小型冷库化霜新方法

冷库的制冷系统工作时,蒸发器表面温度通常在零度以下。因此,蒸发器要产生结霜情况,而霜层热阻较大,所以在结霜较厚时需进行必要的化霜处理。 冷库的蒸发器按其结构分为墙排管式和翅片式,墙排管式为自然对流换热,翅片式为     

单管多翅片排管蒸发器传热性能实验研究

针对食品冷链系统用传统排管蒸发器传热效率低、管材消耗量大等问题,采用ASHRAE 75～77标准中规定的热平衡法,在0℃和-18℃库温分别对应的5个不同蒸发温度下,对冷库用单管双翅片排管蒸发器和单管八翅片排管蒸发器的翅片效率、传热系数和制冷量进行实验研究.结果表明:单管八翅片排管蒸发器的平均翅片效率为96.03％,比单...     

管排数对变频空调系统翅片管蒸发器性能影响研究

通过对2排管和4排管翅片管蒸发器进行实验研究,以确定管排数在变频制冷工况下对翅片管换热器的影响。结果表明管排数对蒸发器换热量影响比较明显,平均单位管排换热量和传热系数2排管的均大于4排管的,析湿工况下2排管的空气侧压降小于4排管的空气侧压降,并随着压缩机频率的增加更明显。     

低温冷库中冷风机与排管基于工程实例的全周期分析对比

作为制冷四大件之一的蒸发器,在整个制冷系统中起到了至关重要的作用,在冷库上最常见的两种蒸发器是冷风机和排管.库内选用冷风机还是排管各有优缺点,本文从结构、投资、运行等方面进行分析.     

单回路蒸发器流程布置方案的研究与探讨

基于湿球温度效率法,建立了蒸发器的稳态分布参数模型.运用该模型详细分析了六种不同流程布置的单回路两排管蒸发器的换热和流动特性,得出了一些实用性的结论.该研究方法为蒸发器流程布置的优化设计提供了理论基础和指导方向.     

某大型冷链物流中心肉类冷藏库的几点创新做法

针对某大型冷链物流中心肉类冷藏库项目定位及经营模式特点,进行了"定制化"的创新设计,采用土建式外围墙体与钢构装配式顶棚板相结合的建筑结构,使用冷风机和顶排管双蒸发器设计,采用下沉式装卸坡道并使用更加合理的仓租"计费"方式,打破了传统的冷库设计模式,促进了冷链产业技术装备转型升级。     

满液式供液系统中氨液分离器保温问题初探

在冻结装置中,有一种特殊形式的重力供液即满液式供液,它是将氨液分离器与蒸发器设在同一层上,利用液体的均压作用,使氨液分离器和蒸发器内液面趋向一致,它的液面高度保证排管容积的60～80％存有液体。其优点是可以免除重力供液系统中静液柱压力对蒸发压力的影响,保证系统达到所设计的蒸发温度,同时可以节约建筑投资。 在满液式供液系统中,氨液分离器必须靠近蒸发器,所以,目前在冻结库中,一般采用将氨液分离器设置于冻结间内的方案。在冻结间内氨液分离器是否需要做     

冷却排管设计、选择要点

冷却排管是蒸发器家族中最简单、实用的一种，也是最为成熟的一种。所以在设计、选择往往考虑不会太过深入研究，本文从制冷剂和润滑油（冷冻油）的物性和互溶性的关系，强调在设计中就需注意最大限度地剔除蒸发器的含油量（内因）；加强回油装置或措施（外因）。使冷却排管达到最佳的换热效果。     

具有180度突转的矩形流道内两相流动与换热数值模拟

汽车空调层叠式蒸发器采用板式Ｕ形流道,流道隔板的深度直接影响层叠式蒸发器的局部换热,了解制冷剂在Ｕ形流道内的两相流动情况对蒸发器优化设计及进行防结霜优化控制非常重要,本文采用数值计算方法,对具有１８０度突转的矩形流道内制冷剂两相流动情况进行了模拟,对层叠式蒸发器内的制冷剂两相流动特点进行了分析,对隔板深度的影响进行了探讨,为层叠式蒸发器的优化设计与防结霜控制提供理论参考。     

冷藏车制冷系统应用层叠式蒸发器与管翅式蒸发器的模拟比较

对一台应用于汽车空调系统的层叠式蒸发器在结构上做一定的改进,并用数值模拟的方法对其应用于冷藏车冷藏蒸发器时的传热和流动性能与传统的管翅式蒸发器进行了比较,结果表明,在冷藏工况范围内,层叠式蒸发器的换热性能优于管翅式,结构也更为紧凑,应用于冷藏车制冷系统会大大提高系统的效率和经济性。     

Heat Transfer in Meshed Metallic Materials with Interchannel Transpiration and Two-Dimensional Intermesh Flow of a Heat-Transfer Fluid

Some experimental data on the heat transfer in different meshed metallic materials with interchannel heat-transfer fluid transpiration and two-dimensional intermesh flow are presented. It is established that the thermal conductivity of a wire mesh material and the relative pathway, intermesh velocity, and thermophysical properties of a heat-transfer fluid has an effect on the heat transfer in meshed metallic materials with the two-dimensional flow of a single-phase heat-transfer fluid.     

传热管道设备的内壁状态监测方法

在特定边界条件下对热传导方程进行求解,优化所得温度分布方程的系数,并利用分段积分法对系数进行化简,建立了传热管道设备表面温度、材料特性与内壁状态3者间的关联模型,并将其应用在传热管道设备的内壁状态监测上。结合导热反问题,利用所建立的关联模型分析传热管道设备外表面的温度数据,得到内壁几何形状。通过仿真实验验证了该方法的可行性,从而为传热管道设备内壁状态的实时监测提供依据。     

Heat transfer between a fluidized bed and an immersed cylinder

An analytical formula is given for the heat-transfer coefficient as a function of the frequency of density fluctuations in a fluidized bed and of the radius of curvature of the heat-transfer surface. Calculation coincides with the experimental data.     

Pressure-drop reduction and heat-transfer deterioration of slush nitrogen in horizontal pipe flow

Cryogenic slush fluids such as slush hydrogen and slush nitrogen are two-phase, single-component fluids containing solid particles in a liquid. Since their density and refrigerant capacity are greater than those of liquid-state fluid alone, there are high expectations for the use of slush fluids in various applications such as clean-energy fuels, spacecraft fuels for improved efficiency in transportation and storage, and as refrigerants for high-temperature superconducting equipment. Experimental tests were performed using slush nitrogen to obtain the flow and heat-transfer characteristics in two different types of horizontal circular pipes with inner diameters of 10 and 15 mm. One of the primary objectives for the study was to investigate the effect of pipe diameter on the pressure-drop reduction and heat-transfer deterioration of slush nitrogen according to changes in the pipe flow velocity, solid fraction and heat flux. In the case of an inner diameter of 15 mm, pressure drop was reduced and heat-transfer characteristics deteriorated when the pipe flow velocity was higher than 3.6 m/s. On the other hand, in the case of an inner diameter of 10 mm, pressure drop was reduced and heat-transfer characteristics deteriorated when the pipe flow velocity was higher than 2.0 m/s. From these results, it can be seen that a larger pipe diameter produces a higher onset velocity for reducing pressure drop and deteriorating heat-transfer characteristics. Furthermore, based on observations using a high-speed video camera, it was confirmed that pressure drop was reduced and heat-transfer characteristics deteriorated when the solid particles migrated to the center of the pipe and the flow pattern of the solid particles inside the pipe was pseudo-homogeneous.     

计算机CPU热管散热器换热性能研究

电子计算机的集成化发展对CPU散热器传热性能提出了新的要求,散热器表面最高温度和表面均温性是保证CPU正常运行的重要参数。本文运用ANSYS软件对CPU热管式散热器和普通翅片散热器进行计算,对二者稳态温度场分布和不同功率下散热器中心点温度变化进行了分析比较,计算结果表明,在稳定状态时,热管式散热器比普通翅片散热器具有更好的热传导性能和表面均温性;在CPU高功率工作（50W）时,普通翅片散热器无法满足换热要求,而热管式散热器仍可达到良好换热效果。搭建实验台对热管式散热器表面温度进行了测定,实验测试数据与模拟计算数据基本吻合,证明了数值模型的正确性和可行性。本研究对于计算机CPU散热器传热性能分析及其优化设计具有一定指导意义。     

Heat exchange of dynamic powder beds with a heat-transfer surface. I. A helical screw conveyer and a horizontal rotating cylinder

Heat exchange of dynamic (mixing) beds of powders with heat-transfer surfaces in a tube with a helical conveyer and in a rotating smooth horizontal cylinder is studied by experimental methods. The heat-transfer coefficients as functions of the regime of powder motion are obtained.     

Determination of surface heat-transfer coefficients of steel cylinder with phase transformation during gas quenching with high pressures

In numerical simulation of quenching process, the boundary conditions of temperature field and stress field are very important, in which the boundary conditions of temperature field are very complicated. In order to simulate the thermal strains, thermal stresses, residual stresses and microstructure of the steel during gas quenching by means of the numerical method, it is necessary to obtain an accurate boundary condition of temperature field. The surface heat-transfer coefficient is a key parameter. The explicit finite difference method, non-linear estimate method and the experimental relation between temperature and time during quenching have been used to solve the inverse problem of heat conduction. The relationships between surface temperature and surface heat-transfer coefficient of cylinder have been given. The non-linear surface heat-transfer coefficients include the coupled effects between phase transformation and temperature. In calculation, physical properties were treated as the function of temperature and volume fraction of constituent. The results obtained have been shown that this technique can determine effectual the surface heat-transfer coefficients during gas quenching.     

Methods of Energy Auditing for Dwellings

Basic methods are given for energy auditing on dwellings. The heat-transfer resistances of surface structures are basic characteristics to be determined in energy auditing for dwellings and industrial buildings. Details are given of the measurement system and methods of making heat-transfer resistance measurements on the outside structures in two dwellings.     

Heat liberation during vapor condensation in a thermosiphon

A method is described for calculation of the heat-transfer coefficient during condensation of vapor of singlecomponent and binary heat-transfer agents in a thermosiphon. Results of processing experimental data are presented.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 43, No. 3, pp. 385–390, September, 1982.     

斯特林制冷机真空环境热模拟试验研究

为了验证空间斯特林制冷与辐射制冷、实现复合制冷系统的可行性,获取斯特林制冷机在真空条件下的散热情况,进行了斯特林制冷机空间真空环境热模拟试验。试验结果表明,真空条件下斯特林制冷机的散热是影响制冷机性能的重要因素。