Technology and Studies for Greenhouse Cooling

Greenhouse technology is an efficient and viable option, especially for the sustainable crop production in the regions of adverse climatic conditions. High summer temperature is one of the worst effects on greenhouse crop production throughout the year. The main purpose of this paper is to present some technologies and studies for greenhouse cooling in summer. In the paper, some applicable and practical cooling technologies have been discussed. The choice of efficient cooling method depends on many aspects, such as local climate, agronomic condition, design and covering materials. To achieve desirable benefits, the combination of different cooling methods is necessarily used. Analysis of earlier studies revealed that a naturally ventilated greenhouse with larger ventilation areas (15% - 30%), provided at the ridge and side covered with insect-proof nets of 20 - 40 mesh size with covering material properties of NIR (near infrared radiation) reflection during the day and FIR (far infrared radiation) reflection during night was suitable for greenhouse production throughout year in some special regions. Evaporation cooling is the most effective cooling method for controlling the temperature and humidity inside a greenhouse. However, its suitability is restricted to the respective region and climate when the humidity level is high. The entry of unwanted radiation or light can be controlled by the use of shading. Researches show that shade net application with different perforated mesh size and their evaluation with respect to local climate and region are necessary to get cooling benefits in summer.

Achieving Cooler Soil as an Effective Heat Sink for Earth-to-Air Heat Exchanger (EAHE) Cooling Technology in Malaysia Tropical Climate

This research is intended to explore the capacity of Malaysia soil in becoming a more effective heat sink for the application of Earth-to-Air Heat Exchanger (EAHE) Cooling Technology in Malaysia. EAHE Cooling Technology consists of buried pipes underground where the ambient air is channeled through from the pipe inlet and produces cooler air at its outlet. Within the buried pipes, heat exchange process occurs between the air and the soil that surrounding the pipe. This building cooling technology has been applied in many countries, mostly in temperate or hot and arid climate where the diurnal temperature is large. However, minimal resources were found on the study of EAHE application to buildings in Malaysia, hence there is room to develop. A parametric study on EAHE cooling application in Malaysia was done through field experiment and concluded that among many parameters affecting the technology performance, the soil temperature which surrounded the pipe was the most influential factor. The study recommended to further reduce the soil temperature to achieve a cooler outlet temperature. In response to that, this research conducted a parametric study of soil temperature under three different soil surface conditions: bare, shaded with timber pallettes and insulated with used tyres at 1.0 m and 1.5 m underground. The data was logged for a month and the result has shown significant reduction in the soil temperature underground below the shaded and insulated soil surface as compared to below bare soil surface condition. The insulated soil surface produced the best result where the soil temperature was reduced up to 26.9°C. The main contribution of this paper is to highlight that the soil surface treatment can be used to reduce solar heat gain within the soil underground and thus improving the performance of EAHE Cooling Technology particularly for the application in Malaysia tropical climate.

Fluid flow characteristics of single inclined circular jet impingement for ultra-fast cooling

The fluid flow characteristics of the single bunch inclined jet impingement were investigated with different jet flow velocities,nozzle diameters,jet angles and jet-to-target distances for ultra-fast cooling technology.The results show that the peak pressure varying significantly from nearly 0.5 to above 13.4 kPa locates at the stagnation point with different jet diameters,and the radius of impact pressure affected zone is small promoted from 46 to 81 mm in transverse direction,and 50 to 91 mm in longitude direction when the jet flow velocity changes from 5 to 20 m/s.However,the fluid flow velocity is relatively smaller near the stagnation point,and increases gradually along the radius outwards,then declines.There is an obvious anisotropic characteristic that the flow velocity component along the jet direction is about twice of the contrary one where the jet anlge is 60°,jet diameter is 5 mm,jet length is 8 mm and jet height is 50 mm.

Case-Based Reasoning(CBR) Model for Ultra-Fast Cooling in Plate Mill

New generation thermo-mechanical control process（TMCP） based on ultra-fast cooling is being widely adopted in plate mill to product high-performance steel material at low cost. Ultra-fast cooling system is complex because of optimizing the temperature control error generated by heat transfer mathematical model and process parameters. In order to simplify the system and improve the temperature control precision in ultra-fast cooling process, several existing models of case-based reasoning（CBR） model are reviewed. Combining with ultra-fast cooling process, a developed R5 CBR model is proposed, which mainly improves the case representation, similarity relation and retrieval module. Certainty factor is defined in semantics memory unit of plate case which provides not only internal data reliability but also product performance reliability. Similarity relation is improved by defined power index similarity membership function. Retrieval process is simplified and retrieval efficiency is improved apparently by windmill retrieval algorithm. The proposed CBR model is used for predicting the case of cooling strategy and its capability is superior to traditional process model. In order to perform comprehensive investigations on ultra-fast cooling process, different steel plates are considered for the experiment. The validation experiment and industrial production of proposed CBR model are carried out, which demonstrated that finish cooling temperature（FCT） error is controlled within±25℃ and quality rate of product is more than 97%. The proposed CBR model can simplify ultra-fast cooling system and give quality performance for steel product.

Electrocaloric cooling technologies for a sustainable world

Our societies are highly dependent on reliable cooling for air conditioning(AC)and refrigeration.Currently,modern cooling is supported by a 19th century technology:vapor compression cycle(VCC)-based cooling.Refrigerants used in the VCC cooling are strong greenhouse gases and thus are among the leading causes of global warming.The electrocaloric(EC)cooling is attractive as an alternative to the VCC cooling.EC cooling is environmentally benign,compressor-free,highly scalable,and has the potential of achieving higher efficiency than VCC cooling.The active EC materials research since the late 2000s has created several EC materials that exhibit giant electrocaloric effect(ECE)(by direct measurement).These EC materials have enabled the demonstration of EC cooling devices that exhibit temperature lifts of more than 8 K.These EC materials and device research reveals the promise of fer-roelectric materials in generating giant ECE at low electric fields and EC cooling devices achieving high performance.This review highlights these advances and offers perspectives of the EC cooling technologies.

HEAT TRANSFER CHARACTERISTICS OF NEW COOLING TECHNIQUE BASED ON THERMAL DRIVING

A new cooling technique based on thermal driving in high centrifugal field （TDHCF） is developed for gas turbine rotational components, such as turbine blades. The key point of TDHCF is to enhance heat transfer by the fluid thermal driving in closed loop small channels placed in the high centrifugal field. Heat transfer characteristics of the new cooling technique are analyzed. In experiments, two different fluids （liquid water and Freon R12） are used as thermal driving media （fluid inside the loop channel）. And the channel width d is 1 mm and the height h is 30 mm. The temperature is measured by thermocouples and an average heat transfer coefficient KH is defined to indicate heat transfer capacity of TDHCF. Experimental results show that KH is enhanced when heat flux and the rotating speed increase. And thermal properties of thermal driving media are also influenced by KH. Larger KH can be achieved by using Freon R12 as thermal driving medium compared with using liquid water. It can increase to 2 300 W/（m^2 · K） and it is much higher than that of the normal air cooling method （usually at the level of 600-1200 W/（m^2·K））. All fundamental studies of TDHCF show that there actually exists thermal driving in the closed loop small channel in the centrifugal field to improve heat transfer characteristics.

Microstructure and Mechanical Properties of Nb-B bearing Low Carbon Steel Plate: Ultrafast Cooling versus Accelerated Cooling

The microstructure and mechanical properties of low carbon bainite high strength steel plate were studied via different cooling paths at the pilot scale. There was a significant increase in mechanical properties, and notably, the yield strength, tensile strength, and toughness at-40 ℃ for the tested steel processed by ultra-fast cooling were 126 MPa, 98 MPa and 69 J, respectively, in relation to steel processed by accelerated cooling. The ultra-fast cooling rate not only refined the microstructure, precipitates, and martensiteaustenite（M/A） islands, but also contributed to the refinement of microstructure in thick plates. The large size M/A constituents formed at lower cooling rate experienced stress concentration and were potential sites for crack initiation, which led to deterioration of low-temperature impact toughness. In contrast, the acicular ferrite and lath bainite with high fraction of high-angle grain boundaries were formed in steel processed by ultra-fast cooling, which retarded cleavage crack propagation.

Nozzle Spray Diffusivity Changing Law for Ultra Fast Cooling in Hot Strip Mill

Slot nozzle and intensive nozzle can be used in ultra fast cooling equipment. The spray cooling method with higher water pressure can be taken in order to achieve ultra fast cooling for hot rolled strip. Water will be diffused after it is sprayed out from ultra fast cooling nozzle. Spray diffusivity will affect water velocity and penetrability of water into residual water layer on top of the strip,and then it will affect strip cooling effect. Water spraying process can be simulated by Fluent and some conclusions were obtained. Slot nozzle width and outlet velocity within setting range could not affect the length of potential core zone and the spray diffusivity. Intensive nozzle diameter and outlet velocity will affect the length of potential core zone and the spray diffusivity with different extent. These conclusions will provide referenced role for confirming ultra fast cooling nozzle size and distance between ultra fast cooling nozzle and hot rolled strip.

X-COOL凉爽纤维针织面料的生产工艺

采用8.3tex X-COOL凉爽纤维纱为原料,根据原料规格、设备参数、线圈结构.开发具有保健功能的罗纹空气层针织面料.分别使用Na2CO3、30%H2O2、分散黄GD对该罗纹空气层针织面料进行高温高压煮练、漂白、染色以及定形等染整工艺,研究煮练、漂白、染色对X-COOL凉爽纤维针织面料白度、顶破强力及染色性能的影响,并对该面料的凉爽性进行测试.结果表明,在该生产工艺下,X-COOL凉爽纤维面料最终强力达到698.5N,上染率78.90%,K/S值为2.684,缩水率横向为-1.86%,纵向为1.16%,符合服用性能的要求,同时其独特的功能性更适应开发具有较高附加值的服装面料.

Fundamental Research on Convective Heat Transfer in Electronic Cooling Technology

During the past six years comprehensive research programs have been conducted at the Beijing Polytechnic University to provide a better understanding of heat transfer characteristics of existing and condidate cool- ing techniques for electronic and microelectronic devices.This paper provides a review and summary of the programs with emphasis on direct liquid cooling.Included in this review are the heat transfer investigations related to the following cooling modes:liquid free,mixed and forced convection,liquid jet impingement,flowing liquid film cooling,pool boiling,spray cooling,foreign gas jet impingement in liquid pool,and forced convection air-cooling.

Effect of Ultra-Fast Cooling on Microstructure of Large Section Bars of Bearing Steel

The ultra-fast cooling technology of large section bars and the microstrueture for different cooling patterns were studied by optical microscope, transmission electron microscope and energy spectrometer. The results indicated that the large section bars were passed through the zone of secondary carbide precipitation quickly by ultra-fast cooling technology （UFC） at instantaneous cooling rate of about 200 ℃/s and the finishing cooling temperature was higher than Ms. The lamellar spacing of pearlite decreased and the microhardness increased with decreasing the rereddening temperature. The precipitation of network carbide was restrained when re-reddening temperature was 690 ℃. And fine laminated pearlite was obtained through transformation of pseudopearlition that induced the reduction of the diameter of pearlite grain and refinement of the lamellar spacing of pearlite, so ideal microstructures of promoting spheroidizing annealing were obtained.

Comparison and suggestion of rail transit equipment cooling technology

The paper introduces the developmentcourse of rail transit equipment cooling technology athome and abroad, compares and analyzes the coolingmodes, and proposes the suggestion for technologyresearch and product development of cooling system.

粮仓能源桩系统绿色储粮技术应用研究

简化粮食入库后全周期控温供冷储粮流程,提出满仓主动降温与夏季粮仓热平衡2种供冷方案。通过理论公式计算2种方案下的供冷量需求,并利用有限元模拟软件计算得出能源桩换热量,由此设计可满足上部粮仓供冷需求的能源桩运行方案。结果表明:在1万t储粮规模下,粮仓能源桩储粮技术可满足2种供冷方案下的能源需求,对比谷物冷却机与地源热泵储粮,其初期投入成本更低;对比空调储粮,其初期投入成本增加,但能源桩储粮技术可利用绿色清洁能源,储粮能耗最低。

热管冷却反应堆系统研究进展和挑战

热管是一种高效的非能动热量传递元件,热管冷却反应堆核动力系统在多场景特种应用领域具备独特优势。本文概述了热管冷却反应堆特种核动力系统发展情况。首先介绍了热管冷却反应堆概念提出以及在海陆空天等领域的应用场景分析,同时总结了国内外典型堆型的发展现状。其次探讨了当前热管冷却反应堆面临的关键技术挑战,包括高性能材料研究、高性能热管研制、高效能量转换技术研究、设计分析技术研究。最后对未来发展趋势进行了分析和展望,强调了整体系统一体化研制、发电器件特性研究以及智能自主控制技术在热管冷却反应堆领域的重要性。本文的系统性总结将推动热管冷却反应堆技术的进一步发展,为未来特种核动力系统的应用提供重要支持。

冷却工艺、填充溶剂对钙钛氧化物的微观形貌及光催化性能的影响

以钛酸正丁酯和无水氯化钙为原料,采用水热法制备了不同显微形貌的钙钛氧化物粉体。研究了冷却工艺与填充剂种类对钙钛氧化相结构、显微形貌和光催化特性的影响。结果表明:当无外加填充溶剂引入,采用不同冷却工艺均可获得具有片状结构的CaTi_(2)O_(4)(OH)_(2)纯相;当分别引入20 mL乙醇或水作为填充溶剂时,制备的粉体相结构和微观形貌在不同的冷却工艺下存在较大差异,粉体的相结构和微观形貌经历了从无定型相的针网状形貌过渡到由纳米纤维聚积夹杂少量块状CaTiO_(3)物相组成的形貌,以及完全由具有片状结构的CaTi_(2)O_(4)(OH)_(2)物相过渡到具有片状结构的CaTi_(2)O_(4)(OH)_(2)以及少量方块状CaTiO_(3)组成的物相。光催化性能显示,引入20 mL乙醇作为填充溶剂,采用缓冷工艺制备的粉体在紫外可见光3 h下对罗丹明B的光催化效率最佳。

汽车发动机冷却系统故障诊断及维修关键技术探索

文章首先阐述了汽车发动机冷却系统的概念,介绍了该系统的设计原理及工作特点,在此基础上总结了系统故障成因,综合分析了导致冷却系统故障的各种因素及其具体表现,针对这些情况,提出针对性的诊断和维修关键技术。这不仅能显著提升发动机的功率和效率,还能降低系统故障率,提高车辆的可靠性,同时实现安全、节能和延长发动机寿命的目标。

干热岩定向钻井关键技术研究与应用

为推动干热岩产业化步伐,中国地质调查局在青海共和盆地部署了我国首例干热岩试验性开发工程,采用一口直井注入和两口定向井采出的开发模式,文章就定向井钻井关键技术进行研究与应用。青海共和盆地干热岩主要为花岗岩,地层硬度大、研磨性强、温度高,加上大规模储存改造的影响,定向井钻井作业存在机械钻速低、碎岩工具寿命短、测量仪器耐温差、信号不稳定、井眼轨迹控制难度大等技术难题。为保证钻井作业顺利推进,从井眼轨迹控制、提高井下工具耐温耐磨能力、提高钻井液高温流变性能、钻井液主动降温等技术手段入手,创新研发了耐高温MWD、抗高温聚合物钻井液体系、螺旋板式钻井液冷却装置等关键技术与装备,优选了“牙轮钻头+单弯螺杆+MWD”钻具组合,安全高效地完成了双靶点定向井施工,AB靶心的中靶精度分别为4.85 m和8.97 m,钻井周期缩短20%以上,并取得了最高进尺175.00 m、最快机械钻速3.74 m/h的提速增效成果。

新能源汽车动力电池冷却技术研究综述

通过综述新能源汽车动力电池冷却技术包括空气冷却技术、液体冷却技术、变相材料冷却、热管冷却技术以及冷媒直冷冷却,分析各种技术的优势、劣势及应用情况,总结动力电池冷却技术的研究现状并对其发展趋势进行展望。未来,新能源汽车动力电池冷却技术需要对冷却介质进行研发,以取代现有的液冷系统,同时还需要将两种及以上的冷却方式相结合并研究更高效灵敏且智能化的预警装置,以得到更好的冷却效果。

国内铜板带发展现状与热轧技术的创新方向分析

文章论述了国内铜板带行业的发展现状,指出铜板带的热轧应分别从理论和技术,生产和工艺,设备设计制造,生产线配置和工程设计等方面进行基础性的研究和改进,并在工程项目的实践中不断创新。