Inlet Temperature Research Articles

Exergetic characterization of flat plate solar collector using genetic algorithm

With the rapid advancement of technology, the global demand for energy is increasing exponentially. It is crucial to focus on energy conservation and conversion across all sectors. This study conducted a second law or exergy analysis on a solar water heating system to uncover hidden losses during the process. To optimize exergetic efficiency, a genetic algorithm was employed to control the overall loss coefficient of a solar flat plate collector. Four decision variables were used in the genetic algorithm—heat flux rate, glass cover temperatures at the inlet and exit, and collector plate temperature to minimize the overall loss coefficient. Energy efficiency, entropy generation, and exergy destruction were estimated for various mass flow rates using thermodynamic equilibrium equations. Exergy correlations were developed concerning mass flow rate (0.001–0.009 kg/s), inlet temperature (300 K–360 K), collector plate area (1–10 m²), incident solar energy (400–900 W/m²), optical efficiency (0.4%–1%), and ambient temperature (300–315 K) under a range of initial conditions. It was found that exergy efficiency slightly increased (0.01%–0.08%) over a 12-h period. Although this increase is small, it can significantly contribute to energy conservation over the long term. The genetic algorithm predicted the minimum loss coefficient occurring during peak hours (12–14 p.m.) with respect to four decision variables. The results of this study were compared with existing literature and showed good agreement. In addition to the exergy analysis, an uncertainty error analysis was performed to assess the reliability and accuracy of the experimental measurements and computational predictions. By quantifying these uncertainties, the study ensured that the reported enhancements in exergy efficiency and the optimization results obtained through the genetic algorithm are robust and credible. This rigorous error analysis adds confidence to the findings, highlighting the potential for improved energy conservation in solar water heating systems.

Thermal performance attenuation characteristics of solar collector field in solar district heating system

In centralized solar district heating systems, the optical performance attenuation of the solar collector field significantly impacts the system’s heating efficiency and economics. However, accurate lifecycle models for the optical performance attenuation of solar collector fields are still needed. In this paper, the attenuation patterns of transmittance, absorption, and emissivity are systematically established through accelerated attenuation tests and calculation models. Based on this, a lifecycle model for optical performance attenuation was developed using TRNSYS and applied to a centralized solar heating system in Langkazi, XiZang. The results indicate that low inlet temperatures and high flow rates reduce optical performance attenuation, with ultraviolet damage of the glass cover being the main cause of performance attenuation, accounting for 74.5 % of heat loss. A 15-year lifecycle analysis shows that performance attenuation in the solar collector field results in a 16.7 % reduction in effective heat collection, a decrease in the solar fraction from 66.1 % to 55.1 %, and a 32.4 % increase in auxiliary heat supply. Increasing the heating area or thermal storage to collection area ratio helps mitigate optical attenuation. Based on this, from the perspective of mitigating the attenuation of collection efficiency, the thermal storage to collection area ratio should exceed 0.2 m3/m2, and the solar fraction is recommended to be kept below 0.7. Additionally, considering optical attenuation, the levelized cost of heat increases by over 0.03 CNY/kWh when the thermal storage to collection area ratio exceeds 0.2 m3/m2. The results provide a methodological basis for more accurate design of the solar heating system.

Thermal characteristics analysis and cooling model optimization of motorized spindle

Aiming at the influence of poor cooling conditions and traditional cooling control strategy on motorized spindle temperature and machining performance. Firstly, the heat transfer model of the motorized spindle cooling system is studied. Secondly, the influence of coolant inlet flow rate and temperature on the thermal characteristics of the motorized spindle is studied. Then, a thermal network model is established to solve the temperature of each temperature measuring point. Finally, the thermal characteristic experiment of the motorized spindle is carried out, and the cooling fluid flow optimization model is established based on the particle swarm optimization algorithm and simulated annealing algorithm. The results show that the temperature difference of the motorized spindle does not exceed 45 °C, the thermal deformation does not exceed 40.2 μm, and the thermal elongation is inhibited by 36 %. The maximum error of the Thermal Network Method and Finite Element Method（FEM）is 14.24 %. The utilization of the average logarithmic temperature difference for assessing the cooling effectiveness of optimal flow rates revealed that the particle swarm optimization algorithm demonstrates a comparatively lower average logarithmic temperature difference in comparison to the simulated annealing algorithm. The heat exchange efficiency of the motorized spindle is higher under the optimal flow rate obtained by the particle swarm algorithm.

Development of a geothermal-driven multi-output scheme for electricity, cooling, and hydrogen production: Techno-economic assessment and genetic algorithm-based optimization

This study aims to develop an environmentally friendly multi-energy system for sustainable production of electricity, cooling and hydrogen. The study introduces a pioneering geothermal-based system, integrating an ejector refrigeration cycle, a dual-loop organic Rankine cycle, and a hydrogen production unit with proton exchange membrane electrolyzers. The study provides a thorough analysis of the system's energy and exergy performance, as well as its economic feasibility. Through sensitivity and parametric analyses, the research identifies key parameters that significantly influence system performance. The system's innovative design promises minimal environmental impact while delivering multifaceted performance: generating 1.38 MW of electricity, supplying 436 kW of cooling load, and producing 5.39 kg/h of hydrogen. In the exergy analysis, Evaporator1 is identified as the primary contributor to exergy loss, representing 34 % of the total exergy destruction. This is followed by the electrolysis unit, the condenser, and the ejector refrigeration cycle, which contribute 18 %, 14 %, and 12 %, respectively. The system achieves optimal efficiency at an organic Rankine cycle turbine1 inlet temperature of 387 K, yielding a power generation of 885.4 kW and an exergy efficiency of 26.7 %. Beyond this temperature, any further increase leads to a decline in power output due to operational disturbances. A multi-criteria optimization using genetic algorithm is applied, resulting in an optimized system with a cost rate of 18.13 $/h and an exergy efficiency of 38.96 %.

Computational investigation of combustion and emission characteristics of HCCI engine fueled with Carbon-Free NH3 –H2O2 blend

A computational investigation is provided of the utilization of blends of NH3 and H2O2 as carbonless fuels for HCCI combustion. A Computational Fluid Dynamics (CFD) model is developed and validated to assess the engine’s performance under varying proportions of NH3 and H2O2, equivalence ratios, and inlet temperatures. The heat release rate profiles demonstrated dual peaks, which were rationalized as an initial fuel decomposition followed by a slow thermal explosion and then a fast depletion of the fuel after the generation of a pool of OH radicals through decomposition of H2O2. Findings suggest that an increase in mole fraction of H2O2 advances combustion. Increasing the H2O2 volume fraction also decreases combustion duration, while increasing the IMEP. In-cylinder peak pressure and Maximum Pressure Rise Rate (MPRR) increase with H2O2 mole fraction, leading to reduced thermal efficiency, particularly at higher equivalence ratios, and an increased danger of uncontrolled combustion (knocking). Additionally, higher inlet mixture temperatures were shown to result in an advancement in the start of combustion and a reduction in combustion duration, with a corresponding increase in peak pressure. This points to the possibility of potentially controlling the notoriously difficult-to-control HCCI combustion through intake temperature for NH3/H2O2 fuel blends. However, increased NOx emissions are observed for increased intake temperature and in any case the NOx emissions are orders of magnitude above current regulatory limits, which means that practical engine operation will only be possible with an aftertreatment scheme based on the de-NOx activity of NH3.

Mathematical modeling and experimental analysis of the double-effect DCMD-heat pump integrated system

High energy consumption represents one of the hindrances in enabling large scale application of membrane distillation. In this work, experimental and simulation studies of a double-effect direct-contact membrane distillation integrated with a single-stage vapor-compression heat pump (DE-DCMD-HP) were carried out for concentrating tap water with the aim to evaluate the energy saving of the integrated system. It was found during our experiments that an auxiliary cooler must be added to remove the excess heat from HP to enable the integrated system to reach the steady-state condition. The temperature-heat flux plots were first utilized to analyze how HP and DE-DCMD affected each other and reveal their coupling mechanism. The simulation results showed that the increase in the first-effect feed inlet temperature, Tfi,1 and the flow rate, V caused the thermodynamic cycle line of refrigerant shift to higher temperature, which led to the increase of the input power of the compressor and the auxiliary cooler, ultimately affecting the water production mass rate, ṁd, the coefficient of performance, COP, the gain output ratio, GOR, and the specific energy consumption, SEC. The experimental and simulation results revealed that increasing Tfi,1 and V increased the permeate flux Nh and GOR and reduced the SEC. The performances for three different DCMD configurations were furthermore evaluated via experiments at constant feed temperature whereby the SEC decreased from 2168 kWh·t−1 for single-effect DCMD to 1085 kWh·t−1 for DE-DCMD to 257 kWh·t−1 for DE-DCMD-HP.

The Impact of Hydrogen on Flame Characteristics and Pollutant Emissions in Natural Gas Industrial Combustion Systems

To improve energy savings and emission reduction in industrial heating furnaces, this study investigated the impact of various molar fractions of hydrogen on natural gas combustion and compared the results of the Non-Premixed Combustion Model with the Eddy Dissipation Combustion Model. Initially, natural gas combustion in an industrial heating furnace was investigated experimentally, and these results were used as boundary conditions for CFD simulations. The diffusion flame and combustion characteristics of natural gas were simulated using both the non-premixed combustion model and the Eddy Dissipation Combustion Model. The results indicated that the Non-Premixed Combustion Model provided simulations more consistent with experimental data, within acceptable error margins, thus validating the accuracy of the numerical simulations. Additionally, to analyze the impact of hydrogen doping on the performance of an industrial gas heater, four gas mixtures with varying hydrogen contents (15% H2, 30% H2, 45% H2, and 60% H2) were studied while maintaining constant fuel inlet temperature and flow rate. The results demonstrate that the Non-Premixed Combustion Model more accurately simulates complex flue gas flow and chemical reactions during combustion. Moreover, hydrogen-doped natural gas significantly reduces CO and CO2 emissions compared to pure natural gas combustion. Specifically, at 60% hydrogen content, CO and CO2 levels decrease by 70% and 37.5%, respectively, while NO emissions increase proportionally; at this hydrogen content, NO concentration in the furnace chamber rises by 155%.

Theoretical and experimental study on the effect of the heat shield on the trough solar cavity receiver in alpine areas

The large heat loss of the cavity receiver limits its application in parabolic trough collectors, matching the environmental factors in alpine areas, in this paper, adding a glass cover plate as a heat shield at the aperture of the trough inverted trapezoidal cavity receiver is investigated. To quantify the optimization of the system performance by adding, an analytical study is carried out for the cavity receiver using theoretical calculations of heat transfer and indoor experimental tests, while “thermal uniformity” is introduced as an indicator of the temperature distribution inside the cavity, and further verifies experimentally by the outdoor real-area environment. The findings indicate that adding a heat shield is significantly effective in reducing heat loss in windy areas. At the flow rate of 250 L/h and inlet temperature of 323 K, the maximum experimental heat loss value is significantly reduced by 70.01 % in the range of 1–5 m/s wind speeds compared to the one without a heat shield. When the wind direction is from −60° to 60°, the heat loss inside the cavity is small after adding, forming a stable stratified flow, and the thermal uniformity decreases by only 0.02, indicating that the stability of the temperature field inside the cavity is high. Furthermore, outdoor validation experiments demonstrate a slower change in heat loss rate with adding the heat shield compared to without, the growth rate of the former is close to 1/3 that of the latter, with a maximum suppressed heat loss rate of 23.49 %. This study provides the theoretical basis and data guidance for optimizing cavity receiver performance in alpine areas.

Experimental investigation of pressure drop oscillation and active mitigation in a pumped two-phase loop

A pumped two-phase loop (P2PL) integrated with a microchannel evaporator is the most favored design for advanced thermal management of modern electronic devices. However, these systems are susceptible to two-phase flow instabilities, in particular pressure drop oscillation (PDO), which can compromise their performance by premature initiation of critical heat flux (CHF), deterioration of the heat transfer capabilities, and inducing severe thermal and pressure fluctuations. This study experimentally investigates PDO in a P2PL with a microchannel evaporator, exploring the underlying mechanisms and mitigation strategies. The range of parameters are: heat flux from 0 to 56 W/cm2, mass flux from 47.9 to 95.9 kg/m2-s, a fixed inlet temperature of 10 °C, initial accumulator gas pressure from 620.5 to 827.3 kPa, and vapor quality from zero (subcooled liquid) to one (pure vapor close to dryout). A consistent trend of high-amplitude, low-frequency PDO at low heat fluxes transitioning to low-amplitude, high-frequency PDO at high heat fluxes was observed across all operating conditions. PDO originating in the evaporator propagated to other loop components with similar characteristics, underscoring the systemic nature of PDO. Further, PDO-driven thermal oscillations were observed to propagate through the evaporator, reaching the heater (heat source) temperature with maximum amplitude of 3.4 °C. These oscillations had a detrimental impact on the heat transfer coefficient by altering the flow boiling regimes within the microchannels. Notably, the subcooled liquid temperatures remained stable, indicating the absence of pressure-induced thermal effects in single-phase regions. Finally, an active control technique, based on controlling the pump flow rate using continuous feedback of flow rate was implemented to mitigate PDO, eliminating both pressure and temperature oscillations, achieving an average reduction of 69.8 % in PDO amplitude.

Inclined Installation Effect on the Offset Strip Finned Heat Exchanger Designed for a Hybrid Electric Propulsion System in Electric Vertical Take-Off and Landing

The plate-fin heat exchanger was designed for the liquid cooling thermal management system of the hybrid electric propulsion system for an electric vertical take-off and landing (eVTOL) vehicle. The offset-strip fin design was applied, and the performance of the heat exchanger was evaluated, particularly with respect to the inclination of the airflow entering the heat exchanger. The estimated performance during the design phase matched well with the experimental results. The inclination of the heat exchanger had a minimal effect on thermal performance, with a slight increase in performance as the inclination increased. However, the pressure difference along the airflow was affected, likely increasing as the inclination increased. The sensitivity of various parameters on coolant temperature was also investigated. The air inlet temperature had a significant effect on coolant temperature, followed by the coolant flow rate. Therefore, when designing the thermal management system, careful consideration should be given to the ambient air temperature and coolant flow rate.

Performance analysis of natural draft power plant cooling tower: Mathematical modeling of cross-flow type, application in capital cities of Iranian provinces

Cooling towers are heat exchangers that reduce the hot water temperature produced by process equipment through heat and mass transfer between water and air stream. This study investigates the performance of cross-flow cooling towers under various geometrical, physical, and environmental conditions. For this purpose, thermodynamic modeling of the cross-flow cooling tower was conducted, and the governing equations were numerically solved using the finite difference method. Unlike previous studies, the effects of water droplet deformation into an elliptical shape during its fall along the cooling tower were also considered. This deformation, which influences the drag coefficient, Reynolds number of the water droplets, droplet surface area, and its cross-section area, along with the incorporation of buoyancy force in the droplet momentum equation, led to an improvement in the results. Consequently, the maximum computational error in this case was reduced to 1.97 %, compared to the scenario where droplet deformation and buoyancy force were neglected. The change in geometrical parameters of the tower in Tehran and Rasht was investigated, revealing that increasing the outlet radius of the tower from 20 m to 22.5 m decreased the outlet water temperature by 1.21 °C and 0.67 °C and increased the thermal efficiency of the tower by 4.94 % and 2.88 % respectively, while increasing the tower height from 100 m to 120 m, only decreased the outlet water temperature by 0.47 °C and 0.26 °C, and increased the thermal efficiency of the tower by 1.89 % and 1.09 % respectively. Additionally, the cooling tower performance was assessed in the centers of different provinces .of Iran. Results showed that with an initial droplet radius of 1 mm and an inlet water temperature of 50 °C, the maximum and minimum temperature reductions occurred in Shahrekord by 20.16 °C and Bandarabbas by 12.37 °C, respectively.

Heat and mass transfer performance of multi-solute electroplating wastewater in spray evaporation separation process

Electroplating wastewater is complex in composition and contains many harmful substances. Based on the single droplet heat and mass transfer method, a one-dimensional mathematical model for the evaporation separation heat and mass transfer process of multi-solute electroplating wastewater is established. In order to validate the model, the experimental system of evaporation separation tower is established, and Nusselt numbers corresponding to metal ion solutions are fitted, reliabilities of models are also verified. The maximum relative errors of mathematical models are within 10.0 %. In addition, effects of the type and concentration of metal ions and air inlet temperature on heat and mass transfer characteristics of spray separation tower are investigated. Experimental results show that when the wastewater inlet concentration is the same, the improvement effects of increasing air inlet temperature on evaporation and separation performance from high to low are ZnCl2, CuCl2, and NiCl2 solutions. When the air inlet temperature increases from 90 °C to 130 °C, the evaporation speed of ZnCl2, CuCl2 and NiCl2 solutions increase by 90.3 %, 84.3 % and 45.7 %, respectively. When the air inlet temperature is the same, with the increase of wastewater inlet concentration, the evaporation separation performance of electroplating wastewater in descending order is ZnCl2, CuCl2, and NiCl2 solutions.

Modelling of a continuous sorption-enhanced methanation process in an adiabatic packed-bed reactor system

The present study investigates a sorption-enhanced methanation process and successive solid regeneration stages using a dual-function catalyst containing nickel as a catalyst and zeolite 13X for water removal. An adiabatic packed bed, modelled by a dynamical and heterogeneous model, has been considered, and a five-stage sequence describes the sorption-enhanced methanation and successive solid regeneration. First, methanation occurs with in-situ water removal; then, the catalyst drying using a pressure and temperature swing approach implemented by blowdown, purge, cooling, and pressurisation stages. In adiabatic operation, heat management is crucial; on the other hand, the heat produced can be efficiently used to dry the zeolite. Process intensification is pursued by addressing the effect of gas inlet temperature, pressure, and GHSV on system performance. Achieving an average purity of 99 % of the methane for pressures greater than 2 bar is possible for long-time operation, with productivity averaging 0.8 mol/(kgads min) at the highest gas hourly space velocity investigated.

In Situ Conductive Heating for Thermal Desorption of Volatile Organic-Contaminated Soil Based on Solar Energy

A novel conductive heating method using solar energy for soil remediation was introduced in this work. Contaminated industrial heritage sites will affect the sustainable development of the local ecological environment and the surrounding air environment, and frequent exposure will have a negative impact on human health. Soil thermal desorption is an effective means to repair contaminated soil, but thermal desorption is accompanied by a large amount of energy consumption and secondary pollution. Therefore, a trough solar heat collection desorption system (TSHCDS) is proposed, which is applied to soil thermal desorption technology. The effects of different water inlet temperature, water inlet velocity and soil porosity on the evolution of soil temperature field were discussed. The temperature field of contaminated soil can be numerically simulated, and a small experimental platform is built to verify the accuracy of the numerical model for simulation research. It is concluded that the heating effect is the best when the water entry temperature is the highest, at 70 °C, and the temperature of test point 4 is increased by 50.71% and 1.42%, respectively. When the inlet water flow rate is increased from 0.1 m/s to 0.2 m/s, the heating effect is significantly improved; when the inlet water flow rate is increased from 0.5 m/s to 1.5 m/s, the heating effect is not significantly improved. Therefore, when the flow rate is greater than a certain value, the heating effect is not significantly improved. The simulation analysis of soil with different porosity shows that larger porosity will affect the thermal diffusivity, which will make the heat transfer effect worse and reduce the heating effect. The effects of soil temperature distribution on the removal of petroleum hydrocarbon C6–C9 and trichloroethylene (TCE) were studied. The results showed that in the thermal desorption process of petroleum hydrocarbon C6–C9-contaminated soil, the removal rate of pollutants increased significantly when the average soil temperature reached 80 °C. In the thermal desorption of trichloroethylene-contaminated soil, when the thermal desorption begins, the soil temperature rises rapidly and reaches the target temperature, and a large number of pollutants are removed. At the end of thermal desorption, the removal of both types of pollutants reached the target repair value. This study provides a new feasible method for soil thermal desorption.

Numerical and artificial neural network inspired study on step-like-plenum battery thermal management system

This study leverage numerical simulation (NS) and artificial neural network (ANN) capabilities to carry out additional investigations on step-like plenum battery thermal management system (BTMS). Different cooling strategies have been developed over the years in BTMSs’ design. Yet, air-cooling strategies still remains relevant, especially in battery-powered aircrafts, where light-weight is important and air is the preferred cooling fluid. Hence, additional study become necessary especially on the step-like plenum design to provide more insight on the performance of the design by considering several number of step, varied air inlet temperature and velocity. Computational fluid dynamics (CFD) approach was employed to obtained results for different number of step; Ns = 1, 3, 4, 7, 9, 15 and 19, varied air inlet temperature; Ti = 278, 298 and 318 K, and varied air inlet velocity; Vi = 3, 3.5, 4, 5 and 6 m/s. Artificial Neural Network (ANN) approach was then employed to predict the BTMSs’ performance for additional values of Ti and Vi. Minimum temperature (Tmin), maximum temperature (Tmax), maximum temperature difference (ΔTmax) and pressure drop (ΔP) were computed. By comparing the CFD results with the result predicted by the ANN, the percentage difference, for the entire dataset were 0.01 %, 0.005 %, 1 % and 0.14 % for Tmax, Tmin ΔTmax and ΔP, respectively. Based on the optimum design parameters predicted using ANN, for Tmax = 299.24 comprises Ns = 4, Vi = 6 m/s and Ti = 278 K, while for ΔP, comprises Ns = 1, Vi = 3 m/s and Ti = 318 K.

Investigation of diesel particulate filter performance under typical failure conditions

Diesel particulate filter (DPF) is one of the most effective particulate reduction components in diesel engine aftertreatment systems. However, prolonged utilization of a DPF might result in a deterioration in performance or even failure, such as ash-clogging, melting, breakage, and catalyst deactivation. It is crucial to conduct research on DPF performance degradation across a series of partially failed conditions. In this study, the morphology and chemical composition of the ash in the DPF samples were characterized. The effects of degree-varying clogging and unplugged-breakage failure on exhaust characteristics as well as DPF temperature, filtration and pressure drop characteristics were investigated. Finally, the sensitivity differences between DPF performance parameters and failure index parameters were examined using a canonical correlation analysis (CCA). When four factors were considered, the ash loading index and breakage index had the greatest impact on DPF temperature difference and filtration efficiency, while the exhaust mass flow rate had the greatest impact on pressure drop. Besides, the influence of the DPF inlet temperature on the pressure drop, filtration efficiency, and temperature difference was not significant. These findings contribute to the prediction of DPF performance in partially failed conditions and the development of DPF failure diagnosis methods.

Optimization of lycopene spray drying encapsulation in basil seed gum: Boosting bioavailability and mayonnaise stability

This study aimed to improve lycopene stability and bioavailability in food products. Lycopene, a potent antioxidant, often has poor stability and undesirable organoleptic properties. Therefore, the impact of basil seed gum (BSG) concentration and spray drying inlet temperature (IT) on the physicochemical, bioaccessibility, and antioxidant properties of encapsulated lycopene emulsion (ENL) was investigated using Central Composite Design (CCD)-Response Surface Methodology (RSM). Optimal encapsulation conditions were IT = 141.96 °C and BSG = 19.507 %. The ENLs had an average particle size of 147.56 nm, a polydispersity index (PI) of 0.263, and a zeta potential of −21.37 mV, indicating good colloidal stability. Antioxidant activity varied slightly during the four weeks of storage (a 9.65 % increase followed by a 13.6 % decrease), but it remained stable overall. Incorporating ENL into mayonnaise significantly reduced the acid value (2.78 mg KOH/g), the anisidine index (12.43), the peroxide value (7.13 meq/kg), and the TBARS index (0.534), and improved color parameters, reducing brightness (79.94) and whiteness (70.64) while masking lycopene's strong yellow and red hues. This study highlights BSG-encapsulated lycopene's potential to improve oxidative stability and sensory properties, offering a natural and effective method to enhance lycopene stability, bioavailability, and sensory acceptance in various food applications.

Experimental study on hydraulic performance and cavitation characteristics of a R134a refrigerant self-lubricating centrifugal pump

As the primary power equipment in pump flooding cooling systems, the efficiency and performance of mechanical pumps play a crucial role in two-phase cooling systems. A high-speed centrifugal pump with self-lubricating working fluid was designed with a speed of 7500 rpm and a flow coefficient of 0.0506. The hydraulic and cavitation performance of the pump were tested with R134a as the working fluid. The results show that the working fluid pump is capable of efficiently pumping R134a with an efficiency of 40.3% and a head coefficient of 0.988 under the design condition. Within the tested range of inlet temperature from 5°C to 15°C, the flow coefficient from 0.01 to 0.105, and the height of the refrigerant tank from 1.4 m to 5 m, lower net positive suction heads available at the same flow rate will reduce the pump head, increase power consumption, and decrease efficiency. Increasing the pump speed from 3000 rpm to 7500 rpm can improve the pump's performance. At 6000 rpm, the critical cavitation number of the working fluid pump increases with the increase in flow coefficient. At 7500 rpm, the critical cavitation number has a minimum value when the flow coefficient φ = 0.0434. At the design speed and flow rate, both the critical cavitation coefficient and fracture cavitation number increase as the inlet temperature decreases. The inducer can significantly reduce the critical cavitation number of the pump. Finally, an empirical correlation considering the thermodynamic effects is proposed to predict the increase in the critical cavitation number.

Study on the recovery temperature and overall cooling effectiveness of the different profiles of the blade under the condition of non-uniform turbine inlet temperature

The Overall Cooling Effectiveness (OCE) is a crucial parameter for the evaluation of the cooling performance of blades in modern gas turbines. However, studies on the local recovery temperature are seldom addressed in the context of the OCE. In this paper, the local recovery temperature and OCE were measured by thermocouples innovatively installed at S2, S5, and S8 profiles having blade heights of 20 %, 50 %, and 80 %, respectively. These were performed under the condition of non-uniform turbine inlet temperature. The cascade pressure ratios of 1.4–1.9 for the OEC tests were similar to those of the recovery temperature tests. The other operating conditions for the OEC tests included the KG in the range of 0.02–0.07 and the KT in the range of 2.0–3.2. Numerical simulation was conducted to analyze the coupling effect of the non-uniform cascade inlet temperature, the passage vortex, and the blade tip leakage vortex. The obtained results showed that the passage vortex led to a marked recovery temperature drop at the trailing edge of the 20% blade height profile compared with the other two profiles at all the cascade pressure ratios. The change of the cascade pressure ratio significantly affected the recovery temperature of the 80 % blade height profile compared with the other two profiles. The differences of the recovery temperature distribution on three blade profiles strongly depended on the distribution of the turbine inlet temperature, the action region of the passage vortex and the tip leakage vortex. The OCE of the three profiles showed the different distributions along the mainstream direction. In the radical direction, the averaged OCE was the highest for the S8 profile, followed by the S5 profile, while S2 profile recorded the lowest value. Finally, based on experimental data collected throughout this study, a correlation equation was established pertaining to averaged OCE.

Study and Analysis thermal performance of Taza gas power plant in Kirkuk –Iraq

In this research, the concept of energy balance was implemented in one of the gas turbine electricity generation units in Iraq (Kirkuk - Taza) K1. The design operating data is taken and compared with the data calculated in the computer model used by Engineering Equation Solutions (EES), and the validity of the model used was confirmed. The results indicate the release of a large amount of thermal energy into the atmosphere due to the open Brayton cycle, as energy losses amounted to 60% of the energy input. The results based on the data of the first unit of the station demonstrated that the theoretical efficiency of the unit is a function of the two variables, which are the temperature of the air entering the compressor and the Turbine inlet temperature: Increasing the compressor inlet temperature leads to a decrease in net power output and first-law efficiency and an increase in the specific fuel consumption rate. Increasing the turbine inlet temperature to 1°C leads to an improvement in both net power output and first-law efficiency by (0.24MW, and 0.04) %), respectively. The results also showed that cooling the air entering the compressor for 1°C leads to improving power output and first law efficiency by (0.72MW, and 0.12%), respectively, and reduces specific fuel consumption by 7.8kg/MWh.