INCREASE OF HIGH-SPEED QUALITIES AND ECONOMIC EFFICIENCY OF USE SYSTEMS OF ECOLOGICAL DIAGNOSTICS DIESEL ENGINES-MICROTUNNELS

Purpose. Reducing the duration and cost of procedures for environmental diagnostics of diesel power plants by increasing the speed of measurements of normalizedРM index – average operating emissions of particulate matters with exhaust gases of diesel engines. Methods. Analysis and synthesis of information, mathematical modeling, experimental studies, calculation experiment. Results.In accordance with the requirements of the international standard ISO 8178, a method of accelerated measurement (МАМ) of the PMindex is proposed, which is characterized by the maximum allowable sample filtration rate and the minimum allowable masses of particulate matter in the filters, the use of which can significantly improve the economic efficiency of applying microtunnels: with singleand multi-filter sampling methods in 3,1 ... 4,1 times and in 5,3 ... 7,1 times, respectively. Conclusions. Compared to the most common methods of control of particulate matter emissions that are realized in mini and microtunnels of Perkins, AVL, Mitsubishicompanies, they are characterized by higher speed and economic efficiency of use indicators that are of great importance in testing high-power diesel engines –locomotive diesel, ships and others. It is substantiated that the use of МАМ allows to shorten the duration and cost of environmental testing of mainline diesel engines 2TE116 and shunting TEM-2 locomotives: certification tests by 9 ... 28%, which is 0.2 ... 0.7 h and 0, 8 ... 1,5 thousand UAH; research tests 43 ... 53%, which is 1.7 ... 3.0 h and 4.0 ... 7.5 thousand UAH. With the reduction of the actual emission levels of particulate matter with the exhaust gases of the diesel engine, the efficiency of the use of МАМ increases.


Introduction
The process of ecologization of transport internal combustion engines is characterized by the phased introduction ofthe value of the average operational discharge of particulate matter (PM) with exhaust gases (EG) to the standardized indicators of the toxicity of diesel engines So, since 1993, this indicator has been measured during ecological tests of automobile diesel engines, since 1997 -diesel engines of agricultural machines, and since 2007 -ship and locomotive diesel engines. In the long run, the PM index will become the normalized value for other types of diesel engines: domestic, industrial, engines of special equipment, etc.
Since the beginning of the normalization of mass emissions of the PM, there appeared a problem of increasing the duration and cost of environmental tests of diesel engines due to increased time expenditures for determining PM. The essence of this problem is as follows. The normative basis for environmental tests of diesel engines is the international standard ISO 8178 1-3. This document provides determining the value of PM together with other indicators of toxicity of diesel EG -the average operational emissions of gaseous pollutants: nitrogen oxides, carbon monoxide and hydrocarbons designated as GAS x . The GAS x and PM indices are determined during the test cycles, which consist of normalized engine operating modes [3]. At each mode sampling of pollutants for analysis is carried out. The technology for controlling PM emissions involves preliminary dilution of the engine EG with atmospheric air and then passing it through the PM sampling filters. In this case, the duration of the sampling is determined by the rate of its filtration and the hanging-on mass of PM that is collected on the filters. During testing one of two methods of sampling PM is possible: single-filter (SF), which involves the use of one filter over the whole test cycle or multi-filter (MF), which involves the use of one filter at each test mode.
The most commonly used way of controlling PM emissions, realized in microand minitunnels of Perkins, AVL 4, 5, Mitsubishi [6], is characterized by increased time expenditure on sampling PM, which substantially exceeds the sampling time for gaseous pollutants -5-7 minutes at each test mode. As a result, the procedure for determining the PM index is more time-consuming and more expensive than the GASx indicator control procedure: at the SF method -1.2 ... 1.5 times more; at the MF method -1,9 ... 2,5 times. The indicated problem is of high relevance in testing high-power diesel engines, in particular − diesel locomotivediesels, marine engines, etc.
To solve this problem and increase the economic efficiency of environmental tests of diesel engines, it is necessary to use more rapid methods of measurement of PM indicator.

Object and methods of research
Technical equipment, procedure for conducting environmental tests of diesel plants. According to the requirements of ISO 8178, environmental tests of diesels are carried out with the help of special equipment, which includes: loading device, system of selection and analysis of samples of gaseous pollutants (GP) and system of sampling and analysis of PM -microtunnel (Fig. 1).
The loading device is used to control the diesel load in the entire range of operating modes of its operation. The system of selection and analysis ofGP samples is intended for measurement of concentrations of gaseous substances contained in diesel EG. This system includes: devices for the selection and transportation of gas samples and gas analyzers.
Devices for the selection and transporttation of gas samples are used to select the amount of EG samples necessary for the analysis and to bring it to gas analyzers. These devices must ensure the immutability of the sample when it is transported from the place of selection to the site of analysis. The control and registration of concentrations of GP in selected samples are carried out by means of gas analyzers. To measure the GAS x normalized parameters, the system for the selection and analysis of GP samples must contain appropriate gas analyzers. In samples selected, the content of other substances, such as: carbon dioxide, oxygen, sulfur dioxide, etc. can also be monitored. The PM sampling and analysis system (microtunnel) is used to measure the concentration of PM contained in diesel EG.
The procedure for ecological diagnostics of a diesel engine is a cycle, which consists of normalized modes of its operation in accordance with the requirements of ISO 8178 3. Taking into account the real conditions of operation of a diesel engine is carried out by using weight factors of the test modes WF, which are equal to the relative durations of diesel operation atthese modes during its service ( Table 1).
The control ofpollutants emissions from diesel EG is carried out as follows. The test starts from the pre-warming stage of the diesel engine in anidlingconditions. This stage is considered to be completed if the regulated values of temperatures and pressures of water and lubricationoil in the systems of cooling and lubrication of a diesel engine have been achieved.  After this the test cycle begins − the successive work of the diesel engine on each standardized test mode, which consists of two stages: temperature stabilization of the diesel engine and sampling pollutants. During the stage of temperature stabilization of the diesel, stabilization of water temperature, lubricationoil and EG, as well as water and oil pressure in the systems of cooling and lubrication of diesel, is achieved. During the samplingpollutants phase a parallel sampling is performed for the analysis of GP and PM contained in the diesel EG. In this case, the sampling of PM can be doneby two methods: SF and MF. At the SF method, sampling PM is carried out by using one filter throughout the test cycle, and at the MF method by using one filter at each test mode. SF method allows to determine only the indicator of average operational PM emissions and is used in the course of certification tests of diesel engines; the MF method allows to determine the mass PM emissions at the normalized operating modes of the engine and the index of average operational PM emissions and is used in conducting research tepollutants sts of diesel engines.
During the samplingpollutants phase the requirements for limiting the sampling time must be fulfilled. According to ISO 8178 the minimum durationof the GP sampling procedure is 5 minutes, it requires at least 3 measurements of GP concentrations per a test mode with 1 min intervals. The minimum allowable duration of the PM sampling procedure is determined indirectly and depends on such parameters of the PM emission control system as the velocity of the filtration of the diluted EG sample and the mass of the PM accumulated on the filters. The minimum permissible duration of the sampling period for pollutants in each mode is defined as the highest of the minimum allowable lengths of sampling procedures for GP and PM.
After performing the test cycle, the results of the tests determine the GAS x and RT.
Analysis of the possibility of increasing the rate of measurement of PM indicator. ISO 8178 has the following limitations of parameters that affect the velocity of PM mass emissions: the filtration rate of a diluted EG-vf sample must be in the range of 35 ... 100 cm/s; The hangingon mass of the PM collected in the filters must not be less than the minimum acceptable value: at the SF method, M f (min) = 0.25 mg, at the MF method, M fi (min) = 0.14 mg (using filters with70 mm in diameters) [1].
The most common methods for controlling PM emissions are characterized by sample filtration velocities − vf = 60 ... 80 cm/s and hanging-on masses of PM at the SF and MF methods of sampling − M f = M fi =1.3 mg (Fig. 2).
As can be seen from Fig. 2, the normative requirements allow the implementation of the method ofaccelerated PM measurement (MAM), which is characterized by the maximum permissible rate of filtration of the sample − v f (max) = 100 cm/s and the minimumpermissiblehanging-on mass of PM -M f (min) = 0.25 mg and M fi (min) = 0.14 mg. Application of this method allows to reduce the time expenditure on PM sampling: at the SF method − 3,1 ... 4,1 times less; at the MF method − 5.3 ... 7.1 times and, consequently, reduce the cost of diesel environmental tests procedure.
It should be noted that the reduction of the hanging-on mass of PM to the minimum allowable value leads to a certain decrease in the accuracy of measurements of PM index. However, as shown by studies presented in papers [7][8][9], the resulting error of measurements of the PM index while implementating MAM does not exceed the permissible value -± 8.5% [2], and, therefore, this method can be applied in practice.
The method of evaluating the expediency of using the method of accelerated PMmeasurement involves a comparative analysis of the effectiveness of two ways of measuring the PM index (see Figure 2) oneof the fastest contemporarymethods − method 1 and MAM − method 2. As the criteria of efficiency of these methods, the following is used: Fig. 2  M і C test corresponding to the procedure for determining PM index to the corresponding quantities conformto the procedure of determining GAS x indicators.

Results and discussion
Investigations of theexpediency of using MAM were conducted on the basis of the results of environmental tests of the mainline -2TE116 and shunting − TEM-2 diesel locomotives equipped with diesel engines 1A-5D49 and PD1M, respectively [10,11]. As a sampler device, a universal system for ecological diagnostics of diesels was considered − the microtunnel MKT-2 [12,13] with the compensatory sampling EG method [14] and the temperature control of thesample preparation for analysis [15]. In the course of the researchtherehas been estimated the influenceof the gradual reduction of the emission norms of PM emissions from diesel EG on the efficiency of the MAM factor as a result of environmental standards improvement.. This factor was taken into account by using a relative magnitude equal to the ratio of current and future levels of PM emissions.
The results of the research prove the cost-effectiveness of using MAM at railway transport, as well as in other industries where diesel plantswhich are characterized by significant fuel consumptions are used (Figures 3, 4)