Abstract:Disk bypass pipeline inspection gauge (PIG) is considered as an efficient device for pigging operations including cleaning, maintaining and inspecting pipelines. The PIG performance is influenced by the fluid flow characteristics as PIG moves forward due to differential pressure of fluid around the PIG. This study focuses on flow characterization of fluid around disk bypass PIG for natural gases pipelines including methane, ethane, and butane using computational fluid dynamics approach. The control volume meth… Show more
“…where, ks is the thermal conductivity of the solid material. The effect of turbulent fluctuations was modelled using standarded k- model [26], and the near-wall regions were treated using the standard wall function.…”
This paper presents a CFD and experimental study of the thermal behavior of the thermoelectric-compartment in a hybrid household-refrigerator that combines thermoelectric and vapor-compression technologies. The hybrid refrigerator has three compartments. One of them is driven by a thermoelectric cooling system, which was made of one Peltier module and two fan-cooled heat sinks mounted on the hot and cold sides. The simulation results were compared with experimental measurements and showed a good agreement. The performance of the thermoelectric refrigerator was tested with changing the pushing direction. Two pushing directions for the fan were examined. In the first one (direction-I), the fan was fixed such that it sucked the air beside the cold heat sink. While in the second direction (direction-II), the fan was assumed to be flipped to push the air over the cold-side heat sink. The results showed that the second fan direction (direction-II) is more effective for heat transfer mechanism between the cold-side heat sink and the inside air of the thermoelectric-compartment.
“…where, ks is the thermal conductivity of the solid material. The effect of turbulent fluctuations was modelled using standarded k- model [26], and the near-wall regions were treated using the standard wall function.…”
This paper presents a CFD and experimental study of the thermal behavior of the thermoelectric-compartment in a hybrid household-refrigerator that combines thermoelectric and vapor-compression technologies. The hybrid refrigerator has three compartments. One of them is driven by a thermoelectric cooling system, which was made of one Peltier module and two fan-cooled heat sinks mounted on the hot and cold sides. The simulation results were compared with experimental measurements and showed a good agreement. The performance of the thermoelectric refrigerator was tested with changing the pushing direction. Two pushing directions for the fan were examined. In the first one (direction-I), the fan was fixed such that it sucked the air beside the cold heat sink. While in the second direction (direction-II), the fan was assumed to be flipped to push the air over the cold-side heat sink. The results showed that the second fan direction (direction-II) is more effective for heat transfer mechanism between the cold-side heat sink and the inside air of the thermoelectric-compartment.
“…Alternatively, complex and costly solid oxide fuel cell experiments require dynamic computational fluid simulations. CFDs have been used in many studies; for example, an overview of computational fluid dynamics modelling in solid oxide fuel cells has been presented in [19], and it has been shown that it is easier to see the flow of natural gas pipelines that are difficult to access through use of CFDs [22]. Fluid aerodynamics have been simulated to visualize the performance of various NACA airfoils [23].…”
The purpose of this research is to present a warm air infiltration simulation for a cold room, considering the effects of an air curtain. At present, there exist a large number of retail businesses, operating within an industry entailing high investment and competition. Therefore, retail operators must distinguish factors that are essential to lowering their costs, one of which is energy reduction. A survey of energy consumption in stores found that most used energy is due to the cooling system. Therefore, we tested the protection of cold rooms against air inflow by conducting three simulations: 1. Without an air curtain; 2. using an air curtain having a common grille; and 3. using an air curtain with a honeycomb grille. The cold room temperature was set to 1 °C, the cold room door was 200 × 100 m2, and the air curtain was installed 5 cm above the cold room door; furthermore, the velocity of air emitted from the air curtain was 6.5 m/s. Warm air infiltration simulations were carried out using SolidWorks Flow Simulation software, in order to determine the temperature change in the cold room and the airflow direction. From the results of the comparative experiments, when using the different wind grilles, there were differences in the infiltration of warm air. The honeycomb grille reduced air turbulence in the cold room more effectively than the common grille. As a result, the temperature in the cold room was consistent, and the temperature inside the cold room was maintained 10.62% lower when using a honeycomb grille compared to a common grille.
“…However, this first law-based energy analysis cannot provide the actual losses of the system in terms of efficiency and thermodynamic losses [1,[8][9][10][11][12][13][14][15][16][17][18]. Therefore, it is important that the energy conversion efficiency of a system be analyzed by considering both the first and second laws of thermodynamics [19][20][21][22][23][24]. Second law-based exergy analysis provides a better view of the energy losses to the environment and the process-related internal irreversibility.…”
Exergy analysis has been found to be a useful method for improving the conversion efficiency of energy resources, since it helps to identify locations, types and true magnitudes of wastes and losses. It has also been applied for other purposes, such as distinguishing high- from low-quality energy sources or defining the engineering technological limits in designing more energy-efficient systems. To identify locations, types, and actual magnitudes of energy losses; exergy analysis has been found to be a valuable way for enhancing the conversion efficiency of the different energy systems. The aim of this research is to analyze the effect of the operation conditions on the performance of coal-fired power plants. As well, this study focuses on the effect of different feedwater heaters' numbers that lead to the highest exergy destruction of the coal-fired power plants. For different values of the superheated steam temperature and the pressure, a parametric study was conducted to determine the efficiency of the coal-fired power plant. The results show that, when the pressures and temperature of the superheated steam increases the evaporator temperature will increases too. Increasing the temperature of evaporator rises the average maximum temperature of the cycle, which improves the thermal efficiency of the cycle as well as the powerplant efficiency. The results show that, at higher boiler pressures and temperatures, the temperature difference between the water/steam and hot gases of the boiler is reduced which means the irreversibility associated with the heat transfer process decreases. Therefore, by increasing the pressure and temperature of the superheater, the exergy efficiency of the thermal cycle is improved. It was observed that operating the coal-fired power plant at high superheated pressure and temperatures produce lead to reduce the exergy losses.
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