Oil coking and turbine seal ring melting are among the main failure modes of engine turbochargers. During the turbocharged internal combustion engine development process, the cooling and lubrication system must be checked for appropriateness of the desired condition for turbocharger journal bearing and seal rings which the turbocharger manufacturer defines. In this study turbine and compressor journal bearings and turbine seal ring temperature were measured at different engine speeds and loads as well as coolant flow at engine hot shutdown conditions. Also, the effect of inlet coolant temperature and exhaust gas entering the turbine housing on bearing housing temperature was investigated. The experimental test shows that maximum heat transfer from the turbocharger to the coolant is at the engine's maximum power point. Among measured points, turbine sealing always has the highest, and Compressor journal bearing has the lowest temperature. Coolant and oil temperature are the main controllers of temperatures but exhaust gas temperature has a lower effect on temperature at the investigated point.

Experiments on a two-phase rotating detonation combustor Operating with gasoline and high total temperature air were conducted to investigate the initiation characteristics, operation mode, and propagation characteristics of a two-phase rotating detonation wave (RDW). The outer diameter, inner diameter, and length of the annular combustor were 204 mm, 166 mm, and 155 mm, respectively. The initiation characteristics, operation mode, and propagation characteristics of the two-phase RDW were studied by varying the total air temperature. The experimental results show that the initiation time of the RDW first decreases and then increases with an increase in the total air temperature and reaches an extreme value at a total air temperature of 713 K. Four operation modes (failure, intermittent detonation, single wave, coexistence of double wave collision, and single wave) of the detonation combustor were found for different total air temperatures. The effect of the total air temperature on the peak pressure stability and propagation frequency of the RDW was studied in detail. From the results, the effect of the equivalence ratio on the working characteristics of a rotating detonation engine (RDE) was investigated at a total air temperature of 713 K. Four detonation propagation modes (sporadic detonation, intermittent detonation, single-wave mode, coexistence of double-wave collision and single wave) were obtained in the combustor. When the equivalence ratio was 0. 52, the detonation initiation failed. The pressure characteristics in the combustor and propagation frequency of the RDW were studied with different equivalence ratios. In addition, a long-duration test was performed for 3 s to verify the continuous working feasibility of the two-phase RDE.

Background and Objectives: Nowadays vermicompost production of food wastes is posed as oneof appropriate methods to food wastes. disposal, itsproduction used in agriculture and gardening.Moreover this process has some by products beside useful fertilizer that one of them is the worms. We can use them in variety of products specially in production of poultry and fish food. So determinationof optimal condition for Operating vermicompostproduction process of food wastes and worms.growth in these wastes is important.The aim of this study was determination of optimal temperature and moisture range for processprogression in vermicompost production of food wastes.Materials and Methods: In this study we used Eisenia foetida species. Process performed in potswith 15 cm (h) and 12 cm (d) and in a mouth period of time. Three ranges of temperature including5-15, 15-25, 25-35 oC and three ranges of moisture including 55-65%, 65-75%, 75-85% were appliedin this study.Results: Multivariate analysis was used for analyze of results and it showed that influence of temperature and moisture on C:N ratio is significant invermicomposting process (p<0.05).Conclusion: The results showed that the range of temperature 15-25oC is more appropriate forOperating of process. Due to these study.s results with increasing or reduction of ambient temperature,like summer and winter, conservation of moisture around the range of 65-75 %, is effective in better performance of the process. According to this studys results, it seems that the temperature of15- 25oC and moisture of 65-75% are better conditions for worm.s growth.

One of the important issues in the production of concrete is environmental variability that affects the concrete and elements constructed from this material. Due to the importance of different characteristics of concrete in short- and long-term conditions, this article aims to investigate the influence of initial temperature conditions of self-compacting concrete on its long-term characteristics and determine the initial optimal temperature of concrete. For these purposes, several experiments under three temperature conditions of 5, 20, and 40 degree-of-Celsius were conducted to evaluate the rheology and mechanical properties of fresh concrete in the range of 7 and 28 days. In these experiments, alternative mineral admixtures of cement such as micro-silica, fly ash, and zeolite were used to build the concrete specimens. Results demonstrate that the mechanical properties of the specimens increase with increasing initial temperature in the short term, while such properties significantly decrease in the long term compared to the specimens constructed under lower initial temperature. Moreover, the fluidity of self-compacting concrete increases with increasing initial temperature.

In order to accomplish the objective of studying and optimizing the flow channel geometries and dimensions for high-temperature proton-exchange-membrane (PEM) fuel cells (with Operating temperatures above 120oC), a mathematical model has been developed in this work. As the major step of the modeling, the average concentrations of gas species in bulk flows as well as in the layers of electrodes are calculated through mass transfer analysis in one-dimensional direction normal to the membrane-electrodes layers. Therefore, the concentration and activation polarizations are simulated with much less computational work compared to a three-dimensional numerical model. The ohmic loss is taken into consideration through analysis of a representative network circuit simulating the electron and proton conduction in the elements of electrodes and electrolyte, respectively. The simulated results for high-temperature PEM fuel cells were compared with experimental results from literature. The results from the simulation and experimental tests showed good agreement, which validated the mathematical model.As the model requires less computational work, it was used to analyze a large number of cases with different gas flow channel dimensions and Operating conditions, and optimization to the dimensions of channels and ribs was accomplished.

In this research, a numerical study was conducted to analyze a novel design for overcoming the detrimental effect of high‑temperature Operating conditions on the separation efficiency of a square-based cyclone. This kind of cyclone can be utilized in the Circulating Fluidized Bed (CFB) boiler and it was shown to become one of the most appropriate cleaning tools for high-temperature gases. Previous studies found that the separation efficiency of a cyclone reduced remarkably with the increment of inlet temperature resulting in weaker swirling flow over cyclones at extremely high temperatures. Hence, it is vital to develop an effective approach to prevent this detrimental impact. The novel cyclone design is based on the idea of altering the inlet shape on the flow field and enhancing the cyclone collecting efficiency in high‑temperature Operating conditions. Three separate inlet configurations, namely flat, oblique, and curved inlets were particularly developed and investigated numerically through the Computational Fluid Dynamics (CFD) method to maximize the low separation efficiency of a square cyclone influenced by the high‑temperature Operating condition. For simulating the flow of particles, the Eulerian-Lagrangian methodology is implemented for solving Unsteady Reynolds-Averaged Navier-Stokes (URANS) equations. The Discrete Random Walk (DRW) is utilized for modeling fluctuations of velocity. Numerical results indicated that using oblique and curved inlets generated a raising in pressure drop but they significantly improved the separation efficiency of the cyclone separator. Among all inlet shapes, oblique inlet dramatically enhanced the separation efficiency by up to 15% at an inlet velocity of 12 m/s.