Low Heating Rates Research Articles

Fast pyrolysis of pulverized coal at high temperatures and fuel nitrogen migration characteristics in a wire mesh reactor

ABSTRACT Pulverized coal (PC) pyrolysis is an indispensable process for coal thermal conversion and utilization. The transformation of fuel-N into fast pyrolysis is a basis for the investigation of nitrogen migration in coal combustion. In this paper, a wire mesh reactor was used to study the initial decomposition processes and to reveal the final pyrolysis yield and composition distribution during the fast pyrolysis process. Furthermore, the initial pyrolysis characteristics of PC with different ash contents were presented and compared. The results showed that both Huangling coal (with higher volatile) and Wuhai coal (with higher ash content) showed a similar trend, and the pyrolysis ratio increased with the increased pyrolysis final temperature. The pyrolysis ratio at the high heating rate was estimated to exceed that at the low heating rate by 2%–10%. With the temperature increased, the char-N yield decreased first and then tended to be stable, and most of nitrogen remained in the char (more than 55%). An increase in heating rate made the pyrolysis zone to shift toward higher temperature, and it enhanced the yields of volatile and tar as well as the proportion of tar in volatile. Besides, the heating rate increased from 10°C·s−1 to 1500°C·s−1, the yield of tar-N increased from 4% to 14% and gas-N decreased from 28% to 19%. Overall, NH3 yielded was higher than HCN, which became more apparent at high heating rates. The content of the N-6 was positively related to the coal pyrolysis ratio.

Squeezing excess meso/macropores via self-assembly of zeolitic imidazolate framework units to synthesize dense carbon for high-volume supercapacitors

The presence of excess meso/macropores accounts for the low density of porous carbon. Large-size meso/macropores can be easily compressed, for example, mechanically, increasing density to nearly 1.0 g cm−3. However, exceeding 1.0 g cm−3 density requires further compression of small-size meso/macropores, which is a challenge for dense carbon synthesis. Herein, we present a high-density zeolitic imidazolate framework-8 derived carbon (ZIF-8-DC) from the standpoint of carbon nano-unit ordering, that is, the self-assembly of ZIF-8 nano-units caused by solvent volatilization. Excess voids between nano-units are squeezed to increase density to 1.15 g cm−3. The low heating rate in the carbonization step ensures that ZIF-8-DC inherits the highly ordered assembly structure. Face-to-face close contact between carbon nano-units caused by self-assembly not only increases density but also establishes interconnected electron transport channels with extended widths via carbonization welding. More micropores and suitable mesopores created during carbonization give electrode/electrolyte systems a balance of electron and ion carrier densities. Supercapacitors made with symmetric ZIF-8-DC electrodes have a very high volumetric capacitance (195 F cm−3) and rate performance while maintaining a high volumetric power (3.55 kW L−1) and a long lifetime (>60 000 cycles). This strategy provides a new insight into the synthesis of high-volume-performance dense carbon.

A Novel Approach to Analysis of Complex Crystallization Behavior in Zr-Based Bulk Metallic Glass by Non-isothermal Kinetics Studies

The complex crystallization behavior of the Zr40Ti15Cu10Ni10Be25 bulk metallic glass (BMG) produced by suction-casting method was studied with the non-isothermal DSC measurements with the heating rate from 5 to 40 K/min. Three exothermic phenomena were observed for the investigated material. The novel evaluation procedure for qualitative and quantitative analysis of intricate crystallization kinetics for Zr-based BMGs is proposed. The unusual deconvolution of the DSC curves based on a Gaussian function and a two-phase exponential decay function allowed for separate, detailed analysis of overlapped peaks. The activation energies for each crystallization stage were studied based on overall (Kissinger) and local (Kissinger–Akahira–Sunose) procedures. The KAS method applied separately for both low and high heating rates showed a significant difference in local activation energies. Finally, the local Avrami exponent evaluation revealed that the first two stages of crystallization are diffusion-controlled with mainly increasing nucleation rate, whereas the third crystallization is more growth-dominated.

Fast pyrolysis behaviors of biomass with high contents of ash and nitrogen using TG-FTIR and Py-GC/MS

In order to examine the effective exploitation of high ash and high nitrogen content biomass, the fast pyrolysis behavior of mushroom bran (MB) and corn straw (CS) was studied utilizing high heating rate TG-FTIR and Py-GC/MS. TG was used to study the pyrolysis behavior of MB and CS under low and high heating rates followed by a seven-stage pyrolysis studies using Py-GC/MS. The results showed that at higher heating rates, there is an overlap of the decomposition of starch and hemicellulose, potentially leading to synergistic effects that would promote the formation of furan and furfural. At heating rates greater than 200 °C/min, nitrogen has a tendency to migrate from hydrogen cyanide to NH3 before 450 °C. Deoxidation and denitrification mainly occurred between the pyrolysis temperature range of 300 °C to 350 °C, which merits further research. Staged pyrolysis interrupts the oil's continuous deoxidation process in comparison to direct pyrolysis, and it reduces the selectivity of aldehydes and ketones in MB and CS pyrolysis by 12.57% and 12.25%, respectively. More importantly, the study of staged pyrolysis in this work provides detailed pyrolysis characteristics for high nitrogen and ash content biomass, allowing for a better understanding of the pyrolysis behavior of such biomass.

A multidimensional numeric study on smoldering-driven pyrolysis of waste polypropylene

The ex-situ smoldering driven pyrolysis reactor can simultaneously remediate the organically contaminated soil/sand and valorize the plastic waste to value-added fuels. This study establishes a multidimensional model to investigate the pyrolysis of polypropylene driven by self-sustained smoldering. The melting and decomposing processes during the pyrolysis of polypropylene have been simulated using the modified apparent heat capacity method and lumped kinetic model. Using a porous structure with high thermal conductivity in the pyrolysis domain proved to be a practical approach to address the non-uniform temperature distribution and low heating rate of plastics during pyrolysis. The research focus of this study is to obtain high-quality plastic pyrolysis liquid (oil, C6–C24) within a reasonable operating time (duration of the plastic pyrolysis process). Also, the operating conditions (Darcy air velocity, initial char concentration, and PP content) determine the yield of pyrolysis products by regulating the temperature and vapor residence time. Therefore, the sensitivity analyses of pyrolysis duration and oil yield to operating conditions have been performed. It is also found that the interface wall (between smoldering and pyrolysis chambers) heat transfer coefficient determines the smoldering chamber's thermal performance. This study provides new insights into the valorization of waste plastics and the remediation of contaminated soil/sand.

TG-DSC and TG-FTIR Studies of Annelated Triazinylacetic Acid Ethyl Esters-Potential Anticancer Agents.

To avoid problems associated with the storage and processing of newly developed potential medicines, there is a need to carry out thermal studies in the preclinical phase of drug development. The thermal behaviour and decomposition pathway of a whole novel class of patented potential molecular pharmaceutics, i.e., ethyl 2-[4-oxo-8-(R-phenyl)-4,6,7,8-tetrahydroimidazo[2,1-c][1,2,4]triazin-3-yl]acetates (1-6) were reported for the first time in inert and oxidative atmospheres. The experiments were conducted with the use of simultaneous thermogravimetry/differential scanning calorimetry (TG-DSC) and simultaneous thermogravimetry coupled with Fourier transform infrared spectroscopy (TG-FTIR). The decomposition pathways of compounds 1-6 were found to be different under oxidative and inert conditions. It was proven that the investigated molecules reveal higher thermal stability under a synthetic air atmosphere than under a nitrogen atmosphere, and their decomposition is preceded by the melting process. Among all the investigated compounds, only the meta-chloro derivative (4) was found to exhibit interesting polymorphic behaviour at a low heating rate (10 °C min-1). It was proven that the oxidative decomposition process of the studied molecules proceeds in three overlapping stages accompanied by strong exothermic effects. Additionally, it was concluded that the title compounds were stable up to a temperature of 195-216 °C in an atmosphere of synthetic air, and their thermal stability decreased in the order of R at the benzene ring: 4-CH3 > 3,4-Cl2 > 4-Cl > H > 2-OCH3 > 3-Cl.

Experimental investigation of variable fin length on melting performance in a rectangular enclosure containing phase change material

The present study proposes a new technique to determine liquid fractions of phase change material during the melting process in a left-side heated rectangular enclosure. The effects of variable fin length arrangements on the melting performance of phase change material (PCM) were also investigated experimentally. Detailed information about solid, mushy, and liquid ratios was obtained by analysing the temperature histograms of real thermal images of the melting zone. In accordance with the nature of the melting, the use of variable-length fins shortens the melting time by 14.9% compared to the equal-length fin arrangement. Similarly, variable-length fins reduce the average temperature of the latent heat thermal energy storage (LHTES) by around 10 °C compared to the equal-length fin arrangement. The use of variable length fin arrangements ensures a more homogeneous melting process within the LHTES. The fin arrangement evenly distributed to the entire heating source is more effective at low heating rates. In contrast, fin arrangements evenly distributed over the lower half of the heating source are more efficient at high heating rates.

Effect of Heating on Hot Deformation and Microstructural Evolution of Ti-6Al-4V Titanium Alloy.

This paper presents a systematic study of heating effects on the hot deformation and microstructure of dual-phase titanium alloy Ti-6Al-4V (TC4) under hot forming conditions. Firstly, hot flow behaviors of TC4 were characterized by conducting tensile tests at different heating temperatures ranging from 850 °C to 950 °C and heating rates ranging from 1 to 100 °C/s. Microstructure analysis, including phase and grain size, was carried out under the different heating conditions using SEM and EBSD. The results showed that when the heating temperature was lower than 900 °C, a lower heating rate could promote a larger degree of phase transformation from α to β, thus reducing the flow stress and improving the ductility. When the temperature reached 950 °C, a large heating rate effectively inhibited the grain growth and enhanced the formability. Subsequently, according to the mechanism of phase transformation during heating, a phenomenological phase model was established to predict the evolution of the phase volume fraction at different heating parameters with an error of 5.17%. Finally, a specific resistance heating device incorporated with an air-cooling set-up was designed and manufactured to deform TC4 at different heating parameters to determine its post-form strength. Particularly, the yield strength at the temperature range from 800 °C to 900 °C and the heating rate range from 30 to 100 °C/s were obtained. The results showed that the yield strength generally increased with the increase of heating temperature and the decrease of heating rate, which was believed to be dominated by the phase transformation.

Determination of running temperature in entrained flow gasifier in regard to coal ash melting thermal kinetic effects

The operating temperature of entrained flow gasifier is one of the important parameters to determine its gasification efficiency, which is empirically estimated by ash fusion temperatures (AFTs) in the industry. However, the measurements of AFTs in labs are conducted at a very low heating rate (5–10 °C/min) compared to industrial entrained flow gasifiers (several hundred °C/s). The melting behaviors of coal ash under such huge varied conditions are different due to thermo-kinetic effects. Here, the factors concerning coal ash melting thermo-kinetics including heating rate, particle size, and retention time are explored by AFTs analyzer, thermal mechanical analysis, in-situ hot stage microscope and differential scanning calorimetry. The results of the investigation demonstrated that ash particle size and retention time showed limited influence on ash fusion behavior, while the influence of heating rates can not be ignored. Furthermore, an Arrhenian-based regression model covering major thermo-kinetics was developed to quantitatively predict the running temperature. The developed model suggested using the temperature that shrinkage corresponds to 75% to extrapolate the running temperature. The model can help to determine the operating temperature of slagging gasifiers.

Advanced Fitting Method for the Kinetic Analysis of Thermogravimetric Data.

The article considered the solution of the inverse problem of chemical kinetics of the analysis of experimental data of a thermogravimetric experiment at a constant sample heating rate. The fitting method for identifying the parameters of a kinetic triplet using the integral method for a model of a solid-state reaction based on the modified Arrhenius equation is described. The effectiveness of the proposed approach was confirmed by solving test cases for low, medium, and high rates of material conversion. Unlike other methods, setting the parameters of the reaction mechanism is not required, as they are determined by the solution. Solutions for real data of TGA studies with high and low sample heating rates were compared with the results obtained by other authors and experimental data. A description of the full cycle of calculations used to identify kinetic parameters from thermogravimetric experimental data is given, from the derivation of calculated relationships to the implementation of a short (three to five formulas) program code for MS Excel spreadsheets. The presented code is easy to verify and reproduce and can be modified to solve various problems.

The selective heating effect of microwave irradiation on a binary mixture of water and polyethylene oxide: a molecular dynamics simulation approach.

In this study, we investigate the molecular mechanisms of a microwave-driven selective heating process by performing molecular dynamics simulations for three different systems including pure water, pure polyethylene oxide (PEO), and water-PEO mixed systems in the presence of a microwave with two different intensities of electric field such as 0.001 V Å-1 and 0.01 V Å-1 at a frequency of 100 GHz. First, from performing molecular dynamics simulations of CO and CO2 in the presence of the microwave, it is confirmed that the molecular dipole moment is responsible for the rotational motion induced by the oscillating electric field. Second, by analyzing the MD simulations of the pure water system, we discover that the dipole moment of water exhibits a time lag with respect to the microwave. During the heating process, however, the temperature, kinetic, and potential energies increase synchronously with the oscillating electric field of the microwave, showing that the heating of the water system is caused by the molecular reaction of water to the microwave. Comparing the water-PEO mixed system to the pure water and pure PEO systems, the water-PEO mixed system has a higher heating rate than the pure PEO system but a lower heating rate than the pure water system. Therefore, we conclude that heating the water-PEO mixed system is driven by water molecules selectively activated by microwave irradiation. We also calculate the diffusion coefficients of water molecules and PEO chains by describing their mean square displacements, demonstrating that the diffusion coefficients are increased in the presence of microwaves for both water and PEO in pure and mixed systems. Lastly, during the microwave heating process, the structures of the water-PEO mixed system are altered as a function of the intensity of electric field, which is mainly driven by the response of water molecules.

Effect of Metal Oxides on Combustion Characteristics of Excess Sludge

In this paper, it was studied that the effects of heating rate and four metal oxide on the combustion characteristics of excess sludge, such as CaO, Fe2O3, MgO and Al2O3, and the combustion kinetic parameters of sludge were obtained based on Coats-Redfern model. This result indicated that the ignition of sludge can be restricted with the increase of heating rate, but it was conducive to burnout, and the increasing about the flammability, stability and comprehensive combustion characteristic index of sludge. The addition of Fe2O3 and Al2O3 could improve the ignition performance of sludge to a certain extent, which was most obvious at the heating rate of 10 and 20 °C/min, respectively. Furthermore, the existence of Fe2O3, MgO and Al2O3 can improve the burnout performance of sludge, represented by MgO. Under the condition of low heating rate, the presence of Fe2O3 and MgO was beneficial to improve the comprehensive combustion characteristics of sludge. According to the distribution of combustion kinetics parameters, it was showed an increasing trend about the activation energy of sludge with the increase of heating rate at the range of 374.88-575.61 °C, which was also unfavorable to the combustion of fixed carbon. At the same heating rate, the activation energy decreased by adding Fe2O3 and Al2O3 at the range of 148.40-374.88 °C, which was beneficial to the release of volatiles and the combustion reaction, while the activation energy at the range of 374.88-575.61 °C decreased after adding CaO, which promoted the combustion of fixed carbon.

Crystallization and melting of unentangled poly(ε-caprolactone) cycles containing pendants.

The Rouse model provides a basic framework to understand the chain dynamics of polymers, which is confirmed to be more suitable for exploring the linear dynamics of unentangled polymers. The crystalline morphology governed by chain dynamics and crystallization kinetics is expected to differ in linear and cyclic polymers. Cyclic poly(ε-caprolactone)s (c-PCLs) containing two bi-anthracenyl group pendants with molecular weights close to the critical molecular weight (Mc) were synthesized to investigate the chain dynamics based crystallization and melting behavior by DSC, POM, and in situ simultaneous small-angle X-ray scattering/wide-angle X-ray scattering (SAXS/WAXS) investigations during heating of the isothermally crystallized samples. Double endothermic peaks were observed in the DSC curves with a low heating rate of c-PCLs without entanglement after isothermal crystallization, especially for c-PCLs with Mc. The structure evolution of the crystalline structures observed from the in situ investigations during the heating and double endothermic peaks in DSC heating curves of the c-PCLs indicate the role of pendants in the chain dynamics, which leads to the reorganization of the metastable structures. Banded spherulites of c-PCL without entanglement were observed for the first time, and the uneven growth of spherulites along the radial direction may be caused by the mismatch between chain dynamics and crystallization kinetics.

Investigation of accelerated recrystallization behavior via electropulsing treatment in CoCrFeMnNi high-entropy alloy

In this work, the effects of annealed temperatures (700 °C, 800 °C) and heating rates (low heating rate (LR) of 0.17 °C/s, medium heating rate (MR) of 500 °C/s and high heating rate (HR) of 4000 °C/s) on recrystallization behavior in equiatomic CoCrFeMnNi high-entropy alloy (HEA) were investigated. The mechanism of accelerated recrystallization behavior induced by electropulsing treatment (EPT) was elucidated through the evolution analysis of microstructure and geometrically necessary dislocations (GNDs). The results showed that the average GNDs density and grain size of the recrystallized region decreased with increasing annealed heating rate. At 700 °C, the average recrystallized grain size decreased from 6.1 μm to 2.2 μm with increasing annealed heating rate. At 800 °C, the HR material exhibited a higher recrystallization percentage and the corresponding decrease in average grain size from 12.5 μm for LR to 4.7 μm for HR. EPT promoted the recrystallization nucleation rate by reducing the recrystallization nucleation barrier. The better combination of grain refinement and dislocation strengthening due to heterogeneous deformation led to the yield strength (772 MPa) and fracture elongation (0.30) of the MR sample increased by ∼31% and ∼25% respectively compared with LR after annealing at 700 °C. This work provides essential insights into accelerating the recrystallization behavior and further improving the degree of grain refinement of CoCrFeMnNi HEA via EPT under the lower rolling amounts.

Quantitative assessment and suppression of anharmonic potential of quadrupole linear radiofrequency ion traps with round electrodes

Precision manipulation of the quantum coherence of radiofrequency (RF) ion trap systems is one of the most important prerequisites for the development of high-performance ion frequency standards, high-fidelity ion trap quantum computing, and ion precision spectroscopy. The anharmonic potential of the ion trap exacerbates the non-ideal kinetic properties of the trapped ions and the simple harmonic motions of the heated ions, which in turn constrain the coherence time of the trapped ion systems. In this study, we developed a precision assessment and optimization method for the potential field of a quadrupole linear RF ion trap with round electrodes based on the joint weight suppression of the multi-order anharmonic potential, which is applicable for ion ensembles of cloud, liquid, and crystalline forms, and for different ion numbers. By quantifying the potential of each radial order of the decoupled transient RF potential, we established the quantitative loss relationship between the structure parameter of the linear RF ion trap with round electrodes and the trapping potential and outlined the influence of the structure parameter of the trap on the weight of the anharmonic potential. We determined the optimal structure parameter k (the ratio of pole radius re to radius r0 of the maximum trapping field) of the quadrupole linear ion trap with round electrodes as 1.1451447, which minimizes the overall anharmonic potential and achieves the highest reported accuracy (Reuben et al., 1996) [1]. This result provides a basis for the solution of problems in physics such as obtaining long-time trapping under low heating rate, precision manipulation of coherence, motion effect suppression, and efficient cooling of 3D ion systems, which are conducive to quantum coherence with time delays, spectral measurement approaching the theoretical accuracy limit, and high-performance frequency standards of 3D ion systems.

Influence of heating rate on the recrystallization temperature of Al–Mg alloy

The influence of low heating rates on recrystallization of Al–Mg alloys was investigated as a complement to the theory of recrystallization related to heating rates. Different from the recrystallization of Al–Mg alloy at high heating rates, the starting recrystallization temperature Ts at 5 °C/min was observed to be higher than that at 10–20 °C/min. Combined with previous studies, a three-stage evolution of Ts verse heating rates was first proposed. With the heating rate increasing, Ts decreases in the range of 5 °C/min to rc2, increases in the range of rc2 to rc, and finally decreases when heating rate is higher than rc. The evolution of Ts was discussed to be dominated by the competition between recovery and recrystallization. Massive consumption of stored energy would reduce the driving force of recrystallization, which leads to the delay of recrystallization at low heating rates.

Understanding the influence of melt dripping on UL94 test response in a PA11 system

A commonly used approach in polyamide systems to achieve a V0 rating in Underwriter Laboratories (UL)-94 test involves the exploitation of melt dripping behavior. That is, not allowing the polymer to completely degrade, and thereby, not creating necessary concentration of volatiles for the flame to sustain on the polymer. However, the governing parameters during this process are yet to be well established and quantified. In this work, some of the parameters that influence this process like the heating rate, melt/flame dripping, frequency and size of drips, molecular weight distribution, and the chemical nature of volatiles are considered. For this purpose, this work revisited the role of melamine cyanurate (MC) in polyamide 11 (PA11) from the viewpoint of UL94 flame test. In contrast to studies on PA6 and PA6,6 with MC that have shown a V0 rating due to enhanced melt dripping, only a V2 rating is achieved in UL94 test even with 20 wt% of MC in PA11. Despite a similar chemical structure, the volatiles emitted during the thermal degradation of these polymers are different and plays an important role in determining the behavior of the sample in UL94 test. Besides, it has been shown that at higher heating rates (as in UL94), the role of MC is primarily limited to dilution in the gas phase as opposed to acceleration in thermal decomposition of PA11 at lower heating rates. The consequence of this behavior is also reflected in the differences in the molecular weight distribution of PA11, its MC formulations, and their melt/flame drips collected during the UL94 tests. Within the framework of the tests carried out in this work, it is also found that mass and size of the drips have no correlation to ratings in a UL94 test. The understanding of these parameters has provided some new insights for building a framework on methodologies for designing polymer formulations for UL94 tests.

Chemometric analysis unravelling the effect of key influencing factors on algal biochar yield

This study attempted to comprehend the key influencing factors amongst 16 variables on algal biochar production by pyrolysis from 115 datasets using chemometric tools such as Principal Component Analysis (PCA) and Multidimensional scaling (MDS). PCA results revealed that the first 5 principal components (PCs) accounted for 81.75 % of available dataset variability. Results of both PCA and MDS marked out the pyrolysis parameters, C (%), H (%), O (%), N (%), H/C, N/C, O/C as the main determining factors of algal biochar yield. The results also tied the occurrence of high algal char yields to low temperature-less residence time-moderate heating rate regimen. The correlations validated with the supportive findings of MDS, further revealed that algal biochar production is a complex process, which is dependent on the interplay of multiple variables involved rather than any singular major factor. The results thus offered an insight into the condensed criteria that presents an important cue for research and industry to achieve high algal biochar yields.

Investigation of Thermal Decomposition and Gases Release from Pre-Drying Municipal Solid Waste (PMSW) Via Pyrolysis Technology

Abstract Present study investigates the thermal decomposition and syngas potential of pre-drying municipal solid waste (PMSW) via pyrolysis using thermo-gravimetric (TGA) analyzer coupled with the mass spectrometer (MS). The experiments were performed at the heating rates 5 and 15°C/min. Differential thermo-gravimetric (DTG) curves exposed four conversion phases at lower heating rate and two conversion phases at higher heating rate. MS analysis of the evolved gases H2, CO, and CH4 revealed that the devolatilization phase played a major role during the processes. Higher H2 generation was observed at a lower heating rate due to more contact among PMSW and process temperature. Higher CO and CH4 were also favored at lower heating rate. Total yield of gases was found higher due to higher CO generation. For the estimation of activation energy (Ea), Flynn-Wall-Ozawa (FWO) kinetic model was applied at the conversion rates (α) ranged from 5–35. In overall, the lower heating rate supported the higher WMSW conversion as well as higher gas released during the process. Hence, this study will help to evaluate the H2 potential of the PMSW using pyrolysis thermal technology.

The Experimental Investigation of Heating Rate Variant Method to Produce Power Output Generated by Thermoelectric Generator SP1848-SA

Thermoelectric Generators (TEG) are a type of energy conversion device that uses the Seebeck effect to directly transform heat energy into electrical energy. The source of heat that will be transformed using this technology is one of many elements that determine TEG performance. Through laboratory-scale experimental tests, this research will examine how the performance of TEG in producing electricity and the temperature distribution profile is affected by changing the heating rate. The hot surface of the TEG module is heated by the heating plate, which is thought of as a source of wasted heat produced by the internal combustion engine. There are three heating rates available: low heating rate (0.35 °C/min), middle heating rate (0.93 °C/min), and high heating rate (1.55 °C/min). To collect temperature data in this research using the Arduino microcontroller temperature data logger, temperature measurements were taken on the TEG module’s hot surface (Th), cold surface (Tc), and ambient temperature (Ta). Arduino data logger is used to measure the electrical output performance in the form of net power output (P) generated by the TEG. The outcomes demonstrate that the pace of heating on the hot surface of the TEG module will impact to the surface temperature differential and the efficiency of the TEG module in producing electricity. The efficiency of TEG in producing electricity in the form of an average net power output increases with an increased heating rate.