Entire Thermal System Research Articles

Influence of environmental parameters on the cold-end and thermal system of coal-fired power plant based on Ebsilon simulation

To analyze the influence of environmental parameters on cold-end systems, especially the natural draft wet cooling tower (NDWCT), and the thermal system, the 660 MW power plant was taken as the research subject. Based on Ebsilon, this paper researched numerically the cooling performance of NDWCT and thermal system under different environmental conditions. The simulation results showed that increasing dry bulb temperature and environmental humidity causes a decline of water temperature drop (△t), which deteriorates the cooling performance and leads to adverse effects on the thermal system. As dry bulb temperature rises from 20℃ to 30℃, total power generation and system efficiency drop by 6484.89 kW and 0.18 %, respectively, and drop by 9912.72 kW and 0.86 % when environmental humidity elevates from 35 % to 75 %. Meanwhile, simulation investigations demonstrated that crosswind affects seriously NDWCT and further affects the thermal system. When crosswind speed increases from 0.21 m/s to 4.75 m/s, △t and system efficiency drop by 1.6℃ and 0.17 %, respectively, and gross coal consumption rate rises by 1.14 g/(kW∙h), which leads to the reduction of thermal system economy. In all, influence of environmental parameters on cold-end system, especially NDWCT, and the entire thermal system were revealed, which provided a basis for dynamic analysis of coal-fired power plants.

Open loop, auto reversing liquid nitrogen circulation thermal system for thermo vacuum chamber

In a thermo vacuum chamber, attaining and controlling low and high temperatures (-100 Deg. C to +120 Deg. C) is a very important task. This paper describes the development of "Open loop, auto reversing liquid nitrogen based thermal system". System specifications, features, open loop auto reversing system, liquid nitrogen flow paths etc. are discussed in this paper. This thermal system consists of solenoid operated cryogenic valves, double embossed thermal plate (shroud), heating elements, temperature sensors and PLC. Bulky items like blowers, heating chambers, liquid nitrogen injection chambers, huge pipe lines and valves were not used. This entire thermal system is very simple to operate and PLC based, fully auto system with auto tuned to given set temperatures. This system requires a very nominal amount of liquid nitrogen (approx. 80 liters / hour) while conducting thermo vacuum tests. This system was integrated to 1.2m dia thermo vacuum chamber, as a part of its augmentation, to conduct extreme temperature cycling tests on passive antenna reflectors of satellites.