苏北地区日光温室能量分配动态研究

为了进一步提高日光温室保温性能,减轻温室内低温寡照灾害发生,以苏北（徐州）番茄日光温室为研究对象,利用采集的2010年12月-2011年4月温室小气候数据及番茄发育数据,根据日光温室小气候形成的物理过程与机理,系统研究了冬春季节不同天气类型及不同叶面积指数对温室能量分配的影响。结果表明：日光温室内潜热、显热随着室内总辐射量的改变而发生变化,阴天以显热消耗为主,潜热消耗量全天低于显热;晴天日光温室内用于作物蒸腾的能量显著多于阴天,阴天室内外贯流传热消耗的能量远远多于晴天;随着叶面积指数增大,到达地面的太阳辐射减少,地面升温慢,室内空气与地表的显热交换量减少,同时室内空气与墙体的显热交换增加。本研究结果可为温室的结构优化及冬春季节日光温室管理提供科学依据。     

Comparative Analysis of Heat Exchange Performance ofEnergy Piles and Borehole Heat Exchangers in GSHP System

Due to their enhanced cost-effectiveness and efficiency over traditional borehole exchangers, energy piles are increasingly used in Ground Sourced Heat Pump (GSHP) projects. In this paper, the structural characteristics of these two types of heat exchangers and their heat transfer mechanism were discussed firstly. The thermal response tests (TRT) were performed on two testing energy piles in one GSHP project in Nanjing, China. The TRT results were then used to verify the numerical simulations, which suggests that the heat exchange performance of energy piles is superior to that of the traditional borehole exchangers. Meanwhile, the numerical simulation method used in this paper was considered applicable to the optimization design of ground heat exchangers in GSHP 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.     

武汉与重庆典型地质结构下的地埋管换热性能

地埋管地源热泵换热器的换热性能受到不同地质结构的影响。以武汉和重庆地区的典型地质构成为边界条件,建立了三维地埋管的单孔双U管换热模型,通过模型计算,获得了两种地质条件下的地埋管换热性能,以重庆地区的地源热泵热响应测试结果以及工程运行数据出发,对模型的计算结果进行了验证,结果表明,模型吻合度较好,可以应用于工程分析。以模型为条件,进行地质结构对换热性能的影响度分析,预测了两地地埋管地源热泵的换热性能并计算得到换热器的平均换热系数分别为武汉地区K₁=1.65（W/m·K）,重庆地区K₂=1.51（W/m·K）。     

Study on Heat Transfer Characteristics in Waste Gas of the Exchanger

By the calculation and experiment,analysed the heat transfer characteristies in waste gas of the high temperature exchanger.The results which the reasonable vertical and horizontal distances were obtained,these turned out that the metallic rediation net was the effectve method intensified heat transfer in hot waste gas.The infulence of the velcity and temperature of waste gas on the multiple heat transfer caefficrent of the exchanger was studied by the experiment data.     

Heat tolerance in spring wheat. I. Estimating cellular thermotolerance and its heritability

High temperature is a major environmental stress factor limiting wheat (Triticum aestivum L.) productivity. Improvement of heat tolerance in wheat is an important breeding objective. Genetic variation in cellular thermotolerance among 56 spring wheat cultivars was evaluated at the seedling stage of growth by cell membrane thermostability (CMS) and triphenyl tetrazolium chloride (TTC) assays. A subset of eight lines was also evaluated at the flowering stage using the same assays. With both assays Average thermotolerance tended to decrease from the seedling to the flowering stages. However, thermotolerance was well correlated between growth stages among the eight cultivars for both CMS (r = 0.92; p = 0.004) and TTC (r = 0.84; p = 0.050). The correlation between TTC and CMS among the eight cultivars tested at the seedling and the flowering growth stages was significant (r = 0.74; p = 0.031 and r = 0.75; p = 0.029, respectively). The same correlation was less strong, though still significant (r = 0.32; p = 0.014) across 56 cultivars at the seedling stage. In a study of the cross V747 (tolerant)/Barkaee (susceptible), broad sense heritability was estimated at 89% for TTC. Most of the genetic variance was additive. CMS in seedlings of 16 cultivars was positively and significantly (p ≤ 0.05) correlated with yields of these cultivars in each of four hot environments in Mexico, Sudan, India, and Brazil. The same correlations for TTC were positive but nonsignificant. This revised version was published online in August 2006 with corrections to the Cover Date.     

Dynamic Heat Transfer Models for Orthogonal Dry Cutting

The models for dynamic heat transfer of chips and tools are developed based on analysing heat source distributions in orthogonal dry cutting process,and a procedure is proposed to compute the temperature distributions of chips and tools,and the heat partition coefficients between the tools and the chips.     

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.     

巴渝地区夯土民居室内热环境

传统民居的传统生态建造经验与价值已得到广泛认可,巴渝地区因特殊的地形与气候,传统民居在热环境的营造上有自身的特点。以重庆江津区龙塘村夯土民居为研究对象,以实地测量的冬季室内热工参数为基础,运用软件模拟分析,对民居全年室内热环境进行评价,发现夯土墙对改善夏季热环境更为有利,夯土民居冬季室内热环境远比夏季差;民居建筑中阁楼空间在调节室内热环境方面作用显著,具有冬季保温,夏季隔热的作用。     

Performonce of Fouling Fluidized-Removing and Heat Transfer Enhancement on Sewage Side of Sewage-Source Heat Pump System

High thermal resistance resulted by fouling in heat exchanger restricts the application of sewage source heat pump (SSHP) system. The fouling forming mechanism was applied with solid-liquid fluidized bed technique for fouling prevention and removing of SSHP system. Shearing stress model of solid-liquid fluidized bed heat-exchanger is analyzed, and collision stress model is modified. Preventing and removing fouling mechanisms of solid-liquid fluidized bed technique by shearing stress and collision stress was explained. An experimental study on how to solve the fouling problem (such as fouling prevention and removing, heat transfer enhancement, etc) is discussed. The results of theory and experiment show that solid-liquid fluidized bed technique can be used not only to increase convection coefficient, but also to restrict fouling growing, it can effectively solve the fouling problem in SSHP system.     

AN EXPERIMENTAL RESEARCH ON ENHANCEMENT OF HEAT TRANSFER OF FINNED TUBES IN REFRIGERANT HEAT EXCHANGER

In this paper,the comparative experimental research that air flows through theout-surface of a single row finned tubes is done in a drawing wind tunnel and the three differnetshapes of rectangluar finned tubes are compared with a plain finned tube that is usually used in therefrigerant heat exchanger, the useful results are obtained. The results show that,in the range ofwind velocity flowing through the marrowest area, W_(max)=2.5m/s to 8.5m/s,the average convec-tion heat transfer coefficient of the two-side V-groove finned tube is higher than that of rectangluarplain finned tube,It is a new type finned tube that has good heat transfer performance and it isworth poplarlzing.     

嗜冷菌及其耐热性酶对乳制品品质的影响

原料乳中的嗜冷菌及其产生的耐热性蛋白酶和脂肪酶是引起液态乳制品多种质量问题的主要原因之一。阐述了嗜冷菌及其耐热性酶的概念及特性,论述了嗜冷菌及其耐热性酶对液态乳制品品质的影响,并对嗜冷菌的检测方法及控制措施进行了展望。     

东北玉米烘干机实施节能减排技术措施

我国东北地区玉米烘干机系统热效率低、能耗高、污染重,对其采取废气回收、烟气余热利用、设备保温处理、改变气流走向、更换分层煤斗和高效换热器等技术措施,收到了明显的节能减排效果。换热器进风口平均风温提高了30℃以上;排烟温度降低了30℃以上;节煤15%以上;废气中的皮屑和粉尘回收率可达80%。既节约了资源,又保护了环境。     

Evaluation of heat stress tolerance in irrigated environment of T. aestivum and related species. I. Stability in yield and yield components

Wheat production is often limited by continual or terminal heat stress. The current study was aimed at the characterization of wild relatives and cultivated Triticum species for their heat tolerance in yield and its analysis in relation to yield components which confer yield stability at the three ploidy levels. Thirty-two non-cultivated and cultivated genotypes belonging to diploid, tetraploid and hexaploid wheat species were evaluated for heat stress tolerance in the field under full irrigation. Wheat species were sown in the field(New Delhi, India; 77°12′E, 28°40′N, 228.6 m m.s.l) at two dates of sowing, November (normal) and January (late Sowing) during winter seasons of 1994–95 and 1995–96. The late sown crop experienced 3°C warmer temperatures than that of the normal sown crop. Wide variability was observed for grain yield stability under heat stress, as the heat susceptibility index (S) ranged from 0.13 to 2.08. Hexaploidy conferred the productive and adaptive advantages as it combined high yield and stability when compared to the tetraploid and diploid groups. However within each ploidy group wide variation was observed for heat tolerance. T. aestivum cv C306 & HI1136, T. dicoccoides, T. monococcum acc. BSP1 and Ae. speltoides ssp. liqustica were highly heat tolerant in their grain yield. Stability in grain no. m- 2 conferred yield stability in all three ploidy levels, although grain weight stability also contributed to yield stability in moderately stable T. turgidum and T. sphaerococcum under heat stress. Higher biomass and grain no. m-2 are the two important traits which could be considered potential selection criteria for yield under heat stress. Of the two components of grain no. m-2, stability in spike no. m-2could be considered more important trait than grain no. spike-1. Since wide variation for heat tolerance of all the yield components are available among the wheat species, these species can be used for improving specific yield components of cultivated wheat. This revised version was published online in July 2006 with corrections to the Cover Date.     

Heat Transfer Performance of Horizontal Enhanced Condenser Tubes

In this paper, experimental results on heat transfer performance of a low integral-fin tube, thermoexcel-C tube (C tube) and a new horizontal double-side enhanced condenser tube (GC tube) have been reported for condensation of R-11. Within our experimental scope,the overall heat transfer coefficient of the GC tube can increase more than 5 times that of the smooth tube . And the relevant friction factor inside the GC tube can be 7 times that of the smooth tube. The Second law of thermodynamics was applied to develop a new criterion to assess the heat transfer performance of the GC tube,the C tube,the low integral-fin tube,and the DAC tube[1] (another doubleside enhanced condenser tube). The result shows the heat transfer performance of the GC tube is superior to the other tubes from a thermodynamical viewpoint.     

Experimental Study of Flow and Heat Transfer in Heat Exchanger with Small Channels

The experimental study of the flow resistance and heat transfer characteristics are conducted for water and ethylene glycol solution (66% Wt) flowing in the heat exchanger with small rectangular microchannels . The heat exchanger having the channels of 0.4 mm in width, 2.0 mm in height, and 20 mm in length is heated by a hearing rod at the bottom surface, the upper and two side surfaces are adiabatic. During experiments, the Reynolds number are ranged from 2 to 2 500. The experimental results show that the flow friction factor decreases and Nusselt number increases with increasing Reynolds number for water and ethylene glycol solution. At a fixed Reynolds number, the Nusselt number for ethylene glycol solution with larger Prandtl number is greater than that for water. Meanwhile, the correlations of flow resistance and heat transfer in the heat exchanger with small channels are obtained for engineering application.     

Entropy Generation Analysis of Heat Transfer Process through a Duct

Based on the first and the second laws of thermodynamic, the entropy generation of heat transfer process from the inside to the outside through a duct is analyzed. A dimensionless entropy generation number based on the fluid of inside duct is introduced and an analytical expression for the dimensionless entropy generation number is obtained. The effect of some dimensionless parameters on the irreversibility performance of heat transfer process through a duct is discussed. The results show that an optimal Reynolds number of fluid inside duct is found to make dimensionless entropy generation number minimum , the dimensionless entropy generation number increases with the increment of the ratio of the Reynolds number of inside and outside duct fluids, dimensionless inlet temperature difference and dimensionless characteristic geometric dimension. The results from this paper provide a reference for the thermodynamic performance evaluation on the basic heat transfer process through a duct and enhancement in double sides of duct.