Dynamic Heat Transfer Analysis of a Water Storage Roof

On the basis of analyzing the complicate heat and humid exchange between the outdoor air and the water layer of the roof,the authors obtained a heat transfer model and it's transmit matrix. The temperature and heat flux responses of the internal roof surface is greatly lowered than that of non-water layer roof. It can be concluded that the maintenance of a water layer on the roof is a good way to resist the fluctuation of outdoor temperature and significantly reduce the cooling load of a building.     

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.     

Experimental Analysis on Power Consumption of Chilled Water Pump by Constant Pressure Difference Method with Bypass Valve

The power consumption of frequency conversion chilled water pump of an office building regulated by constant pressure difference method with bypass valve is studied experimentally. A model of power consumption of chilled water pump is proposed. The effects of pressure difference set point of bypass valve on instantaneous and annual power consumption of chilled water pump are analyzed. The simulation results are validated experimentally, which shows that there is a maximum water flow rate which increases with the increase of the pressure difference set point of bypass valve at equilibrium state. There are three pressure operation regions of the bypass valve: under pressure region, constant pressure region and over pressure region. The power consumption of frequency conversion chilled water pump is affected by the pressure difference set point of bypass valve significantly, and it would be minimized as the pressure difference set point of bypass valve is equal to the pressure difference between supply water and return water of the farthest user.     

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.     

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.     

变流量冷冻水系统温差控制法的适用性

研究了末端设置通断控制阀的一次泵变流量系统在温差控制下的水力特性,并结合风机盘管与房间的非线性换热耦合特性,进一步探讨了温差控制的适用条件以及变温差控制温差值的设定方法。结果表明：末端设置通断控制阀的系统,当管网整体负荷分布均匀且各开启用户的负荷变化规律相近时,温差控制同样是较为适用的,此时系统的水力失调对室内温湿度的影响较小;采用变温差控制时,仅以不同的总负荷率分段设置温差值,并不能获得良好的室内温湿度控制效果,建议以优先保证风盘除湿能力和室内干球温度为原则设定温差值,相比于目前的方法,在同等的室内相对湿度波动下,室内温度的稳定性可以得到保证。     

Characteristics of combustion and NOx emission in lowconcentration coal bed methane boiler retrofitted from coal fired boiler

Coal fired chain grate boiler is retrofitted to coal bed methane boiler. The flow, combustion and NOx emission characteristics of low concentrations methane in the boiler furnace are studied by the numerical simulation and experiments. The results show that the axial velocity reaches the maximum at 0.5 m from the nozzle and declines sharply in the range of -0.4~0.4 m on the width direction. With the heat load increases, the position of highest temperature moves to the rear of furnace and the simulation and experimental results agree well. At the front of the furnace, the obvious bimodal distribution of temperature at low heat load along the width direction is found, but it is a single peak distribution at 100% heat load. At the rear of the furnace, the temperature shows bimodal distribution at all kinds of heat loads. Gas temperature at boiler furnace outlet increases linearly with the increasing of heat load but the experimental results are slightly lower than the simulated results. The NOx is mainly produced in the middle and rear of furnace with high temperature, and the position of NOx peak lags far behind that of temperature peak. With the excess air coefficient increases, the highest furnace temperature and NOx generation increases and then decreases.     

呼和浩特地区不同类型日光温室光热性能研究

本研究主要对新引进的日光温室与当前厚墙体温室的光热性能进行对比研究,为呼和浩特地区日光温室的建设提供参考依据.根据4种类型日光温室小气候监测数据,分析温室内外日平均温度、温室内外日最低温度、温室内外日最高温度、温室内光照度等气象要素变化规律.双膜双被日光温室为室内温度水平最高的日光温室,越冬期间(1月12日-2月21日...     

乌兰布和沙区不同供水量下杨树林地土壤水分和温度效应研究

为了提高干旱区水资源利用率,确定沙区杨树人工速生林的合理供水量,实现杨树人工林的科学化管控目标,通过4年定位观测试验,研究了乌兰布和沙区‘小美旱杨’林地不同年供水量(1500、3000、4500、6000、7500 m3/hm2)下的土壤水分和温度效应。结果表明,不同供水量对土壤的增湿效应存在差异。各土层、各月土壤含水量均随供水量的增加而增加;最大年供水量的土壤含水量峰值出现在7月,而其他的出现在6月;‘小美旱杨’速生丰产的年供水量阈值为7500 m3/hm2,它能使剖面土壤水分补给层达70 cm以上,且补给层以及6-9月高温时期的土壤含水量均保持在20%以上;供水量越大,土壤含水量随树龄增加而降幅越大。年供水量每增加1500 m3/hm2可提高土壤贮水量4.69%~7.43%,增加土壤有效含水量1.42%~15.5%;供水量对田间持水量影响不明显;随供水量的增加,土壤水分亏缺明显趋于平缓,土壤温度递减,在同一土层内下降1.66~3.26℃,沿剖面向下降低8.64~9.66℃。最小和最大供水量应分别在4月低温期和7月高温期进行,以满足林木生长的水分和温度之需。     

The Key Parameters Method of Calculating Geothermal Heat Exchanger Length

The geothermal heat exchanger is the key component of ground coupled heat pump systems. We discuss the key parameters method of calculating geothermal heat exchanger length based on line source theory. Typical meteorological year data is used to determine the hottest month, the coldest month and annual average surface temperature. The building hourly load can be obtained by introducing the concept of equilibrium temperature. The cooling fraction and the heating fraction then can be calculated using building hourly load and performance parameters curve fit of a water source heat pump unit. The method for selecting the hottest and lowest entering fluid temperature and calculating the borehole and ground thermal resistance is given. A vertical U tube heat exchanger length calculation procedure is proposed.     

Investigation of Cold Water System in Dry Fan-coil Unit

A study was carried out for the appropriate pattern of cold water system and the problems with which should be concerned in dry fan-coil unit air conditioning system. The methods of how to determine the supply water temperature of fan-coil unit and the cold water flow rate were also discussed.     

Constant Temperature Control System for Gas Water Heater Based on Fuzzy Reasoning Arithmetic

Basing on Fuzzy reasoning technology, this paper introduces the work flow of Gas water heater, and the trait of papilionaceous valve. It also describes the designing process of Fuzzy controller, its theory and the method of making parameter. The experiment results show that this temperature control system has better characteristics such as high- precision, good dynamic performance, excellent control effect, and so on. The design shows its validity and practicability.     

Load dynamic matching of supply and demand side based on the utilization of urban sewage heat energy

Flowing dynamic characteristics and its temperature dynamic characteristics of a three-level sewage pipe network in Chongqing were analyzed. A mall's building whole year load was simulated. In the adverse condition of wastewater flow, the market construction peak discharge heat was compared with the sewage heat load, the balance between the most adverse flow and the building demand was found. Explored supply and demand matching method between urban sewage and city building load in flow adverse condition to take full advantage of the urban sewage cold and hot resources. the composite system was adeptcd to make up the most unfavorable flow time of sewage average heat load and the construction load difference; it also puts forward principle of load sharing and control strategy aimed at compound system.     

Influence of heat storage mode of domestic hot water on the performance of ground heat exchanger in ground-source heat pump system

The vertical U-tube ground-coupled heat pump system provides cold and heat for the controlling of indoor environment. Under the air-conditioning condition, the vertical U-tube ground-coupled heat pump system with heat recovery can provide domestic hot water. The influence of supplying domestic hot water on the heat transfer performance of ground heat exchangers is different under different operating modes in summer and winter. Through a project design of ground-source heat pump system, the influence of supplying domestic hot water under heat storage mode on the heat transfer performance of ground heat exchangers in summer and winter is respectively analyzed. The dynamic performance of heat exchangers under different working conditions is analyzed, and through numerical calculation, the heat transfer performance parameters of ground heat exchangers under different operating modes are obtained. From the calculation results, the adjusting methods based on the load characteristics of this project represent.     

A simulated experiment on the high titanium slag rheological behavior

The rheological property of high titanium slag is a main factor to influence the vanadium titanomagnetite smelting in blast furnace. It plays a great role in discharging slag, separating iron and slag and even the life of blast furnace hearth. The acrylonitrile-butadiene-styrene multipolymer(ABS) dense suspension is taken to simulate the system of high titanium slag. Apparent viscosity is measured by a NXS-11A rotating cylinder viscometer. The impact of temperature, volume fraction and particle sizes on the suspension apparent viscosity is studied. The results show that temperature and volume fraction have a strong influence on the suspension apparent viscosity, while the particle size has a weak effect. The suspension shows Bingham behavior within a wide concentration range. The dependence of the appear viscosity on temperature and amount of solid addition can be described by a binary function equation.     

Heat Conduction due to Moving Heat Sources in Semi infinite Body

Combined image method with heat source function method,heat conduction due to moving heat sources is analysed in semi infinite body and cylinder with heat exchanging on its surface.The distribution of temperature is obtained when the wall temperature is constant and the wall heat flux is zero.The result is useful for engineering calculation.     

氧气高炉工艺研究进展及新炉型设计

从氧气高炉的数学模型、实验室实验以及工业试验角度系统分析了氧气高炉工艺的发展现状及趋势,同时讨论了氧气高炉炉型的设计依据。论述了氧气高炉的静态工艺模型研究需要计算合适的直接还原度和热空区温度,同时应考虑氧气高炉工况下生产率的变化、热损失的变化、风口煤粉的喷吹上限以及N₂的循环积累等问题。指出了多维动力学模型和多目标优化模型中尚需解决的问题,以及氧气高炉数学模型的主要发展方向。结合文献研究中的氧气高炉特点,从炉身高度设计、炉腹角和炉身角设计以及风口设计3方面综述了氧气高炉炉型设计的变化规律。     

Mathematical Model of Oxygen Blast Furnace with Preheating Gas Injection into Upper Shaft

An One-dimensional mathematical model,based on oxygen blast furnace with preheating gas injection into upper shaft,has been developed to describe the variation of innerdiameter of blast furnace,13 chemical reactions,the heat losses through the furnace wall,the heatexchange and pressure losses between gas phase and solid phase.The characters of oxygen blastfurnace are discussed,The simulated results indicate that the tem perature of burden in creasesthroughout the upper shaft with the incrcasement of the flow and the temperature of preheating gasinjected,and that the effect of the heating-up of burden is not so large when the com positions ofpreheatin8 gas injeetion are changed.The model is contributed to obtain a deeper understanding ofthe oxygen blast furnace process.     

微波干燥过程中的土豆组织温度变化及水分迁移特性

为探索淀粉类果蔬多孔介质在微波干燥过程中的热质传递特性,以土豆为研究对象,测量其不同功率下微波干燥过程中土豆组织的温度和质量以及水分状态变化。结果表明,微波干燥过程中土豆组织的温度可以分为快速升温、恒温及降温段3个阶段,土豆质量减少主要发生在恒温段,且该阶段物料的失重率占总失重率的90%以上。微波干燥过程中自由水短暂升高至93.21%后逐渐降低至15.61%,而不易流动水和结合水均先降低后升高。淀粉对于微波干燥中的水分迁移有重要影响,淀粉失去薄膜水后固化,使得土豆片的骨架硬度增加,从而增大水分迁移阻力。     

Research and Application of Temperature-field Digitalizing of the Tuyere and Raceway Section in Blast Furnace

It is useful for diagnosing coal combustion status and the tuyere and raceway in blast furnace, at the same time, it is supervision running state to study on temperature-field of also helpful for supervising the structure of oxygen and coal burning apparatus, improving coal combustion technology and coal injection operation. The model between red and green information of true color flame image and temperature is established and two dimension raceway section projection temperature-field are achieved by applying no-touch radiation temperature measurement theory and technology. It is proved with experimentation that the method is effective and feasible, and the testing precision can reach 98.09% compared to the testing result of thermocouple of taking out gas.