Inlet Exhaust Research Articles

Influences of exhaust gas temperature and flow rate on optimal catalyst activity profiles

This paper presents an optimization of an axial catalyst distribution for the two types of optimal axial catalyst distributions: continuous exponential and discrete two-zone, to enhance the light-off of a catalytic converter with a fixed amount of a catalyst. The influences of exhaust gas temperature and mass flow rate on the two types of optimal active component distribution profiles are identified and hence an optimum value for each of the operating conditions is quantitatively established. The catalyst surface area of the optimal distribution in the upstream section is greater, and in the downstream is lower than that of the uniform distribution. As an inlet exhaust gas temperature becomes lower than the catalyst light-off temperature, i.e., about 600K, the catalyst surface area of the optimal distribution at the monolith inlet increases greatly to attain high reaction rates at the monolith entrance. In contrast, at temperatures above 600K, it decreases slightly and hence its variation becomes negligibly small, as compared to the variation of the inlet gas temperature. The catalyst surface area at the monolith entrance decreases gradually with the increasing mass flow rate at gas temperatures above 550K.

The Design of Exhaust Gas Cooler for Diesel Particulate Bag Filter

Currently, the application of bag-filter technology in controlling diesel exhaust particulate emissions has been close to practical stage. As one of the key links in bag-filter technology, engine exhaust cooling can directly influence working safety of the entire exhaust particulate filter system. Thermodynamic calculations and experimental research of water-cooled chiller has provided a feasible basis for water cooler to be used in actual diesel exhaust particulate emission control system. The cooler can make engine exhaust temperature drop from 400 to 180 . Even when engine works in high-speed and high-load condition, inlet exhaust temperature of cooler can descend from 500 to 190 or so after cooling, which can still meet bag-filter system requirement of below 200 .

The Design and Research of the New Energy Efficient Combustion Stove

For overcoming flaws of traditional gas stove and kitchen ventilator, the structure and principle of internal combustion stove was proposed. While working, the mixture of oil smoke, water vapor, air and natural gas was completely mixed and burned in furnace chamber. The inner pressure of furnace chamber is higher than atmosphere. In the process of being emitted outdoor, the exhaust gas in high temperature heated the gas mixture into the furnace chamber. So theoretically, the internal combustion stove has these characters such as higher thermal efficiency, lower cost, easy maintenance, safety and environmental protection, and so on. The prototype was developed and the working principle of internal combustion Stove was verified. The flow state in the furnace chamber and the thermal of inlet pipe and exhaust pipe was analyzed based on ANSYS, GAMBIT and FLUENT. The verification test further confirmed the principle of internal combustion stove and was consistent with the experimental data, which has important reference value for the improvement and optimization in structure of internal combustion stove.

Radiated Noise Source Localization of Hydraulic Excavator Based on Wavelet Packet Analysis

Collect a hydraulic excavators radiated noise ten meters away under set conditions, and also the relevant noises near the excavator. Analyze noise signals with wavelet packet to get the main band of energy distribution. Then calculate the two signals correlation coefficient, which identifies the muffler exhaust noise and inlet noise as the main source for right rear radiated noise.

Design of a New Type Low Heating Vapor Recovery Pump

In order to solve the problem of high-heating and motor burning for the vapor recovery pump, this paper designs a low heating pump with some radiating mechanical measures, which are improving the structure of the flame arrester, using PTFE diaphragm and adding the heat sink. The structure and the operating principle of the pump are given. All indicated that the flame arrester has a reasonable structure, can effectively improve the inlet and outlet exhaust efficiency. And by using PTFE diaphragm and the heat sink, the friction of the piston and the piston cavity is reduced and the heat dissipating efficiency is increased.

Preliminary Study on Exhaust Efficiency of Smoke Management System in Tunnel Fires

Exhaust efficiency in tunnel fires with mechanical means was discussed. Heat exhaust efficiency and smoke exhaust efficiency were defined and studied under two different exhaust modes (longitudinal exhaust and transverse exhaust) respectively. Exhaust efficiency depends on smoke generation rate, exhaust rate, heat loss through walls of tunnel, configuration of extraction installations and so on. Under smoke extraction, smoke exhaust efficiency equals 1 if a quasi-steady vented stage without upstream outflow forms, otherwise smoke exhaust efficiency is less than 1. Heat exhaust efficiency is always less than 1 since part of the heat released by the fire is lost through the solid boundaries of tunnel by radiative and convective heat transfer between the smoke and ceiling lining. Based on experimental data obtained from a series of fire tests in a model tunnel, heat exhaust efficiency was estimated and influencing factors were discussed. In tunnel fires with transverse mechanical exhaust system, heat exhaust efficiency varies from 20% to 50%. Heat exhaust efficiency increases along with the reduction of the number of exhaust inlets turned on while extracting and decreases along with the increase of the area of exhaust inlet. However, quantitative influence of inlet position on exhaust efficiency still need further study and will be reported later.

Energetic Based Organic Fluid Selection for a Solid Oxide Fuel Cell-Organic Rankine Cycle Combined System

In this study, energetic based fluid selection for a solid oxide fuel cell-organic rankine combined power system is investigated. 9 dry organic fluids with varied critical temperatures are chosen and their corresponding ORC cycle performances are evaluated at different turbine inlet temperatures and exhaust gas temperature (waste heat source) from the upper cycle. It is found that actual ORC cycle efficiency for each fluid strongly depends on the waste heat recovery performance of the heat recovery vapor generator. Exhaust gas temperature determines the optimal fluid which yields the highest efficiency.

An integrated system combining chemical looping hydrogen generation process and solid oxide fuel cell/gas turbine cycle for power production with CO2 capture

In this paper, the solid oxide fuel cell/gas turbine (SOFC/GT) cycle is integrated with coal gasification and chemical looping hydrogen generation (CLHG) for electric power production with CO2 capture. The CLHG-SOFC/GT plant is configurated and the schematic process is modeled using Aspen Plus® software. Syngas, produced by coal gasification, is converted to hydrogen with CO2 separation through a three-reactors CLHG process. Hydrogen is then fueled to SOFC for power generation. The unreacted hydrogen from SOFC burns in a combustor and drives gas turbine. The heat of the gas turbine exhaust stream is recovered in HRSG for steam bottoming cycle. At a system pressure of 20 bar and a cell temperature of 900 °C, the CLHG-SOFC/GT plant has a net power efficiency of 43.53% with no CO2 emissions. The hybrid power plant performance is attractive because of high energy conversion efficiency and zero-CO2-emission. Key parameters that influence the system performance are also discussed, including system operating pressure, cell temperature, fuel utilization factor, steam reactor temperature, CO2 expander exhaust pressure and inlet gas preheating.

A two-dimensional model for control of centrifugal fan inlet noise in a notebook computer

Previous work on active control of exhaust noise from small centrifugal fans demonstrated significant reductions of the blade passage frequency (BPF) tone. A fan and heat-sink were placed within a mock-up notebook computer case, and control of the fan exhaust noise was measured. It was found that control of the BPF in the exhaust did not significantly affect noise radiated from the fan inlets into the notebook casing, suggesting that exhaust noise and inlet noise may be controlled separately without one adversely affecting the other. In the current work, a two dimensional half-space, source coupling model has been developed to calculate the field within the notebook casing caused by the inlet noise. As a first approximation, free-space boundary conditions were used. A two-dimensional space was constructed to test the model, and error sensor placement was predicted. Measurements of radiated sound power show significant reduction of the blade passage frequency tone. Factors influencing experimental agreement with the model are discussed, such as modal effects and primary source location.

Research on the Parameter Optimization of Certain Complex Structure

Using the method of the parameter study, some important dimensions of the cylinder head of an internal-combustion engine are analyzed. Under the mechanical load, the variational rules of the Von Mises maximum stress on cylinder head are obtained, which are influenced by the thickness of the floor plate, head plate, jobbing sheet, standing partition board, and side plate of inlet port and exhaust port. A hypothesis is verified that there is an ideal matching point among those above-mentioned main parameters. The quantificational proportion relations, between these key structural parameters and Von-Mises maximum stress of cylinder head, can provide a good help for the cylinder head’s structural design.

A New System to Produce Cooling and Power Using Solar Thermal Energy

A new system to produce cooling and power with the energy obtained from low-temperature as a thermal resource is presented in this work. This resource can be obtained from concentrating solar thermal energy (parabolic trough). This system belongs to the broader class of low temperature, Rankine cycles, which have been shown to be one of the most effective means for utilizing low temperature resources. They have been applied to the production of mechanical power using heat from solar. The system uses thermal energy in a low-temperature boiler to partially boil working fluid mixture (ammonia-water). The theoretical study is presented, which identifies expander inlet conditions, expander efficiency, and exhaust pressure as the factors determining exhaust temperature. It is concluded that the proposed system improves the expander performance, output power, and cooling production and can be satisfied with this concept.

ВЛИЯНИЕ ПЛОЩАДИ И КОЛИЧЕСТВА ДЫМО-ПРИЕМНЫХ ОТВЕРСТИЙ В ЗАВИСИМОСТИ ОТ РАСХОДА УДАЛЯЕМЫХ ПРОДУКТОВ ГОРЕНИЯ НА ЭФФЕКТИВНОСТЬ РАБОТЫ ИМПУЛЬСНОЙ ПРОТИВОДЫМНОЙ ВЕНТИЛЯЦИИ ЗАКРЫТЫХ АВТОСТОЯНОК

ВЛИЯНИЕ ПЛОЩАДИ И КОЛИЧЕСТВА ДЫМО-ПРИЕМНЫХ ОТВЕРСТИЙ В ЗАВИСИМОСТИ ОТ РАСХОДА УДАЛЯЕМЫХ ПРОДУКТОВ ГОРЕНИЯ НА ЭФФЕКТИВНОСТЬ РАБОТЫ ИМПУЛЬСНОЙ ПРОТИВОДЫМНОЙ ВЕНТИЛЯЦИИ ЗАКРЫТЫХ АВТОСТОЯНОК

Characteristics of ventilating flow generated by a rotating swirler in a vortex vent

A vortex ventilation system with a rotating annular disk installed coaxially with the exhaust inlet is a very effective local ventilator. A swirling flow generated by a rotating swirler makes the ventilation flow concentrated around the axis of rotation, which can increase the ventilation depth by a factor of five compared to a conventional exhaust hood. Despite the well-documented excellent ventilation performance of such a system, detailed flow characteristics are not well understood. In this study, the swirling flow field in the vortex vent was tested, and a number of peculiar flow characteristics were observed. When the rotational speed was varied, a series of different flow patterns appeared, and the changes in the flow pattern showed rapid transition, hysteresis, and flow instability similar to the vortex. The transition of the flow pattern could be explained based on the ratio of the centrifugal force to exhaust pressure. Hysteresis of the flow transition occurred in an unstable equilibrium mode between the two forces, and an unstable flow pattern occurred when the secondary recirculating flow was located beneath the swirler. A formula for the critical rotational speed was derived, which showed satisfactory agreement with experimental observation.

CFD ANALYSIS FOR DETACHED HOUSE

This paper describes the distribution of local air exchange efficiency (εp) in the living room when the layout of supply outlets and exhaust inlets and the position of air-conditioners is changed.The results are as follows;(1) The value of mean εp of breathing zone becomes about 1.0 because fresh air spread completely in the room when airconditioners are operated.(2)In the case when air-conditioners are not operated, the mean εp becomes smaller than 1.0, and the poor area of ventilation efficiency becomes large.(3) Ventilation efficiency is influenced by the layout of the supply outlets and exhaust inlets.

Performance of the Vortex Ventilator System Based on Capture Velocity and Capture Efficiency

The vortex ventilator (VV) is a new concept of a local exhaust ventilation system that uses a vortex flow to improve the directional capture ability and thus overcomes the critical defects of the general local exhaust ventilation (LEV) system. The LEV has a rapid decrease of the capture velocity with distance from the exhaust inlet, resulting in a very poor capture efficiency when contaminants are generated far away from the exhaust inlet. In this study, the capture characteristics of the VV are evaluated with respect to the capture efficiency as well as the capture velocity. Three-dimensional computational fluid dynamics simulations are performed together with experiments using the tracer gas method with SF6. Compared with simple suction, the VV gives more than nine times as large a capture velocity and thus has a capture efficiency of higher than 70%. The larger capture velocity and the higher capture efficiency of the VV guarantee a more flexible layout of the equipment in the working area.

Experimental study of sources of noise from heavy earth-moving machinery

An experimental study was carried out to investigate the principal sources of sound from heavy earth-moving machinery, namely a bulldozer and a front-end loader. Major sound sources were the exhaust and air inlet for the engines and the engine cooling fan on the bulldozer. Sound from the exhaust was an important source at nominal one-third-octave midband frequencies from 25 Hz to 250 Hz; sound from the air inlet was a significant contributor in the range of midband frequencies from 25 Hz to 500 Hz. Cooling fan noise for the bulldozer was important in the frequency range from 315 Hz to 3150 Hz. For the front-end loader, the enclosed cab in which the operator sits provided good noise reduction at frequencies greater than 400 Hz up to 20 kHz. Examination of the spectrum of the sound produced by these and other heavy earth-moving machines can indicate the need for maintenance efforts to restore noise-control capabilities that were originally installed or which should be installed.

Study on the design of inlet and exhaust system of a stationary internal combustion engine

The design and operational variables of inlet and exhaust systems are decisive to determine overall engine performance. The best engine overall performance can be obtained by proper design of the engine inlet and exhaust systems and by matching the correct turbocharger to the engine. This paper presents the results of investigations to design the inlet and exhaust systems of a stationary natural gas engine family. To do this, a computational model is verified in which zero dimensional phenomena within the cylinder and one dimensional phenomena in the engine inlet and exhaust systems are used. Using this engine model, the effects of the parameters of the inlet and exhaust systems on the engine performance are obtained. In particular, the following parameters are chosen: valve timing, valve diameter, valve lift profiles, diameter of the exhaust manifold, inlet and exhaust pipe lengths, and geometry of pipe junctions. Proper sizing of the inlet and exhaust pipe systems is achieved very precisely by these investigations. Also, valve timing is tuned by using the results obtained in this study. In general, a very high improvement potential for the engines studied here is presented.

Evaluation and Validation of a Fully Instrumented Hüttlin HKC 05-TJ Laboratory-Scale Fluidized Bed Granulator

The instrumentation and validation of a laboratory-scale fluidized bed apparatus is described. For continuous control of the process, the apparatus is instrumented with sensors for temperature, relative humidity (RH), and air velocity. Conditions of inlet air, fluidizing air, product, and exhaust air were determined. The temperature sensors were calibrated at temperatures of 0.0°C and 99.9°C. The calibration of the humidity sensors covered the range from 12% RH to 98% RH using saturated electrolyte solutions. The calibration of the anemometer took place in a wind tunnel at defined air velocities. The calibrations led to satisfying results concerning sensitivity and precision. To evaluate the reproducibility of the process, 15 granules were prepared under identical conditions. The influence of the type of pump used for delivering the granulating liquid was investigated. Particle size distribution, bulk density, and tapped density were determined. Granules were tableted on a rotary press at four different compression force levels, followed by determination of tablet properties such as weight, crushing strength, and disintegration time. The apparatus was found to produce granules with good reproducibility concerning the granule and tablet properties.

Selection and Substantiation of an Organic Solvent Removal Apparatus at a Print Shop by Comparative Experiments Using the Activated Carbon Adsorption and Catalytic Oxidation Methods

ABSTRACT The investigation of an appropriate organic solvent removal apparatus for installation in a newly reconstructed print shop as a countermeasure for preventing the exhaust of organic solvents was conducted. The selection of an organic solvent removal apparatus was made after bench-scale tests of the activated carbon adsorption method and the catalytic oxidation method, both of which are effective for the removal of organic solvents, were performed on the actual exhaust gas at the print shop. The results showed that both methods were efficient enough to be applied to the removal of organic solvents, but the activated carbon adsorption method had many drawbacks, such as the need for frequent replacement of activated carbon and complex maintenance. For the catalytic oxidation method, running costs are high, but there are many merits, such as that the catalysts do not have to be replaced as often and maintenance is simple. After considering these factors, a catalytic oxidation removal apparatus was installed at the new print shop. In the results of the substantiation test on the actual apparatus using mixed catalysts of platinum and manganese plus copper, the removal efficiency was 97.998.7% and the concentration of the outlet exhaust gas was about 10 ppm (the average concentration of the inlet exhaust gas was 528 ppm) at a space velocity of 30,000 hr-1 and a reaction temperature of 200 °C. The results of this study were substantiated.

The control of press cleaning solvent vapors in a small lithographic printing establishment.

Small businesses frequently have inadequate in-house expertise to solve a variety of safety and health problems. The National Institute for Occupational Safety and Health (NIOSH) has therefore conducted a demonstration project in the commercial lithographic printing industry, which consists largely of small companies, in an effort to establish suitable control technology for airborne solvent vapors released primarily during press cleaning operations. These solvent vapors have a number of potential adverse health effects, including narcosis, kidney and liver damage, and cancer. Also, airborne anti-offset powder is a potential allergic sensitizer and cause of occupational asthma. As a means of controlling worker exposures to the vapors and dust, a local exhaust inlet was attached to the side of the press adjacent to the paper delivery point. Tempered outside air was introduced through ceiling outlets installed to make up for the exhausted air. Measurements of press operator exposure and area concentrations of solvent vapors and area concentration of anti-offset powder were made before and after installation of the new ventilation controls. Vapor concentrations were reduced by 73 percent for the press operators. Area concentrations of the vapors were reduced by 86 percent and dust concentration by 67 percent. The ventilation system was found to be suitable for vapor and dust control, although substitution of a cleaning solution containing non-carcinogenic solvents for solutions containing carcinogens was recommended.