Using the condenser effluent from a nuclear power plant for Ocean Thermal Energy Conversion (OTEC)

There has been increasing interest in clean energy over past few years. Ocean Thermal Energy Conversion (OTEC) power plants have been examined as a viable option for supplying clean energy. This paper evaluated the thermodynamic performance of the OTEC power system. Computer simulation programs were developed under the same conditions but with various working fluids for a closed system, a regeneration system, an open system, a Kalina system, and a hybrid system. The results showed that the regeneration system using R125 showed a 0.17 to 1.56% increase in system efficiency. Moreover, the system can generate electricity when the difference in temperature between the warm and cold seawater inlet temperatures is greater than 15 °C. In addition, the system efficiency of OTEC power plants using the condenser effluent from a nuclear power plant instead of surface water was increased by approximately 2%.     

海洋热能利用进展

海洋热能储量巨大,随时间变化相对稳定,具有广阔的开发利用前景。当前,海洋热能利用技术主要包括海洋温差能发电技术、海洋温差能制淡技术以及海水源热泵技术。发电技术要求海水温差不小于20℃,制淡技术要求海水温差不小于10℃,海水源热泵技术则在不同纬度地区、不同季节均能应用。本文重点分析了海洋温差能发电技术的3种循环方式,针对低温差导致低发电效率的问题,提出了利用太阳辐射加热温海水以提高温差和利用波浪能驱动泵以降低系统能耗两种提高发电效率的方法。     

Hydro energy potential of cooling water at the thermal power plant

The hydro energy of the gravity water flow from the coal-fired thermal power plant units to the river in an open cooling system of turbine condensers is determined. On the basis of statistical data for a long time period, the water net head duration curve due to the river annual level change, as well as the reduction of the hydro energy potential due to the thermal power plant overhauls periods, are evaluated in the case study of the Thermal Power Plant “Nikola Tesla B” in Serbia. A small hydro power plant is designed for the utilization of this hydro energy, and the economic benefits of the project are calculated. The internal rate of returns and pay back periods are calculated in dependence of the electricity price and total investment costs. The increase of profitability is assessed, bearing in mind that the plant might be realized as the Clean Development Mechanism project according to the Kyoto protocol. The obtained results show that the project is economically attractive, and it can be carried out with standard matured solutions of hydro turbines available at the market. Even for the relatively low electricity price from small hydro power plants in Serbia of 0.08 €/kW h the internal rate of return and the pay back period are 17.5% and 5.5 years.     

海洋温差发电系统热力学及热经济性分析

以热力学基本原理为基础,建立了海洋温差发电系统仿真模型,对比分析了亚临界状态下R717、R134a和R600三种工质系统在约束蒸发器窄点温差条件下优化目标函数随蒸发温度的变化规律。结果表明:蒸发温度越高,不同系统换热器的热负荷以及冷、热海水泵功率越小,最佳蒸发压力和工质泵功率越大;不同系统的热效率和单位换热面积输出电量与蒸发温度的相关性较大,随蒸发温度的增加近似线性递增。蒸发器的换热面积与循环工质种类的相关性较小,但冷凝器的换热面积与循环工质种类的相关性较大。R717循环更接近于卡诺循环,R717的系统热效率最大,热负荷及泵功率最小,且其热经济性目标函数值在合适的范围内,是海洋温差发电系统较为理想的循环工质。研究结果可为海洋温差发电系统的设计、试验及设备选型提供理论参考。     

A novel integrated solar desalination system with multi-stage evaporation/heat recovery processes

A novel small-sized integrated solar desalination system with multi-stage evaporation/heat recovery processes is designed and tested in this study. The system consists of four linked collecting units and operates under barotropic and atmospheric pressure. Each of the four units contains a seawater tank and at least one solar collecting/desalination panel mainly comprising a simplified CPC (Compound Parabolic Concentrator) and an all-glass evacuated tube collector. In the last three units, heat exchangers made of copper tubes are inserted concentrically into the all-glass evacuated tubes to recover heat. In each unit, an independent desalination process including solar collecting, heat recovery (no heat recovered in the first unit) and seawater evaporation can be carried out completely. The experimental results show that the freshwater field of the designed system can reach as high as 1.25 kg/(h m²) in the autumn and the system total efficiency is close to 0.9. Both experimental results provide a striking demonstration that the designed solar desalination system has outstanding performance in solar collecting, heat recovery and seawater evaporation.     

Combining the nuclear power plant steam cycle with gas turbines

Nuclear steam power plants (NPP) are characterized by low efficiency, compared to steam power plants using fossil fuels. This is due to the relatively low temperature and pressure-throttling conditions of the NPP compared to those using fossil fuel. The light water pressurized water reactor (LW PWR) commercially known as AP600 was suggested for Kuwait cogeneration power desalting plant (CPDP). It has 600 MW nominal power capacity and 33% overall efficiency. Meanwhile, the Kuwaiti Ministry of Electricity and Water (MEW) installed plenty of gas turbines (GTs) to cover the drastic increase in the peak electrical load during the summer season. Combining some of these GTs with the AP600 can increase the capacity and efficiency of the combined plant, compared to either the GT open cycle or the NPP separate plants. This paper investigates the feasibility of utilizing the hot gases leaving the GT to superheat the steam leaving the steam generator of the AP600 NPP, as well as heating the feed water returning to the steam generator of the NPP condenser. This drastically increases the power output and the efficiency of the NPP. Detailed modifications to the NPP power cycle and the resulting enhancement of its performance are presented.     

Evaluation of thermal power plant operational performance in Taiwan by data envelopment analysis

Electricity is essential in the economic development of a nation. Due to the rapid growth of economy and industrial development in Taiwan, the demand for use of electricity has increased rapidly. This study evaluates the power-generation efficiency of major thermal power plants in Taiwan during 2004–2006 using the data envelopment analysis (DEA) approach. A stability test was conducted to verify the stability of the DEA model. According to the results, all power plants studied achieved acceptable overall operational efficiencies during 2004–2006, and the combined cycle power plants were the most efficient among all plants. The most important variable in this DEA model is the “heating value of total fuels”. Findings from this study can be beneficial in improving some of the existing power plants and for more efficient operational strategies and related policy-making for future power plants in Taiwan.     

海洋温差能发电热力循环技术进展

受传统化石能源日趋枯竭和环境污染的影响,海洋能作为一种清洁可再生能源得到了广泛关注。海洋温差能作为海洋能的重要组成部分,其储量和可转化电能巨大,且发电波动小、能量密度高,积极开发海洋温差能资源对实现科技兴海战略具有重要意义。海洋温差热力循环是海洋温差能开发利用的关键技术,其循环效率的高低直接决定了海洋温差发电系统的技术和经济性。本文综述了海洋温差能发电热力循环技术研究现状,对其基本原理及形式、热力循环构架、循环工质和热力学分析方法进行了详细阐述,并对海洋温差能发电热力循环技术进行了深入分析和展望。     

Exergy analysis of a 420 MW combined cycle power plant

Combined cycle power plants (CCPPs) have an important role in power generation. The objective of this paper is to evaluate irreversibility of each part of Neka CCPP using the exergy analysis. The results show that the combustion chamber, gas turbine, duct burner and heat recovery steam generator (HRSG) are the main sources of irreversibility representing more than 83% of the overall exergy losses. The results show that the greatest exergy loss in the gas turbine occurs in the combustion chamber due to its high irreversibility. As the second major exergy loss is in HRSG, the optimization of HRSG has an important role in reducing the exergy loss of total combined cycle. In this case, LP‐SH has the worst heat transfer process. The first law efficiency and the exergy efficiency of CCPP are calculated. Thermal and exergy efficiencies of Neka CCPP are 47 and 45.5% without duct burner, respectively. The results show that if the duct burner is added to HRSG, these efficiencies are reduced to 46 and 44%. Nevertheless, the results show that the CCPP output power increases by 7.38% when the duct burner is used. Copyright © 2007 John Wiley & Sons, Ltd.     

Electricity and potable water from a solar tower power plant

The cogeneration of electricity and potable water utilising solar energy is studied, assuming solar tower power plants with the open volumetric PHOEBUS receiver. The results for alternative plant configurations show that the water production cost is about the same or even lower than the cost of water produced by conventionally fired systems. Furthermore, the integration offers a reduction of CO₂-emissions related to the water production of up to 50%, additionally to the environmental benefits of solar electricity production.     

Regenerative OTEC systems using condenser effluents discharged from three nuclear power plants in South Korea

In this study, the availability of ocean thermal energy conversion (OTEC) power plant has been evaluated and analyzed with condenser effluents discharge from nuclear power plant. For this, we have also calculated the performance of OTEC power system by various computer programs based on thermodynamical theories. The computer programs are developed for simulation of the closed cycle, regenerative cycle, Kalina cycle, open cycle, and hybrid cycle under equivalent conditions and various working fluids. Among these OTEC cycles, the regenerative cycle with R‐134a shows the highest efficiency. It also has used the condenser effluents from the Kori, Wolsong, and Uljin nuclear power plants instead of the surface water to analyze the thermodynamic performance of the OTEC regenerative cycles. The Kori, Wolsong, and Uljin nuclear power plants have shown maximum efficiencies of 5.21%, 5.15%, and 4.83%, respectively. The net powers are 131, 93, and 192 MW at the three locations, respectively. Copyright © 2014 John Wiley & Sons, Ltd.     

Energy management in solar thermal power plants with double thermal storage system and subdivided solar field

In the paper, two systems for solar thermal power plants (STPPs) are devised for improving the overall performance of the plant. Each one attempts to reduce losses coming from two respective sources. The systems are simulated and compared to a reference STPP.     

Thermal performance study of integrated cold plate with power module

A novel cold plate for cooling of the electronic components with high heat flux and high heat dissipation requirements is proposed. The cold-plate structure of the S-type with guide plates is introduced to avoid the heat hot concentration and increase the heat transfer area. The experimental results show that the maximum chip temperature of the novel cold plate is approximately 40% lower than those of the conventional cold plate. Thermal performance optimizations are conducted, indicating that it is extremely effective to install the heat source on two sides of the cold plate. Compared with the single-side heat source, the maximum chip temperature is increased only 20%. However, the heat dissipation is doubled in the limited space for the double-sides arrangement heat source. Moreover, the integrated density of the power module is greatly enhanced by using the cold plate. Transient state temperature variation indicates that the cold plate have quick thermal response in start-up process. It is beneficial to the heat dissipation of integrated module for high power density.     

Problems of hydrogen application in space power plants and power propulsion plants

Application of hydrogen is a necessary condition to achieve acceptable power and overall-dimensional characteristics of space power and propulsion plants. Some functional elements as part of the plants require protection from hydrogen, which is provided by construction and technological preparation of materials. For subsequent improvement of the plants, it is necessary to look for materials with low hydrogen penetrability in the temperature range of 800–2500 K and also for protective coatings on graphite for conditions of thermocycling in the range of 300–2100 K.     

Thermal performance analysis on unit tube for heat pipe receiver

To reduce the mass and improve the thermal performance of the heat receiver, a heat pipe receiver was researched for the space solar dynamic power system. Corresponding mathematical and physical models were built, and a method was devised to provide a numerical equation by which the temperature of the containment canister outer wall, heat pipe wall temperature, working fluid exit temperature and the liquid PCM fraction of the total heat transfer tube were calculated and compared with those obtained from the baseline heat receiver. The results show that it is possible to improve receiver performance, to reduce the fluctuation of the working fluid temperature and to decrease the weight of the heat receiver.     

Energy,exergy and exergoeconomic analysis of a steam power plant: A case study

The objective of this paper is to perform the energy, exergy and exergoeconomic analysis for the Hamedan steam power plant. In the first part of the paper, the exergy destruction and exergy loss of each component of this power plant is estimated. Moreover, the effects of the load variations and ambient temperature are calculated in order to obtain a good insight into this analysis. The exergy efficiencies of the boiler, turbine, pump, heaters and the condenser are estimated at different ambient temperatures. The results show that energy losses have mainly occurred in the condenser where 306.9 MW is lost to the environment while only 67.63 MW has been lost from the boiler. Nevertheless, the irreversibility rate of the boiler is higher than the irreversibility rates of the other components. It is due to the fact that the combustion reaction and its high temperature are the most significant sources of exergy destruction in the boiler system, which can be reduced by preheating the combustion air and reducing the air–fuel ratio. When the ambient temperature is increased from 5 to 24°C, the irreversibility rate of the boiler, turbine, feed water heaters, pumps and the total irreversibility rate of the plant are increased. In addition, as the load varies from 125 to 250 MW (i.e. full load) the exergy efficiency of the boiler and turbine, condenser and heaters are increased due to the fact that the power plant is designed for the full load. In the second part of the paper, the exergoeconomic analysis is done for each component of the power plant in order to calculate the cost of exergy destruction. The results show that the boiler has the highest cost of exergy destruction. In addition, an optimization procedure is developed for that power plant. The results show that by considering the decision variables, the cost of exergy destruction and purchase can be decreased by almost 17.11%. Copyright © 2008 John Wiley & Sons, Ltd.     

Performance analysis of a solar chimney power plant in the southwestern region of Algeria

In this paper, we present the performance analysis of a solar chimney power plant expected to provide the remote villages located in Algerian southwestern region with electric power. Solar energy and the psychometric state of the air in the south of Algeria are important to encourage the full development of solar chimney power plant for the thermal and electrical production of energy for various uses. We are interested in Adrar where solar radiation is better than other areas of Algeria. The obtained results show that the solar chimney power plant can produce from 140 to 200 kW of electricity on a site like Adrar during the year, according to an estimate made on the monthly average of sunning. This production is sufficient for the needs of the isolated areas.     

Energy efficiency criteria in uninterruptible power supply selection

With the generalized use of microelectronic devices, server computers and other susceptible equipment, the subject related to power quality (PQ) and its relationship to vulnerability of high performance plants are becoming an increasing concern to the industry. This paper addresses how uninterruptible power supply (UPS), particularly when configured in distributed DC mode, can become an energy efficient (EE) solution in high-tech buildings, especially when integrated with complimentary PQ measures. The paper is based on PQ audits conducted at different high-tech industries over the last years. It was found that the main problems for the equipment installed were voltage sags (or dips). Among all categories of electrical disturbances, voltage sags and momentary interruptions are the nemeses of the automated industrial process. The paper analyzes the capabilities of modern electronic power supplies and the convenience of embedded solution. Finally it is addresses the role of the Standards on the protection of electronic equipment and the implications for the final costumer.     

Heat transfer in a conical cavity calorimeter for measuring thermal power of a point focus concentrator

A theoretical study of the heat transfer process that takes place in a special calorimeter of conical cavity named CAVICAL is presented. This instrument is used to measure the thermal power of a point focus solar concentrator system named DEFRAC, developed at the Center for Energy Research of the National University of Mexico. The DEFRAC concentrator has a power of 1.3 kWth and a very fine optical system. The calorimeter has a cavity opening of 8.24 cm². A detailed heat transfer study was done using FLUENT code. The heat transfer processes taken into account for the analysis were the radiative energy absorbed by the inner cavity wall, the energy transfer from the outer cavity wall to the air by natural convection, the energy transferred by conduction through the inner metallic wall of the calorimeter, and by forced convection to the fluid in the cooling system. The calorimetric information gathered allowed determining the thermal power that the concentrator is able to capture. Temperature and velocity fields have been calculated for each of the thermal fluids considered inside of the calorimeter. The analysis gave thermal losses and measured the thermal efficiency of the device. The information generated is useful to further optimize the design of the calorimeter.     

Predictive economic efficiency of combining nuclear power plants with autonomous hydrogen power complex

Currently, the United Energy System (UEC) of Russia is trending in the deficit of peak and half-peak capacity with a simultaneous increase in the number of nuclear power plants (NPPs), which will require the participation of the NPPs in the variable part of the schedule of electrical loads.In addition to the economic need to maintain the high-level utilization rate, there are technological limitations of maneuverability for NPPs.The authors developed an approach to solving this problem by combining with an environmentally friendly energy source – an autonomous hydrogen power complex, which includes thermal batteries and an additional multifunctional low-power steam turbine installation.The developed energy complex can also provide reliable reservation of electricity supply to consumers of their own needs of the nuclear power plant in case of complete blackout of the plant.The feasibility study of the main equipment of the autonomous hydrogen power complex, which is necessary for combining with a two-unit nuclear power plant with WWER-1000, has been evaluated.On the basis of the assessment of the inflation indicators of the Russian economy over the past 11 years, three variants of fuel cost dynamics and tariff rates for electricity (capacity) as well as the size of operating costs, including depreciation deductions to the main equipment, are defined, taking into account the current principles of price formation.The result is a value for accumulated net present value, depending on the ratio of the cost of the half-peak and off-peak electricity at different inflation rates.The positive economic effect of reducing the risk of the core damage accident, replacing the construction of the gas turbine unit as a maneuverable source of electricity in the power grid and increasing the income of the Russian federal budget from the savings of natural gas has been taken into account.The greatest economic efficiency is achieved with maximum projected inflation, which is associated with the maximum rate of discounting and the high rate of growth of electricity tariffs.Reducing the risk of the core damage accident ensures that the proposed approach is competitive in all the inflation options under consideration and the ratio of electricity tariffs.