scholarly journals Thermal Efficiency of Oxyhydrogen Gas Burner

Energies ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 5526
Author(s):  
Roberto Moreno-Soriano ◽  
Froylan Soriano-Moranchel ◽  
Luis Armando Flores-Herrera ◽  
Juan Manuel Sandoval-Pineda ◽  
Rosa de Guadalupe González-Huerta
Keyword(s):  
Flow Rate ◽  
Thermal Energy ◽  
Thermal Efficiency ◽  
Combustion Process ◽  
High Energy ◽  
High Energy Density ◽  
Time Interval ◽  
Burner Surface ◽  
Hydrocarbon Combustion ◽  
Gas Burner

One of the main methods used to generate thermal energy is the combustion process. Burners are used in both industrial and residential applications of the open combustion process. The use of fuels that reduce polluting gas emissions and costs in industrial and residential processes is currently a topic of significant interest. Hydrogen is considered an attractive fuel for application in combustion systems due to its high energy density, wide flammability range, and only produces water vapor as waste. Compared to research conducted regarding hydrocarbon combustion, studies on hydrogen burners have been limited. This paper presents the design and evaluation of an oxyhydrogen gas burner for the atmospheric combustion process. The gas is generated in situ with an alkaline electrolyzer with a production rate of up to 3 sL min−1. The thermal efficiency of a gas burner is defined as the percentage of the input thermal energy transferred to the desired load with respect to a given time interval. The experimental results show a thermal efficiency of 30% for a minimum flow rate of 1.5 sL min−1 and 76% for a flow rate of 3.5 sL min−1. These results relate to a 10 mm height between the burner surface and heated container.

Combustion of Boron Nano-Particles in Ethanol Spray Flame

2010 ◽  
Author(s):  
Srinibas Karmakar ◽  
Sumanta Acharya ◽  
Kerry M. Dooley
Keyword(s):  
Energy Density ◽  
Particle Surface ◽  
Combustion Process ◽  
High Energy ◽  
Nano Particles ◽  
High Energy Density ◽  
Particle Analysis ◽  
Fuel Additive ◽  
Hydrocarbon Combustion ◽  
Spray Flame

Biofuels such as ethanol have lower energy density than conventional petroleum-based fuels, and therefore enhancing its energy density via addition of high-energy density components is an attractive option. Boron is an attractive fuel additive because it has among the highest volumetric heating value among potentially suitable additives. The present study deals with an experimental investigation of boron combustion in an ethanol spray flame. A constant low particle loading density of boron nanoparticles (60nm SMD), around 1% (by weight) of the liquid fuel flow rate, has been used. Though it has high energetic potential, the combustion process of boron is retarded by the initial presence of the oxide coating the particle surface. In the present study, measurements have been made of the emission of intermediate sub-oxide like BO2 using spectroscopy and imaging with interference filters. The effect of boron on the hydrocarbon combustion has also been studied by examining the heat release and product mole fractions. In addition, particle characterization has been carried out to know the size, surface structure/composition of the injected boron nano powders using XRD, XPS and TEM. A preliminary investigation has also been performed on the burnt particle collected from the exhaust structure using XRD. The chemiluminescence and spectroscopic signatures indicate that boron combustion is facilitated and that hydrocarbon combustion is enhanced. The particle analysis shows differences in the imaged and spectroscopic characteristics of the unburnt and burnt nano-particles reflecting the particle-combustion processes.

scholarly journals Nucleation Triggering of Highly Undercooled Xylitol Using an Air Lift Reactor for Seasonal Thermal Energy Storage

2018 ◽  
Author(s):  
Marie DUQUESNE ◽  
Elena PALOMO DEL BARRIO ◽  
Alexandre GODIN
Keyword(s):  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
High Energy ◽  
Operating Conditions ◽  
High Energy Density ◽  
Bubble Generation ◽  
Spontaneous Nucleation ◽  
Air Lift Reactor ◽  
Air Lift

Xylitol is an organic, non-toxic, biosourced phase change material with high potential for seasonal thermal energy storage material. It has a high energy density, a high and stable undercooling allowing storing solar energy at ambient temperature thus, reducing thermal losses and the risk of spontaneous nucleation (i.e., the risk of losing the stored energy). When the energy is needed, the discharge triggering of the storage system (i.e., Nucleation triggering of highly viscous undercooled Xylitol) is very difficult as well as reaching a sufficient power delivery (i.e., the control of the subsequent crystal growth rates). Both are the mains locks for the use of Xylitol in seasonal energy storage. Different techniques to crystallize highly undercooled Xylitol have hence been considered. It has been proven that nucleation triggering of highly undercooled Xylitol using an air lift reactor would allow reaching performances matching with building applications (i.e., at medium temperatures, below 100 °C). The advantages of this technique compared to other existing techniques to activate the crystallization are discussed. The mechanisms triggering the nucleation are investigated. The air bubble generation, transportation of nucleation sites and subsequent crystallization are discussed to improve the air injection operating conditions.

Towards High Energy Density, High Conductivity Thermal Energy Storage Composites

2012 ◽  
Author(s):  
Patrick J. Shamberger ◽  
Daniel E. Forero
Keyword(s):  
Thermal Conductivity ◽  
Energy Storage ◽  
Energy Density ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
High Energy ◽  
High Energy Density ◽  
Lithium Nitrate ◽  
Nitrate Trihydrate ◽  
Graphitic Foam

Thermal energy storage (TES) materials absorb transient pulses of heat, allowing for rapid storage of low-quality thermal energy for later use, and effective temperature regulation as part of a thermal management system. This paper describes recent development of salt hydrate-based TES composites at the Air Force Research Laboratory. Salt hydrates are known to be susceptible to undercooling and chemical segregation, and their bulk thermal conductivities remain too low for rapid heat transfer. Here, we discuss recent progress towards solving these challenges in the composite system lithium nitrate trihydrate/graphitic foam. This system takes advantage of both the high volumetric thermal energy storage density of lithium nitrate trihydrate and the high thermal conductivity of graphitic foams. We demonstrate a new stable nucleation agent specific to lithium nitrate trihydrate which decreases undercooling by up to ∼70% relative to previously described nucleation agents. Furthermore, we demonstrate the compatibility of lithium nitrate trihydrate and graphitic foam with the addition of a commercial nonionic silicone polyether surfactant. Finally, we show that thermal conductivity across water-graphite interfaces is optimized by tuning the surfactant concentration. These advances demonstrate a promising route to synthesizing high energy density, high thermal conductivity TES composites.

Computational Fluid Dynamic Analyses of Flow and Combustion in a Domestic Liquefied Petroleum Gas Cookstove Burner—Part II: Burning Characteristics and Overall Performance

2019 ◽  
Vol 12 (3) ◽  
Author(s):  
Mithun Das ◽  
Ranjan Ganguly ◽  
Amitava Datta ◽  
Meenam M. Verma ◽  
Ashis K. Bera
Keyword(s):  
Heat Flux ◽  
Flow Rate ◽  
Thermal Efficiency ◽  
Equivalence Ratio ◽  
Vessel Diameter ◽  
High Energy ◽  
Liquefied Petroleum Gas ◽  
Fuel Flow Rate ◽  
Fuel Flow ◽  
Load Height

Abstract Liquefied petroleum gas (LPG) is widely used in domestic cookstoves as it is a clean and high energy content fuel in comparison with other traditional cooking fuels. With the increasing demand of LPG, study and improvement of cookstove performance have become an important subject. In the present work, a numerical study of the flow and thermal fields for a domestic cookstove burner has been investigated and the performance of the stove is analyzed at different parametric conditions, like the equivalence ratio of the primary fuel–air mixture, fuel flow rate, thermal load height, and loading vessel size. The maximum thermal efficiency has been found for an equivalence ratio of 1.4 for the LPG–air mixture and at load height of 20 mm. The heat flux distribution at the bottom of the vessel is found to be bimodal with the higher peak occurring closer to the center of the vessel. The thermal efficiency of the stove increases with the rise in the fuel flow rate, and it decreases with reducing cooking vessel diameter. As the vessel diameter increases, the fraction of the total heat supplied through the vessel bottom increases. The radiative component of the heat flux is found to be much smaller compared to the convective component.

Numerical Investigation of the Influence of Impeller-Diffuser Gap (A- and B-Gaps) on Unsteady Flow in a Centrifugal Pump at Part Flows

2019 ◽  
Author(s):  
Taiki Takamine ◽  
Satoshi Watanabe
Keyword(s):  
Unsteady Flow ◽  
Centrifugal Pump ◽  
Flow Rate ◽  
Internal Flow ◽  
Leading Edge ◽  
High Energy ◽  
Rotating Stall ◽  
Rotor System ◽  
The Other ◽  
High Energy Density

Abstract Because of the high energy density of multi-stage centrifugal pump, it is really important to ensure the reliability of the pumps thus the stability of rotor system in the wide flow rate range. Rotating stall is a well-known unsteady flow phenomenon in which one or several stall cell structures propagate circumferentially in impeller and/or diffuser. Rotating stall alters the peripheral pressure distribution of rotors, and therefore it is often regarded as one of the primary trigger of unstable fluid force acting on the rotor system. One possible factor which could affect the rotating stall is a geometrical relationship between the rotor and the stator. In the present study, unsteady RANS simulations of internal flow in a centrifugal pump are carried out. The pump is the partial model of the final stage of the three-stage centrifugal pump used in our previous study. In order to investigate the effect of the gap between impeller trailing edge and diffuser leading edge on the unsteady flow of the pump, three cases of impeller-diffuser gap is simulated; one is the smaller gap case with original impeller. The other cases are two larger gap cases with only cutting the impeller blades and with cutting the both impeller blades and impeller shroud walls. For all gap cases, the computations are conducted for the nominal flow rate and the low flor rate with 10% of the nominal flow rate. As a result, the rotating stall is observed only in the larger gap case with the cut shroud walls, indicating that the key phenomenon for the stable formation of the stall cell is not only the weakened rotor-stator interaction, but also the other phenomenon attributed to the enlarged gap between the impeller shroud walls and the diffuser walls. In the shroud cut case, a part of the main flow blocked by the stalled region and the secondary flow on the diffuser walls tend to flow into the side gaps more easily than other cases. They might be the important phenomenon associated with the diffuser rotating stall in the enlarged wall gap condition.

scholarly journals Nucleation Triggering of Highly Undercooled Xylitol Using an Air Lift Reactor for Seasonal Thermal Energy Storage

2019 ◽  
Vol 9 (2) ◽  
pp. 267 ◽  
Author(s):  
Marie Duquesne ◽  
Elena Palomo Del Barrio ◽  
Alexandre Godin
Keyword(s):  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
High Energy ◽  
Operating Conditions ◽  
High Energy Density ◽  
Bubble Generation ◽  
Spontaneous Nucleation ◽  
Air Lift Reactor ◽  
Air Lift

Bio-based glass-forming materials are now considered for thermal energy storage in building applications. Among them, Xylitol appears as a biosourced seasonal thermal energy storage material with high potential. It has a high energy density and a high and stable undercooling, thus allowing storing solar energy at ambient temperature and reducing thermal losses and the risk of spontaneous nucleation (i.e., the risk of losing the stored energy). Generally when the energy is needed, the discharge triggering of the storage system is very difficult as well as reaching a sufficient power delivery. Both are indeed the main obstacles for the use of pure Xylitol in seasonal energy storage. Different techniques have been hence considered to crystallize highly undercooled Xylitol. Nucleation triggering of highly undercooled pure Xylitol by using an air lift reactor has been proven here. This method should allow reaching performances matching with building applications (i.e., at medium temperatures, below 100 °C). The advantages of this technique compared to other existing techniques to activate the crystallization are discussed. The mechanisms triggering the nucleation are investigated. The air bubble generation, transportation of nucleation sites and subsequent crystallization are discussed to improve the air injection operating conditions.

scholarly journals An Innovative Calcium Looping Process as Energy Storage System Integrated With a Solar-Powered Supercritical CO2 Brayton Cycle

2021 ◽  
Vol 2 ◽  
Author(s):  
Salvatore F. Cannone ◽  
Andrea Lanzini ◽  
Stefano Stendardo
Keyword(s):  
Energy Storage ◽  
Thermal Energy ◽  
Storage System ◽  
High Energy ◽  
Solar Thermal ◽  
High Energy Density ◽  
Brayton Cycle ◽  
Solar Thermal Energy ◽  
Global System ◽  
Calcium Looping

Coupling solar thermal energy with the hybrid TC/CG-ES (thermochemical/compressed gas energy storage) is a breakthrough option used to overcome the main challenge of solar energy, i.e., intermittent resource and low density. This paper proposes an innovative storage system that improves the competitiveness of solar thermal energy technologies compared to conventional fossil-based power plants, potentially leading to deep decarbonization of the energy and industrial sectors. This study uses thermochemical energy storage based on the calcium looping (CaL) process and takes advantage of a number of factors: high energy density (2 GJ/m3), absence of heat loss (seasonal storage), high operation temperature (high efficiency of the power plant), and use of cheap and environmentally friendly reactant feedstock (CaO/CaCO3). This work deals with the integration of the solar CaL storage system with an unconventional supercritical CO2 (s-CO2) Brayton cycle. We analyze different s-CO2 Brayton cycle layouts suitable for direct integration with the storage system. Energy integration via pinch analysis methodology is applied to the whole system to optimize the internal heat recovery and increase the efficiency of the system. A parametric study highlights how the integration of solar CaL with an intercooling Brayton cycle shows better results than the combination with the Rankine cycle that we investigated previously, resulting in net and global system efficiencies equal to 39.5 and 51.5%. Instead, the new calculated net and global system efficiencies are 44.4 and 57.0%, respectively, for TC-CG-ES coupled with the Brayton power cycle.

scholarly journals Nucleation Triggering of Highly Undercooled Xylitol Using an Air Lift Reactor for Seasonal Thermal Energy Storage

2019 ◽  
Author(s):  
Marie Duquesne ◽  
Elena Palomo Del Barrio ◽  
Alexandre Godin
Keyword(s):  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
High Energy ◽  
Operating Conditions ◽  
High Energy Density ◽  
Bubble Generation ◽  
Spontaneous Nucleation ◽  
Air Lift Reactor ◽  
Air Lift

Bio-based glass-forming materials are now considered for thermal energy storage in building applications. Among them, Xylitol appears as a biosourced seasonal thermal energy storage material with high potential. It has a high energy density, a high and stable undercooling allowing storing solar energy at ambient temperature thus, reducing thermal losses and the risk of spontaneous nucleation (i.e., the risk of losing the stored energy). Generally when the energy is needed, the discharge triggering of the storage system is very difficult as well as reaching a sufficient power delivery. Both are indeed the mains locks for the use of pure Xylitol in seasonal energy storage. Different techniques have been hence considered to crystallize highly undercooled Xylitol. Nucleation triggering of highly undercooled pure Xylitol by using an air lift reactor has been proven here. This method should allow reaching performances matching with building applications (i.e., at medium temperatures, below 100 °C). The advantages of this technique compared to other existing techniques to activate the crystallization are discussed. The mechanisms triggering the nucleation are investigated. The air bubble generation, transportation of nucleation sites and subsequent crystallization are discussed to improve the air injection operating conditions.

Performance of Hybrid Photovoltaic and Thermal (PV/T) Collector With and Without Electricity Generation

2009 ◽  
Author(s):  
Erkata Yandri ◽  
Naokatsu Miura ◽  
Sadsuke Ito ◽  
Toru Fujisawa ◽  
Mika Yoshinaga
Keyword(s):  
Steady State ◽  
Flow Rate ◽  
Thermal Performance ◽  
Thermal Energy ◽  
Thermal Efficiency ◽  
Electricity Generation ◽  
Water Flow Rate ◽  
Photovoltaic Cells ◽  
Heat Losses ◽  
Wind Environment

This paper presents the experimental results that involve the analysis of a photovoltaic and thermal (PV/T) hybrid collector, which has an integration of the photovoltaic cells and a solar thermal panel into one collector, by focusing on its thermal efficiency when both thermal and electrical energies are generated and when only thermal energy is generated. The experiment was performed at 4 different collector input temperatures, i.e., 12°C, 15°C, 20°C, and 25°C under the condition that the water flow rate was 4 l/min. We analyzed during the period of peak irradiation from 12:00 to 13:00 to obtain the semi-steady-state thermal performance. Besides, in order to remove the differences of the wind environment, the wind heat losses are calculated in the analysis. The result shows that the thermal efficiency of the PV/T collector decreases slightly when only thermal energy is generated as compared to that when both thermal and electrical energies are generated.

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