Influence Of Inlet Temperature Research Articles

Efficient construction of self-assembled starch colloidosomes for controlled-release of pesticides

Biodegradable colloidosomes have attracted increasing attention for their applications to enhance the efficacy and reduce wastage of pesticides in agriculture. In this study, we present a continuous and highly efficient method for production of starch colloidosomes. The starch particles with an average particle size of 230.2 nm and good dispersibility were prepared using surface modification technology, and then used as environment-friendly shell materials to form self-assembled starch colloidosomes using spray drying technology. The influences of inlet temperature, feed rate and air flow rate on the morphologies of colloidosomes were also studied. This strategy enables the construction of starch colloidosomes with uniform spherical morphology and controllable pore sizes under different pH, and can be used for pesticide encapsulation. After loading pyraclostrobin (PYR), the regular spherical colloidosomes not only achieve a small mean diameter of 2.35 µm, but also realize a high encapsulation efficiency of 82 %. The release performance of PYR has an obvious pH response and follows the segmented Ritger-Pepapes model of sustained-release. The colloidosomes were used to prevent the photodegradation of pesticides. The PYR loaded colloidosomes exhibit excellent UV resistance with a retention rate of 72.7 %. In addition, the loading of Fe3O4 nanoparticles and the embedding of carbon dots were also explored.

Design and optimization of the radial inflow turbogenerator for organic Rankine cycle system based on the Genetic Algorithm

The backdrop of energy-saving and emission-reduction sets a higher demand for low-grade energy utilization which can be realized by Organic Rankine Cycle systems. A 50-kW radial inflow turbogenerator, the crucial heat conversion equipment, with aerostatic bearings for Organic Rankine Cycle system, is designed. It is optimized focusing on the performance of the turbogenerator which uses R245fa as the working fluid. The study employs a one-dimensional thermodynamic model, developed in MATLAB and bolstered by real-time data from Refprop, ensuring the model’s precision and dependability. On this basis, Genetic Algorithm is applied to optimize design parameters and significantly elevate the system’s efficiency, achieving circumferential efficiency of 85.29%. The turbogenerator demonstrates a rated bearing load capacity of 2.43 kN. The research delves into the influence of inlet temperature, inlet pressure, and rotational speed of turbogenerator on its performance. It reveals that an increase in both inlet temperature and inlet pressure lead to a decrease in isentropic efficiency and an increase in output power. The research also shows that an increase in the rotational speed contributes to increases in isentropic efficiency and output power.

Simulation of underground coal gasification ignition in deep coal seam based on transitional diffusion mechanism: Influence of inlet temperature and O2

Underground coal gasification (UCG) in deep coal seam was attracting more and more attentions all over the world due to its characteristics of safety, clean and low carbon. In the study, the ignition of UCG in deep coal seam was simulated by employing computational fluid dynamics (CFD). A new method setting gas diffusion in coal seam as transitional diffusion (TD) was put forward, and the TD and Fickian diffusion (FD) mechanism were compared. It was elucidated that TD mechanism was more accurate for UCG model. The default FD mechanism in coal seam overestimated the reaction rate of coal seam. With TD mechanism, coal seam in turn went through external heating controlled (EHC) region and hybrid heating controlled (HHC) region during the ignition of UCG. The demarcation temperature between EHC and HHC regions was 720 K. Then, various inlet temperatures and mass fractions of O2 were attempted during the simulation of UCG ignition. The time spent by the ignition was shortest with 1100 K inlet temperature and it was ∼180 s. The less the inlet mass fraction of O2 was used, the slower combustion rate was. CO2 was the most potential indicator to get access to the underground condition.

Effect of inlet temperature on flow boiling behavior of expanding micro-pin-fin type heat sinks

Heat sinks that cool electronic systems through flow boiling are exposed to working fluids at different inlet temperature. Therefore, in the present study, influence of inlet temperature on boiling performance of a micro-pin-fin-type heat sink with expanding cross-sectional area is experimentally investigated. The analysis is supported by comparing the results with those obtained via a plain-wall (conventional) heat sink. The experimental range covers two heat sinks (HS − 1: Conventional; HS-2: Expanding pin-fin-type), two values of mass flux (G = 120 and 190 kg m−2 s−1), three inlet temperatures (Ti = 25 °C, 45 °C, 65 °C) and five values of heating power (170 W – 210 W with 10 W increments). It is concluded that inlet temperature is an influential parameter for thermal characteristics as well as values of pressure drop. A remarkable increase is obtained for heat transfer coefficient with decreasing inlet temperature for HS-2. When a decrease occurs from Ti = 65 °C to Ti = 25 °C, heat transfer coefficient increases between 94.7%–620.8% for HS-2 at G = 190 kg m−2 s−1. HS-2 increases heat transfer coefficient up to 841.3% compared those of HS-1. Regarding both HS-1 and HS-2, a decrease in inlet temperature also leads a decrease in pressure drop for a given heat flux.

Thermal storage performance of a horizontal eccentric distance spiral shell-tube heat storage tank

Considering the delayed thermal response rate exhibited by a horizontal spiral shell-tube heat storage tank during the heat storage process, we introduce an eccentric distance spiral shell-tube heat storage tank model to address the above-mentioned limitation and enhance overall performance. The numerical simulation is used to simulate the thermal loading behavior of the three-dimensional model structure with different eccentric distances throughout the melting process. The results demonstrate that an eccentric distance can effectively expedite the melting process of the PCM. When the eccentricity of the tank is raised from 0 mm to 20 mm, the amount of heat storage remains relatively constant throughout this range. However, the melting time experiences a notable reduction of 47.19 %. Additionally, the average heat storage rate significantly increases by 83.85 %. It is worth noting that further increasing the eccentricity to 30 mm doesn’t lead to significant optimization in the melting process. Subsequently, the influence of inlet temperature and flow rate on the thermal storage performance is investigated using a tank with an eccentricity of 20 mm as a reference unit. The results show that when the inlet temperature is increased from 343 K to 358 K and the flow rate is increased from 0.034 kg/s to 0.136 kg/s, the heat storage capacity is increased by 11.02 % and 2.21 %, the melting time is shortened by 46.21 % and 25.44 %, and the average heat storage rate is increased by 106.41 % and 37.07 %, respectively. However, it is essential to note that at an inlet temperature of 363 K, the thermal storage performance of the tank experiences a notable decline. The results of this research provide useful guidelines for enhancing the thermal storage efficiency of the horizontal spiral shell-tube heat storage tank.

Performance analysis of a novel absorption-refrigeration driven membrane condenser system for recovery of water and waste heat from flue gas

Dehumidification of industrial flue gas with a membrane condenser requires cooling energy so that the water in the flue gas will recover as it gets condensed due to the cooling process. In this study, the utilization of the waste heat energy of the flue gas to drive an absorption refrigeration cycle is suggested. In return, the cooling energy of the refrigeration cycle is utilized to cool the flue gas before it is admitted to the membrane condenser. The thermal analysis of the refrigeration cycle is carried out by considering a numerical heat transfer analysis at the desorber. The energy and mass balance of the whole refrigeration cycle is carried out based on thermodynamic governing equations. Furthermore, the water recovery process of the membrane condenser which is integrated with the absorption refrigeration cycle is studied. The numerical modeling of the refrigeration cycle and the membrane condenser are combined to investigate the operating parameters of the system. The influence of inlet temperature and mass flow rate of the feed flue gas on the performance of both the refrigeration cycle and membrane condenser is studied.

Numerical and experimental investigation on condensation inside a turbine designed for an 100 kW polymer electrolyte membrane fuel cell system

This work presents mathematical modelling of moist air condensation process in a fuel cell turbine. A condensation model based on the classical nucleation theory and the Hertz–Knudsen droplet growth model is established. The numerical approach is validated through experimental results of the MS nozzle and a fuel cell turbine, and the simulation fits the experimental data well. Influences of inlet temperature and pressure on condensation process in the turbine is examined. Results show that increase of inlet temperature apparently weakens condensation and inlet heating can be realized by arranging a gas-to-gas heat exchanger in the air supply subsystem without consuming additional energy. Moreover, at the same mass flow rate increase of inlet pressure reduces the expansion ratio, thereby curbing the condensation. Compared with the matching scheme of a bypass valve, turbocharger matching with a back-pressure valve allows higher inlet pressure to be achieved and can effectively suppress the condensation.

Effect of spray drying conditions on physicochemical and functional properties of apple cider vinegar powder

AbstractBackgroundApple cider vinegar (ACV) contains many health benefits due to its antioxidant and acetic acid content. However, the adverse effects of directly consuming the vinegar should be eliminated to make it possible to regulate its intake as a dietary supplement. The objective of the study is to optimize the spray drying operating conditions to produce ACV powder with health benefits. A central composite design (CCD) of response surface methodology (RSM) was used to optimize the spray drying process of ACV. The influences of inlet temperature (130°C–170°C), gum Arabic concentration (5%–15% w/w), and feed flow rate (1–2 kg/h) on some product and process aspects were investigated. Spray‐dried powders were evaluated for their moisture content, process yield, acetic acid content, solubility, and antioxidant content.ResultsThe relationships between the model factors and final powder properties were established with ANOVA and multiple regression analysis. The model factors affected the investigated powder properties at different significance levels, where carrier concentration was the main influencing factor. Gum Arabic contributed to the retention of volatile and heat‐sensitive compounds providing health benefits. All powders showed high solubility (>94%) and high antioxidant recovery, and most treatments achieved a drying yield of higher than 50%.ConclusionOptimization of spray drying process was achieved with application of RSM and relationships between model factors and powder properties were established. This study highlighted the feasibility of the development of ACV‐based functional powder as a dietary supplement.

Analysis of Hydrogen Use in Gas Turbine Plants

Improvement of the efficiency of modern power systems requires the development of storage technologies, optimization of operation modes, and increased flexibility. Currently, various technical solutions are used for electricity storage. The results of a literary review with an analysis of existing energy storage systems are presented, their advantages and disadvantages are considered. One of the promising solutions is the use of hydrogen as an energy storage medium. The creation of corresponding energy complexes makes it possible to obtain hydrogen by electrolysis of water, and then use it to cover peak loads. Various schemes with hydrogen-fired gas turbines with a pressure up to 35 MPa and a temperature of 1500–1700 °C were considered. The new scheme of power plant with hydrogen-fired gas turbines was synthesized, which includes a power block, hydrogen generation blocks and hydrogen and oxygen preparation unit for burning. An atmospheric electrolyzer was considered as a hydrogen and oxygen generator. For the proposed scheme, parametric optimization was performed, where the storage efficiency factor has been used as a criterion. The influence of inlet temperature in the combustion chamber, the compression rate of hydrogen and oxygen, as well as the specific energy costs of the electrolyzer were analyzed. The results of the numerical experiment were approximated in the form of polynomial dependencies, and can be used in further research on the economic efficiency of proposed power plant.

Research on the Ignition Process and Flame Stabilization of a Combination of Step and Strut: Experimental and Numerical Study

A combined application of step and strut was put forward to achieve reliable ignition and flame stabilization. In this work, the ignition process and temperature distribution have been tested, and a new reduction approach applied to jet fuel oxidation mechanism was developed to present a flow map via tracking C and H reaction paths, then the minor and major reactions were verified according to relative occurrence probabilities. With the half decrease of mechanism size, bias occurred and was controlled within 1.8%. This reduction method had such characteristics as universality, intuition, and quantification, due to its inherent simplification theory. This simulation of ignition process was always consistent with experimental results, which depicted kernel generation, flamelet breakup and flame propagation. Also, the influence of inlet temperature on outlet temperature and component distribution was performed, the biases of experimental and numerical results were within 5%. Chemical characteristics of Kerosene/air premixed combustible had changed and side reactions occurred to jet fuel above 900 K, which led to a converse effect on flame spreading. The side reactions aggravated the increasing coproducts of CO and CH4, which caused the decrease of volumetric heat production.

Influence of Inlet Mud Temperature on Bottom Hole Mud Temperature During Horizontal Well Drilling

Abstract The high temperature in the horizontal section and bottom of a horizontal well has a significant impact on the performance of mud and the safety of drilling equipment. The high bottomhole temperature is lowered often by reducing the inlet temperature. To explore how the inlet temperature impacts the bottomhole temperature during horizontal well drilling, a computational model for transient temperature during horizontal well drilling was established in this paper. Finite difference approach was utilized for the model discretization, while the relaxation iteration technique was adopted for the model resolution. The influence of inlet temperature on bottomhole temperature was analyzed during alterations of inlet flowrate and horizontal section length. On the basis of the obtained results, the impact of inlet temperature on bottomhole temperature decreases as the horizontal section length increases. On the premise that the horizontal section is long enough, lowering the inlet temperature exerts little impact on the bottomhole temperature fluctuation. As the inlet flowrate declines, the influence of inlet temperature on bottomhole temperature decreases. In addition, with the inlet flowrate being small enough, lowering inlet temperature rarely impacts the bottomhole temperature fluctuation.

Modeling and analysis of thermodynamic performance of 6F unit based on Thermoflow

With the continuous development of combined cycle technology, mastering the thermal performance of combined cycle unit is beneficial to the system performance analysis, operation optimization and debugging. In this paper, the mathematical model of each component of the gas-steam combined cycle was established. Thermoflow software was used to calculate the thermodynamic performance of the system, and the influence of inlet temperature and gas turbine load on the thermodynamic performance of the system was analyzed. The results show that the model is reliable and the maximum error is 1.47%. When compressor inlet temperature increases by 10°C, gas turbine power decreases by about 5.8% and power generation thermal efficiency decreases by 0.15%. When the gas turbine load decreases by 10%, the thermal efficiency of combined cycle power generation decreases by 1.4%.

Experimental study on thermal performance of phase change heat storage device with rectangular shell structure

To solve the imbalance between energy supply and demand, it is necessary to explore the heat exchange performance of large-scale phase change heat storage devices in line with engineering applications. Based on the principle of low-cost enhanced heat transfer, a shell and tube phase change heat storage device with a rectangular shell with annular fins was designed in this paper. Using paraffin as phase change material (PCM) and water as heat transfer fluid (HTF). The effects of different flow rates and inlet temperature on the temperature distribution, heat, power, and efficiency of phase change materials during melting and solidification were studied experimentally. It is found that when the flow rate is 4 L/min, the total heat release was 61.06 MJ and the minimum heat release rate was 81.23%. The increase in flow rate and inlet temperature will shorten the heat storage time. The influence of inlet temperature on the heat storage time is more obvious than flow rate. Along with the raise of flow rate the shortening range of heat storage time decreases gradually. Additionally, the increase of the flow rate not only causes the enhancement of the heat storage and release power, but also results in the reduction of the average efficiency. Therefore, to improve the heat exchange speed in practical application, priority should be given to changing the inlet temperature.

Influence of inlet temperature on the performance of cascade and hybrid storage tank for CSP plants

• The impact of inlet temperature is investigated using a numerical model. • The thermal performance of the various thermocline tank configurations is evaluated. • As the inlet temperature rises, the thermocline zones shrink. • The HSLHS configuration is more efficient than the TLTES structure by 71.6% at T in = 520 °C. For the current thermal performance of the concentrating solar power (CSP) plants, the thermocline storage approach in a packed bed is recommended to be a favorable thermal energy storage (TES) system because of its cost effectiveness. Based on this, several parametric studies were performed to examine the thermal efficiency of various configurations of packed bed thermocline TES schemes. However, the impact of inlet temperature fluctuations on the storage tank's thermal performance has not been studied. The main objective of this research is to analyze, examine and evaluate the charge and discharge control strategies under different meteorological conditions using different storage configurations. A two-phase dispersion-concentric approach is formulated and verified to analyze the system's periodic thermal characteristics. The results indicate that the hybrid sensible-latent heat storage (HSLHS) case has the highest capacity ratio, utilization ratio, recovered energy, and overall efficiency over the changing inlet temperature, which is equal to 85.2%, 82.5%, 150.7 MWh, 95.2%, respectively, at T in = 565 °C. In addition, the findings proved that the overall efficiency improved by 19.2% using the HSLHS configuration at low temperature while it improved by 34.4% at a higher temperature.

Numerical Investigation of Heat Transfer Characteristics of scCO2 Flowing in a Vertically-Upward Tube with High Mass Flux.

In this work, the heat transfer characteristics of supercritical pressure CO2 in vertical heating tube with 10 mm inner diameter under high mass flux were investigated by using an SST k-ω turbulent model. The influences of inlet temperature, heat flux, mass flux, buoyancy and flow acceleration on the heat transfer of supercritical pressure CO2 were discussed. Our results show that the buoyancy and flow acceleration effect based on single phase fluid assumption fail to explain the current simulation results. Here, supercritical pseudo-boiling theory is introduced to deal with heat transfer of scCO2. scCO2 is treated to have a heterogeneous structure consisting of vapor-like fluid and liquid-like fluid. A physical model of scCO2 heat transfer in vertical heating tube was established containing a gas-like layer near the wall and a liquid-like fluid layer. Detailed distribution of thermophysical properties and turbulence in radial direction show that scCO2 heat transfer is greatly affected by the thickness of gas-like film, thermal properties of gas-like film and turbulent kinetic energy in the near-wall region. Buoyancy parameters Bu < 10−5, Bu* < 5.6 × 10−7 and flow acceleration parameter Kv < 3 × 10−6 in this paper, which indicate that buoyancy effect and flow acceleration effect has no influence on heat transfer of scCO2 under high mass fluxes. This work successfully explains the heat transfer mechanism of supercritical fluid under high mass flux.

Design of a Supercritical CO2 Compressor for Use in a 1 MWe Power Cycle.

Supercritical CO2 power cycles are considered to be a more effective means to replace the steam Rankine cycle in power generation by power coal in the future. However, CO2 compressors for this application have not been well developed. A conceptual design of the compressor for a 1 MWe cycle has been summarized and a calculation method of the axial force of a supercritical CO2 compressor has been introduced. The influences of inlet temperature and pressure near the critical point on compressor performance, the rotor dynamics analysis for this compressor, and the influence of the rotation factor C0 on compressor axial force were also investigated. The results show that the changes in inlet temperature and pressure near the critical point have great influences on compressor performance and the axial force of the compressor is closely related to the selection of the rotation factor C0. The pressure ratio and power decrease with the increase of inlet temperature; when the inlet temperature increases by 2 °C, the pressure ratio decreases by 7–24% and the power decreases by 1–9%. With the increase of inlet temperature, the maximum efficiency of the compressor decreases, and the maximum pressure ratio of the compressor decreases with the increase of inlet pressure. When the rotation factor C0 is equal to 0 and 0.2, the axial force of the compressor decreases with the increase of rotating speed. When the rotation factor C0 is equal to 0.4, the curves of the compressor with the flow rate at different speeds begin to produce intersections. When the rotation factor C0 is equal to 0.6, 0.8, and 1, the axial force of the compressor increases with the increase of rotating speed.

ANALISIS PENGARUH INLET TEMPERATUR SISTEM PENDINGIN BUATAN TERHADAP KENYAMANAN TERMAL KELAS UNIVERSITAS NUSA PUTRA DENGAN METODE CFD

Air circulation needed to meet comfort standards in classrooms with artificial cooling systems (Air Conditioning) to achieve thermal comfort (Thermal comport), Thermal comfort is one aspect that must be considered when designing a classroom. because at the time of learning there is an accumulation of heat and humidity of the air that will make the room uncomfortable. This research focuses on using the Simulation Computational Fluid Dynamic (CFD) method in the classrooms of Nusa Putra Sukabumi University.&#x0D; Simulation using Flovent 10.1 software, the simulated room is a B3D classroom on the 3rd floor of building B of Nusa Putra University which measures 10.15 m x 4.8 m x 3.25 m. The main purpose of this study is to find out the influence of inlet temperature on artificial cooling systems. Through simulation can predict efficiently and effectively setting the temperature inlet of the most optimal artificial cooling system. In the simulation conducted 5 variations, the result is the most ineffective temperature in variation 1, variation 2 and variation 3 at room temperature 16.32 °C – 20.06 °C, belongs to the category of too cold which means the room is uncomfortable. While the room with inlet temperature variation 4 and variation 5 temperature between 21.34 °C – 22.59 °C belongs to the category of comfortable cool based on the thermal comfort standard SNI 03-6572-2001.

Field Test and Numerical Simulation on Heat Transfer Performance of Coaxial Borehole Heat Exchanger

Ground thermal properties are the design basis of ground source heat pumps (GSHP). However, effective ground thermal properties cannot be obtained through the traditional thermal response test (TRT) method when it is used in the coaxial borehole heat exchanger (CBHE). In this paper, an improved TRT (ITRT) method for CBHE is proposed, and the field ITRT, based on the actual project, is carried out. The high accuracy of the new method is verified by laboratory experiments. Based on the results of the ITRT and laboratory experiment, the 3D numerical model for CBHE is established, in which the flow directions, sensitivity analysis of heat transfer characteristics, and optimization of circulation flow rate are studied, respectively. The results show that CBHE should adopt the anulus-in direction under the cooling condition, and the center-in direction under the heating condition. The influence of inlet temperature and flow rate on heat transfer rate is more significant than that of the backfill grout material, thermal conductivity of the inner pipe, and borehole depth. The circulating flow rate of CBHE between 0.3 m/s and 0.4 m/s can lead to better performance for the system.

Effects of Direct Contact Condensation on Flow Characteristics of Natural Circulation System at Low Pressure

Direct contact condensation (DCC) as a complex thermal-hydraulic phenomenon has been performed a great deal of research under forced flow conditions. It is an interesting challenge to study the phenomenon in a natural circulation system (NCS). In this paper, the flow behaviors along with DCC phenomena were experimentally investigated by visualization method in a NCS at low pressure. Moreover, the influence of initial parameters including heat flux, inlet temperature and resistance of the heated section on the NCS was analyzed in detail. The experimental results revealed that two types of DCC phenomena were found in the NCS. When Type I DCC occurs, the interface wave will be formed due to the hydraulic jump caused the reverse flow of subcooled water. Interface wave easily contributes to occurring Type II DCC due to the Kelvin-Helmholtz instability. In addition, the NCS tends to be more unstable with the increase in the heat flux or the inlet resistance. The influence of inlet temperature on the flow rate should comprehensively consider the changes of outlet parameters and subcooled degree of the steam and the subcooled water.

Numerical investigation of thermo-physical properties of non-newtonian fliud in a modelled intestine

Several kinds of researches have been conducted on peristaltic flow of non-Newtonian fluid in modelled oesophagus, stomach and intestine. However, further investigation is still needed especially in the area of mechanical shear stress, the influence of inlet temperature and velocity, Nutsselt number and the history of strain rates experienced by fluid particles. This study presents the numerical investigation of thermo-physical properties of non-Newtonian fluid in a modelled intestine. The properties investigated were fluid temperature, velocity, Nutsselt number and wall shear stress. Numerical simulation was performed by solving 3D Navier-Stokes and continuity equations. The intestinal model was drawn by using Autodesk Inventor 2017 while the numerical investigation was conducted by using ANSYS FLUENT 16.0. The Computational Fluid Dynamics solver employs the Finite Element Method (FEM) to discretize the governing equations. Chyme, Hibiscus Sabdariffa Roselle (Sobo), Soymilk (Soya) and Pap (Ogi) were the working fluids used for the investigation. Analyses of the results showed that the variation of fluid temperature and heat transfer with axial position across the length of intestinal model were not significantly influenced by the variation of the inlet velocity. Expansion of the model about the pulsating part enhanced heat transfer and nutrient delivery to the intestinal walls. Variation of the inlet velocity did not affect the average Nutsselt number. Chyme and Sobo had the highest and lowest Nutsselt number, respectively. Sobo displayed the best fluid properties considering flow behaviour while Soya displayed the best properties for thermal history. The results presented in this study are of countless importance in medical, paramedical, engineering applications, thermoregulation system, thermotherapy, and biomedical disciplines, where analyses and investigation of gastrointestinal tract history can be understudied.