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In this paper, an effort has been made to evaluate the convective heat transfer coefficient and mass of water evaporated from a single-slope passive solar still for different water depths (0.01, 0.015, 0.02 and 0.025?m) by various thermal models, namely Dunkle’s model, Chen et al.’s model, Clark’s model, Adhikari et al.’s model, Kumar and Tiwari’s model, Zheng Hongfei et al.’s model and Tsilingiris’s model. These models were studied and compared with our experimental work. Also, the energy and exergy efficiency were calculated and the percentage deviation between experimental and theoretical prediction is also listed out. The experimental validation of energy and exergy efficiency of single slope passive solar still using different thermal models was carried out at Chennai, Tamil Nadu, India. By comparing the theoretical values of the hourly yield with the experimental data it was found that Dunkle’s, Chen et al.’s and Tsilingiris’s models gave better conformity between the forecasted and experimental results. Kumar and Tiwari’s model yield is very high, whereas Clark’s model, Adhikari et al.’s model and Zheng Hongfei et al.’s model predict lower values as compared with our experimental results. 相似文献
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S. Shanmugan V. Manikandan K. Shanmugasundaram B. Janarathanan J. Chandrasekaran 《国际自然能源杂志》2013,34(3):142-151
A single slope basin type solar still has been designed and fabricated. The still is provided with a dripping arrangement to pour saline water drop by drop in the basin. Thermal modelling has been proposed based on the energy balance equations of the temperature elements of the still. A computer program has been written for the analytical solutions for the temperature of glass cover, water and basin, respectively, and numerical results are validated with the experimental for one of the typical days in summer and winter (2 October 2010 and 30 May 2011). The numerical results are in close agreement with the experimental results. Also exergy and energy analysis have been carried out to find the parametric influence on the performance of the still and to evaluate the fractional exergy and energy, instantaneous exergy and energy efficiency of the still. 相似文献
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Exergy-based ecological optimisation of a universal endoreversible thermodynamic cycle model is performed using finite time thermodynamics or entropy generation minimisation. The cycle consists of two constant thermal-capacity heating branches, a constant thermal-capacity cooling branch and two adiabatic branches. An ecological optimisation criterion is taken as the objective, which consists of maximising a function representing the best compromise between the power output and exergy loss rate of the heat engine. The analytical formulae for power, efficiency and ecological function of the universal endoreversible thermodynamic cycle with heat resistance loss are derived. The comparative performance analyses for Diesel, Otto, Atkinson, Brayton and Dual-cycles are carried out by a detailed numerical example, which show that the ecological criterion is more available. 相似文献
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ABSTRACT This paper deals with a solar still for distilled water, using the heat of the sun to evaporate, cool and then collect the water. They are used in areas where drinking water is unavailable, so that clean water is obtained from dirty water or from plants by exposing them to sunlight; vacuum pressure is delivered to still-type solar. The reason for selecting vacuum pressure is that during the monsoon and cloudy days, solar intensity will not be high as it leads to evaporation at lower temperature saline water under the soar still. The basin area for the production of 5 litres per day of fresh water is determined as 1.44?m2and the solar still basin area of 1.44?m2 and 21.5° tilt angle are designed. Solar energy be may used full to alternate in electrical power and to purify water in future. Finally, the performance was analysed for the solar still with a vacuum pressure at 0.6 bar. The outcome of the theoretical analysis shows that adoption of 0.6 bar pressure inside the solar still improves the average performance by 30%. In order to overcome this problem, vacuum could be applied for the better performance of the solar still during the low solar intensity periods. 相似文献
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Hitesh Panchal Yazan Taamneh Ravishankar Sathyamurthy A. E. Kabeel S. A. El-Agouz P. Naveen Kumar 《国际自然能源杂志》2013,34(6):571-576
This paper presents the detailed exergy and economic investigation of triangular pyramid solar still under passive and active mode of operation. For validation, experiments were carried out at different water depth maintained inside the basin under a continuous flow of water from an inclined solar still. Results confirm that the effect of integration rises the exergy efficiency during the offshine period, whereas during the sunshine hours the exergy efficiency decreases when the maintained the depth of water inside basin decreases. Similar study on economic analysis shows that the net pay back period increases from 5.6 to 11.4 with an increase in the water depth at an average selling price of water Rs 5/kg in a standalone triangular pyramid solar still. 相似文献
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ABSTRACT This paper deals with solar still. Today fresh water demand is increasing continuously, because of the industrial development, intensified agriculture, improvement of standard of life and increase in the world population. Only about 3% of the world water is potable and this is not evenly distributed on the earth. On deserts and islands, underground water is not readily available and the cost of shipping to other places is high, it is worthwhile to consider producing potable water from saline water using solar energy that is in abundant in deserts. The efficiency of the solar still can be increased by increasing the evaporation rate and by minimising the convective and radioactive losses in still. The evaporation rate can be increased effectively by coating the still base with photocatalyst materials or by pre-heating the inlet water of still. The easily available GAC is one of the best photocatalyst materials suitable for the solar still for enhancing the evaporation rate. Solar-still technology is a renewable and efficient technology for pre-heating the inlet water to solar still. Hence the combination of GAC coating and solar-still technology can increase the evaporation rate and efficiency of solar still. 相似文献
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In this work, an experimental study is carried out to investigate the influence of the presence of porous media on the performance of solar still. Two different shapes of sponge pieces, namely cube and tetrahedron, are considered for this study. Experiments are conducted on a single-slope solar still with condensing cover of 30° inclination. This study was performed in Indian coastal climatic condition for 24?h. The experimental study emphasises on the overall distillate yield, and the efficiency of the still with sponge cubes and tetrahedrons is compared with the conventional still. The size of the pieces is selected such that the volume of both shapes is the same. As the surface area to volume ratio is more for tetrahedral sponge piece, the highest distillate production is observed in that of sponge cube. It is observed that the maximum distillate yield is produced at optimum values of water depth at 5?cm, single piece sponge volume of 216?cm3 and sponge volume of 30% of the basin water volume. The increase in yield is due to the capillary effect and high evaporation rate and it varies from 45% to 219% with tetrahedral sponge pieces when compared to conventional still. 相似文献
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发电环节按燃煤电厂考虑,针对空气源热泵热水供热系统进行了一次能源热效率和[火用]效率的计算和分析,结果表明:热泵机组COP分别为3和4时,其一次能源热效率均大于100%,但热泵机组的一次能源[火用]效率、热泵供热系统的一次能源[火用]效率都远小于100%。热泵供热系统的一次能源[火用]效率表征了热泵供热系统对一次能源[火用]价值的利用程度,可称为热泵供热系统的一次能源利用率。而热泵机组的COP及其一次能源热效率虽然不能直接反映一次能源价值的利用程度,但它们都与热泵供热系统的一次能源[火用]效率呈正比关系,所以也都可以用于对热泵供热系统进行能效比较和评价。合理降低热泵机组输出水温可以提高机组的COP,从而提高热泵供热系统的一次能源[火用]效率,实现相同供暖目标的一次能源消耗量减少。 相似文献
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热电冷三联供供冷方式的分析与评价 总被引：1，自引：0，他引：1
依据热力学第二定律的(火用)分析方法,从能量利用的全过程出发,考虑输送能耗的影响,利用能源(火用)效率代替设备的能量利用效率对热电冷三联供的集中供冷和常规的电供冷方式进行了比较,从而得出了更客观、合理的结论,为合理采用热电冷三联供的集中供冷方式提供了判断依据。 相似文献
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Solar energy is an abundant and secure source of vitality and thus is described as one of the most promising alternative energy options. Nevertheless, solar energy is intermittent in nature as there is no sun at night. Its total availability value is seasonal and is hooked on the meteorological conditions of locations. Hence, solar energy presents an unsteady energy resource. So, thermal energy storage will be necessary to save the available solar energy at a period of no load or when excessive solar energy is available, and to make up for the shortage of energy when the load is in need of energy. This article reviews the different energy storage materials tried by various researchers to improve the distillate output of solar stills. 相似文献
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Energy and exergy analysis of a Brayton cycle gas turbine power plant with regenerator, reheater and intercooler is carried out in this work. It has been found that the effects of the regenerator, intercooler and reheater are significant. Although, the energy analysis shows that the first law efficiency is more effective than the second law efficiency and there are significant losses in these components which cannot be neglected, and hence proper care should be taken for the size and operating conditions of these components. Efficiency of some components is 100% especially when energy balance is applied, while it is not 100% in the case of energy consuming/conversion systems like compressor, turbine, etc. The energy loss in reheater is zero while there is a small amount of exergy loss. The intrercooler has both energy and exery losses, so proper care should be taken in intercooler. 相似文献
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利用被动太阳能改善中部地区城镇住宅室内热环境 总被引：1，自引：0，他引：1
从应用动态软件进行围护结构热工性能参数研究，并从优化设计着手，利用被动太阳能技术实现水平室内热舒适环境条件，试点建筑科夏季实测，证明达到预期目标。 相似文献
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In the present research paper, experimental analysis is based on the fresh water output rate due to different structural arrangements of two different stills. In the performance evolution, the operational parameters such as water temperature, ambient temperature, inner glass temperature, and productivity have been predicted. A comparative performance between two different solar stills was carried out to evaluate the distillation and effective parameters under the same climatic conditions for several days with different depths of water (2.5 and 3.5?cm) and also to provide a large evaporation surface and utilise the latent heat of condensation using jute cloth. The experimental results show that efficiencies of these solar stills confirm that the fresh distilled water output of the pyramid-shaped solar still is higher than that of the single-slope solar still under different effective parameters. 相似文献
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Etienne TISoN 《建筑电气》2011,30(10):14-17
从定义上而言．能效可以分为两种类型：旨在减少能源消耗的被动能效（passive energy efficiencv）和旨在控制能源消耗的主动能效（active energy efficiency）。给出在低压电气装置中实现主动能效所采用的迭代过程的基本特性．根据迭代过程的结果．可以对低压电气装置的配置概况进行定义,给出... 相似文献
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Water is a basic necessity of man. Economical and efficient production or recycling of water is very much needed in today's world. Solar still has emerged as a life-saving technology to distil brackish water and produce drinkable water using solar energy. The aim of this project was to improve the performance of solar still by adding an air blower which creates a bubbling effect in the still due to which the evaporation rate increases. The bubbling effect using the blower makes the raw water to circulate and to distribute heat energy equally. The evaporated raw water was collected in the glass plate as drop particles. The drop condenses due to ambient air and finally distillate output is collected in the jar, which is placed outside the still. The solar still with air blower arrangement gave higher difference in efficiency and higher distilled output when compared with solar still without an air blower. 相似文献
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分析了天然气燃烧应用过程的类型,论述了天然气燃烧利用过程的热效率和火用效率的计算方法,比较了天然气燃烧应用过程热效率与火用效率。 相似文献
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本文从黄河三角洲地区典型农村——窦家村现状入手,通过了解农村住宅的现状、建筑能耗以及舒适度等情况,进而对黄河三角洲地区农村住宅从规划设计、单体设计、节能设计等方面进行研究,提出比较适宜的节能技术措施;希望本文的研究成果对黄河三角洲地区新农村节能住宅的设计具有一定的指导意义,对新农村建设具有一定的推进作用. 相似文献