Conventional Electric Heating Research Articles

Microwave-Assisted Pyrolysis of Biomass for Bio-Oil Production: A Review of the Operation Parameters

As compared with the conventional electrical heating pyrolysis, microwave-assisted pyrolysis (MAP) is more rapid and efficient due to its unique heating mechanisms. However, bio-oil production from MAP of biomass is strongly dependent on the operation parameters. Based on the recent researches, this study reviews the effects of the main operation parameters including microwave power, pyrolysis temperature, and pyrolysis time on the bio-oil yield obtained from MAP of biomass. The results show that microwave power, pyrolysis temperature, and pyrolysis time usually increase the bio-oil yield initially and decrease the bio-oil yield finally. The reported optimal microwave powers, pyrolysis temperatures, and pyrolysis times were mainly in the ranges of 300–1500 W, 400–800 °C, and 6–25 min, respectively. The mechanisms for bio-oil produced from MAP of biomass as affected by the main operation parameters were also analyzed.

A kinetic study of facile fabrication of MIL-101(Cr) metal-organic framework: Effect of synthetic method

MIL-101(Cr) metal–organic framework samples were successfully synthesized through the conventional electrical heating (CE), ultrasound (US), and microwave (MW) synthetic methods at three different temperatures and various synthesis times. These were done with the aim of understudying the crystallization kinetics of these complex MIL’s structures. The nucleation and crystal growth steps were thus, quantified through measuring the relative crystallinity of the prepared MIL-101(Cr) utilizing the PXRD and FESEM analysis under various synthesis conditions. In addition, the textural properties of the fully crystallized samples measured through the N2 adsorption–desorption isotherms at 77 K. The rates of these steps estimated from crystallization curves revealing changes of relative crystallinity with synthesis time. The activation energies (Ea) and pre-exponential factors (A) of each step calculated from their corresponding Arrhenius plots. This demonstrated that the rate of crystallization steps (i.e., both nucleation and crystal growth) downgraded in the order of CE ≪ MW < US. Moreover, it turned out that increasing of pre-exponential factors played more important role in accelerated crystallization under MW and US conditions in comparison to lowering of the activation energies. Hence, it was suggested that physical effects (i.e., hot spots) were playing more important role in comparison to the chemical ones (i.e., acidity of the reaction medium) in the accelerated synthesis of the MIL-101(Cr) utilizing US and MW techniques.

Facile preparation of nanocubes zinc-based metal-organic framework by an ultrasound-assisted synthesis method; precursor for the fabrication of zinc oxide octahedral nanostructures

Synthesis of metal-organic framework (MOF) materials via ultrasound (US) irradiation involves shorter reaction times and offers enhanced control of particle size and morphology compared to conventional electric (CE) heating. Nanocubes of an interpenetrated pillared-layer Zn(II) metal-organic framework, [Zn2(NH2-BDC)2(4-bpdh)]·3DMF (TMU-16-NH2) (NH2-BDC=amino-1,4-benzenedicarboxylate, 4-bpdh=2,5-bis(4-pyridyl)-3,4-diaza-2,4-hexadiene, DMF=N,N-dimethylformamide), have been synthesized by US process and characterized by Field Emission Scanning Electron Microscopy (FE-SEM), powder X-ray diffraction, thermogravimetric analysis (TGA), elemental analysis and FTIR spectroscopy. The role of initial reagent concentrations and power levels of US irradiation and also reaction time, on size and morphology of nanostructure TMU-16-NH2 have been studied. Moreover, ZnO octahedral nanoparticles were simply prepared through direct pyrolysis of the TMU-16-NH2 nanocubes asa precursor at 520°C without any surfactant or capping molecules.

Microwave synthesis of SAPO-11 materials for long chain n-alkanes hydroisomerization: Effect of physical parameters and chemical gel composition

The present work concerns the preparation of SAPO-11 materials using microwave (MW) heating during the crystallization process. Different experimental conditions such as crystallization temperature and time were explored, together with different Si sources. The final materials were fully characterized using chemical analysis, XRD diffraction, pyridine adsorption followed by FTIR, nitrogen sorption and NMR spectroscopy and compared with the respective conventional SAPO-11 materials, synthesized using the same initial chemical composition of the gel but under conventional electric heating. The results showed that SAPO-11 materials can be synthesized in less time (within minutes) and at lower temperature (170°C) with MW heating than with conventional heating (respectively 24h and 200°C). MW heating allows nanosized SAPO-11 materials to be obtained but the nature of the Si source used has a marked influence on the textural properties and, especially, on the acidity of SAPO-11. The catalytic properties of the materials (with 0.5wt.% Pt) were evaluated in the hydroisomerization of long chain n-alkanes using n-decane as model molecule. Optimized MW samples using colloidal AS-40 Si source showed higher yields in monobranched isomers due to a joint effect of low acidity and suitable textural properties.

Enhanced Thermo-Optical Switching of Paraffin-Wax Composite Spots under Laser Heating

Thermo-optical switches are of particular significance in communications networks where increasingly high switching speeds are required. Phase change materials (PCMs), in particular those based on paraffin wax, provide wealth of exciting applications with unusual thermally-induced switching properties, only limited by paraffin’s rather low thermal conductivity. In this paper, the use of different carbon fillers as thermal conductivity enhancers for paraffin has been investigated, and a novel structure based on spot of paraffin wax as a thermo-optic switch is presented. Thermo-optical switching parameters are enhanced with the addition of graphite and graphene, due to the extreme thermal conductivity of the carbon fillers. Differential Scanning Calorimetry (DSC) and Scanning electron microscope (SEM) are performed on paraffin wax composites, and specific heat capacities are calculated based on DSC measurements. Thermo-optical switching based on transmission is measured as a function of the host concentration under conventional electric heating and laser heating of paraffin-carbon fillers composites. Further enhancements in thermo-optical switching parameters are studied under Nd:YAG laser heating. This novel structure can be used in future networks with huge bandwidth requirements and electric noise free remote aerial laser switching applications.

Synthesis of MgAPO-31 nanocrystals via different heating methods and their catalytic performance in the hydroisomerization of n-decane

MgAPO-31 molecular sieves substituted by different magnesium contents were synthesized using microwave irradiation (MW) and conventional electrical heating method, respectively. The bifunctional catalysts Pd/MgAPO-31 were prepared by the incipient wetness impregnation technique. The structure and acidity of MgAPO-31 were characterized by XRD, SEM, N2 physical adsorption, FT-IR, and Py-IR. The catalytic performance of Pd/MgAPO-31 were tested in the hydroisomerization of n-decane, which was used as the probe-reaction, and the effect of heating method on acidity of MgAPO-31 and the catalytic performance of Pd/MgAPO-31 were investigated. The results showed that all of the MgAPO-31 samples with ATO topology structure were pure phase and high crystalline materials. The Mg(II) heteroatoms were confirmed to isomorphously substitute for the framework atoms of AlPO4-31 molecular sieve. These Pd/MgAPO-31catalysts showed good catalytic performance for the hydroisomerization in the temperature range of 330–370 °C. The activity of Pd/MgAPO-31 in the hydroisomerization of n-decane and the selectivity for i-decanes were considered to depend on the crystal size and acidity of MgAPO-31.The highest selectivity for i-decanes was obtained over the catalyst Pd/0.05MgA31-MW prepared using the MW method.

Missing Building Blocks Defects in a Porous Hydrogen-bonded Amide-Imidazolate Network Proven by Positron Annihilation Lifetime Spectroscopy

In situ imidazolate-4,5-diamide-2-olate (L2) linker generation under conventional electrical (CE) heating and microwave (MW)-assisted conditions leads to the formation of the porous three-dimensional hydrogen-bonded molecular building block (MBB) [Cd14(L2)12(O)(OH)2(H2O)4(DMF)4] based network, named as HIF-3. In the MBB a Cd6 octahedron is inscribed in a Cd8 cube. The evacuated materials show good N2, CO2, and H2 gas sorption, in comparison with other H-bonded networks. The desorption branches exhibit a broad hysteresis, suggesting that the materials show flexible behavior during gas uptake. Positron annihilation lifetime spectroscopy (PALS) shows inherent crystal defects of the materials. PALS indicates that the contribution of mesopores (10 and 14 % for HIF-3-CE and -MW, respectively) due to missing building blocks, makes the frameworks structurally flexible.

Revisiting household energy rebound: Perspectives from a multidisciplinary study

In this paper, an interdisciplinary team of economists and anthropologists study the perplexing case of Norwegian households’ heat pump ownership. The heat pump is a technology that has the potential to reduce electricity consumption by up to 25% compared to conventional electric heating, but, as we demonstrate in this study, when taken into use it results in little or no change in electricity consumption. To explain this large rebound effect, we use a quantitative economic analysis combined with qualitative interviews attuned towards examining the effect of heat pumps on people’s everyday practices. We find that, on average, households with and without a heat pump use approximately the same amount of electricity. The main sources of rebound identified was higher indoor temperature and heated living space, less firewood and fuel oil use and less use of night-set-backs or reduced temperature while away from the home.

Conversion of Y into SSZ-13 zeolites and ethylene-to-propylene reactions over the obtained SSZ-13 zeolites

Y zeolites having wide ranges of SiO2/Al2O3 ratios (silica/alumina ratios or SARs) were converted into SSZ-13 zeolites in the presence of N,N,N-trimethyl-1-adamantanamine iodide (TMAda-I) as a template. SSZ-13s with increased SARs could be obtained from Y zeolites having SARs of 5.1–80 and sodium silicate by both conventional electric (CE) and microwave (MW) heating. The syntheses conducted using MW and CE heating at 140°C were completed in 2h and 144h, respectively, because of accelerations by MW in both the nucleation and crystal growth stages. The obtained yields of SSZ-13 decreased as SARs of the starting Y zeolites increased, demonstrating the relatively easy conversion of aluminous Y into SSZ-13. The obtained SSZ-13s with wide SAR ranges (19–287) were applied as catalysts in the direct conversion of ethylene-to-propylene (ETP) to understand the effect of the SARs on the ETP performances, including the conversion of ethylene and propylene selectivity. The stability of ETP was highly dependent on the SAR of the SSZ-13 zeolites. SSZ-13s with excessively high or low SARs caused low ethylene conversion (from the beginning of the reaction) or rapid deactivation in the conversion, respectively. The propylene selectivity or yield (at a fixed ethylene conversion of 80%) generally increased with decreasing SARs (up to 19) of SSZ-13s under the studied conditions because of a steady increase in the selectivities for butenes and higher products with increasing SARs of SSZ-13s.

Modulated Synthesis of UiO-67 for High Resistance to CH&lt;sub&gt;2&lt;/sub&gt;Cl&lt;sub&gt;2&lt;/sub&gt;

UiO-67 has been synthesized by using the acetic acid as a template via conventional electric (CE) heating method. With the same adding of acetic acid, different crystallinity and pore structure are obtained through change the order of addition of acetic acid. The BET surface area and total pore volume are 2861 m2 g-1 and 1.14 cm3 g-1 for of CE-0-3, and 1650 m2 g-1 and 0.67 m2 g-1 for CE-1-2, respectively. Although CE-0-3 has a better crystallinity, higher BET surface area and total pore volume than those of CE-1-2, CE-1-2 presents a better resistance to CH2Cl2 than CE-0-3.

Combined active solar and geothermal heating: A renewable and environmentally friendly energy source in pig houses

Increased energy price and CO2 emissions through burning fossil fuel for heating nursery pig houses in winter are major problems. This study was conducted to evaluate the combined effects of an active solar and geothermal heating system (CSGHP) on electricity use, cost, and CO2 and noxious gas emissions from pig houses during heating in winter at the experimental farm of Sunchon National University, Korea. The electricity use, inside room temperature, humidity, and noxious gas emissions were measured and CO2 emissions and costs were calculated based on the difference in electricity used by control (conventional electric heating system) and CSGHP supported pig houses. A significant increase in internal room temperature was found in the CSGHP system relative to the control house (P &lt; 0.05). Electricity use, CO2 emissions and costs were reduced substantially in the CSGHP system compared with the control house. Moreover, noxious gas emissions were reduced significantly in the CSGHP system relative to the control (P &lt; 0.05). Overall, the results of this study indicated that the CSGHP system has the potential to reduce electricity use, overall cost and CO2 and noxious gas emissions. Therefore, the CSGHP system has the potential for use as an environmentally friendly renewable energy source for animal houses. © 2016 American Institute of Chemical Engineers Environ Prog, 35: 1156–1165, 2016

Microwave-Assisted Synthesis of Defects Metal-Imidazolate-Amide-Imidate Frameworks and Improved CO2 Capture.

In this work, we report three isostructural 3D frameworks, named IFP-11 (R = Cl), IFP-12 (R = Br), and IFP-13 (R = Et) (IFP = Imidazolate Framework Potsdam) based on a cobalt(II) center and the chelating linker 2-substituted imidazolate-4-amide-5-imidate. These chelating ligands were generated in situ by partial hydrolysis of 2-substituted 4,5-dicyanoimidazoles under microwave (MW)-assisted conditions in DMF. Structure determination of these IFPs was investigated by IR spectroscopy and a combination of powder X-ray diffraction (PXRD) with structure modeling. The structural models were initially built up from the single-crystal X-ray structure determination of IFP-5 (a cobalt center and 2-methylimidazolate-4-amide-5-imidate linker based framework) and were optimized by using density functional theory calculations. Substitution on position 2 of the linker (R = Cl, Br, and Et) in the isostructural IFP-11, -12, and -13 allowed variation of the potential pore window in 1D hexagonal channels (3.8 to 1.7 Å). The potential of the materials to undergo specific interactions with CO2 was measured by the isosteric heat of adsorption. Further, we resynthesized zinc based IFPs, namely IFP-1 (R = Me), IFP-2 (R = Cl), IFP-3 (R = Br), and IFP-4 (R = Et), and cobalt based IFP-5 under MW-assisted conditions with higher yield. The transition from a nucleation phase to the pure crystalline material of IFP-1 in MW-assisted synthesis depends on reaction time. IFP-1, -3, and -5, which are synthesized by MW-assisted conditions, showed an enhancement of N2 and CO2, compared to the analogous conventional electrical (CE) heating method based materials due to crystal defects.

Energetic Macroscopic Representation of an Electrically Heated Building with Electric Thermal Storage and Heating Control for Peak Shaving

As a part of the Smart Grid concept, an efficient energy management at the residential level has received increasing attention in lately research. Its main focus is to balance the energy consumption in the residential environment in order to avoid the undesirable peaks faced by the electricity supplier. This challenge can be achieved by means of a home energy management system (HEMS). The HEMS may consider local renewable energy production and energy storage, as well as local control of some particular loads when peaks mitigation is necessary. This paper presents the modeling and comparison of two residential systems; one using conventional electric baseboard heating and the other one supported by Electric Thermal Storage (ETS); the ETS is employed to optimize the local energy utilization pursuing the peak shaving of residential consumption profile. Simulations of the proposed architecture using the Energetic Macroscopic Representation (EMR) demonstrate the potential of ETS technologies in future HEMS.

Desilication of ZSM-5 zeolites for mesoporosity development using microwave irradiation

Highlights: • Microwaves have beneficial effects on desilication of zeolites. • Produced mesopores with microwaves have narrow pore-size distribution. • Advantages and disadvantages of various desilicating agents were also reported. - Abstract: Mesoporous ZSM-5 zeolite was obtained by desilication in alkaline solutions with microwave (MW) and conventional electric (CE) heating under hydrothermal conditions. Both methods were effective in the production of mesoporous zeolites; however, MW was more efficient than CE as it led to well-defined mesopores with relatively small sizes and a narrow size distribution within a short treatment time. Moreover, the mesoporous ZSM-5 obtained through this method was effective in producing less bulky products from an acid-catalyzed reaction, specifically the butylation of phenol. Finally, various bases were found to have advantages and disadvantages in desilication. NaOH was the most reactive; however, macroporosity could develop easily under a severe condition. Ammonia water was weakly reactive; however, it could be used to precisely control the pore architecture, and no ion exchange is needed for acid catalysis. Organic amines such as ethylenediamine can also be used in desilication.

Pyrolyzed Waste Engine Oil Properties by Microwave-Induced Reactor

This study investigates the properties of pyrolyzed waste engine oil to determine the fuel properties for recycling purpose. Waste engine oil was pyrolyzed in a microwave-induced pyrolyzer at 400 °C under vacuum and the N2 was used to purge the pyrolysis zone to minimize O2. The fresh and waste engine oils were pyrolyzed and determined it by-products yield, and then the original and pyrolyzed waste engine oils were analyzed its chemical composition for their fuel properties following the standard method. The by-products fuel-related properties obtained from the only waste engine oil were comparable to those mixing oil with particulate carbon and different media of microwave and conventional electric heating reactors. In term of its feasibility application to energy and chemical industries this finding could be better with lower production cost.

Application and Realization of Electromagnetic Induction Heating in the Production of Fused Cast

Different heating has an important influence on the efficiency of the production casting. Electromagnetic induction heating technology is a new heating technology. Metallic materials is heated itself directly through the Eddy current effect with the high-frequency electric heating principle. Because of its concentrated heat, high power density and high thermal efficiency, it has more superiority than the current conventional electric furnace heating technology. In this paper, the electromagnetic induction heating system has been designed, and this heating method is applied to the casting production. The results show that the electromagnetic induction heating is very suitable for casting production, which can greatly shorten the production time and improve productivity.

Microwave-induced fast crystallization of amorphous hierarchical anatase microspheres.

The fabrication of hierarchical anatase microspheres with potential photocatalytic properties eventually comprises a consolidation step in which a high degree of crystalline order is typically achieved through conventional electric heating treatments. This however entails a substantial reduction in the specific surface area and porosity of the powders, with the consequent deterioration in their photocatalytic response. Here, we have tested the employ of microwave heating as an alternative energy-saving sintering method to promote fast crystallization. The results obtained suggest that under the microwave radiation, the TiO2 hierarchical structures can effectively crystallize in a drastically reduced heating time, allowing the specific surface area and the porosity to be kept in the high values required for an improved photocatalytic performance.

고성능 히트펌프 해석모델 개발 연구

히트 펌프는 지열이나 태양열 등의 신재생 에너지를 이용하거나 기타 폐열을 재활용하여 기존의 전기 히팅 난방 시스템들보다 에너지 소비율을 낮출 수 있다는 장점으로 인해 그린 에너지 시스템으로써 주목을 받아 왔다. 고효율 히트펌프 시스템 설계를 위한 연구는 오랫동안 지속되어 왔지만, 각각의 구성요소가 유기적이며, 변화에 유연한 해석모델은 존재하지 않는다. 따라서 본 연구에서는 공기 열 원식 히트 펌프를 AMESim Software를 이용해 구성하였다. 독자적으로 개발한 스크롤 압축기 해석 모델을 히트펌프 시스템에 조합함으로써 효율 향상 방안을 모색하였으며, 실험 데이터를 이용하여 개발한 해석모델을 검증하였다. 실험 데이터와 개발한 해석 모델을 이용하여 예측된 데이터를 비교한 결과 최대 오차가 10% 이내로 두 데이터가 잘 일치하였다. 본 연구에서 개발한 히트펌프 해석모델은 향후 시제품을 개발하고 효율 향상을 위한 연구 등에 유용하게 사용될 것으로 사료된다. Heat pumps have attracted considerable attention as a green energy system because they use renewable energy, such as geothermal, solar energy and waste heat, and can have a low electricity consumption rate compared to other conventional electric heating system. Many studies of high efficient heat pump system design was performed previously,but it is not easy to find any an analytical model that consists of components (e.g. compressor, heat exchangers, and expansion valve), not only having an interrelation and interconnection each other but also being flexible to any change in geometry and operating parameters. In this study, a computational model was developed for a heat pump with warm air as a heat source using the one-dimensional modeling software, AMESim. In combination with an independently-developed analytical model for a scroll compressor, the heat pump model can simulate the physical characteristics and actual behavior of the heat pump precisely. In addition, the reliability of the model was improved by verifying the simulation results using experimental data. The simulation data fell into the 10% error range compared with the experimental data. The heat pump model can be used for system optimization studies of product development and applied to other applications in a range of industrial field.

Continuous hydrogen production by biomass gasification in supercritical water heated by molten salt flow: System development and reactor assessment

Hydrogen production by biomass gasification using solar energy is a promising approach for overcoming the drawbacks of fossil fuel utilization, but the storage of discontinuous solar flux is a critical issue for continuous solar hydrogen production. A continuous hydrogen production system by biomass gasification in supercritical water using molten-salts-stored solar energy was proposed and constructed. A novel double tube helical heat exchanger was designed to be molten salts reactor for hydrogen production. Model compounds (glycerol/glucose) and real biomass (corn cob) were successfully gasified in this molten salts reactor for producing hydrogen-rich gas. The unique temperature profiles of biomass slurry in the reactor were observed and compared with that of conventional electrical heating and direct solar heating approaches. Product gases yield, gasification efficiency and exergy conversion efficiency of the reactor were analyzed. The results showed that the performances of reactor were determined by feedstock style, biomass concentration, residence time and biomass slurry temperature profiles.

Synthesis of Mesoporous SAPO-34 Molecular Sieves and Their Applications in Dehydration of Butanols and Ethanol

Microporous SAPO-34 molecular sieves were hydrothermally synthesized with microwave irradiation in the presence of tetraethylammonium hydroxide (TEAOH) as a template. SAPO-34 molecular sieves with mesoporosity were also prepared in the presence of carbon black as a hard template. By increasing the content of the carbon black template in the synthesis, the mesopore volume increased. Dehydration of alcohols (butanols and ethanol) was carried out with the synthesized SAPO-34 molecular sieves, and the lifetime of the catalysts for the dehydration reaction increased as the mesoporosity increased. Moreover, the performance of the microporous catalyst synthesized with microwave was better than that of the catalyst obtained with conventional electric heating. The relative performance of the catalytic dehydration may be explained by the mesoporosity and the crystal size. Therefore, it may be concluded that small-sized SAPO-34 molecular sieves with high mesoporosity can be produced efficiently with microwave irradiation in the presence of carbon black template, and the molecular sieves are effective in the stable dehydration of alcohols.