Thermal Energy Harvesting System Research Articles

Influence of functionalized and non-functionalized 2D graphene nanomaterial with organic phase change materials: Thermal performance comparison

Thermal energy storage and harvesting using phase change materials (PCMs) is a crucial aspect of solar thermal utilisation and energy management. However, the intrinsic limitations associated with PCMs, such as their relatively lower thermal conductivity and sluggish thermal transport pose significant obstacles in the advancement of thermal energy harvesting and storage systems reliant on PCMs. Research explored by inclusion of nanomaterial with the PCM matrix is predominant depending on uniform diffusion and stability of the developed nanocomposite. In this research endeavour, we introduce a novel and synergistic approach to synthesis a functionalized graphene nanomaterials and compare its performance with non-functionalized graphene nanomaterial at various concentrations within organic PCMs, operating at a phase change temperature of 54 °C. The formulated nanocomposite’s thermophysical properties morphology, chemical stability, optical absorbance & transmittance, melting enthalpy, thermal stability and thermal reliability were investigated using sensitive instruments. The findings unveil a remarkable enhancement in thermal conductivity with functionalized graphene dispersed PCM exhibiting an astonishing surge of 106.7 % at a mere 0.8 wt% loading, when contrasted with conventional PCM. The optical transmittance of RT54-0.8fGr was significantly reduced from 56 % to 17.2 %, which enabled the effectiveness for solar thermal energy harnessing; meanwhile the melting enthalpy was energised to 193.4 J/g from 182.6 J/g. The developed nanocomposite with better optical property and melting enthalpy were tested for 500 numbers of accelerated thermal cycles and its chemical stability and thermal property were compared with PCM. Furthermore, a heat transfer analysis is numerically simulated to exhibit the thermal conductance performance of functionalized nanocomposite PCM over base PCM. The findings suggest that the functionalized graphene dispersed PCM matrix to exhibit highly favourable attributes for renewable thermal energy storage due to their exceptional comprehensive features.

Design and analysis of a machine learning-optimized multi-layered absorber for renewable energy applications

Harvesting solar energy into other useful energy sources are essential now a days, hance there are many systems available for that, such as solar absorbers, solar PV, etc. In this study, we have investigated four different solar absorber designs. Out of that four, the Hash-Shaped Solar Absorber (HSSA) structure is more effective for absorbing solar radiation and converting it into heat energy. With the broad response range this structure absorb more than 90 % of the radiation in observed range (100–5000 nm). The HSSA structure demonstrates absorption > 99 % at specific wavelength peaks, including 170 nm, 550 nm, 1790 nm, 2750 nm, 3090 nm, and 3700 nm within the solar spectrum. With this the HSSA structure is having more than 93 % absorption in the 3000–4000 nm range, whereas more than 97 % absorption is achieved in the visible region. Further, the HSSA structure is treated with the Machine Learning model as the parameter optimization. The greatest R2 value for this structure is 0.999592with a test size of 0.25, and the mean squared error is 1.79801 × 10−4. The ML reduces time (takes ¼ of the traditional time) and other simulation requirements. Additionally, the structure is polarization insensitive and up to 60° incident angle insensitive. Due tothese characteristics, the HSSA structures find usage in variousapplications, including solar thermal energy harvesting systems, plasmonic sensors, and detectors.

MODELING AND OPTIMIZATION OF A PCM-BASED OCEAN THERMAL ENERGY HARVESTER FOR POWERING UNCREWED UNDERWATER VEHICLES

Abstract As oceans cover over 70% of the planet's surface, they represent a large reservoir of resources that remained vastly untapped. Uncrewed Underwater Vehicles (UUVs) are becoming key technology for ocean exploration. Ocean thermal gradient is a permanent and reliable energy source that can be used to power UUVs using phase change material (PCM)-based thermal engines. When using PCM-based thermal engines to power UUVs, there are different energy conversion stages, thermal, hydraulic, kinetic, and electrical, dependent on a wide variety of parameters. Thus, optimization of the overall energy conversion is still a challenge for powering the increasing energy demanding UUVs for long missions. The goal of this study is to propose a PCM-based ocean thermal energy harvesting system for powering float type UUVs such as the Solo II float. This reduces the cost for battery replacement and expands the float's mission time. For this purpose, we developed a model consisting of hydraulic and electrical systems, designed to provide the electrical power needed by the UUV. The hydraulic and electrical systems are implemented using MATLAB-Simulink. The model developed can provide 13.66 kJ of electrical energy, which is more than 1.5 times the energy requirement per cycle for the SOLO II float.

Predictive model using artificial neural network to design phase change material-based ocean thermal energy harvesting systems for powering uncrewed underwater vehicles

Uncrewed underwater vehicles (UUVs) significantly benefit from phase change material (PCM)-based ocean thermal energy harvesting for long mission duration. However, this technology relies on different parameters that are critical to its efficiency. Sea trials indicated that a design using this technology has lower performance than its initial specifications. This underperformance results from different factors—mainly, the UUV's trajectory, travel time, temperature fluctuations, and biofouling on the heat exchanger due to long-term underwater operations. Therefore, there exists a need to continuously monitor the ambient energy harvesting system and predict system performance for mission planning. Two major parameters that influence the energy harvesting system include the pressure inside the hydraulic accumulator and the electrical load. This work focuses on the hydraulic-to-electric energy conversion system. A combination of numerical simulation and experimental tests is used to develop a predictive model using artificial neural network (ANN) in MATLAB. 1000 data samples from a numerical model are used to train the ANN. Compared to experimental results, the ANN model predicts the designed benchtop system's total efficiency with a maximum efficiency of 51 % and an overall relative error of less than 15 %. This work will enable energy-efficient mission planning for UUVs using PCM-based ocean thermal energy harvesting.

Thermoelectric coupling effect in BNT-BZT-xGaN pyroelectric ceramics for low-grade temperature-driven energy harvesting

Pyroelectric energy harvesting has received increasing attention due to its ability to convert low-grade waste heat into electricity. However, the low output energy density driven by low-grade temperature limits its practical applications. Here, we show a high-performance hybrid BNT-BZT-xGaN thermal energy harvesting system with environmentally friendly lead-free BNT-BZT pyroelectric matrix and high thermal conductivity GaN as dopant. The theoretical analysis of BNT-BZT and BNT-BZT-xGaN with x = 0.1 wt% suggests that the introduction of GaN facilitates the resonance vibration between Ga and Ti, O atoms, which not only contributes to the enhancement of the lattice heat conduction, but also improves the vibration of TiO6 octahedra, resulting in simultaneous improvement of thermal conductivity and pyroelectric coefficient. Therefore, a thermoelectric coupling enhanced energy harvesting density of 80 μJ cm−3 has been achieved in BNT-BZT-xGaN ceramics with x = 0.1 wt% driven by a temperature variation of 2 oC, at the optical load resistance of 600 MΩ.

An integrated thermal and RF energy harvesting system with rectifying combination and storage controller for IoT devices

This work presents an integrated thermal/RF energy harvester. The harvesting system can combine energy from two sources simultaneously (one DC and one AC) and deliver a regulated combined voltage of 1.75 V to a load and a storage controller. The output power of the harvester is in the range of hundreds of μWatts which is suitable for low-power wireless sensor networks. Maximum power point tracking (MPPT) is achieved by reconfiguring the number of stages of the DC path, the frequency driving the charge pump, and the capacitors of the matching network in the RF-path. The storage controller charges a supercapacitor to 3.5 V to power up the system during power shortage periods. The system is implemented in a 180 nm CMOS technology and utilizes a total on-chip capacitance of 2.4 nF. The peak end-to-end efficiency of the system reaches 60.3 % at output load power of 1.275 mW.

A wide input range, 94% peak efficiency auto‐select multi‐mode boost converter for thermoelectric energy harvesting

SummaryIn this paper, a high‐efficiency DC–DC boost converter is proposed for thermal energy harvesting systems. The converter's efficiency is improved using a low‐power digital operating mode detector circuit. The operating mode detector circuit changes the converter's operating mode between the continuous conduction mode (CCM) and discontinuous conduction mode (DCM) at a specific input voltage (boundary input voltage), which reduces the total losses, thus improves the efficiency and increases the input voltage range. Besides, the proper boundary input voltage is calculated as a function of the boost converter's parameters. Finally, the proposed converter is designed in a standard 0.18 μm CMOS process. Simulation results show that the peak efficiency of the converter can be up to 94%, 60.4%, and 35% at 300, 20, and 15 mV of the open‐circuit voltage, respectively.

Real-time Thermal Energy Harvesting from Solar Radiation in Malaysia at Low-Temperature Difference

.Malaysia is located in a tropical climate with an abundance of solar radiation. Due to the low albedo of roofing material, around 20 % to 90 % of heat is absorbed from solar radiation. Thus, it is possible to harvest thermal energy from solar radiation using TEG, which promotes the diversity of renewable energy sources in Malaysia. Previous research evaluates the potential of thermal energy harvesting of the TEG open circuit voltage and unipolar condition. Thereby, this research focuses on designing and developing a thermal energy harvesting system (TEHS) for harvesting thermal energy at low-temperature differences from solar radiation. The TEHS can harvest thermal energy in bipolar conditions, different voltage levels, TEG input voltage fluctuations, and rapid weather-changing conditions during real-time field tests. Parallel with series balance TEG array configuration obtained impedance matching at 125 Ω. The field test method was conducted for 105 days. The maximum mean efficiency obtained is 94.33 %, with an output power range between 0.46 mW and 66.10 mW. The promising finding indicates that the developed TEHS is robust and capable of operating at optimum power transfer at uncontrollable solar radiation and weather conditions. In addition, the potential of the power generated evaluation is to be used as a power supply to several sensor nodes.

Tungsten nanodisc-based spectrally-selective polarization-independent thermal emitters

Thermophotovoltaic (TPV) cells convert thermally emitted photons into electrical power using photovoltaic (PV) detectors. To realize highly efficient thermal energy harvesting using TPV conversion, high-temperature stable spectrally-selective emitters are needed. The deployment of TPV technology lags behind conventional solar-PV technology due to the lack of large-scale fabrication of efficient thermal emitters, which would preferentially emit in the PV cell absorption band. In this work, we demonstrate a simple large-area nanofabrication method based on the hole-mask colloidal lithography and sputtering, which allows one to fabricate tungsten (W) nanodisc spectrally-selective emitters (consisting of a metal-insulator-metal configuration) with a high emissivity below the InGaAsSb PV-cell cut-off wavelength of 2.25 μm and a gradually decreasing emissivity (down to < 10%) in the mid-infrared region. Frequency-domain time-domain (FDTD) simulations reveal that the spectral selectivity is achieved due to the localized surface plasmon resonance of W nanodiscs strongly influenced by the insulator thickness. Importantly, the W emitters show thermal stability at temperatures of up to 1100 °C, and emissivity invariance to changes in polarization and incidence angles up to 65°. This work represents a significant step towards the realization of high-temperature stable efficient thermal emitters by a facile and cost-effective fabrication method, thereby promoting the implementation of photonic/plasmonic thermal emitters in the next-generation thermal energy harvesting systems. The method proposed in this study holds potential for scalability; however, empirical evidence to demonstrate this scalability has not yet been established. Subsequent studies are needed to confirm the scalability of the proposed method and its extensive applicability.

Add-On Energy Harvesting of Diesel Exhaust Muffler Using Thermoelectric Generator

Trends Light fossil fuel vehicles are now turning to electricity. The electric vehicle transition begins with a hybrid car. The Hybrid vehicle uses an internal combustion engine as a generator. Controller systems, driving safety and entertain light vehicles are growing so that they consume a lot of electricity, Safe devices and driving lifestyle support. An additional battery charging system for a hybrid car now is being developed by the automotive manufacturer at least the system can increase the fulfilment of electricity consumption needs.The charging system can utilize waste energy vehicle itself or even from outside the vehicle system. In this research, the author wants to explore the thermal energy harvesting system in the remaining exhaust gases. The concept of this research is to develop a Thermoelectric Generator (TEG) as a power producer. The heat source uses a 140kW diesel engine with a heat potential of 523K at stationary conditions, and an exhaust velocity of 1407.05 m / s. This study demonstrates the potential prototype TEG then compared Ansys simulation and manual calculations as the first step for further research. The results obtained, the Exhaust TEG can produce a voltage of 2.1 Volt at 30 seconds of data collection. The cooling system on the TEG exhaust from the HVAC cooler with a temperature of 289K and a Velocity of 0.8 can produce a significant temperature difference.Keywords: Diesel Engine, Thermoelectric, Exhaust TEG system, Electricity.

Development of a Hybrid Solar and Waste Heat Thermal Energy Harvesting System

This research aims to develop a Hybrid Solar and Waste Heat Thermal Energy Harvesting System that integrates Thermoelectric Generator (TEG) with a solar PV system. The main focus is given to the development of the hybrid solar and waste heat released from the solar panel by using the TEG system. This hybrid system consists of photovoltaic (PV) cells to absorb the solar energy and the TEG attached to the back of the panel to absorb heat waste and convert it into usable electricity. The PV cell and the TEG are integrated with each other in order to obtain maximum energy and increased system efficiency. The experimental results show that the maximum output voltage produced from the solar PV is 20.37V and the maximum output current generated is 203.72mA. The maximum output voltage obtained from the TEG is 18.92V and the maximum current produced is 189.265mA. This experimental result shows that the maximum voltage and current produced from solar and waste thermal heat from PV panels can be used to charge and to power up portable electronic devices. More efficiency is accomplished by combining the TEG to absorb waste heat loss from the PV cell, thus improving the performance of the PV panel system.

Thermally reused solar energy harvesting using current mirror cells

AbstractThis paper implements a simultaneous solar and thermal energy harvesting system, as a hybrid energy harvesting (HEH) system, to convert ambient light into electrical energy through photovoltaic (PV) cells and heat absorbed in the body of PV cells. Indeed, a solar panel equipped with serially connected thermoelectric generators not only converts the incoming light into electricity but also takes advantage of heat emanating from the light. In a conventional HEH system, the diode block is used to provide the path for the input source with the highest value. In this scheme, at each time, only one source can be handled to generate its output, while other sources are blocked. To handle this challenge of combining resources in HEH systems, this paper proposes a method for collecting all incoming energies and conveying its summation to the load via the current mirror cells in an approach similar to the maximum power point tracking. This technique is implemented using off‐the‐shelf components. The measurement results show that the proposed method is a realistic approach for supplying electrical energy to wireless sensor nodes and low‐power electronics.

Recent Developments in Thermoelectric Generation: A Review

The world’s growing energy demand poses several concerns regarding the rational and efficient use of energy resources. This is also the case for many industrial processes, where energy losses and particularly thermal losses are common. Thermoelectric generators offer an alternative to address some of these challenges by recovering wasted heat and thereby increasing the overall efficiency of these processes. However, the successful operation of the thermoelectrical modules meant to carry this process is only possible when pairing these to an external control system; such a system plays an important role in predicting and operating such modules at its maximum power point. In this review paper, recent developments in the field of thermoelectric technology are discussed along with their mathematical models, applications, materials, and auxiliary devices to harvest thermal energy. Moreover, new advancements in phenomenological models are also discussed and summarized. The compiled evidence shows that the thermal dependence properties on the thermoelectric generator material’s modules and the mismatching thermal conditions play an important role in predicting power output in those systems, which prove the importance of including those parameters to enhance the accuracy of the energy production prediction. In addition, based on the evaluation of the mathematical models, it is shown that more studies are required to fill the gap between the current state-of-the-art of the technology and adjacent modeling techniques for the design and evaluation of thermal energy harvesting systems employing thermoelectric arrays under mismatching thermal conditions.

Thermoresponsive ionic liquid for electrochemical low-grade heat harvesting

Thermally regenerative electrochemical cycle (TREC) is a promising technology for low-grade heat harvesting by employing the thermogalvanic effect of the electrodes. Whereas the electrolytes applied in TREC systems have a negligible response to temperature variation. In this study, a thermoresponsive ionic liquid (TRIL) is added to an electrolyte to endow it with temperature-driven phase change behavior, and the electrolyte is then utilized in a copper hexacyanoferrate-based TREC system for ultralow-grade heat harvesting. The TREC system is operated between 10 and 30 °C across the phase change critical point (Tc), so that the solvation states of the ions varied during the charging and discharging process, and a high energy density of 1.30 J g−1 and high energy conversion efficiency of 1.32% (20.0% for the Carnot efficiency) are achieved. The energy efficiency is 10 times that achieved by the conventional non-TRIL system under the same conditions. Moreover, the Tc of the TRIL can be tuned according to the species and concentrations of the electrolyte salt, which enhances the feasibility and resilience of the TRIL-containing TREC system. This study provides a novel perspective for electrolyte design in electrochemical cells, promoting the applicability of electrochemical cells in high-performance ultralow-grade thermal energy harvesting systems.

A Solar, Thermal, and Piezoelectric Based Hybrid Energy Harvesting for IoT and Underwater WSN Applications

Background: There has been an increasing interest in the research community regarding the development of new energy harvesting systems/architectures for sensor networks deployed at critical locations. Various types of energy harvesting techniques like solar, thermal, aquatic, and wind energy harvesting systems are popular in the research community. It has been found in a survey that a single energy harvesting technique is not enough for the wireless sensor network, especially when the nodes are deployed in critical areas, like volcanoes, underwater, ocean, rivers, etc. Objective: This study aimed to explore energy solutions for perpetual, battery-less, and critical places where human intervention is impossible. Method: In this study, a hybrid energy harvesting solution using solar, pressure, and thermal has been proposed. An optimized framework has been proposed, implemented, and analyzed for the underwater sensor network application. Furthermore, mechanical and electrical schematic models have been designed, implemented, and realized. Result and Discussion: The physical parameters of solar, thermal, and piezoelectrical transducers have been analyzed along with mathematical equations to find the best possible solutions for the optimized framework. Conclusion: The model was theoretically implemented and investigated, and it was found that 22.3KJ of energy can be extracted in 24hrs from the proposed design, which guarantees a perpetual life of the sensor node.

Dual-Level Voltage Bipolar Thermal Energy Harvesting System from Solar Radiation in Malaysia

Harvesting energy from solar radiation in Malaysia attracts the attention of researchers to utilize the potential by ongoing improvement. Roofing material with low albedo absorbs the heat, that can then be harvested using a thermoelectric generator. Previous research only measured the open-circuit voltage with different thermoelectric generator configurations. Low power output limits the potential to be utilized. The low output power can be increased using a DC converter. However, the converter must be tuned concerning low- and high-voltage levels, bipolar, and the maximum power point tracking. Therefore, this paper presents a dual-level voltage bipolar (DLVB) thermal energy harvesting system. The circuit is tested at constant and various time intervals to evaluate the system’s functionality and performance. Experiment results show that the proposed harvesting system can boost from 0.6 and 1.6 V to achieve the optimum level. The mean efficiency of the harvesting circuit obtains 91.92% at various time intervals. Further, the field test result obtains output power from 1.45 to 66.1 mW, with the mean efficiency range of 89.62% to 92.98%. Furthermore, recommendations are listed for future research.

CO2 capture-driven thermal battery using functionalized solvents for plus energy building application

Renewable energy has the drawback of intermittent power generation, and it should be linked to an energy storage system. However, the efficiency and density of the conventional thermal energy storage technologies are low. Herein, for building applications, CO2 capture-driven thermal battery has been developed using solvents composed of amine-functionalized mesoporous silica (3-APTES-SBA-15) and an amine absorbent (MEA). The thermal energy is discharged through the exothermic reaction of amine-CO. When the renewable energy is supplied to the battery, amine-CO2 bonds are broken, which corresponds to charging process. 3-APTES-SBA-15/MEA presents a superior energy storage density of 2.187 kJ/g and an efficiency of 91.5%. It is sufficient for producing heating/hot water considering the discharging temperature, and there is no loss even if stored for a long time. The thermal battery system presents a coefficient of performance of 0.66 and a thermal energy storage density of 0.57 kJ/g. When the thermal battery is combined with solar thermal energy harvesting system, the thermal and electric energy consumptions are reduced by 22.0% (477.9 MJ/m2) and 19.6% (156.9 MJ/m2), respectively. The CO2 capture-driven thermal battery will contribute to manage renewable energy and reduce grid energy consumption for building applications.

Recent Advances in Hybrid Energy Harvesting Technologies Using Roadway Pavements: A Review of the Technical Possibility of Using Piezo-thermoelectrical Combinations

Currently, we are facing an energy transition due to pollution and depletion issues related to fossil energy sources. Among all the efforts to develop alternative green energy sources, there are other energy sources that remain unexplored. Ambient energies present on roadway pavements are one example. Thermal energy from solar radiation and the mechanical vibrations induced by passing vehicles are promising ambient energy sources available from roadway pavements. The aim of this study is to examine the existing energy harvesting systems for these ambient energy sources. This paper also summarizes existing study efforts on hybrid (thermal and mechanical vibration) energy harvesting systems in general. This hybrid system can overcome the limitations of a single source-based system as intermittent and low power generation. Energy harvesting technologies can generate green energy without negative environmental impact during the conversion process. This article solely contains references to studies examining the technological feasibility of a road energy harvesting project. Despite their importance, this bibliographic research did not include attempts to address costs, life cycle analyses, or the impact of the systems on the road structure. The reasons for this omission are due to the difficulty of obtaining this information in the scientific literature for comparison with the suggested systems.

Investigation of temperature gradient between ambient air and soil to power up wireless sensor network device using a thermoelectric generator

This paper proposes a study of an energy harvesting system for powering wireless sensor network (WSN) devices. The thermal energy harvesting system used is based on the thermal energy source between ambient air at the soil surface with five depth levels. Measurement was taken for 46 days in a garden area located in Melaka, Malaysia. A feasibility study of soil temperature measurement to obtain a temperature gradient can be used for harvesting by using thermoelectric generators (TEG) modules. Then, the efficiency of TEG with several different configurations based on temperature gradient data has been tested in the laboratory. The results revealed that the depth of soil 6 cm between sensors 1 and 3 will gave the best representation of level average temperature different around 1 ℃. Based on the temperature gradient data, the combination of three TEG SP1848 in a series connection with DC-DC step-up circuit DC1664 will produce an optimum voltage output of about 3 V. This output voltage is enough to operate low power IoT device derived from thermal energy.

Development of a Thermal Energy Harvesting Converter with Multiple Inputs and an Isolated Output

In this paper, an isolated multi-input single-output (MISO) converter is developed and applied to a thermoelectric energy conversion system to harvest thermal energy. The thermoelectric generators have individual maximum power point tracking functions. Furthermore, such a converter has a high step-up voltage conversion ratio. In addition, the presented converter is imposed on the thermoelectric energy conversion system with the three-point weighting strategy adopted to realize the maximum power point tracking (MPPT). In this paper, the basic principles of this converter are first described and analyzed, and finally some simulated and experimental results are offered to verify the feasibility and effectiveness of such a thermal energy harvesting system.