Calculation Method of Hydraulic Characteristics for Direct-Return Chilled Water System

In order to optimize design and operation, it is necessary to calculate accurately hydraulic characteristics large central air-conditioning systems. Simplified Model can not be applied to hydraulic calculation of large pipe network topological structure for its large calculation error. Taking into account the regulating characteristics of terminal branch temperature regulating valve, a direct-return chilled water system is studied, an accurate mathematical model of pipe network hydraulic characteristics has been established and a computer logic algorithm with virtual flow has been given. A direct-return pipe network with ten AHU branches is used as simulation calculation object, the pipe network supply-return water pressure difference is calculated, and also the temperature regulating valve opening and actual flow of each branch are calculated in the condition of different supply-return water pressure difference. The calculated results accord with the natural characteristics of high pressure difference unbalanced for direct-return pipe network. The calculation method can ensure calculation convergence.     

Energy Efficiency of Water Transportation System for Surface Water Source Heat Pump

The forms of water transportation, arrangement and operation of pumps contribute to the water transportation energy consumption, which influences the energy-saving effect of surface water source heat pump. The relation between the pumping height and energy consumption of pumps is found by analyzing the model of pump energy consumption. The concept and calculation of critical pumping height is presented considering the limited rate of system energy efficiency. Based on the principle that the pump power changes with water flow rate, the determination of pumps arrangement of one or two stage pumps is described with a concrete example. The influence of water flow rate on heat pumps and water pumps is analyzed, and the energy efficiency of constant and variable water volume are compared. The operation way of this example is concluded for the optimal system energy efficiency. It is found that there is a critical pumping height for the energy-saving effect of surface water source heat pump compared with the traditional system. Moreover, the operation strategies should be determined by the system optimal model since the energy consumptions proportions of heat pumps and water pumps are variable.     

Pressure Drop and Evaporative Heat Transfer Characteristics of Air-water Bubbling Flow

A new kind of evaporative heat transfer experiment for the cooling process of condensers is conducted. The test coil is immersed in an air-water bubbling layer. The air-water two-phase flow passes through the heating tubes of the coil. Due to the motion of the air bubbles in the water, a thin water film forms on the surface of the heating tubes. As the air bubbles passing by the tubes the water is evaporated into the air. The tubes of coil reject heat to the water film, and the evaporation of the water film then rejects heat to the air bubble stream. This heat transfer mode significantly increases the heat transfer coefficient between tubes and air. The consumption of the power of a water pump can be decreased. Moreover, the airflow rate required is less than that of an air-cooled condenser.The pressure drop of air through air-water bubbling layer and the heat transfer between the tubes and water are experimentally investigated in the paper. The results show that the factors affecting the pressure drop and the heat transfer coefficient involve the pore geometry of sieve plate, the height of the air-water bubbling layer, the air flow rate through the sieve plate and the heat flux of tubes. The heat transfer coefficient between tube and water is two times larger than that of falling film of water on the outer surface of tube.     

Properties of Temperature Difference Self-power Adjusting Valve Used in Blast Furnace

Blast furnace campaign life has a great effect on technical and economical indexes of ironmaking production. Cooling condition and life-span of cooling apparatus have a great influence on campaign life of blast furnace. Owing to constant flux water supply used for blast furnace cooling at present, cooling intensity doesn't meet the demand of heat load in peak value, concurrently, cooling water supply lacks equilibrium and stability, which will cause burnout of cooling apparatus and diminution of blast furnace campaign life. So temperature difference self-power adjusting valve is introduced to make BF cooling apparatus change constant flux water supply mode to constant temperature difference water supply mode in order to satisfy the need of cooling intensity when heat load wis in peak value.Principle, structure ,properties and function of temperature difference self-power adjusting valve are explained. The flux in different temperature is measured.     

Selection of Hot Water Circulating Pump Related Parameters

In multistoried or the high-rise civil constructions the full-time machinery hot water circulation supply system design,whether the design parameters for the flow and the lift of circulating pump are appropriate or not,will be related to continuously,safe,stably running of the hot water supply system.This paper introduces parameter selections of hot water circulating pump both at home and abroad.Based on the difference of these selection means it analyzes the calculating means of the flow and the lift of circulating pump.Whether the circulator flow should join the additional circulating flow or not is the focal point in the argument.In China's present "Code for design of building water supply and drainage" the additional circulating flow is considered not flowing through the circulating pump,so in calculation the additional circulating flow does not contain the circulator flow.By analysis of the water distribution operating mode and various ring circuits difference,as well as considering that for the very small circulator flow it is more difficult to use the valve regulation and to achieve balance between various ring circuits resistance loss,inaccessible absolute circulation in the same regulation,short circuit and so on,the circulator flow should be the sum of circulating flow and additional circulating flow.To calculate lift head the additional circulating flow should be considered through the calculating loop.     

基于PLC的自动灌溉控制系统设计

为了加快农业生产信息化和数字化的发展,节约宝贵的水资源,降低能耗,提高灌溉的质量和效率,提升控制管理水平,笔者以维控LEVI102A型触摸屏为人机界面,台达DVP60ES2型可编程控制器为控制核心构建了一套自动灌溉控制系统。该系统不仅可以根据当前土壤中含水率和用户设定的土壤含水率的情况自动控制水泵电机和电磁阀的启闭,遇到雨天自动停止灌溉,还可以按照用户设定的时间自动进行灌溉。该系统实现了灌溉的自动监控功能,节省了人力,节约了用水,提高了灌溉的质量和效率,具有造价低廉,运行稳定,操作便捷,维护简易,人机界面友好等优点,具有广阔的应用前景和实际使用价值。     

Pump Selection in the Secondary Pump Station of Water Works

In this paper, the suitable conditions of using constant speed pumps, variable speed pumps or combination of both in the secondary pump station of water works are analyzed. Then, from the point view of energy saving and based on the principle of high efficiency operation, the method for selecting pumps in the secondary pump station of water works is provided. Eventually, the method is examined with examples.     

The determination method of limit energy consumption of water supply in open-loop surface water source heatpump systems

For the open-loop surface water source heat pump systems, energy consumption of water supply is the key factor for energy saving of system. On the basis of energy consumption model of heat pump unit and energy consumption model of water supply etc., open-loop surface water source heat pump system energy efficiency ratio coupling model is established. Based on energy efficiency ratio,the coupling limit value of surface water source heat pump system in different temperature of water supply and different energy consumption of water supply is obtained.Through the actual case, energy saving rate of the system is calculated in different temperatures of water supply and different system modes. And the determination method of the limit energy consumption of water supply of open-loop surface water source heatpump systems is established.     

Temperature Fuzzy PID Control for Variable Air Volume System

Fuzzy PID controller was applied in variable air volume system. The task was to control the temperature of supply air and the temperature of air conditioned room (the return air temperature) close to their respective targets. The fuzzy PID control system of supply air temperature and return air temperature was designed respectively. The supply air temperature was controlled through adjusting the valve opening of chilled water. And the indoor temperature was controlled through adjusting the rotational speed of variable frequency ventilator. The supply air temperature and the indoor temperature (return air temperature) were controlled online by fuzzy PID controller. Thus, it was shown that the design of fuzzy PID controller was reasonable and the effect of fuzzy PID control was well.     

覆盖措施对春小麦田土壤含水量及耗水规律的影响

高效节水措施的使用有利于提高作物水分利用效率,缓解我国荒漠绿洲区灌溉农业生产中水资源不足的问题。基于此设定了大田定点观测试验研究不同覆盖措施对荒漠绿洲区春小麦耗水规律的影响,试验分别设置石子覆盖(S)、地膜覆盖(B)、秸秆覆盖(M)和对照(CK)4个处理。试验结果表明：覆盖措施使土面蒸发量降低了25.6%~37.9%,有效的提高了土壤含水量。春小麦耗水量分别为B处理减少了13%,M处理减少了14%,S减少了8%,但B处理下的春小麦水分利用效率(WUE)和灌溉水分利用效率(WUEi)最高。可见,地膜覆盖是是适合该地区最佳的节水种植方式。     

Junction stiffness analysis and vibration noise prediction of wind power speed-increase gearbox

In order to study the vibration characteristics and radiation noise of wind power speed-increase gearbox, a torsional vibration model of wind power speed-increase gearbox is established based on the analysis of supporting stiffness of bearing and contact stiffness of gear pairs. By solving the vibration differential equation with the help of Matlab, the frequency and corresponding vibration mode are obtained. With taking stiffness excitation, error exaction and meshing impact exaction into account, the dynamic finite element model of speed-increase gearbox is set up, and the dynamic response simulation is carried out. Regarding vibration displacement of the nodes on gearbox surface as boundary condition, an acoustic boundary element model of speed-increase gearbox is built. The surface acoustic pressure of gearbox and the radiation noise of field points are solved by the direct boundary element method. The results show that there is a great difference between torsion frequency and excitation frequency of wind power speed-increase gearbox, and so the resonance doesn't occur. The maximum structural noise and radiation noise mainly appear near the double octave of the gears meshing frequency of high-speed grade.     

Calculation of Constant Pressure Values for Relief Valves in the Fire Suppression Systems of High-Rise Buildings

The calculation of constant pressure values for relief valves in the fire suppression systems of high-rise buildings usually is based on the working pressure of pipe systems by experience.However,this method only is applied in the condition that the relief valves are installed on the effluent pipes of pumps.In order to confirm the proper constant pressure values of relief valves in fire suppression systems,a formula is deduced using hydraulics theory.The applications of the formula in fire suppression systems are also discussed.The constant pressure values for relief valves are directly related to three factors,namely,the flux and pressure of the fire pump,the located height of the relief valves,and the head loss of flux from the pump exit to the inlets of the relief valves.It is necessary to analyze the working condition of fire suppression systems and to be certain of the permissive pressure range for overpressure.     

重庆村镇空气源热泵供暖系统夜间性能实测分析

针对重庆山地村镇迫切的供暖需求,选取该地区典型村镇搭建了空气源热泵供暖系统实验平台,分析了空气源热泵系统性能影响因素,并从供回水温度、系统耗电量、供热量、性能系数COP等角度对运行过程中的阶段特性(启动、稳定运行及全阶段)进行阐述,发现系统在3个阶段特点差异很大：启动阶段初始温度对COP影响较为明显,除霜时系统性能下降25%;稳定阶段特性与初始温度无关,室外条件较好时,降低设定温度,COP提高明显;总体来看,启动阶段COP最高,全阶段次之,稳定阶段COP最低。     

中亚食品车间节能减排措施

对中亚食品研发中心(有限公司)车间节能减排措施进行统计分析。统计结果显示,喷淋杀菌机冷却水的循环利用使工厂生产节约水160 m3/班次,直接节约经费355.2元/班次;蔬菜罐头的清洗浸泡用水工艺经改良后,现在可以浸泡黄瓜7~8 t/m3;车间安装高压杀菌锅后,天然气的使用量由2 000 m3/d降至200 m3/d,直接节约2 754元/d;车间照明节能系统的整改大大降低了工厂的用电量;环保节能包装材料EVOH的应用降低了生产运输成本,又符合环保卫生。中亚食品企业车间节能减排措施显著提高企业系统能效。     

Analysis of the Temperature Limit of Dynamic Water Intake of Open loop Surface Water Source Heat Pump Systems

Energy consumption of water intake is one of the key factors for energy saving in the application of the open loop surface water heat pump system. An energy efficiency ratio coupling model for open loop surface water source heat pump systems was established on the basis of the energy consumption model for the water intake and the heat pump units. According to energy saving rate and regulation of energy consumption of water intake, dynamic temperature limits of water intake in different water supply temperature of cooling tower and different pump head were proposed so as to find a calculation method of temperature limits of water intake of open loop surface water heat pumps. Moreover, the energy saving rate of surface water source heat pump systems compared with traditional air conditioning systems under various condition was also calculated.     

Thermodynamic Analysis of River Water Fouling on Constant Wall Temperature Tube of Small Diameter

In order to improve utilization of cold and heat source from river, turbulence theory and entropy generation theory were adopted to analyze the effect of fouling on convective heat transfer performance in small diameter tube of constant wall temperature.It is found that the entropy generation caused by conduction of fouling plays a more important role in total entropy generation of heat transfer process through a duct than that in cveast rate of caused by temperature difference.The entropy generation caused by viscous flow is more than the entropy generation caused by temperature difference in flow with bigger Reynolds and small radius.The increase rate of entropy generation monotonically increase with Reynolds and the generation process of fouling resistance.Thereafter, the effect of fouling resistance on the heat transfer performance of water source heat pump heat exchanger should be paid more attention, when river water are used as the cold and heat source of heat pump.     

The Energy Saving Design of Domestic Water Supply for a Residential Quarter of High-rise Buildings

The schemes of domestic water supply for a residential quarter of high-rise building are introduced.The energy consumptions of water supply schemes selected are compared and analyzed.The energy saving of the water supply schemes with water tank and variable velocity variable frequency pump are obtained.And demonstrated the domestic water supply system of combination the roof water tank and variable velocity variable frequency pump is good at energy saving.Furthermore,by the comparison of the investment and cost of these schemes in their lives,the best choice of domestic water supply system is gained.     

THE ANALYTICAL EQUATIONS OF HYDRO-THERMAL POWER SYSTEM ECONOMIC DISPATCH

The paper developes the analytical equations of the power economic dispatch by using the modified coordination equation, it also developes the explicit functional relation between the hydro-coal conversion factor and the daily water consumption. Using these expressions,the calculating amount of the hydro-thermal system economic dispatch is greatly reduced and the convergency is much better. Finally a numerical example is given to show these advantages.     

Influential factors analysis on photoacoustic signal of photoacoustic spectroscopy monitoring trace gases

Photoacoustic spectroscopy (PAS) is a highly sensitive gas analyzing method without the shortcoming of gas consumption, which can be used in transformer oil trace gases dissolved in on line monitoring. The photoacoustic signal is detected with a microphone, which is the only feature in gas concentration analysis. A portable and tunable experimental setup has been developed based on the photoacoustic spectroscopy fundamental. Through the photoacoustic signal stimulate mechanism analysis, this paper thoroughly discusses the influences of gas pressure, temperature, laser power, gas concentration, background gas, chopped frequency and the resonant frequency drift on the gas photoacoustic signal. The theoretical and experimental results supply reference and technical support for further improvements in oil gas photoacoustic spectroscopy of on-line monitoring system.     

匀播和密度对小麦萌发及幼苗性状的影响

为研究匀播和密度对小麦萌发和幼苗性状的影响,选用新春31号小麦为供试材料,种植方式设匀播和条播2个处理,密度设25、36、49和64株/箱（分别以D1、D2、D3和D4表示）4个处理,测定了小麦胚根和幼苗性状的各项指标。结果表明,与条播方式相比,匀播小麦幼苗胚根根尖数、分叉数、表面积和体积均增大,幼苗茎秆直径和苗高分别增高6.15?％和1.02?％,且随着种植密度增大,幼苗茎秆直径和苗高均表现为先增大后减小的变化趋势。匀播方式下胚根快速伸长的时间比条播缩短1.16?d,理论最大胚根长度降低2.95?％,而根系最大伸长速率则升高8.96?％。胚根长度与胚根重、茎叶重呈显著或极显著正相关,与籽粒残留物重呈极显著负相关;胚根平均直径与胚根重、茎叶重和幼苗重均呈显著性负相关;胚根重与茎叶重和幼苗重均呈极显著正相关。其中,种植模式和密度对23?d的根干重有显著性影响,对其他时段各项指标均无显著性影响。萌发期间籽粒贮藏干物质的转化率和消耗率均呈先升高后降低的变化趋势,且转运率于第15?d时达到最大,匀播比条播高0.26?%,差异不显著。而消耗率于第11?d左右达到最大,匀播比条播高10.61?%,差异达显著性水平。种植密度无显著性影响。本研究结果为进一步研究匀播栽培技术提供了理论依据。