Numerical Study on Heat Transfer to an Arc Absorber Designed for a Waste Heat Recovery System around a Cement Kiln

Mirhosseini, Mojtaba; Rezaniakolaei, Alireza; Rosendahl, Lasse

doi:10.3390/en11030671

Cited by 13 publications

(22 citation statements)

References 28 publications

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“…Previously, the authors showed that the rotating effect mixed by free convection from the kiln is significant and cannot be neglected [17]. This statement is confirmed in Fig.…”

Section: Heat Loss From the Kiln Without Absorbersupporting

confidence: 63%

“…By finding the temperature distribution along the kiln length, heat transfer mechanisms including free convection, forced convection, radiation and convection due to rotation of the kiln can be calculated, as represented in Fig. 2(b), by using empirical and analytical correlations as expressed in [16,17].…”

Section: Heat Loss From the Kiln Without Absorbermentioning

confidence: 99%

“…Since the heat transfer mechanism is combination of different kinds of heat transfer, pattern of air flow, and diameters of kiln and absorber, magnitudes of Rayleigh and Reynolds number are great. Therefore, this problem is intrinsically turbulent [17]. The simulation has been carried out with a two dimensional (2D) unsteady solution.…”

Section: Numerical Study and Verificationmentioning

confidence: 99%

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Harvesting waste heat from cement kiln shell by thermoelectric system

Mirhosseini

Rezania

Rosendahl

2019

Energy

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Waste heat recovery in high temperature industries such as cement factory has undeniable benefits. In this study, an annular panel is considered as the thermal absorber around the external surface of the kiln at the location with highest surface temperature along kiln. By using a comprehensive numerical simulation, the temperature on the absorber is obtained and utilized as the hot side boundary condition of thermoelectric generator (TEG) system. For efficient design of the thermoelectric unit on outer surface of the absorber, effect of critical parameters such as thermoelectric leg length and fill factor are studied. Two different thermoelectric materials, bismuth telluride (Bi 2 Te 3) and β-phase zinc antimonide (Zn 4 Sb 3), efficient over different ranges of temperature are considered in order to evaluate electrical power output and performance of the system. Matched power output and conversion efficiency of the system are investigated. A doubleobjective optimization is carried out to minimize cost per power. The results show, the optimum leg length obtained by analysing cost per power ratio is shorter than the leg length corresponding to the maximum peak power output at a fixed fill factor. Zn 4 Sb 3 shows higher conversion efficiency at maximum peak power output than Bi 2 Te 3 , except for fill factor of 0.01.

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“…Previously, the authors showed that the rotating effect mixed by free convection from the kiln is significant and cannot be neglected [17]. This statement is confirmed in Fig.…”

Section: Heat Loss From the Kiln Without Absorbersupporting

confidence: 63%

Section: Heat Loss From the Kiln Without Absorbermentioning

confidence: 99%

Section: Numerical Study and Verificationmentioning

confidence: 99%

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Harvesting waste heat from cement kiln shell by thermoelectric system

Mirhosseini

Rezania

Rosendahl

2019

Energy

Self Cite

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“…The absorption coefficient and the scattering coefficient could be neglected in the model, and the model was suitable for the analysis because there was no permeable medium in the analytical domain of this study [19]. For a somewhat larger scale with geometry similar to that of this study, Mirhosseini et al [20] conducted 2D numerical analysis on the radiative heat exchange of an arc absorber around a cylindrical cement kiln using an S2S model. Table 5 shows the boundary conditions used for heat flow analysis.…”

Section: Numerical Analysis Model and Boundary Conditionsmentioning

confidence: 99%

Heat Transfer Characteristics of Heat Exchangers for Waste Heat Recovery from a Billet Casting Process

Kang

Kim

2019

Energies

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The application of the thermoelectric generator (TEG) system to various industrial facilities has been explored to reduce greenhouse gas emissions and improve the efficiency of such industrial facilities. In this study, numerical analysis was conducted according to the types and geometry of heat exchangers and manufacture process conditions to recover waste heat from a billet casting process using the TEG system. The total heat absorption increased by up to 10.0% depending on the geometry of the heat exchanger. Under natural convection conditions, the total heat absorption increased by up to 45.5%. As the minimum temperature increased, the effective area increased by five times. When a copper heat exchanger of direct conduction type was used, the difference between the maximum and minimum temperatures was significantly reduced compared to when a stainless steel heat exchanger was used. This confirmed that the copper heat exchanger is more favorable for securing a uniform heat exchanger temperature. A prototype TEG system, including a thermosyphon heat exchanger, was installed and a maximum power of 8.0 W and power density of 740 W/m 2 was achieved at a hot side temperature of 130 • C. The results suggest the possibility of recovering waste heat from billet casting processes.

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“…TEGs are being developed for use in automobiles for generating electricity from exhaust gases in order to improve overall engine efficiency [30]. Several studies have testified TEGs as a viable option for waste heat recovery in domestic, industrial, and other processes [2,[31][32][33]. Recently, TEGs have been introduced in the consumer market as a power device to charge small electronics such as sensors and cell phones by utilizing heat from candles [34] and propane stoves [35].…”

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confidence: 99%

Combinatory Finite Element and Artificial Neural Network Model for Predicting Performance of Thermoelectric Generator

2018

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Thermoelectric generators (TEGs) are rapidly becoming the mainstream technology for converting thermal energy into electrical energy. The rise in the continuous deployment of TEGs is related to advancements in materials, figure of merit, and methods for module manufacturing. However, rapid optimization techniques for TEGs have not kept pace with these advancements, which presents a challenge regarding tailoring the device architecture for varying operating conditions. Here, we address this challenge by providing artificial neural network (ANN) models that can predict TEG performance on demand. Out of the several ANN models considered for TEGs, the most efficient one consists of two hidden layers with six neurons in each layer. The model predicted TEG power with an accuracy of ±0.1 W, and TEG efficiency with an accuracy of ±0.2%. The trained ANN model required only 26.4 ms per data point for predicting TEG performance against the 6.0 minutes needed for the traditional numerical simulations.Energies 2018, 11, 2216 2 of 17 in the Thomson heat, which is proportional to the electric current and absorbed or released based on the direction of the current [4].Continuous efforts have been made toward developing high performance n-type and p-type thermoelectric (TE) materials [1,[7][8][9]. The performance of TE materials is measured in terms of a dimensionless metric called the figure of merit, which is denoted as ZT. It combines three key material properties: thermal conductivity (κ), electrical resistivity (ρ), and the Seebeck coefficient (S), along with the absolute temperature (T), and it is given as ZT = S 2 κρ T [10,11]. The magnitude of ZT for most of the commercial thermoelectric materials is close to unity; however, recent studies have reported higher values for some of the state-of-the-art TE materials, such as a quantum-dot superlattice with ZT~3.5 at 575 K [12], a superlattice structure with ZT~2.4 at 300 K and ZT~2.9 at 400 K [13], and lead antimony silver telluride with ZT~2.2 at 800 K [14]. The thermoelectric modules built using nanostructured materials have been reported to exhibit thermal-to-electrical energy conversion efficiency up to 10% at a temperature difference of 500 K [15].The performance of TEG modules depends not only on the ZT of the TE material, but also on the geometric dimensions of the thermocouples and operating conditions such as the temperature difference and electrical load [16,17]. Several researchers in the past have attempted to optimize p-n leg geometry comprising of length, a cross-sectional area, and the number of thermocouples [18][19][20][21]. A few studies have attempted to provide optimal shape factor parameters such as the area ratio for p-n legs (Ap/An), the aspect ratio (leg length/leg area), and the slenderness ratio ((Ap/Lp)/(An/Ln), where Ap and An denote base area and Lp and Ln denote length of p-and n-type legs) [22,23]. However, these parameter changes depend upon the TE material used for fabricating TEG legs, the materials used in assembling the TEG modules, and oper...

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Numerical Study on Heat Transfer to an Arc Absorber Designed for a Waste Heat Recovery System around a Cement Kiln

Cited by 13 publications

References 28 publications

Harvesting waste heat from cement kiln shell by thermoelectric system

Harvesting waste heat from cement kiln shell by thermoelectric system

Heat Transfer Characteristics of Heat Exchangers for Waste Heat Recovery from a Billet Casting Process

Combinatory Finite Element and Artificial Neural Network Model for Predicting Performance of Thermoelectric Generator

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