Values Of Inlet Temperature Research Articles

Investigation of the effect of biofuel addition to jet fuel on engine performance and emissions in model jet engine

The use of biofuel reinforced fossil fuels is increasing day by day, thanks to such as reducing the carcinogenic effects of fossil fuels and reducing the global warming effect. The unmanned aerial vehicle breakthrough made in our country, especially in the defense industry, will ensure that the use of smaller unmanned aerial vehicles becomes more widespread in the future, allowing us to reach more effective and economical solutions. In this study, biofuel was obtained from safflower oil, and the effect of adding various amounts of biofuel to kerosene in a model jet engine on engine performance, and emissions was examined. The closest results to kerosene in fuel consumption, thrust force and the use of biofuel to reinforce fossil fuels is increasing day by day. This is due to its ability to reduce the carcinogenic effects of fossil fuels and also to reduce the global warming effect. In Türkiye, especially in the defense industry, there has been a significant breakthrough in unmanned aerial vehicle technology. This breakthrough will ensure that the use of smaller unmanned aerial vehicles becomes more widespread in the future, allowing us to reach more effective and economical solutions. In this study, biofuel was produced from safflower oil. Researchers examined the effect of adding different amounts of biofuel into kerosene fuel in a model jet engine. Engine performance and emissions were analyzed in the study. When the specific fuel consumption of kerosene fuel is compared to the average of all cycles of other fuels, it is 5.6 % more than B10 fuel, 12.4 % more than B20 fuel and 15 % more than B30 fuel. 8.3 % less thrust force was obtained. The highest turbine inlet temperature values were obtained with Kerosene fuel. Similar results were obtained in terms of emissions, but the best results were obtained with Kerosene fuel. When the averages of the entire experiment with biodiesel blend fuels were compared, it was stated that it constituted an acceptable alternative fuel.

Economic Optimization of a Thermal Solar Power Plant That Operates With a HRB Cycle by Improving the Operation Schedule

In this paper, two solutions are proposed to increase the sales revenue of a pre-sized solar thermal power plant (STPP) that operates with a Hybrid Rankine Brayton cycle (HRB) by changing the reference operating parameters. In the first solution, the turbine inlet temperature value is optimized to increase the energy production. In the second solution, a new dispatch strategy that prioritizes energy production during the hours of higher sales price is additionally implemented in low solar radiation months. In the remaining months, the reference dispatch strategy that prioritizes production from energy coming directly from the solar field over energy from storage system is maintained. The incremental sales revenue of each solution proposed over the reference case is calculated considering hourly SPOT prices for a three-year period and considering hourly annual simulations for a typical year.

Numerical validation of Parabolic Trough Collector: An approach to problem

The validations of Computational Fluid Dynamic (CFD) simulations are necessary to develop trust worthiness of the simulation results. Also, it is necessary to provide the exact boundary condition to the problem statement encrypted in CFD solvers and that boundary conditions can be determined with the help of some other trusted open source softwares or codes. Here in this study, it has been focused to show how validations can lead to development of correct solutions of the problem statements. The CFD simulations need to be validated with experimental results of some prestigious international institute or laboratory and also with Filonenko and Gnielinski equations that can make the outcomes of the results more trust worthy. The results in this study are concluded with the fact that thermal efficiency (ηthr) is a function of variable operating parameter (Popr = Tinlet- Tamb/Ibeam) and mass flow rate (ṁ). The value of ηthr of PTC was seen to be decreased from 0.419 to 0.347 with increase in Popr from 0.05 to 0.35. Also, the most effective value of ṁ was found to 0.44 kg/s for all values of inlet temperature (Tinlet) conditions varying from 375.5 K to 525.5 K.

Determination of Solar Chimney Inlet Temperature by Regression Methods

Abstract Because the greenhouse gases caused by fossil fuels contribute to global warming, the orientation toward renewable energy sources is increasing rapidly. One of these sources is solar chimneys. The region where a solar chimney is installed is important for its efficiency, and if the energy to be produced from the solar chimney can be determined, comments can be made about the region where it will be installed. In determining the energy to be produced from a solar chimney, the chimney inlet temperature must be known. In this study, it is planned to make an application on a solar chimney in Isparta province. First, a prototype solar chimney was installed on the campus of Süleyman Demirel University (SDU) by the SDU Renewable Energy Resources Research and Application Center. A unique data set was created with input data from sensors in the collector area of the solar chimney and output data from a sensor located at the mouth of the chimney. In this study, the flue inlet temperature values were estimated by using 10 different regression methods, one of which was a model specific to this study. In addition, hyperparameter adjustments of the regression models were made with different optimization methods. With Random Forest- Elastic-Lasso.Net (REL.Net) and ElasticNet architecture among the 10 methods, the chimney inlet temperature was obtained with accuracy rate of approximately 99 %.

Investigation of Outdoor Air Temperature Effects on Heat Recovery in Cross Flow Heat Exchanger

A heat recovery device was designed and manufactured to provide air-to-air heat transfer by using a cross-flow heat exchanger on the pipe bundles. For this purpose, different cold air inlet temperature values and the temperature values of high temperature hot exhaust gases in the tube bundle heat exchanger were determined as operating parameters. According to the temperature increase of the cold air entering the heat exchanger; The kinematic viscosity values of the air increased and the maximum Reynolds number in the flow state of the air passing through the test heat exchanger was decreased. The average Nusselt numbers and average air convection coefficients in the flow of air decreased according to the temperature increase of the cold air. According to the temperature increase of the cold air entering the heat exchanger, both the analytical and experimental outlet temperature values of the cold air leaving the heat exchanger increase very close to each other. With this increase, the amount of heat transferred from the fluid to the fluid in the heat exchanger decreases. While the temperature value of the cold air entering the heat exchanger increases, the temperature difference value of the advancing air from the beginning to the outlet (ΔT= Ts – Ti) decreases. Due to this decrease, a decrease was observed in the amount of heat transfer.

MULTI-OBJECTIVE OPTIMIZATION OF PARAMETERS AFFECTING THE PERFORMANCE OF PARABOLIC SOLAR COLLECTORS BY TAGUCHI, ANOVA, AND GREY RELATIONAL ANALYSIS METHOD

In this study, a combined simulation-optimization study was carried out on parabolic solar collectors. The parameters of energy and exergy efficiencies of parabolic solar collectors examined theoretically were optimized by the grey relational analysis method. A simulation model was developed to determine the performance of parabolic solar collectors. The results obtained from this model were shown to be in good agreement with the previous results in the literature. Four parameters such as wind speed, fluid flow rate, solar radiation value, and fluid inlet temperature were selected for statistical analysis. A statistical analysis was carried out to observe the effect of these parameters on the first- and second-law efficiencies of the collectors. Optimum values and contribution rates of the parameters were determined due to statistical analysis and optimization. As a result, the optimum conditions were obtained, i.e., wind speed value of 5 m/s, flow rate of 100 L/min, solar radiation value of 1000 W/m<sup>2</sup>, and fluid inlet temperature value of 400 K. Under these conditions, energy and exergy efficiencies were found to be 73.34% and 20.53%, respectively. As a result of the statistical analysis, it was seen that the fluid inlet temperature was the most effective parameter with 72.81%. In addition, the effect rate of solar radiation value was 15.59%, the effect rate of fluid flow rate was 10.01%, and the effect rate of wind speed, which was the parameter with the lowest effect, was found to be 0.24%.

Three-Dimensional Numerical Study of the inlet Temperature Effects on the Performance of Planar PEMFCs

In the present study, a CFD (computational fluid dynamics) three-dimensional model is performed to investigate the effects of the inlet temperature on the power density, pressure and local transport phenomena of a single cell PEMFC (proton exchange membrane fuel cell) with straight channels. Deferent inlet temperatures of the reactants (333, 343 and 353 K) have been investigated using ANSYS-FLUENT. The interest of our work is focused on obtaining I-P and I-V curves as well as the pressure, hydrogen, oxygen and water mass fraction profiles to analyze the effect of the oxygen and hydrogen inlet temperature on the current, voltage and power densities of the studied PEMFC. From the results obtained its appears that the variation in the inlet temperature values of the PEMFC has a significant influence on the cell performances at medium and higher current density. Therefore, the results analysis of the three-dimensional and single-phase model indicates that the increase in the reactants’ inlet temperature of the studied PEMFC shows a negative impact on the generated power densities, which have an inversely proportional effect.

Presenting a power and cascade cooling cycle driven using solar energy and natural gas

A configuration is presented where solar energy is parallel with fossil fuel to steadily supply a combined power and cascade cooling system. The cascade cooling system produces a steady cooling load at shallow temperatures. The variations of solar radiation during a year are considered. The system combines an improved ammonia-water power cycle with an absorption-compression cascade refrigeration system. The exhaust from the power cycle drives the absorption chiller. Working fluids are ammonia-water for absorption and power cycles and R134a for compression chiller. The effects of turbine inlet temperature, the ammonia concentration in the power cycle, boiler pressure, and generator temperature are investigated. Considering the cooling section's exergy efficiency, the generator temperature is optimized at 110.5 °C. The power cycle's boiler pressure and ammonia concentration are optimized using a genetic algorithm for various cooling loads at various turbine inlet temperature values to find the maximum annual exergy efficiency. The results show that, in all investigated cooling loads, the maximum annual exergy efficiency with a mean value of 65.66% happens at the turbine inlet temperature of 210 °C, an average boiler pressure of 58.56 bar, and an average ammonia concentration of 81.16%.

Tailoring hydroxyapatite microspheres by spray-drying for powder bed fusion feedstock

The present work deals with a study on the physical characteristics of stoichiometric hydroxyapatite microspheres produced by spray-drying process through different operating conditions. Obtained hydroxyapatite microspheres are intended to be used as powder feedstock in powder bed selective laser processing additive manufacturing technologies where the flowability and the particle size distribution of the powder feedstock are of special importance. The powders produced at different spray-drying operating parameters were evaluated by analysing the particle size, shape, moisture, and agglomerates strength. Spray air pressure (0.25–2 bars) and the solid content of the slurries (10–50% wt.) were the most influent parameters to control the final particle size distribution, whereas the higher process recovery rate (79%) was obtained at specific values of inlet temperature (250 °C), spray air pressure (2 bar), and feed rate (4.9 kg.h−1). A 5 wt% of polyvinyl alcohol as an organic binder to the ceramic part was found to increase the strength of the granules. The flowability of the produced hydroxyapatite microspheres (x50 = 64 μm; span = 1.77) was found to fulfil the defined feedstock requirements (e.g., Hausner ratio < 1.25), without alteration of the physico-chemical properties of the material. These promising results confirm the use of a spray dryer as an efficient method for the production of hydroxyapatite microspheres for powder bed selective laser processing.

Experimental and numerical investigation of heat transfer in a channel with multiple phase change materials (PCMs)

In this study, the thermal performance of an air-phase change material (PCM) unit used in free cooling applications was examined experimentally and numerically by Comsol finite element simulation software. Effects of the air inlet temperature, velocity and also PCM configuration on the efficiency of the air-PCM unit were investigated. Experiments were performed on PCM unit, which is a channel including PCM plates inside and exposed to medium air entrance from one side. The air in contact with the plates inside this unit is cooled and contributes the room temperature to decrease. The experimental work was carried out at two different ambient temperatures in a well-insulated room. Three different configurations of paraffin-based pure RT22HC and RT25HC were studied. Effects of air inlet temperature and velocity on the heat transfer, channel outlet temperature, performance of the air-PCM heat exchanger, cooling power of the system and also total amount of heat absorbed by the PCM were investigated. The initial temperature of the PCMs is 16 ᵒC and experiments were carried out for two different average inlet temperature values (27 and 29 ᵒC) and two different average velocities (1.3 and 1.8 m/s) of the air at the channel entrance. According to the results, it was concluded that the air inlet temperature and air inlet velocity have a substantial effect on the thermal performance of the air-PCM unit. It was observed that the melting time decreased and the channel outlet temperature increased with the increase of air inlet temperature and velocity. 2 ᵒC increase of in the inlet temperature increased the total amount of heat absorbed by PCMs by 31%, while an increase of the inlet velocity by 0.5 m/s increased it by 16%. The results revealed that the increase of the inlet velocity and with the inlet temperature increased the thermal energy absorbed by 44%. In addition, it was observed that the average efficiency increased by 37% with 2 ᵒC increase of inlet temperature and 0.5 m/s decrease in the inlet velocity.

Performance of nano encapsulated phase change material slurry heat transfer in a microchannel heat sink with dual-circular synthetic jets

This study analyzes the hydrodynamic and heat transfer performance of the nano encapsulated phase change material (NEPCM) slurry in a microchannel heat sink (MCHS) equipped with two circular synthetic jets (SJs). It focuses on understanding the effects of major influencing parameters on energy efficiency, including the NEPCM concentration, frequency, amplitude, inlet velocity, latent heat storage, heat flux, inlet temperature, and phase actuation. The heat transfer coefficient (HTC) enhancement is maximized to 28.5% at the particle concentration of 0.2 and 180˚ out-of-phase actuation. However, the figure of merit (FOM) decreases as the NEPCM concentration increases. The optimum thermal performance is obtained at the NEPCM concentration of 0.05 in the 180˚ out-of-phase SJs. The convective heat transfer is remarkably improved using actuators with higher frequency and amplitude values. The thermal performance of 180˚ out-of-phase actuation is better than in-phase jets. The FOM is significantly enhanced by increasing the inlet Reynolds number. The latent heat of fusion intensifies the convection and conduction rate by 17% and 31%, respectively, as it increases from 107.1 to 250 kJ/kg. When the inlet temperature values are set to accommodate the melting range of the NEPCM, the maximum Nusselt number is obtained at the temperature of 297.15 K.

Experimental study on cooling performance of nanofluid flow in a horizontal circular tube

In this experimental study, the cooling performance of alumina/water nanofluid flow in a heated copper tube with constant heat flux is explored. The experiments are conducted for the nanoparticle's concentration in the range of 0 to 10%, the Reynolds number in the range of 168 to 2031, two values of inlet temperature of fluid, 25 °C and 50 °C, and the imposed heat flux in the range of 3979 to 7957 W.m − 2. The influences of these parameters on the friction factor, Nusselt number, temperature on internal wall of tube, the bulk temperature of fluid, the profit index, and the heat transfer effectiveness ratio are investigated. The experimental data and compared with the numerical results. The experimental results clearly exhibit a good agreement with the theoretical data existing in the literature and the numerical results. The outcomes indicate that for a constant value of nanoparticles concentration, the heat transfer effectiveness ratio and the profit index increase as the inlet temperature of fluid is increased. In addition, boosting the concentration of nanoparticles causes the increase in heat transfer effectiveness ratio. The maximum heat transfer effectiveness ratio of 1.105 is achieved by using the nanofluid. The maximum profit index of 1.065 can be achieved at the concentration of 10% and the inlet temperature of 50 °C. The heat flux has no considerable effect on the temperature on the internal wall of tube and the bulk temperature of fluid.

Optimization of the thermal performance of nano-encapsulated phase change material slurry in double pipe heat exchanger: Design of experiments using response surface methodology (RSM)

The immersion of nano-encapsulated phase change material (NPCM) in a carrier fluid to form NPCM slurry can ensure of the latent heat absorption and effective heat transfer. Here, the convective heat transfer of the NPCM slurry stream in a double-pipe heat exchanger were studied experimentally. PCM nanocapsules have been prepared via a mini-emulsion polymerization process. The nanocapsules consisting of n-dodecanol as the core, and polymethyl methacrylate (PMMA) as the shell were modified by graphene oxide (GO) nanosheets as an additional protective layer. Morphology as well as thermal and structural features of nanocapsules were examined and analyzed. The least particle size corresponded with a latent heat of 148.5 J/g. The enhancement mechanism of the convective heat transfer of NPCM slurry was studied via the response surface method. The heat transfer features were evaluated based on experiments designed statistically to determine the optimal values of inlet temperature (Tin), NPCM concentration (ϕ), and Reynolds number (Re). The optimization was performed aiming at the maximum enhancement of thermal efficiency (η). The validity of the developed regression models was assessed using the ANOVA technique. It is found that in the turbulent tubular flow of NPCM slurry, the inlet temperature and the mass fraction of nanocapsules have the most significant effects on the heat transfer performance. The optimum values of ϕ, Tin and Rein were found to be 14%, 83 °C and 5046, respectively, resulted in the maximum η of 4.5.

Numerical and experimental analysis of heat and mass transfer in the drying process of the solar drying system

Design in a solar food drying system is crucial for food drying performance. In order to make effective use of the sun, the use of air-heated solar collectors is gradually increasing in drying systems. Dryer room temperature and pressure distribution modelling is a very important factor for system design and product selection. In this study, the drying air speed, drying temperature, and product moisture content values of a solar drying system were numerically modelled in a time dependent manner. In numerical analysis, temperature and drying air velocity were defined as variable under initial and boundary conditions. Polynomial equations based on time obtained from drying room inlet temperature and drying air velocity data were used. The R2 values of these equations were calculated as 0.96 and 0.91, respectively. COMSOL multiphysics program was used for temperature values, drying air velocity, product moisture content values and drying chamber pressure values modelling. Depending on the position of the sun and the time, the drying chamber inlet temperature values and air velocity values have been change. During the drying process of the product, moisture content values, heat and mass transfer values, drying efficiency values, diffusion coefficient and activation energy values were examined. Experimental data and computed fluid dynamics analysis (CFD) data were compared. Using the CFD numerical analysis program, the drying room temperature, moisture content and air velocity values were modelled with mean absolute percent error (MAPE) of 5.34%, 3.74% and 6.30%, respectively.

Lehimli Plakalı Isı Değiştiricisi Isı Transferinin Sayısal Analizi

In this paper, we investigated the heat transfer characteristics of a brazed plate heat exchanger by using Computational Fluid Dynamics (CFD). Heat exchangers were generally analyzed considering both rating and sizing parameters. We just examined the rating parameters such as flow direction, mass flow rate, and the inlet temperature value of hot water on the thermal performance of a brazed plate heat exchanger, numerically. We also employed experiments for getting comparative results and each experiment was performed under the same conditions selected in the numerical simulations. Theoretical calculations were achieved by using the Logarithmic Mean Temperature Difference (LMTD) method for a single-phase flow and the thermal efficiency of the heat exchanger was evaluated for different conditions. The maximum total heat transfer rate was calculated about 3.1 kW for experimental study whereas this value was lower than 3 kW for numerical study in counter flow conditions. Another important result was that the effectiveness values of the heat exchanger were calculated higher under counter flow conditions as expected. The numerical results were in good agreement with the experimental data used in the study.

Thermodynamic Performance Evaluation of Concentrating Solar Collector with Supercritical Carbon Dioxide (sCO2) Base Nanofluids

The use of supercritical carbon dioxide as a working fluid is an important alternative to enable the use of parabolic collectors in the high-temperature applications field. In the present paper, the effects of carbon black nanoparticles dispersed in supercritical carbon dioxide (sCO2) base fluid on the energetic and exergetic performance of parabolic trough collectors are theoretically investigated. Thermal modeling and performance analyses are performed through the developed model in the Engineering Equation Solver software. To present operating conditions of the system, all working fluids are tested under a pressure of 80 bar at a mass flow rate of 1.1 kg/s. In these analyses, the fluid inlet temperature, ambient temperature, and nanofluid concentration are determined as the variable indicators. Up to approximately working fluid inlet temperature of 705 K, the exergy efficiencies of the concentrating collectors using the sCO2 nanofluids are higher than that of the concentrating collector using the sCO2 base fluid. Additionally, the exergy efficiency increases in the systems using nanofluids with 2% and 4% concentration ratio are between 0.34–6.96% and 0.49–11.44%, respectively, according to the system using base fluid. Besides, at the working fluid inlet temperature values greater than 705 K, the exergy efficiency of the collector of using the sCO2 working fluid is found higher than the collectors using the nanofluids. However, at the same working fluid inlet temperatures, the fluid outlet temperatures of the collectors with the sCO2 nanofluids are higher than the system with sCO2 working fluid.

Experimental Analysis of Solar Dish Concentrators With Cylindrical, Oval, and Conical Cavity Receivers

Abstract Three experimental models including cylindrical, oval, and conical cavity receivers were analyzed and tested to estimate the optimum geometry for parabolic dish collector cavity receivers . The main contribution of this paper is that new experimental models are suggested and examined to strengthen the capability of absorbers of solar thermal dish collectors to absorb solar energy. The models were examined for three values of mass flow rates and five values of inlet temperatures of the heat transfer fluid. The thermal performance was evaluated by estimating the thermal efficiency , exergetic performance , and pressure difference. The results recorded the highest values of and for the conical cavity receivers, equal to , and the lowest values of the pressure drop.

Response surface methodology based optimization of air-film blade cooled gas turbine cycle for thermal performance prediction

The present study analyses simple gas turbine cycle (SGT) for carrying out optimization of input variables for optimum performance evaluation. The study uses response surface methodology (RSM) for prediction of optimum input variables. The study takes into consideration turbine inlet temperature (TIT), compressor pressure ratio (rp), ambient temperature (AT) and ambient relative humidity (RH) as input variables for prediction of optimum cycle performance parameters. Study reveals that maximum gas turbine specific work has been observed at rp value ~ equal to 18–20 while turbine inlet temperature value of ~1520 K. Optimum values of thermal efficiency, rational efficiency, mass of coolant and gas turbine specific work are 39.03%, 36.98%, 0.0665 kg/kg of air and 363.59 kJ/kg respectively, with the corresponding gas turbine cycle input variables at turbine inlet temperature value of 1476.76 K, compressor presssure ratio value of 19.8788, ambinet temperature equal to 288 K and relative humidity value of 53.03%. The results of gas turbine cycle code response and optimum value obtained from resposne surface methodology have been observed within error margin of 0.14% (min.) – 0.6% (max.) and advocates the adoption of resposne surface methodology optimization technique. Higher rational efficiency has been obtained at lower ambient temperature (~293 K), further optimum value of rational efficiency (>36.5%) can be obtained at turbine inlet temperature ~1470 K.

Optimal Analysis of Entropy Generation and Heat Transfer in Parabolic Trough Collector Using Green-Synthesized TiO2/Water Nanofluids

This study presents an experimental nanoparticle synthesis and the numerical analysis of a parabolic trough collector (PTC) operating with olive leaf synthesized TiO2/water nanofluid. The PTC is modeled after the LS-2 collector for various operating conditions. An analysis of the heat transfer and entropy generation in the PTC is carried out based on the first and second laws of thermodynamics for various parameters of nanoparticle volumetric concentration (0 ≤ φ ≤ 8%), mass flow rate (0.1 ≤ m˙ ≤ 1.1 kg/s), and inlet temperatures (350–450 K) under turbulent flow regime. The effect of these parameters is evaluated on the Nusselt number, thermal losses, heat convection coefficient, outlet temperature, pressure drop, entropy generation rate, and Bejan number. The results show that the values of the Nusselt number decrease with higher concentrations of the nanoparticles. Also, the addition of nanoparticles increases the heat convection coefficient of the nanofluid compared to water. The thermal efficiency of the system is improved with the use of the new nanofluid by 0.27% at flow rates of 0.1 kg/s. The entropy generation study shows that increasing the concentration of nanoparticles considerably decreases the rate of entropy generation in the system. It is also observed that increasing the volumetric concentration of nanoparticles at low mass flow rates has minimal effect on the rate of entropy generation. Finally, a correlation that provides a value of mass flow rate that minimizes the entropy generation rate is also presented for each values of inlet temperature and nanoparticle volumetric concentration.

Bir gövde borulu ısı değiştiricisinde farklı levha türlerinin ısıl performansa etkisinin sayısal olarak incelenmesi

In this study, the thermal performance of a small scale shell and tube heat exchanger was performed according to the baffle type by using three dimensional Computational Fluid Dynamics (CFD) method. In numerical calculations, segmental and continuous helical baffle types were selected to get the comparative results. For helical baffle type, we used two different models that the numbers of helical rotations and baffle spacing length were different. Thus, we determined five different numerical models and the thermal performance of each models were evaluated under different inlet temperature values selected as 50, 60 and 70°C for the tube side. The inlet temperature value and the mass flow rate of shell side were kept constant during all the numerical calculations. The heat transfer calculations were achieved by using Logarithmic Mean Temperature Difference (LMTD) method. We also employed the Bell-Delaware method which can be used accurately for shell and tube heat exchangers. The highest thermal performance was determined in Case-IV which had equal baffle spacing and the maximum number of rotations for continuous helical baffle. The predicted total pressure drop results obtained from the numerical calculations were in good agreement with the calculated total pressure drop from Bell-Delaware method. The lowest pressure drop and the highest thermal performance were achieved for continuous helical baffle type compared to the segmental equal spacing baffle type. The numerical simulations based on CFD analysis can provide more information about heat exchangers and this tool can be used to improve both design and the thermal performance of heat exchangers.