燃气轮机箱装体排气引射通风冷却的试验研究

本文通过一系列排气引射试验,得出了引射系数和引射工作段几何参数配合、排气烟道阻力、被引射气流道阻力的关系,得出了箱体内冷却气流的流场,同时,首次提出引射冷却时,燃气倒灌入箱体的可能性。从这些试验曲线出发,提出在设计燃气轮机排气引射通风冷却时,几何参势选取原则及其最佳值的范围。     

DF7G模块化机车司机室的空调设计

通过计算分析以前DF7型机车司机室通风系统存在的缺欠,提出了DF7G型机车司机室空调系统新的设计理念。通过改进风道设计等,使DF7G型机车司机室空调系统通风得到改善,实际运用表明效果良好。     

超临界直接空冷排汽管道系统内流场的数值模拟

排汽管道布置形式和内部结构是直接空冷排汽系统优化设计的基础,直接影响各蒸汽分配管内的流动阻力和流量分配。利用计算流体动力学软件（CFD）,对某660MW超临界直接空冷机组排汽管道内的水蒸汽流场进行了数值模拟。通过对三维排汽管道内水蒸汽流场的模拟、分析和研究,为直接空冷排汽管道系统的优化设计提供帮助。     

The zinc chloride process for the hydrocracking of coal

The molten zinc chloride process is a unique hydrocracking system that converts coal to gasoline in a single step. an economically attractive process is currently under development at the one ton per day process development unit (PDU) scale. the design and economics of a plant to produce 53,000 bbl/day of gasoline with 90–92 unleaded research octane number from Western coal is discussed. the construction cost of the plant will be about 1.9 billion dollars (1979); the cost of manufacturing gasoline is about 76c/ gallon (20c/litre).     

Thermochemical hydrogen production with a copper–chlorine cycle. I: oxygen release from copper oxychloride decomposition

A key challenge facing the future hydrogen economy is a sustainable, lower-cost method of hydrogen production, with reduced dependence on fossil fuels. Thermochemical water splitting with a copper–chlorine (Cu–Cl) cycle is a promising alternative that could be linked with nuclear reactors to thermally decompose water into oxygen and hydrogen, through intermediate copper and chlorine compounds. Heat is transferred between various endothermic and exothermic reactors in the Cu–Cl cycle, through heat exchangers that supply or recover heat from individual processes. This paper examines the heat requirements of these steps, in efforts to recover as much heat as possible and minimize the net heat supply to the cycle, thereby improving its overall efficiency. Also, this paper examines the thermal design of the oxygen production reactor, which is a key process to split water by decomposing an intermediate compound, copper oxychloride (Cu₂OCl₂), into oxygen gas and molten cuprous chloride. The equipment design is analyzed to scale-up past work in small proof-of-principle test tubes, up to larger capacities of oxygen production with engineering lab-scale equipment.     

Multiphase reactor scale-up for Cu–Cl thermochemical hydrogen production

This paper examines selected design issues associated with reactor scale-up in the thermochemical copper–chlorine (Cu–Cl) cycle of hydrogen production. The thermochemical cycle decomposes water into oxygen and hydrogen, through intermediate copper and chlorine compounds. In this paper, emphasis is focused on the hydrogen, oxygen and hydrolysis reactors. A sedimentation cell for copper separation and HCl gas absorption tower are discussed for the thermochemical hydrogen reactor. A molten salt reactor is investigated for decomposition of an intermediate compound, copper oxychloride (CuO·Cl₂), into oxygen gas and molten cuprous chloride. Scale-up design issues are examined for handling three phases within the molten salt reactor, i.e., solid copper oxychloride particles, liquid (melting salt) and exiting gas (oxygen). Also, different variations of hydrolysis reactions are compared, including 5, 3 and 2-step Cu–Cl cycles that utilize reactive spray drying, instead of separate drying and hydrolysis processes. The spray drying involves evaporation of aqueous feed by mixing the spray and drying streams. Results are presented for the required capacities of feed materials for the multiphase reactors, steam and heat requirements, and other key design parameters for reactor scale-up to a pilot-scale capacity.     

Low energy consumption in Swedish single-family houses

In Sweden, as well as in many other countries, the energy consumption in residential buildings is a burning question.Due to this, the thermal insulation and the tightness of new buildings gradually has been increased.A well defined ventilation is because of this even more important, and the minimum level is given in regulations prescribed by the National Board of Housing, Building and Planning.To fulfil the regulations it is almost necessary to use mechanical ventilation. Since an ordinary ventilation causes a substantial energy loss it is of vital interest to reduce this.The most efficient way of reducing the ventilation loss, is to use an exhaust air heat pump which recovers energy from the exhaust air and supplies it to heating and hot water.In Sweden there have been about 100.000 units installed in single family houses until today.The paper will describe the regulations, the ventilation system, the exhaust air heat pump and the results achieved when installed in single family houses.     

Thermal modeling of integrated roof air heater for passive solar space heating of a non-air-conditioned building

This communication presents the periodic heat transfer analysis for solar space heating of an unconditioned building with an integrated roof air heater. The system consists of an air duct within the roof such that the air is continuously or intermittently forced to circulate the cooler room air through the inlet of the air duct. Time dependence of the air flow is represented by a step function of time for daily operation and, hence, has been expressed as a Fourier series in time. The analysis takes into account air ventilation, ground heat conduction and furnishings. The effects of depth of the air duct from the outer surface of the roof and the magnitude and duration of air flow rate on indoor air temperature have been studied for a typical cold winter day in Delhi. It is seen that a time dependent air flow through the duct is desirable from the point of view of increasing the indoor air temperature in the case of a bare roof. However, in the case of a blackened and glazed roof, continuous air flow is needed for increasing the room air temperature. The results are desirable from the point of view of efficient space heating of solar passive buildings.     

空冷汽轮发电机转子风道中气体运动流场分析

针对转子高速转动的特点,分析了转子风道气体运动状态,建立了数值计算模型.分析结果表明,转子风道气体运动是由风扇和转子高速转动共同作用的结果,以吸入式空冷汽轮发电机通风结构为例,转子以3 000 r/min转速绕轴高速转动可以使风道中进风量由0.14 kg/s增加到0.21 kg/s,必须考虑转子转动对风道中气体运动的影响;粘性模型应选择无粘,相同条件下转子风道出口风速模型试验和数值模拟结果对比表明,数值模拟结果符合工程实际.转子风道中气体运动流场合理计算模型应为:以吸入式风扇和转子风道进口为进出口边界条件,流体边界条件考虑转子转动,墙边界条件中反映管壁表面粗糙度的相对粗糙度系数和常量分别取为k~+_s=500～1000和C_(ks)=1.0,粘性模型选择无粘,可用此计算模型对空冷汽轮发电机转子风道中气体运动流场进行分析.     

Research on a Refrigeration Dehumidification System with Membrane-Based Total Heat Recovery

An independent air dehumidification system is helpful to improve indoor air quality and decrease energy consumption by heating, ventilation, and air conditioning (HVAC). A refrigeration dehumidification system with membrane-based total heat recovery is the key equipment to realize this goal. The system comprises two subsystems: a membrane total heat recovery and a direct expansion refrigeration system. The total heat exchanger has a membrane core where the incoming fresh air exchanges moisture and temperature simultaneously with the exhaust air. In this manner, the total heat or enthalpy from the exhaust air is recovered. Then the fresh air flows through a cooling coil where it is dehumidified below the dewpoint. Finally, the cold and dry air is supplied to indoors. A prototype of practical application is designed and fabricated. Experiments are conducted under variable operating conditions in the psychrometric calorimeter chamber. The effects of varying operating conditions like temperature and air humidity on the air dehumidification rate, cooling power, coefficient of performance, and compressor power are evaluated with indoor exhaust air dry bulb 27°C, wet bulb 19°C, and fresh air flow rate 200 m³/h. In comparison with a conventional refrigeration dehumidification system, the coefficient of performance and air dehumidification rate of the prototype are 2.3 times and 3 times higher, respectively. The performance of the prototype is rather robust under a hot and humid environment.     

Energy savings in indoor swimming-pools: comparison between different heat-recovery systems

In indoor swimming-pool facilities, the energy demand is large due to ventilation losses with the exhaust air. Since water is evaporated from the pool surface, the exhaust air has a high water content and specific enthalpy. Because of the low temperature, the heat from the evaporation is difficult to recover. In this paper, the energy demand for the conventional ventilation technique in indoor swimming pools is compared to two different heat-recovery techniques, the mechanical heat pump and the open absorption system. The mechanical heat-pump is the most widely used technique in Sweden today. The open absorption system is a new technique in this application. Calculations have been carried out on an hourly basis for the different techniques. Measurements from an absorption system pilot-plant installed in an indoor swimming pool in the northern part of Sweden have been used in the calculations. The results show that with the mechanical heat pump, the electrical input increases by 63 MWh/year and with the open absorption system 57 MWh/year. However, a mechanical heat-pump and an open absorption system decrease, the annual energy demand from 611 to 528 and 484 MWh respectively, which correspond to decreases of approximately 14 and 20% respectively. The electricity input will increase when using heat-recovery techniques. Changing the climate in the facility has also been investigated. An increased temperature decreases the energy demand when using the conventional ventilation technique. However, when either the mechanical heat-pump or the open absorption system is used, the energy demand is increased when the temperature is increased. Therefore increasing the temperature in the facility when using the conventional technique should be considered the first measure to reduce the energy demand.     

Molten carbonate fuel cell (MCFC)-based hybrid propulsion systems for a liquefied hydrogen tanker

This study proposes a molten carbonate fuel cell (MCFC)-based hybrid propulsion system for a liquefied hydrogen tanker. This system consists of a molten carbonate fuel cell and a bottoming cycle. Gas turbine and steam turbine systems are considered for recovering heat from fuel cell exhaust gases. The MCFC generates a considerable propulsion power, and the turbomachinery generates the remainder of the power. The hybrid systems are evaluated regarding system efficiency, economic feasibility, and exhaust emissions. The MCFC with a gas turbine has higher system efficiency than that with a steam turbine. The air compressor consumes substantial power and should be mechanically connected to the gas turbine. Although fuel cell-based systems are less economical than other propulsion systems, they may satisfy the environmental regulations. When the ship is at berth, the MCFC systems can be utilized as distributed generation that is connected to the onshore-power grid.     

Early development of a shaftless horizontal axis wind turbine for generating electricity from air discharged from ventilation systems

The air discharged from ventilation systems is a high potential wind resource for generating electricity in countries where wind speed is unreliable or weak, such as in Thailand. The air discharged from ventilation systems produces consistent and high-speed wind when benchmarked against natural wind. However, the limitations of conventional wind turbines are that they have negative impacts on the ventilation system and are inconvenient to install in many areas. The innovative shaftless horizontal axis wind turbine (SHWT) introduced in this article has been designed to close the gap between the wind source and the conventional wind turbines in this process. The concept design shows how it could be mounted next to sources of waste wind, requiring only a small space for installation. An open hole is provided to enable airflow to be discharged into the environment. This SHWT has high market potential for utilizing man-made wind to generate electricity from an alternative source which supports sustainable energy development. The purpose of this study is to demonstrate the concept design of a prototype SHWT used for energy recovery from the discharged air of a ventilation system. How the rotor and stator design of the SHWT optimize wind turbine performance and minimize the negative effects on the ventilation system efficiency are also addressed in this study. The performance of the SHWT is demonstrated in a lab-scale test using the type of propeller fan that is generally applied in many sectors in Thailand. The results showed that the SHWT was successful in generating electricity and produced minimal negative effects on the ventilation system's performance. The maximum power output of the prototype SHWT is 7.4 W at a rotational speed of 1644 rpm using eight sets of magnets and 5.1 m/s wind speed. The maximum wind turbine efficiency is 51%. However, it still requires further optimization to enhance the SHWT performance.     

Modelling of energy flows in potato crisp frying processes

Food frying is very energy intensive and in industrial potato crisp production lines frying is responsible for more than 90% of the total energy consumption of the process. This paper considers the energy flows in crisp frying using a First Law of Thermodynamics modelling approach which was verified against data from a potato crisp production line. The results indicate that for the frying process considered, most of the energy used is associated with the evaporation of water present in the potato and on the surface of potato slices. The remainder is from evaporation of frying oil and air of the ventilation system and heat losses from the fryer wall surfaces by convection and radiation. The frying oil is heated by an industrial gas furnace and the efficiency of this process was calculated to be 84%. The efficiency of the overall frying process which was found to be of the order of 70% can be improved by employing exhaust heat recovery and optimising other operating and control parameters such as exhaust gas recirculation.     

Evaluation of energy conservation potential by exhaust air recirculation for a commercial-type heated-air batch hay dryer

Energy conservation in drying and processing operations is essential in order to improve the reliability of low and moderate temperature renewable energy systems, and to reduce operating costs and energy consumption in systems using high-energy content fossil fuels in farms and processing plants especially in industrialized economies. An experimental evaluation of energy conservation potential by recirculating exhaust air in a commercial heated-air batch hay dryer is presented. The design of the exhaust recirculation unit is such that only about 30% of the total exhaust air is recirculated through the heater inlet. Experimental tests were conducted on the dryer with and without exhaust air recirculation. Maximum energy savings of 27% and 17% were achieved with exhaust air recirculation during fall and summer dryer operation, respectively.     

Zonal thermal model of the ventilation of underground transformer substations: Development and parametric study

An algebraic thermal zonal model of the ventilation of underground transformer substations during a standardised temperature rise test is presented in this paper. The development and adjustment of the proposed model rely on the analysis of the air flow pattern and temperature distributions obtained by a more complex model numerically solved by means of CFD techniques. The flow domain of the model represents a section of the substations divided into several interrelated zones where the mass and the energy conservation equations are formulated and the generated system of nonlinear algebraic equations is solved. The model is validated by comparing its results with the ones obtained by the CFD model and with the experimental results of eight temperature rise tests under different conditions. A parametric analysis was carried out on the model to prove its utility as an efficient tool to improve and optimise the thermal performance of transformer substations during the design process. From the parametric study it has been inferred that the main parameters affecting the ventilation of the substations are the pass area between the LV–MV zone and the transformer zone, the surface area of the ventilation grilles in the substation with horizontal ventilation, and the perimeter of the protruding ventilation vents in the substation with vertical ventilation.     

内燃机台架试验室设计分析

内燃机试验室设计对其今后的使用效果有着决定性的影响,分析了车用发动机试验室的总体规划和布局、供电、通风、内燃机进排气、循环水、污水、隔振隔噪、消防等方面应满足的设计要求,并对设计施工的经验教训进行了总结。试验准备间面积过小、油库面积过小、测功器循环回水落差过小、房顶水塔下水管部分为U型管、在最低处无放气阀等,都会给使用带来不便。     

基于CFD分析的车辆冷却风道综合性能评价

为了优化车辆冷却风道,提出了基于计算流体力学(CFD)分析的车辆冷却风道综合性能评价方法,建立了风道CFD模型并对模型精度进行了试验验证,确定了由CFD分析可获得的风道总压降、散热器压降、风扇消耗功率和排气百叶窗出口温度作为风道综合性能评价指标,应用隶属度线性加权规划法建立了评价模型。实例应用显示,在动力舱空间尺寸允许并保证满足设计散热量的前提下,增大散热器芯体的宽度和长度、蜗壳出口高度和侧出口高度、排气百叶窗尺寸和减少进气百叶窗叶片,可以使冷却风道的综合性能得到提高。     

大型粮仓中非均匀气流分布的数值模拟

基于Fluent软件,利用Ergun方程模拟大型粮仓中的非均匀气流分布。通过对粮堆孔隙率与浓度特性的描述以及数学模型的建立,研究了尖顶粮堆穿孔板通风和平顶粮堆环形通风两种工况的流动过程,得出其速度和压降的变化情况。结果表明,穿孔板通风尖顶粮堆增加了粮仓中心垂直方向的阻力,而环形通风平顶粮堆的气流沿仓壁向上流动,以致粮仓内空气的非均匀流动。     

Geometry development of the internal duct system of a heat pump tumble dryer based on fluid mechanic parameters from a CFD software

One aspect of reducing the energy consumption of a household tumble dryer is to reduce the pressure drop of the circulating air in the internal duct system. It is, however, costly and time consuming to design several prototypes for airflow measurements. In this paper, several fluid mechanic parameters in a partial model of the internal duct system of a tumble dryer have been studied in the CFD software Comsol MultiPhysics. The purpose was to establish a numerically based design process, where the design is conducted based on visual analysis of air velocity and vorticity, and two design criteria. The geometry design was conducted by a CAD-engineer, which was the counterpart of this project. In order to enable a successful design process, it was essential to establish a strong relation between fluid parameters and design criteria in order to share knowledge effectively with the CAD-engineer. Two geometry modifications, based on a standard model, were conducted on the duct. Based on the design criteria, the pressure drop and the non-uniformity coefficient of the outlet airflow, the second modification (Modification 2) represents an improvement as the pressure drop is reduced by 23% and the uniformity at the outflow section is increased by 3%.