harvesting
Figure 5 shows the simulation circuit to convert the measurement collected using the TEG configuration shown previously. The main part of the circuit is coupled inductor step-up transformer (LPR6235-752SMR) and the ultralow voltage step-up converter (LTC3108). The input voltage V1 come from TEG and has been set according to the collected data.
Figure 5: Circuit simulation of LTC3108 using LTspice (βLTC3108 Datasheet and Product Info | Analog Devicesβ, n.d.)
5. Results and Discussion
The voltage and current from the TE module have been measured every 5 minutes using two multi-meters for 30 minutes for each home appliances using the single TEG and double TEG connection to obtain the voltage and current. Table 1 shows the average of voltage and current from a single TEG connection measured from the home appliances.
Table 1: Average of voltage and current for a single TEG connection Appliances Average Voltage
π½ (ππ½)
Average Current π° (ππ¨)
Refrigerator 5.71 2.50
Rice cooker 10.77 4.80
Laptop 3.57 1.34
Television 4.29 1.70
Water Heater 12.21 3.81
After 30 minutes of data collection, water heater has the highest average voltage and current reading. Even so, it has not reached the threshold voltage required by LTC3108 to initiate the conversion.
Table 2 shows data measurement of the average of voltage and current from double TEGs connected in series from the same home appliances.
Table 2: Average of voltage and current for double TEG connection Appliances Average Voltage
π½ (ππ½)
Average Current π° (ππ¨)
Refrigerator 23.00 1.21
Rice cooker 44.30 3.67
Laptop 9.44 0.87
Television 10.90 1.02
Water Heater 34.93 2.40
After 30 minutes of data collection, the rice cooker has the highest value for the average voltage and current. However, in contrast to Table 1, three home appliances which are the refrigerator, rice cooker and water heater have voltage reading higher than the required threshold for conversion by the LTC3108.
Table 3 shows the results from the simulation of voltage conversion of the input voltage from the measured data using LTspice for the duration of 1 second with an initial voltage of 3.3 V. Based on the results, it shows that with higher input voltage, the time needed to achieved the desired output voltage.
Table 3: Output voltage from LTspice simulation for the duration of 1 second.
Appliances Vin
(ππ½) Vout
(π½) Refrigerator 23.00 3.33 Rice cooker 44.30 3.59
Laptop 9.44 - Television 10.90 - Water Heater 34.93 3.49
6. Conclusion
As a conclusion, waste heat emission of home appliances can be harvested by using a thermoelectrical device. Each electrical appliance has a different amount of thermal energy. Some tools need two TEGs connected in series to produce enough voltage at least 20 mV to energise the ultralow voltage step-up converter (LTC3108) to boost the voltage. The more the number of TEGs, the higher is the output voltages. Low-power electronics, especially IoT devices, can benefit from this harvested energy as the source of power and thus may eliminate the need for batteries.
7. Acknowledgement
The authors would like to acknowledge the School of Electrical System Engineering, Universiti Malaysia Perlis (UniMAP) for providing research facilities and funding for the project.
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