Effect of the use of natural gas–diesel fuel mixture on performance, emissions, and combustion characteristics of a compression ignition engine

A compression ignition engine with a mechanical fuel system was converted into common rail fuel system by means of a self-developed electronic control unit. The engine was modified to be operated with mixtures of diesel and natural gas fuels in dual-fuel mode. Then, diesel fuel was injected into the cylinder while natural gas was injected into intake manifold with both injectors controlled with the electronic control unit. Energy content of the sprayed gas fuel was varied in the amounts of 0% (only diesel fuel), 15%, 40%, and 75% of total fuel’s energy content. All tests were carried out at constant engine speed of 1500 r/min at full load. In addition to the experiments, the engine was modeled with a one-dimensional commercial software. The experimental and numerical results were compared and found to be in reasonable agreement with each other. Both NO x and soot emissions were dropped with 15% and 40%, respectively, energy content rates in gas–fuel mixture compared to only diesel fuel. However, an increase was observed in carbon monoxide emissions with 15% natural gas fuel addition compared to only diesel fuel. Although smoke emission was reduced with natural gas fuel addition, there was a dramatic increase in NO x emissions with 75% natural gas fuel addition

Single phase flow of nanofluid including graphite and water in a microchannel

In this study, convective heat transfer performance of a nanofluids containing graphite is studied in an industrial microchannel. In the experiments, initially, to prepare nanofluids at the volume fraction values of 0.5, 1, 1.5, 2%, distilled water has been employed as the base liquid. To provide sedimentation and stabilization of nanofluids in distilled water, Cetyltrimethylammonium bromide (CTAB) is utilized as surfactant. Thermophysical properties of nanofluids such as thermal conductivity, dynamic viscosity, and specific heat are determined experimentally. Furthermore, by building an experimental setup, in the temperature range of 20–30 °C and with temperature intervals of 2 °C, performance experiments are carried out in a microchannel of which hydraulic diameter is 1.6 × 10-3 m. Additionally, experiments have been conducted using nanofluids at different volumetric rates from 1 to 7 l min-1, heat fluxes from 100 to 1100 W, and volume fractions from 0.5 to 2%. Measuring heat flux, temperature, and flow rate, outcomes such as convective heat transfer coefficient, Reynolds number, and Nusselt number are calculated. The validation process of the experimental results has been performed by plotting the figures of Nusselt numbers vs Reynolds ones, and heat transfer coefficient vs supplied heat considering distilled water and nanofluids having various volumetric proportions. Regarding with the performance of nanofluids against distilled water under similar operating conditions, some proportional positive increase are acquired. Using outcomes attained from experiments, new correlations for Nusselt number have been derived with the R2 values around 0.96, and afterward by means of those correlations experimental data have been compared with those in the literature. A large number of measured and calculated data are given in the paper for other researchers to validate their theoretical models. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature.Thailand Research Fund King Mongkut's University of Technology Thonburi Riordan FoundationThis study has been financially supported by Niğde Ömer Halisdemir University Scientific Research Projects Coordination Department, Project Number: FEB 2013/08-BAGEP. All authors also grateful for the Thailand Research Fund (TRF), the National Research University Project (NRU) and King Mongkut’s University of Technology Thonburi through the “KMUTT 55 th Anniversary Commemorative Fund”