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Boiler Plant Operations
Published in Carl Bozzuto, Boiler Operator's Handbook, 2021
Power turbines can be used to drive large pieces of equipment, everything from sewage treatment plant pumps to chillers. Every electric utility plant, whether burning hydrocarbon fuels or with nuclear energy, uses power turbines to generate electricity exclusively. In order to maximize power output and efficiency, those plants use condensers. Some plants with back pressure turbines will also use condensers. Condensers can be air cooled or water cooled. Most are water cooled. Water cooling is preferred because the temperature of the water is normally much lower than the air temperature. That, in turn, means that the temperature at which the steam condenses is lower. The lower the temperature, the lower the vapor pressure of water at that temperature. That lowers the exhaust pressure of the steam turbine. The water used for cooling the condensers can be drawn from a well, a city water supply, a river, a lake, or the sea. When using well water or city water, a closed-loop system utilizing cooling towers dramatically reduces that water consumption. For that reason, nearly all electric generating stations in the US now must use cooling towers.
Vacuum Tube Principles
Published in Jerry C. Whitaker, Power Vacuum Tubes, 2017
The main factor that separates tube types is the method of cooling used: air, water, or vapor. Air-cooled tubes are common at power levels below 50 kW. A water cooling system, although more complicated, is more effective than air cooling—by a factor of 5–10 or more—in transferring heat from the device. Air cooling at the 100 kW level is virtually impossible because it is difficult to physically move enough air through the device (if the tube is to be of reasonable size) to keep the anode sufficiently cool. Vapor cooling provides an even more efficient method of cooling a power amplifier (PA) tube than water cooling, for a given water flow and a given power dissipation. Naturally, the complexity of the external blowers, fans, ducts, plumbing, heat exchangers, and other hardware must be taken into consideration in the selection of a cooling method. Figure 3.19 shows how the choice of cooling method is related to anode dissipation.
Permanent Magnet Brushless Motors
Published in Jacek F. Gieras, Electrical Machines, 2016
Electric motors for passenger hybrid cars are typically rated from 30 to 75 kW. Water cooling offers superior cooling performance, compactness and lightweight design over forced-air motor cooling. The water cooling permits weight reductions of 20% and size reductions of 30% as compared to forced-air designs, while the power consumption for cooling system drops by 75%. The use of a single water cooling system for the motor and solid state converter permits further size reductions.
Simulation Study to Evaluate the Hybrid Photovoltaic - Thermoelectric Energy Generation System with Heat Recovery Mechanism
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2021
Muhammad Suleman Malik, Muhammad Naeem Arbab, Muhammad Omer Khan, Muhammad Arsalan Malik, Muhammad Usman Asghar
Figure 16 (a) andFigure 16 (b) shows the simulation results of the overall losses in 5 kW solar PV system, mounted at UET Peshawar. These losses include horizontal global irradiation losses on the incident collector plane, PV conversion losses, PV loss due to temperature, PV loss due to irradiance level, module quality loss, Mismatch loss in modules and strings, wiring loss, Inverter loss during operation and inverter loss due to voltage threshold. In this study, two different cooling mediums have been considered that can be used for the cooling of thermo-electric cells for thermo-electric power generation, that is, natural Air Cooling and Water-Cooling. The power loss due to rise in the temperature of the solar panels is utilized by TECs connected to the backside of solar panels, to generate electrical power. It is noted that the water-cooling system is superior and more efficient in comparison to the air-cooling system in terms of power generation. Power generated by both the sources, is injected into the grid. The total energy generated and energy loss is shown in Table 7.
Effect of dry ice jet velocity on cooling characteristics of electronic chip based on optimized geometry
Published in Experimental Heat Transfer, 2023
Jinghong Ning, Luyao Sun, Ziliang Ren, Xue Gao
Traditional cooling methods include forced air cooling, water cooling, and heat pipe cooling. Mathew and Hotta [5] conducted steady-state experimental analysis on seven asymmetric IC chips under laminar forced convection heat transfer mode. By increasing the air velocity from 4.5 m/s to 8 m/s, the temperature of the IC chips could be maintained at 69°C. Air cooling is cost-effective and readily available, but it is unsuitable for efficient heat dissipation of high heat flux density chips in fixed substrate packages due to the risk of uneven temperature distribution and excessive thermal stresses. He et al. [6] established a finned liquid-cooling radiator model using Comsol software to study the influence of different radiator structures on chip cooling. However, water cooling as a traditional cooling method has limitations. Currently, the TDP (thermal design power consumption) of mainstream CPUs is higher than 95W, surpassing the capabilities of water cooling for heat dissipation. Moreover, water cooling systems are prone to issues such as pipe leakage, damage to electronic devices, and clogging due to scale formation. Siricharoenpanic et al. [7] simulated heat pipe cooling and obtained heat transfer coefficients. Deng et al. [8] conducted tests on multiple heat sources using heat pipes under natural air cooling, achieving significant improvements in total thermal resistance and temperature rise. Current heat pipe coolers are mostly combined with air cooling, and the heat dissipation efficiency of heat pipes relies heavily on the ambient temperature. Chen et al. [9] effectively cooled chips using a 9% volume concentration of titanium dioxide-water nanofluid as the cooling medium. Mashali et al. [10] studied the thermal behavior of specific nanodiamond water-based suspensions, which can increase the heat transfer coefficient by up to 69%. Kaya and Alp [11] experimentally investigated the thermal performance of different particle shapes of iron oxide nanofluids under impinging jet conditions. Compared to pure water, the Nusselt number enhancement was approximately 27.3%. Hamza [12] analyzed the effect of a water-alumina nanofluid with a particle concentration of 0.04 on the heat transfer coefficient under a constant bottom thermal boundary condition, resulting in an approximate 5% improvement, significantly enhancing heat transfer performance. Chu et al. [13] studied the heat transfer of electronic chips in a mixture of aluminum nitride (AIN), aluminum oxide (Al2O3), and water nanofluid. They found a higher Nusselt number compared to distilled water. Ghadikolaei et al. [14] achieved CPU cooling using graphene nanosheets combined with a novel fin design, resulting in a heat transfer coefficient of 8582.3 W/(m2·K) and an output improvement of approximately 8.5%. The nanofluid concentration and Reynolds number directly influenced the heat transfer coefficient. Nanofluids are promising as a new cooling medium with relatively good heat dissipation performance. However, they have strict requirements for the nanofluid concentration, and currently, nanomaterials are relatively expensive, leaving room for further improvement in their economic viability.