一种新型环保、节能除湿技术——热电冷凝除湿

回顾了传统除湿技术的发展以及目前所存在的弊端。系统介绍了热电冷凝除湿技术的工作原理、理论模型、国内外研究进展。详细比较了热电冷凝除湿技术与传统除湿技术,表明随着热电技术的发展、热电冷凝装置性能的提高以及太阳能电池的成本降低,热电冷凝除湿技术作为一种节能、环保的新型除湿技术,将具有非常广阔的发展前景。

热电冷凝除湿技术的应用研究

本文重点研究了热电制冷方式的除湿能力,并列出了热电冷凝除湿器的4种不同冷端结构形式,通过实验测量除湿量法,对比分析了不同结构对除湿能力的影响,并选出最优冷端结构形式,为以后热电冷凝除湿器结构优化设计提供依据。

新型除湿技术的研究进展

空气除湿在日常生活和生产中是一个很重要的课题。但是,传统的除湿技术例如冷冻除湿、液体除湿等,虽然已经被广泛应用,但是仍有一定的不足。针对这些不足,很多新型的除湿技术应运而生。本文综述了近年来发展起来的一些新型除湿技术,包括膜除湿、热泵除湿、HVAC除湿、热电冷凝除湿和电化学除湿等技术,介绍了它们的工作原理、优缺点以及装置等,并且指出了它们未来的发展方向。

气体干燥技术及装置

概括了一些传统气体干燥方法和装置及其最新进展,并比较其优缺点,适用范围。在此基础上,介绍一些新兴气体干燥技术及其工作原理,包括膜法除湿、热泵除湿、热电冷凝除湿和电化除湿。

变电站35kV封闭母线桥绝缘与除湿分析及预防

变电站的电源进出线间隔及主变间隔引线均采用母线桥架连接,由于结构紧凑,对运行环境提出更高的要求,当运行环境湿度更大时,将会引起电气绝缘强度降低,局部放电现象更加明显。从多种方面对造成母线桥架的绝缘故障的原因进行分析,以便采取相应措施,消除因导体的湿度升高的故障隐患,保证母线桥架安全可靠运行。

Coupling effect of evaporation and condensation processes of organic Rankine cycle for geothermal power generation improvement

Organic Rankine cycle(ORC)is widely used for the low grade geothermal power generation.However,a large amount of irreversible loss results in poor technical and economic performance due to its poor matching between the heat source/sink and the working medium in the condenser and the evaporator.The condensing temperature,cooling water temperature difference and pinch point temperature difference are often fixed according to engineering experience.In order to optimize the ORC system comprehensively,the coupling effect of evaporation and condensation process was proposed in this paper.Based on the laws of thermodynamics,the energy analysis,exergy analysis and entropy analysis were adopted to investigate the ORC performance including net output power,thermal efficiency,exergy efficiency,thermal conductivity,irreversible loss,etc.,using geothermal water at a temperature of 120℃as the heat source and isobutane as the working fluid.The results show that there exists a pair of optimal evaporating temperature and condensing temperatures to maximize the system performance.The net power output and the system comprehensive performance achieve their highest values at the same evaporating temperature,but the system comprehensive performance corresponds to a lower condensing temperature than the net power output.

Dropwise condensation heat transfer enhancement on surfaces micro/nano structured by a two-step electrodeposition process

Condensation is an important regime of heat transfer which has wide applications in different industries such as power plants,heating,ventilating and air conditioning,and refrigeration.Condensation occurs in two different modes including filmwise (FWC) and dropwise (DWC) condensation.DWC occurring on hydrophobic and superhydrophobic surfaces has a much higher heat transfer capacity than FWC.Therefore,wide investigations have been done to produce DWC in recent years.Superhydrophobic surfaces have micro/nano structures with low surface energy.In this study,a two-step electrodeposition process is used to produce micro/nano structures on copper specimens.The surface energy of specimens is reduced by a self-assembled monolayer using ethanol and 1-octadecanethiol solution.The results show that there is an optimum condition for electrodeposition parameters.For example,a surface prepared by 2000 s step time has 5 times greater heat transfer than FWC while a surface with 4000 s step time has nearly the same heat transfer as FWC.The surfaces of the fabricated specimens are examined using XRD and SEM analyses.The SEM analyses of the surfaces show that there are some micro-structures on the surfaces and the surface porosities are reduced by increasing the second step electrodeposition time.

Experimental Study of Condensation Heat Transfer on Tube Bundles in Large Power Plant Condensers

In order to clarify the effect of condensate inundation on steam condensation in a large tube bundle, condensation heat transfer and the condensate flow pattern in the tube bundle have been experimentally investigated. Test tube bundle consists of 36 cooling tubes, 12 condensate supply tubes and 24 un-cooled dummy tubes. Cooling test tubes are made of copper and have an outer diameter of 19.1 mm and condensing length of 150 mm, Steam flows horizontally through the test tube bundle at gap velocities 15-27 m/s at pressures of 8.8 kPa. In this study, experimental data about condensate flow pattern and condensation heat transfer in a tube bundle were collected for the optimization of tube arrangement in large power plant condensers.

A new power generation method utilizing a low grade heat source

Energy crisis make the effective use of low grade energy more and more urgent. It is still a worldwide difficult conundrum. To efficiently recover low grade heat, this paper deals with a theoretical analysis of a new power generation method driven by a low grade heat source. When the temperature of the low grade heat source exceeds the saturated temperature, it can heat the liquid into steam. If the steam is sealed and cooled in a container, it will lead to a negative pressure condition. The proposed power generation method utilizes the negative pressure condition in the sealed container, called as a condensator. When the condensator is connected to a liquid pool, the liquid will be pumped into it by the negative pressure condition. After the conden- sator is filled by liquid, the liquid flows back into the pool and drives the turbine to generate electricity. According to our analysis, for water, the head pressure of water pumped into the condensator could reach 9.5 m when the temperature of water in the pool is 25 ℃, and the steam temperature is 105 ℃. Theoretical thermal efficiency of this power generation system could reach 3.2% to 5.8% varying with the altitude of the condensator to the water level, ignoring steam leakage loss.

Experimental Study on the Condensation of a Thermosyphon by Electrical Capacitance Tomography

The study on the condensation and the two-phase flow pattern in the condensation section is important to understand the operating mechanisms in a thermosyphon. In this paper, a new electric capacitance tomography(ECT) sensor was designed for the visualization measurement in a liquid by removing the shielding case and sealing with insulating hydrophobic material. It was successfully used to measure the condensation process in a thermosyphon under different operating temperatures. The thermosyphon was made of silica glass, and alcohol was used as a working fluid. The alcohol vapor was cooled to condense through the heat convection with the cooling water. The operating temperature was controlled by a heater with different power outputs. The experimental results show that the alcohol vapor condensed in stripes and unevenly on the wall surface at a low operating temperature. The liquid bridge will be formed periodically at the operating temperature of 90?C, and the time interval between two liquid bridges will be shorter with the increase of the operating temperature. At 117?C or even higher operating temperatures, the complete liquid bridge cannot be formed sometimes due to the difference of the growth rate of the surface wave around the circumference.