Regenerative Chamber Research Articles

Velocity and Temperature Simulation for a Cylindrical Regenerative Thermal Oxidizer.

The cylindrical regenerative thermal oxidizer (CRTO) came into being later than the three-chamber regenerative thermal oxidizer (TRTO). Compared with TRTO, CRTO has a smaller size and a larger regenerator volume for absorbing and releasing heat. There are few studies on CRTO despite its numerous applications. A CRTO was selected in industrial applications for simulation research. The velocity and temperature of the CRTO were investigated after error analysis of industrial and simulated data. It was found that the velocity and temperature in the regenerative chamber had obvious stratification and gradients after homogenization by the regenerator unit. The velocity and temperature distribution in the oxidation chamber were independent of the position of the CRTO inlet and outlet or the structure below the regenerator, and there were identical periodic changes in each period. A TRTO with primary parameters as those of the CRTO was employed for comparison. The time of the intake and exhaust periods of a CRTO regenerative chamber were 30 s longer than those of a TRTO. The regenerator volume of heat storage used by CRTO for heat exchange increased by 1/6 compared to that of TRTO at the same total regenerator volume. Simulation shows that CRTO had a more uniform velocity and temperature in the regenerative chamber compared to those in TRTO, increasing by approximately 2%; the thermal efficiency is higher, with an average increase of about 3%.

The Use of Uncertainty Quantification and Numerical Optimization to Support the Design and Operation Management of Air-Staging Gas Recirculation Strategies in Glass Furnaces

The reduction in energy consumption and the increasingly demanding emissions regulations have become strategic challenges for every industrial sector. In this context, the glass industry would be one of the most affected sectors due to its high energy demand and emissions productions, especially in terms of NOx. For this reason, various emission abatement systems have been developed in this field and one of the most used is the air staging system. It consists in injecting air into the upper part of the regenerative chamber on the exhaust gases side in order to create the conditions for combustion that reduces NOx emissions. In this work, the combined use of CFD with data analysis techniques offers a tool for the design and management of a hybrid air staging system. Surrogate models of the bypass mass flow rate and uniformity index in the regenerative chamber have been obtained starting from DoE based on different simulations by varying the air mass flow rate of the two injectors located in a bypass duct that connects the two regenerative chambers. This model allows a UQ analysis to verify how the uncertainty of the air injectors can affect the bypass mass flow rate. Finally, an optimization procedure has identified the optimal condition for the best bypass mass flow rates and uniformity of the oxygen concentration in the chamber. High values of the mass flow rate of the pros injector and medium-low values for the cons injectors are identified as operating parameters for best conditions.

A CFD Based Approach for the Simulation of Gas Recirculation Systems in Regenerative Chambers for Glass Production Plants Consistent with Functional Details Found in Real Geometries

A CFD Based Approach for the Simulation of Gas Recirculation Systems in Regenerative Chambers for Glass Production Plants Consistent with Functional Details Found in Real Geometries

Numerical Prediction of the Flow Structure Inside Components of Industrial Glass Furnace Systems

An important aspect in the glass production industry is related to the heat recovery of the combustion gases. It is usually obtained throughout the use of well-tested technologies, such as regenerative towers with refractory material. For an effective heat recovery, a good distribution of the flow rate at the entrance of the chambers is crucial. The use of Computational Fluid Dynamics (CFD) allows the detailed analysis of the gas evolution during the process; the same would be impractical with experimental measurements, due to prohibitive ambient local conditions. The CFD approach during the design phase typically considers CAD geometries without the level of details related to technological features of the actual installed configuration (i.e. sharp edges vs rounded edges). A brand new built furnace has blunt edges in every connection between 3D walls of refractory blocks. The above edges will be rounded by the erosion-corrosion process due to the harsh chemical/mechanical/thermal environmental conditions inside the plant components (i.e. regenerative chambers, connecting ducts, furnace). The purpose of this work is to evaluate the influence of the geometrical details of the CAD (with focus on the edges connecting adjacent walls), due to technological or erosion aspects, on the flow structure in the furnace components.

Comparison of Convection Models for Hot Blast Stove Regenerative Chamber

Low error numerical solutions of convective heat transfer in high-temperature air regenerative heat exchangers in the convective regime rely on the correct determination of the wall heat transfer coefficient. Presented are results of simulations computed using a similarity theory-based numerical model. They imply that the current empirical formulas based on the theory of similarity, derived for analogous model cases of convective heat transfer do not allow to achieve satisfactory accuracy. Actual dependencies of parameters and criteria yielding more representative heat transfer coefficient values might be obtained through the means of experimental research in thermodynamics of an experimental device.

Transient Numerical Simulation of Regenerative Systems with Waste Gas Recirculation Strategies in Glass Production Plant

The glass production industry has one of the highest energy consumption rates and environmental emission impacts with respect to the existing industrial sectors. Glass furnaces nowadays are conceived with regenerative systems to take advantage of the residual heat from the combustion exhausts in order to increase the thermal efficiency of the system. The exhaust gases are also used in innovative systems to reduce the NOx emissions in specifically designed gas recirculation systems tailored to the glass furnace. In this paper, a numerical model for the simulation of the regenerative chambers in both steady and unsteady conditions is presented. The option of gas recirculation is also included. Special attention has been focused on the radiative heat transfer from the recirculated gases using a gas emissivity model previously developed by the authors.

Simulation strategies for regenerative chambers in glass production plants with strategic exhaust gas recirculation system

Simulation strategies for regenerative chambers in glass production plants with strategic exhaust gas recirculation system

CFD Analysis of Regenerative Chambers for Energy Efficiency Improvement in Glass Production Plants

The overall efficiency of a regenerative chamber for a glass furnace mainly relies on the thermo-fluid dynamics of air and waste gas alternatively flowing through stacks of refractory bricks (checkers) determining the heat recovery. A numerical approach could effectively support the design strategies in order to achieve a deeper understanding of the current technology and hopefully suggest new perspectives of improvement. A computational fluid dynamics (CFD) scheme for the regenerator is proposed, where the real geometry of the solid phase is modelled as a porous solid phase exchanging heat with the gas stream. Satisfactory data fitting proved the reliability of the present approach, whose applications are proposed in the last section of this study, to confirm how such a CFD modelling could be helpful in improving the overall energy efficiency of the regeneration chamber.

Methods of effectiveness increase for regenerative chamber of the second stage of Gifford - Mcmahon cryocooler.

Methods of effectiveness increase for regenerative chamber of the second stage of Gifford - Mcmahon cryocooler.

Modality-Specific Axonal Regeneration: Toward Selective Regenerative Neural Interfaces

Regenerative peripheral nerve interfaces have been proposed as viable alternatives for the natural control of robotic prosthetic devices. However, sensory and motor axons at the neural interface are of mixed sub-modality types, which difficult the specific recording from motor axons and the eliciting of precise sensory modalities through selective stimulation. Here we evaluated the possibility of using type specific neurotrophins to preferentially entice the regeneration of defined axonal populations from transected peripheral nerves into separate compartments. Segregation of mixed sensory fibers from dorsal root ganglion neurons was evaluated in vitro by compartmentalized diffusion delivery of nerve growth factor (NGF) and neurotrophin-3 (NT-3), to preferentially entice the growth of TrkA+ nociceptive and TrkC+ proprioceptive subsets of sensory neurons, respectively. The average axon length in the NGF channel increased 2.5-fold compared to that in saline or NT-3, whereas the number of branches increased threefold in the NT-3 channels. These results were confirmed using a 3D “Y”-shaped in vitro assay showing that the arm containing NGF was able to entice a fivefold increase in axonal length of unbranched fibers. To address if such segregation can be enticed in vivo, a “Y”-shaped tubing was used to allow regeneration of the transected adult rat sciatic nerve into separate compartments filled with either NFG or NT-3. A significant increase in the number of CGRP+ pain fibers were attracted toward the sural nerve, while N-52+ large-diameter axons were observed in the tibial and NT-3 compartments. This study demonstrates the guided enrichment of sensory axons in specific regenerative chambers, and supports the notion that neurotrophic factors can be used to segregate sensory and perhaps motor axons in separate peripheral interfaces.

Computer Simulation of Heat Transfer in Regenerative Chambers of Self-preheating Hot Blast Stoves

Heat transfer in chambers of self-preheating hot blast stoves in Anshan Iron and Steel Co., China, has been numerically simulated with a three-dimensional unsteady heat conduction equation and an energy conservation equation for fluid flowing through channels in the chambers. The blast temperature and air preheating temperature in the numerical simulation study are in good agreement with those in measurement. The numerical results show that hot blast temperature can reach 1 200°C by using a self-preheating process and low calorific blast furnace gas under the studied operational conditions. Amount of heat exchange between the checkerwork and the fluids and usable heat increase in the middle and low parts of the chambers of the hot blast stoves due to the application of the self-preheating process.

Effects of extracellular ATP on survival of sensory neurons in the dorsal root ganglia of rats.

ATP was added to the cultured sensory neurons obtained from the dorsal root ganglia of the neonatal rats and PBS was added to serve as control. MTT assays were conducted to evaluate the survival and activity of the cultured neurons. And the silicone regenerative chamber was used after the sciatic nerve incision of the mature SD rat. 1 mmol/L ATP was injected into the left chamber and 0.09% natrium chloride was injected into the right chamber as controls. The changes of nitric oxide synthase (NOS) activity in the corresponding dorsal root ganglia were measured histochemically and image analysis was also performed 4 days after the sciatic nerve injury. The results showed that extracellular ATP could enhance the survival of the neurons and the number of NOS positive neurons were significantly different between the ATP and control groups (P < 0.05). It was suggested that extracellular ATP had neurotrophic effect on neurons survival and could inhibit the NOS activity of the sensory neurons after the peripheral nerve incision, hence exerting the protective effect on the neurons, which was valuable for nerve regeneration after nerve injury.