Study on limited-flux coefficient to achieve spare transportation of heat-supply network

Limited-heating is one of the heating statuses which can meet the reliability requirement of those uninterrupted heat-users under the accidental status of heat-supply network.It requires the network to be provided with both ability of spare-structure and spare-transportation,and the later one is depended on the limited-flux coefficient.This paper investigates the relationship between the limited-flux coefficient and limited-heating coefficient of indirect connection system.The optimal value of the limited-flux coefficient is presented as well.

Magnetic configuration effects on the edge heat flux in the limiter plasma on W7-X measured using the infrared camera and the combined probe

Controlling the heat and particle fluxes in the plasma edge and on the plasma facing components is important for the safe and effective operation of every magnetically confined fusion device.This was attempted on Wendelstein 7-X in the first operational campaign,with the modification of the magnetic configuration by use of the trim coils and tuning the field coil currents,commonly named iota scan.Ideally,the heat loads on the five limiters are equal.However,they differ between each limiter and are non-uniform,due to the（relatively small） error fields caused by the misalignment of components.It is therefore necessary to study the influence of the configuration changes on the transport of heat and particles in the plasma edge caused by the application of error fields and the change of the magnetic configuration.In this paper the upstream measurements conducted with the combined probe are compared to the downstream measurements with the DIAS infrared camera on the limiter.

Evidence of vapor shielding effect on heat flux loaded on flowing liquid lithium limiter in EAST

A lithium(Li)vapour layer was formed around a flowing liquid Li limiter to shield against the plasma incident power and reduce limiter heat flux in the EAST tokamak.The results revealed that after a plasma operation of a few seconds,the layer became clear,which indicated a strong Li emission with a decrease in the limiter surface temperature.This emission resulted in a dense vapour around the limiter,and Li ions moved along the magnetic fleld to form a green shielding layer on the limiter.The plasma heat flux loaded on the limiter,measured by the probe installed on the limiter,was approximately 52%lower than that detected by a fast-reciprocating probe at the same radial position without the limiter in EAST.Additionally,approximately 42%of the parallel heat flux was dissipated directly with the enhanced Li radiation in the discharge with the liquid metal infused trenches(LIMIT)limiter.This observation revealed that the Li vapour layer exhibited an excellent shielding effect to liquid Li on plasma heat flux,which is a possible beneflt of liquid-plasma-facing components in future fusion devices.

Influence of heating and water-exposure on the liquid limits of GMZ01 and MX80 bentonites

Bentonite has been considered as a buffer material for embedding canisters with high-level radioactive waste（HLW） in deep geological repositories.GMZ bentonite deposit,located in Xinghe County,Inner Mongolia Autonomous Region,China was proposed as a buffer/backfill material for HLW repository in China.The liquid limits of natural Na-bentonite GMZ01 and commercial Na-bentonite MX80,which are previously heated at 80 ℃ and 95 ℃,respectively,and exposed to water for different times are measured.It is observed that the liquid limit of GMZ01 increases slightly at the beginning,and then decreases as the heating time increases,while the liquid limit of MX80 decreases with the heating time.The liquid limits of both GMZ01 and MX80 decrease with increasing water-exposure time.After the samples are heated at 80℃and 95 ℃ for several months,the mineralogical composition of GMZ01 does not exhibit evident change,whereas MX80 experiences some changes.In addition,the chemical composition,cation exchange capacity（CEC） and exchangeable cation of all the samples do not change significantly.

Numerical Investigation of Heat Deposition Patterns on the Surface of HT-7 Actively Cooled Toroidal Limiter

Two water cooled toroidal limiters were used in HT-7 to exhaust power effectively since the spring campaign of 2004. The heat flux deposition pattern on their surfaces both in steady state and transient state, caused only by plasma displacement, were studied with ANSYS code. The ripple of the toroidal magnetic field was taken into account. The heat flux deposition appeared to be periodic. The ripple and the relative location of the limiter to the toroidal field （TF） coils, as well as the shift of the center of the last closed flux surface （LCFS）, had a vital influence upon the heat flux profile. The location with maximum temperature didn＇t coincide with that for the maximum heat flux in a transient state. The shift of the center of LCFS, caused by plasma displacement, made the heat flux on the limiter more uneven. The heat flux deposition pattern concerning the real shift of the center of LCFS at a transient state calls for further research.

Simulation Study of Heat Flux Deposition Pattern on the Surface of HT-7 Toroidal Limiters

The heat flux deposition pattern on the toroidal limiters installed in HT-7 was simulated with ANSYS code. The simulation model was established with the ripple of the magnetic field. The heat deposition pattern and temperature distribution on the surface of the toroidal linfiters were obtained. A comparison of the results obtained with and without the shaped tiles, used to reduce the heat flux on the leading edge of the limiters, was made. The maximum heat load allowed at the leading edge was about 1.8 MW/m2 because of the poor power removing capacity on the ends of the limiters. This approach can also be applied to other devices with a limiter configuration in a circular cross-section shape.

Application of high temperature heat pipe in hypersonic vehicles thermal protection

In order to develop further the application of high temperature heat pipe in hypersonic vehicles thermal protection, the principles and characteristics of high temperature heat pipe used in hypersonic vehicles thermal protection were introduced. The methods of numerical simulation, theory analysis and experiment research were utilized to analyze the frozen start-up and steady state characteristic of the heat pipe as well as the machining improvement for fabricating irregularly shaped heat pipe which is suitable for leading edge of hypersonic vehicles. The results indicate that the frozen start-up time of heat pipe is long （10 min） and there exists large temperature difference along the heat pipe （47 ℃/cm）, but the heat pipe can reduce the temperature in stagnation area of hypersonic vehicles from 1 926 to 982 ℃ and work normally during 1 000-1 200℃. How to improve the maximum heat transfer capability and reduce the time needed for start-up from frozen state of the heat pipe by optimizing thermostructure such as designing of a novel wick with high performance is the key point in hypersonic vehicles thermal protection of heat pipe.

Fabrication and thermal performance of grooved-sintered wick heat pipe

Some novel grooved-sintered composite wick heat pipes(GSHP) were developed for the electronic device cooling.The grooved-sintered wicks of GSHP were fabricated by the processes of oil-filled high-speed spin forming and solid state sintering.The wick could be divided into two parts for liquid capillary pumping flow:groove sintered zone and uniform sintered zone.Both of the thermal resistance network model and the maximum heat transfer capability model of GSHP were built.Compared with the theoretical values,the heat transfer limit and thermal resistance of GSHP were measured from three aspects:copper powder size,wick thickness and number of micro grooves.The results show that the wick thickness has the greatest effect on the thermal resistance of GSHP while the copper powder size has the most important influence on the heat transfer limit.Given certain copper powder size and wick thickness,the thermal resistance of GSHP can be the lowest when micro-groove number is about 55.

Optimal trajectory and heat load analysis of different shape lifting reentry vehicles for medium range application

The objective of the paper is to compute the optimal burn-out conditions and control requirements that would result in maximum down-range/cross-range performance of a waverider type hypersonic boost-glide(HBG) vehicle within the medium and intermediate ranges,and compare its performance with the performances of wing-body and lifting-body vehicles vis-a-vis the g-load and the integrated heat load experienced by vehicles for the medium-sized launch vehicle under study.Trajectory optimization studies were carried out by considering the heat rate and dynamic pressure constraints.The trajectory optimization problem is modeled as a nonlinear,multiphase,constraint optimal control problem and is solved using a hp-adaptive pseudospectral method.Detail modeling aspects of mass,aerodynamics and aerothermodynamics for the launch and glide vehicles have been discussed.It was found that the optimal burn-out angles for waverider and wing-body configurations are approximately 5° and 14.8°,respectively,for maximum down-range performance under the constraint heat rate environment.The down-range and cross-range performance of HBG waverider configuration is nearly 1.3 and 2 times that of wing-body configuration respectively.The integrated heat load experienced by the HBG waverider was found to be approximately an order of magnitude higher than that of a lifting-body configuration and 5 times that of a wing-body configuration.The footprints and corresponding heat loads and control requirements for the three types of glide vehicles are discussed for the medium range launch vehicle under consideration.

Solution of Combined Heat and Power Economic Dispatch Problem Using Genetic Algorithm

This research proposes a synergistic meta-heuristic algorithm for solving the extreme operational complications of combined heat and power economic dispatch problem towards the advantageous economic outcomes on the cost of generation. The combined heat and power (CHP) is a system that provides electricity and thermal energy concurrently. For its extraordinary efficiency and significant emission reduction, it is considered a promising energy prospect. The broad application of combined heat and power units requires the joint dispatch of power and heating systems, in which the modelling of combined heat and power units plays a vital role. The present research employs the genetic optimization algorithm to evaluate the cost function, heat and power dispatch values encountered in a system with simple cycle cogeneration unit and quadratic cost function. The system was first modeled to determine the various parameters of combined heat and power units towards solving its economic dispatch problem directly. In order for modelling to be done, a general structure of combined heat and power must be defined. The test system considered consists of four units: two conventional power units, one combined heat and power unit and one heat-only unit. The algorithm was applied to test system while taking into account the power and heat units, bounds of the units and feasible operation region of cogeneration unit. Output decision variables of 4-unit test systems plus cost function from Genetic Algorithm (GA), was determined using appropriate codes. The proposed algorithm produced a well spread and diverse optimal solution and also converged reasonably to the actual optimal solution in 51 iterations. The result obtained compared favourably with that obtained with the direct solution algorithm discussed in a previous paper. We conclude that the genetic algorithm is quite efficient in dealing with non-convex and constrained combined heat and power economic dispatch problem.

Nitrogen Gas Heating and Supply System for SST-1 Tokamak

Steady State Tokamak （SST-1） vacuum vessel baking as well as baking of the first wall components of SST-1 are essential to plasma physics experiments. Under a refurbishment spectrum of SST-1, the nitrogen gas heating and supply system has been fully refurbished. The SST-1 vacuum vessel consists of ultra-high vacuum （UHV） compatible eight modules and eight sectors. Rectangular baking channels are embedded on each of them. Similarly, the SST-1 plasma facing components （PFC） are comprised of modular graphite diverters and movable graphite based limiters. The nitrogen gas heating and supply system would bake the plasma facing components at 350 ~C and the SST-1 vacuum vessel at 150 ~C over an extended duration so as to remove water vapour and other absorbed gases. An efficient PLC based baking facility has been developed and implemented for monitoring and control purposes. This paper presents functional and operational aspects of a SST-1 nitrogen gas heating and supply system. Some of the experimental results obtained during the baking of SST-1 vacuum modules and sectors are also presented here.

Improved Efficiency of Heat Exchange Using KELEA Activated Water

An environmental force termed KELEA (kinetic energy limiting electrostatic attraction) is postulated to reduce the strength of intermolecular (hydrogen) bonding of water molecules, resulting in increased kinetic activity of the water. While regular water does not directly absorb KELEA from the environment, various dipolar compounds with separated electrical charges can seemingly act as a primary antenna for KELEA, with secondary transfer of energy into nearby water. Moreover, once sufficiently activated, the separated electrical charges in activated water can apparently function as a receiver for KELEA, leading to further activation of the water and also to the activation of added water. Prior publications have addressed the agricultural and potential clinical benefits of using KELEA activated water. This article is intended as the first in a series of papers describing useful industrial applications of KELEA activated water. The focus of the present paper is on the improved efficiency of industrial water heating and cooling systems by using KELEA activated water provided by pelleted, ground and heated volcanic rock as supplied by Kiko Technology.

Arrangement of Multirow Solar Collector Array on Limited Roof Width

At the limited roof north-south （N-S） width of a building, for the array with multirow collectors based on no shading at winter solstice noon and sloped at latitude, this paper studied the shading and the radiant energy striking on solar collector array. Based on Kunming solar radiation data, the annual and monthly solar radiant energy striking on multi-array collectors was analyzed and estimated, from no shading to partial shading by adding 1-3 collector row, at the slopes of 10°, 15°, 20°, 25°, 30°, 35° and 40°, respectively. The results showed that properly increasing the row number by reducing the slope of collectors was reasonable in order to get more annual radiant energy. Adding 1 row at 10° of slope was economical for Kunming, based on the 5-row array at 25°. And adding collector row by 20% at 10° of slope could increase the radiant energy striking on the array by 19%.

高温环路热管设计方法研究与传热极限分析

高超声速飞行器在以高超声速飞行时尾喷管会面临严酷的燃烧热考验,结合高温热管导热性强和环路热管传热距离长等优势,高温环路热管可以作为尾喷管热防护的新方法.根据液态钠高导热系数及高表面张力的物性设计了一种新型蒸发器,提出了一套高温环路热管的设计流程.使用这套设计流程设计了一根高温环路热管,结合热管传热极限的计算方法,对钠热管进行仿真计算,分析了温度和结构对热管传热极限的影响.研究发现在高温环路热管的运行温区内,热管的传热性能随着温度升高一般由声速极限、毛细极限和沸腾极限依次决定.结合研究结论提出了热管结构优化方法,为热管设计提供了理论依据.

关于耐火风管的特性研究

目前,工程中耐火风管只关注耐火极限,缺少抗震、隔热、燃烧性能方面的要求,造成耐火风管的部分性能不符合规范要求。针对此问题,结合规范要求,对耐火极限、抗震性能、隔热性能、燃烧性能对耐火风管的特性进行研究,给出了相应的指标要求。

绝热段阻力对CO_(2)、R134a和R410A分离式热管传热性能的影响

通过实验研究了上升管和下降管阻力对CO_(2)、R134a和R410A分离式热管传热性能的影响,分析了热管传热极限和传热热阻的变化规律。研究发现阻力变化对不同工质热管的影响不同,对于CO_(2)热管,上升管阻力和下降管阻力对其传热性能的影响程度接近,当上升管或下降管阀门开度从90°降至30°时,CO_(2)热管的传热极限均由1200 W降为700 W。对于R134a和R410A热管而言,上升管阻力对其传热性能的影响更大,当上升管阀门开度从90°降至30°时,R410A热管的传热极限由1300 W降为700 W,R134a热管则未出现正常运行状态,管内始终存在较大的过热过冷度,两种热管的传热热阻也显著增大。而下降管阻力增大对R134a和R410A热管的传热性能几乎无影响。因此,在实际工程设计中,CO_(2)热管应采用上升管和下降管管径相同或相近的结构,而R134a和R410A热管适合采用上升管管径明显大于下降管管径的结构,以达到节省管材的目的。

常用航天铝合金热渐进成形极限的研究进展

铝合金因其轻质、高强、良好的加工性能以及优异的耐腐蚀性,在航天领域得到了广泛的应用。随着科技的进步和航天技术的发展,对铝合金材料的性能要求越来越高,促使铝合金材料不断向高性能、轻量化的方向发展。热渐进成形作为一种先进的板料成形技术,为航天用铝合金零件的制造提供了新的解决方案,并获得了当今学者的广泛关注。根据渐进成形加热方式不同,总结了近年来典型的加热方法为电加热、激光加热、电磁感应加热。在此基础上,综述了铝合金热渐进成形极限方面的研究,并总结了多种工艺参数对材料成形极限的影响规律。

北方煤矿矿井乏风余热回收换热器设计与试验

在煤矿乏风余热利用领域,换热器乏风风阻利用不充分,导致传热系数通常较低。针对以上问题,基于乏风压降不高于200 Pa的限制条件,进行了煤矿乏风余热利用换热器的设计。提出了基于换热管压降约束的圆管顺排设计方法,分析获得了竖-横向管心距比为5∶8的圆管顺排结构的换热器;二次开发了基于Excel VBA的多变量寻优、多方案比对的自动化方案决策工具,实现了陕煤榆林红柳林煤矿二号风井换热器等3个换热器近百个设计方案的选优,并在柠条塔煤矿南翼风井和红柳林煤矿二号风井完成了建造安装。红柳林煤矿二号风井安装的圆管顺排换热器的数据采集与分析表明,与合阳煤矿方管堆砌换热器传热系数17 W/(m^(2)·K)相比,其传热系数提升了近76%,达到30 W/(m^(2)·K);与红柳林煤矿原二号风井口锅炉年运行能耗7.65×10^(6) kWh相比,节约了近81%,仅为1.47×10^(6) kWh。圆管顺排换热器年实际热回收量为1.79×10^(6) kWh,柠条塔煤矿南翼风井换热器年实际热回收量为1.16×10^(6) kWh。将圆管顺排换热器在北方地区所有煤矿广泛推广后,预计每年可回收热能1.09×10^(10) kWh,减少8.64×10^(6) t二氧化碳、2.36×10^(6) t碳粉尘、2.6×10^(5) t二氧化硫、1.3×10^(5) t氮氧化物的排放。

井下大型排水泵站电动机外部水冷却系统设计

井下大型排水泵站装机容量大,设备发热量大,散热条件差,为防止泵站内空气温度超限,水泵机组配套水冷电动机,采用外部水冷却系统对电动机进行降温,将电动机工作过程中产生的热量排出至泵站外。文章以雅店煤矿实际工程为例,通过计算冷却系统所需换热能力、冷却水量,提出开式直排和二次换热两种方案,并经技术经济方案对比,确定采用二次换热冷却系统方案。依据确定的技术方案和设计原则,笔者对冷却系统换热、加压、过滤、循环、定压补水、控制等设备进行计算选型。

可燃制冷剂在轨道交通车辆空调中的应用

[目的]为分析轨道交通车辆空调中的可燃制冷剂允许充注量,需研究可燃性环保制冷剂在轨道交通车辆空调中安全应用的可行性及方案。[方法]分析空调的安装场所及访问类别,结合不同可燃制冷剂热物性,计算当前轨道交通车辆空调中制冷剂的允许充注量。进一步通过空调间接换热系统的设计,提高轨道交通车辆空调中可燃制冷剂充注量限值,并就不同制冷剂的空调性能进行对比分析。[结果及结论]不同燃烧等级的制冷剂在轨道交通车辆空调中的允许充注量不尽相同,基于制冷剂燃烧下限的限制,可燃制冷剂在轨道交通车辆空调中难以直接使用,而通过间接换热设计可以有效提高可燃制冷剂在空调中的允许充注量,解决制冷剂燃烧性带来的安全风险问题,实现环保制冷剂在轨道交通车辆空调上的应用。