Dilution tunnel

A Fuel Aromatics + NO B Filter Extract New Engine c Dilution Tunnel Sediment Extract... 

Analysis of nitroaromatics found by treating diesel fuel with NO2 (column A) compared to nitroaromatics found in extracts of filters of exhaust from a diesel engine (column B) or in extracts of diesel soot deposited in a dilution tunnel of an animal exposure system (13). 

Moreover, a CRT-equipped heavy-duty diesel engine was investigated utilizing the partial flow sensor head applied to the secondary dilution tunnel of a full flow CVS system. (Anderson, 2003). In Figure 35 the EC mass concentration during a ETC test cycle is depicted for four consecutive tests. From these measurements, it could be seen that LII is feasible to detect EC mass concentrations with high signal dynamics and... 

The ISO/TC 116 SC 3 draft standard ISO/DIS 13336 [2] is based on measurement of the Total Suspended Particles (TSP) in a dilution tunnel, where the due gas is diluted with ambient air to a constant dow (Constant Flow Sampling, CFS), As an option, ca bon monoxide emissions can also be measured in the dilution tunnel. The heat output and efficiency arc directly measured with a calorimeter room, an insulated cabin which is cooled with ambient air. The ISO/DIS standard requires tests of three different bum rates with settings at the minimum, medium and maximum bum rate. 

Within the scope of a research project [3], the prEN and ISO/DIS draft type test standards, especially the methods for determination of the efficiency and the measuring of the emissions, were compared with a continuous burning appliance by the Center of Appropriate Technology, Langenbruck. The efficiencies evaluated by both methods vary only marginal at all tested bum rates. The differences are within the accuracy range of the said test methods. The same is true for emission measuring methods. The measurements show that the test method with direct determination (calorimeter room) and the indirect determination (flue gas) of the efficiency can be considered as equivalent (Fig. I) The same can be concluded for the measurements of emissions in the flue gas and the dilution tunnel (Fig. 2). Provided that the test procedures are identical for both standards, equivalent results for efficiencies and emissions are obtained. 

Fig. 3 Test rig Calorimeter room combined with the dilution tunnel...

The gas sampling in the flue duct is designed in accordance with CEN/prEN. Flue gas temperature and concentrations of carbon dioxide (COj) and carbon monoxide (CO) are measured. In parallel, a dilution tunnel (Fig. 3) is used in accordance with ISO/DIS. The dilution tunnel collects the flue gases of Ae appliances at the end of the flue duct, where they are mixed with ambient air. A fan in the dilution tunnel ensures a constant volumetric flow (Constant flow sampling, CFS). 

In addition, the particle emissions arc measured in the dilution tunnel as well as in the flue duct (Fig, 4). 

Fig. 4 Particulate measurement in the dilution tunnel (arrangement based...

In addition to the TSP measurements some fractions of nanoparticle emissions in the range of 30 to 400 nm were done with Scaning Mobility Particle Sizer (SMPS), and particles in the range of 400 nm to 20 jim with an optical Aerosol Spectrometer. The sampling point in the dilution tunnel was close to the gas sample point. 

Detemiination of efhciencies by flue loss method vs. calorimeter room. Measurements of emissions in the flue duct vs, dilution tunnel. 

The measurements of the emissions in the flue duct and in the dilution tunnel started with the ignition of the kindling and ended, when CO2 content in the flue gas became lower than 2 vol%. The measurement of the calorimeter room and the surface temperature measurements were performed during the entire heat release period. 

The measurements of CO emissions were just done in the flue duct, because of the fact that simultaneous measurements in the dilution tunnel and the flue duct showed equivalent results in a recently published study (3). 

The measurerneiit of particle emissions was done over a entire bum cycle of the slow heat release appliance. The total suspended particles (TSP) were measured in the flue duct and in the dilution tunnel. The particle size distribution was just measured in the dilution tunnel. 

Total suspended particles measured in the dilution tunnel (DT)... 

Total suspended particles measured in the flue gas PM 0,4 DT Particulate matter of the fractions < 400 nm and particle number (f/) with SMPS measured in the dilution tunnel (DT) ... 

The emission factors determined in the dilution tunnel with the flat filter are approx. 12 % lower than those measured in the flue gas (Table 4). The variation though of the emission factors overlaps. 

Further criteria for the justification of the TSP-measurement in the dilution tunnel are more of a practical nature. It turned out that some condensation problems arise on the filters at the flue duct because of strong formation of water vapor at the beginning of the bum cycle. These problems arise because of the characteristic bum cycle of a slow heat release appliance In the initial phase after igniting the fuel batch, the wood logs catch fire and release the fuel water over a short time period, thus generating water vapor while the stove is still cold. Even heating of the flat filter holder could not solve this problem entirely. 

The Hue gases are leaded in a flue duct with a fixed height. The flue gas measuring section according to CEN/prEN e.g. 13240 standards is situated in the flue duct. The effluents leaving the flue duct are diluted with ambient air and guided to the dilution tunnel where the particulates are measured. The flow In (he dilution tunnel is kept at a constant flow rale and monitored. 

In the flue gas carbon monoxide and particulate shall be measured. CO-data can be used from the flue loss measurements. The data needs to be standardized to a given oxygen content (e.g. 13 vol %). If required also additional flue gas components can be analyzed such as nitrogen (NOx) and hydrocarbons (HC). The particulate measurements are done in the dilution tunnel. The particulate measurements shall not be interrupted during a bum cycle. 

Figure 13. Particle number distributions for a diesel engine (2.5 L displacement, direct injection, 4-cylinder, 1500 rpm, 7.5 kW) mn with 300 ppm sulfur content diesel fuel. Distributions are measured using a dilution tunnel with conditions simulating those expected in the environment (final dilution ratio of approximately 100 1). From Collings and Graskow (2000). Used by permission of the Royal Society.

Figure 6. Dilution tunnel to measure the particulate mass emission from diesel powered passenger cars.

Determination of particulate matter emissions from wood heaters (dilution tunnel sampling location)... 

For particulate emissions tests simultaneous particulate samples were collected upstream and downstream of the catalyst using two mini-dilution tunnels. In separate tests the time of the low temperature storage segment was varied from 30 to 120 min. and after each storage the ramp to high load was run. The results for inlet versus outlet levels of total particulates and their breakdown into components is shown in Figure 3 as a function of storage time. 

Diesel particles collected by the dilution-tunnel method (10) were Soxhlet-extracted with dichloromethane and solvent-partitioned into organic acids, bases, and neutral components ... 

The other procedure makes use of collection of particulate samples via proportional streams from the diluted exhaust, known as dilution tunnel technique (8, 9). Figure 2 displays a flow diagram for this procedure. 

The dilution tunnel for the PAH collection has been described (9, 10). This system consists of a stainless steel dilution tunnel, a CVS device, and the unit for drawing off proportional streams from the total gas flow. The length of the tunnel is 6 m and its diameter is 0.45 m. At the point where the exhaust gas enters the tunnel there is an orifice creating turbulence for mixing the exhaust more thoroughly with the filtered air. The velocity of flow... 

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