Direct Air Cooling Research Articles

Performance Analysis for Battery Stability Improvement using Direct Air Cooling Mechanism for Electric Vehicles

Safety concerns about the battery are primary challenges for the maker of the electric vehicle (EV) system. At continuous work, maintaining the optimal temperature is a crucial scientific issue. It has restricted the widespread use of batteries. Hence, maintaining the optimal temperature for E-vehicles has been analyzed in this study. To achieve more energy density in charging, the discharging cycle and compact structure have been essential. In this study, a direct air-cooling system has been addressed to reduce the temperature of the battery pack, resulting in a significant improvement in system efficiency. The 1.44 kgwatt (kW) battery back has been constructed for the E-vehicle by Simulink diagram to analyze the system. In this study, two various scenarios have been made, such as with air cooling and without cooling, to validate the outcomes. Torque and speed characteristics have been analyzed for this study. Air-cooling-based batteries for e-vehicle simulation have delivered better outcomes, such as high power charging and discharging and a discharge depth of 92%. The differential battery pack temperature has been reduced by increasing the cooling air flow rate to 2 ms−1, 4 ms−1, and 6 ms−1. To attain an even delivery of coolant air flow, a design criterion has been suggested. The outcome of the study has been evaluated through numerical analysis.

Numerical Study on the Application of Pressure-Swirl Atomizing Nozzles in a Direct Air Cooling Condenser of the Power Plant

Abstract In this paper, a pressure-swirl atomizing nozzle was proposed to improve the atomization characteristics and enhance the heat transfer characteristics. By modifying the structural parameters of the nozzle, the effect of angles of inclined holes on the swirl plate on the heat transfer characteristics was studied, and the structure of the nozzle was optimized based on fluent software. The corresponding relationship between the pressure difference between the inlet and outlet of the nozzle and the flowrate was obtained, which provides a basis for the parameter setting of the discrete phase model. The nozzle was then applied to a spray humidification system of a direct air cooling unit in the power plant. The influences of nozzle arrangements and spray directions on the vacuum degree of the system were studied. The results of the numerical study show that the nozzle with the angle of inclined holes at 45 deg not only has the highest heat transfer efficiency but also has the highest heat transfer uniformity among all the simulated cases. In the air cooling unit of the power plant, when the nozzles are arranged in staggered rows and the angle between the spray direction and the positive direction along the height is kept at 15 deg, the heat transfer performance of spray humidification is the best. The vacuum degree of the condenser is the highest.

Diagnostic Analysis Method of Direct Air Cooling Unit Limited Output Based on Pressure Ratio

Given the limited output of a 600MW direct air cooling steam turbine unit, through the thermal performance test, historical operation data extraction, and comparative analysis combined with the data after the latest overhaul, it is found that the extraction pressure of the first section of the high-pressure cylinder began to appear over-pressure in recent two years. After further calculating the pressure ratio of the HP cylinder flow passage stage group, it is found that the pressure ratio of HP cylinder exhaust steam to Section I extraction steam has increased by nearly 4% in the last two years, indicating that the area of flow passage part of this stage group has become smaller and serious salt deposition has occurred, resulting in the reduction of HP cylinder flow passage capacity and the ultimate limitation of the output of the whole unit. The cylinder uncovering inspection results verify the correctness of the diagnosis. The diagnosis method is simple and suitable for the fault diagnosis of the actual flow passage.

Energy and Exergy Analysis of a New Cogeneration Heating System Based on Condensed Waste-Heat Utilization in the Direct Air Cooling Coal-Fired Power Plant

Energy and Exergy Analysis of a New Cogeneration Heating System Based on Condensed Waste-Heat Utilization in the Direct Air Cooling Coal-Fired Power Plant

Analysis of Influence of 1000MW Unit Boiler Side Wind, Side Wind and Solar Radiation on Direct Air Cooling System

In the operation of direct air-cooled units, there are many factors that affect the safety and economy of the unit. The “hot air recirculation” and “backfill” phenomena caused by lateral wind, the influence of high ambient wind on the heat transfer performance of the air cooling unit near the windshield wall, and the “hot air recirculation” phenomenon caused by the back wind of the furnace, these may affect the direct air cooling unit. Safe and economical operation. Through carrying out on-site test research, collecting the actual operating conditions of the unit operation, the organic combination of laboratory simulation data and actual data is provided to provide a strong basis for the development of corresponding technologies.

Application of Thermoelectric Technology in Direct Air Cooling System of Thermal Power Plant

In recent years, with the improvement of the coefficient of merit of thermoelectric materials, the research of thermoelectric power generation has entered a new climax. The developed countries have listed the development of thermoelectric power generation technology into the medium and long-term energy development technology. The research on thermoelectric power generation in China started relatively late, mainly focusing on the theory and preparation of thermoelectric materials. At present, the field of semiconductor thermoelectric power generation is just introduced, and its practical application is still blank. Thermal power generation technology is used to recover waste heat from direct air cooling system of thermal power plant. Power supply of wireless temperature sensor can be realized through energy storage components or integrated power management system, which can reduce energy waste and environmental pollution. It is of great significance for industrial waste heat recovery and clean energy development.

Dynamic modeling and control of direct air-cooling condenser pressure considering couplings with adjacent systems

Direct air-cooling is considered as a promising technique in power generation because of its huge water-saving advantages. However, this is accompanied by inherent sensitivity to meteorological and ambient conditions, which is liable to cause frequent detrimental fluctuations in the condenser pressure and unit operation stability/economy. Therefore, a higher requirement has been imposed on the control system to achieve stable and economic operation of direct air-cooling condenser. To this end, a dynamic direct air-cooling condenser pressure model is first established in this paper after taking fully consideration of both condenser dynamics and couplings with adjacent systems. Then, two control methods, namely zone model predictive control and zone economic model predictive control are applied to the established model to realize zone control of the condenser pressure while suppressing control quantity variations resulting from time-varying ambient temperature. Detailed quantitative analysis of the influence of direct air-cooling condenser pressure on the turbine bleed flow and unit economy has been performed after both model steady-state and dynamic verification, and the comparative control simulation results under two typical cases have illustrated that the proposed zone economic model predictive controller provides a flexible way to simultaneously deal with the ambient temperature changes and economic optimization issues.

Performance evaluation of decay heat removal systems of Fluoride-salt-cooled High-temperature Reactor (FHR)

The Fluoride-salt-cooled High-temperature Reactor (FHR) is one of the Generation IV nuclear reactor concepts being investigated mainly in the U.S. and China. Liquid salt with high boiling point of over 1400 °C is used as a coolant and its baseline fuel is the graphite-matrix coated-particle fuel developed for high-temperature gas-cooled reactors. To establish advanced safety systems in FHR, passive decay heat removal system which utilizes fluid’s natural circulation is considered. Three systems are proposed: Direct Reactor Air Cooling System (DRACS), Reactor Vessel Air Cooling System (RVACS), and Silo Cooling System (SCS). Although these three safety systems were previously developed for other types of reactors, their heat removal performances need to be evaluated for the FHR plant. The current study provides evaluation of decay heat removal systems of FHR during thermal-hydraulic transient. In addition, FHR’s grace period to start the reactor cooling was determined under the condition where no operable heat removal systems are available. The current study shows that FHR’s decay heat removal systems possess sufficient heat removal capability to avoid catastrophic accidents. The construction of Fluoride-salt-cooled High-temperature Test Reactor (FHTR) is currently being planned and its development is a key step to realize the commercialization in near future. This study provides performance evaluation of decay heat systems for FHTR under thermal-hydraulic transient, and also suggests the adequate operation procedure suitable for FHTR to avoid a severe accident.

On the dynamic modeling and control of the cold-end system in a direct air-cooling generating unit

Direct air-cooling is considered as a promising technique in power generation because of its distinct water-saving advantages, where ambient air is utilized instead of water, to cool down the exhaust steam in the direct air-cooling condenser. However, the relatively poor heat transfer characteristics and thermodynamic properties of air also brings higher backpressure in the direct air-cooling generating unit compared with conventional water-cooling generating unit, as well as the sensitivity of condenser performance to meteorological and ambient conditions. Therefore, the unit backpressure control for the direct air-cooling generating unit has been a challenging task in the recent years. To this end, a control-oriented mechanism dynamic cold-end system model is built for the direct air-cooling generating unit in this paper. The modified moving boundary method is utilized to capture the dynamic process of exhaust steam condensation in the condenser, wherein a time-variant mean void fraction is adopted to enhance model accuracy and robustness. Validation results with operating data have shown the established model can capture the dynamics of direct air-cooling cold-end system with satisfied accuracy. Based on the established model, a model predictive controller with feedforward compensation is proposed to keep unit backpressure steady at the desired set-point while suppressing the time-varying stochastic ambient temperature disturbances by regulating the rotation speed of fan array appropriately. The simulation results have verified the merits and effectiveness of the proposed strategy in achieving both satisfactory backpressure regulation and disturbance rejection performance.

Modelling and Optimization of the Direct Air Cooling Power Generation Unit

Abstract Fossil fuel power plants dominate the energy structure in China. However, the water scarcity, in Southeast/Southwest China, results in the development of the dry cooling power plants. Direct air cooling condenser (DACC) is appealing for its water saving ability. In DACC, the exhaust steam is cooled and condensed to water by the air flow, which is provided by the fan array at the cost of electricity. There exists a varying optimal exhaust steam pressure under different air temperatures and loads. The static model of the turbine-DACC system is built to quantify the influences of the air temperatures and loads. An on-line optimization is used here to set the reference value of the exhaust steam pressure for the turbine-DACC system for economic operation. The objective is to maximize the net power production while satisfying the constraints on the safety pressure and the available air flowrate. The optimization is conducted in a model 660MW power plant selected on a random summer/winter day. The hourly optimal exhaust steam pressure and the operation instructions are calculated as the reference values for the control layer. The optimization results show that the optimal exhaust steam pressure may be too close to the safety limits in winter, suggesting the safety also to be considered in the optimization. In summer, the DACC system cannot satisfy the condensation load sometimes. Thus, a complementary cooling method, for example, the wet cooling, is needed to reduce the burden on the DACC system.

Analysis of Feasibility of Peak Cooling Device Used with Direct Air Cooling Unit in Power Plant

In order to reduce the back pressure of direct air cooling unit and increase power output of steam turbine in summer, the cold end system of a power plant is optimized through adding evaporative condenser as peak cooling device. Through experiments, this article compares the effect on back pressure in the case of inputting the peak cooling device and cutting off peak cooling device with different load and different temperature in summer, also the effect of ash deposition on exhaust pressure is studied. The results show that the unit in different load of 500WM, 400WM, 380WM, 300WM and different temperature of 29℃,33℃,30℃ ,27 ℃ respectively, when putting into the peak cooling device, back pressure reduces 22kPa,13.1kPa,10.8kPa,6.7kPa respectively; when cutting off the peak cooling device, the back pressure increases 27kPa, 14kPa, 11.4kPa and 5.4kPa respectively. The ash deposition can increase the back pressure. The back pressure has been reduced about 9kPa after cleaning ash deposition when cutting off the peak cooling device.

600 MW Direct Air-Cooling Unit Back-Pressure Optimization and Theoretical Analysis

In recent years, direct air cooling units have developed rapidly in China, but in the actual operation, the back-pressure often deviate from the optimal back-pressure, which affect the economy of the unit. The paper has figured out the optimum back-pressure, fan speed and power gain with the method of equivalent enthalpy drop; the paper also worked out the exergy loss of each device before and after the optimization. Through the exergy efficiency analysis of the devices before and after the optimization, we find out that after optimization, exergy loss of the turbine reduces by 0.954MW and the net amount of the generated power increases 130.5kW, the net exergy efficiency of units improves about 0.018 percent points.

Simulate Design of Direct Air Cooling Exhausted Duct System for 1000MW Super-Critical Thermal Power Unit

Balancing flow distribution and decreasing the pressure drop in each vapor distributing pipe are the importance of the study of exhaust pipe of direct air cooling power unit.In order to balance flow distribution and decreasing the pressure drop in each vapor distributing pipe,and simulate the flow field when add different chamfer on the back of exhausted pipe or not ,then using the CFD software called FLUENT,the steam flow field of exhausted pipe for a 1000 MW power unit with direct air cooling is stimulated under typical steam turbine conditions.The result shows that the steam flows through each distribution pipe with balanced flow under the condition of chamfer angle of 30 °and the flow resistance is much lower than before．

Numerical Simulation on Adding Chamfer Angle of Direct Air Cooling Exhausted Duct for Large Thermal Power Generator

The optimal design for exhausted ducting mode and internal structure in direct cooling exhausted duct system influence every steam to assign the flow obstruction and flow while managing to assign directly.The flowing filed of steam in direct air cooling exhausted duct for 1000MW power generating unit is simulated via Computational Fluid Dynamics(CFD) software under typical steam turbine conditions,and the best chamfer angle can be get by adding different chamfer angles in back of exhaust pipe.The result shows that the steam flows through each distribution pipe with balanced flow under the condition of chamfer angle of 30 °and the flow resistance is much lower than before

Fuzzy Control Approach of Back Pressure Protection for Direct Air-Cooling Unit

Fuzzy Control Approach of Back Pressure Protection for Direct Air-Cooling Unit

Development of High-Strength Cu-Ni-Ti-B Multiphase Steel by Direct Air Cooling

The present study concerns development of high-strength low-carbon Cu-Ni-Ti-B multiphase steels in the as-hot-rolled condition. An attempt has been made to predict the microstructural evolution of the chosen steels during continuous cooling transformation by artificial neural network modeling as well as dilatometric study. Experimental results have demonstrated that direct air cooling of the hot-rolled Cu-Ni-Ti-B steel resulted in a microstructure containing intercritical ferrite and finer low-temperature transformation products of austenite. An attractive strength-ductility combination was achieved in the case of as-hot-rolled Cu-Ni-Ti-B steel with a dual-phase-like microstructure. Age hardening of the steels has further enhanced the mechanical properties. Analysis of the work-hardening behavior by differential Jaoult–Crussard (J-C) analysis has revealed the effect of aging on the work-hardening behavior.

Direct Air Cooling of Electronic Components: Reducing Component Temperatures by Controlled Thermal Mixing

This paper discusses forced convection heat transfer in a channel populated with discrete components similar to those found in electronics cooling situations. The temperature rise of each component is expressed as the sum of two parts; its adiabatic temperature rise, Tad–Tin, due to the thermal wakes of upstream components; and its self-heating temperature rise, Te–Tad due to its own power dissipation. A component’s temperature can be reduced either by reducing the adiabatic temperature rise or the self-heating temperature rise, or both. This investigation concentrates on the former: reducing the adiabatic temperature rise through increased thermal mixing in the coolant flow. The temperature of the air near the components exceeds the mean temperature of the cooling fluid, often by a large amount. In the present work, small scoops were installed in regions of high temperature but low velocity fluid (i.e., in between rows of components rather than in the free stream) to augment thermal mixing and reduce the nonuniformity. This approach does not induce as large a pressure drop as some conventional “turbulators” for a given decrease in operating temperature. In the present work, the scoops reduced the adiabatic temperature rises by 10 to 55 percent, resulting in up to 19 percent reduction in the overall temperature rise. The test section pressure drop increased 11 percent.

A Study of Forced Convection Direct Air Cooling in the Downstream Vicinity of Heat Sinks

An experimental study of forced convection heat transfer is reported. Direct air cooling of an electronics packaging system is modeled by a channel flow, with an array of uniformly sized and spaced elements attached to one channel wall. The presence of a single or complete row of longitudinally finned heat sinks creates a modified flow pattern. Convective heat transfer rates at downstream positions are measured and compared to that of a plain array (no heat sinks). Heat transfer rates are described in terms of adiabatic heat transfer coefficients and thermal wake functions. Empirical correlations are presented for both variations in Reynolds number (5000 < Re < 20,000) and heat sink geometry. It is found that the presence of a heat sink can both enhance and degrade the heat transfer coefficient at downstream locations, depending on the relative position.