成型线圈热压型机的设计

简述了成型线圈热压型机的设计。包括设计的出发点 ;热压型机的工作原理与结构 ;调试过程中出现的典型问题及解决措施等方面。

把“炎帝故里”的文章做透——宝鸡旅游业的最佳切入点

全国旅游热点区按区位条件可分为三类:①资源型;②市场型;③资源市场混合型。从国内近年旅游实践看,资源市场混合型的北京,旅游业始终名列第一,饭店业人均实现利润、平均利率等均在全国高居榜首。除首都而外的两大类中,资源型的西安、桂林。

正确用好保安单元

正确认识保安单元的防护过电压过电流的作用是正确选好保安单元用好保安单元的前提和基础.

电阻法测温的原理及数学计算

文中简单介绍了电阻法测量温度的原理,然后从理论和实际应用两方面重点阐述了对电阻法测温所获得数据的处理及数学计算,及回归方程应用于热态线圈电阻的推算。

Fluid Flow and Heat Transfer Characteristic of Outer and Inner Half Coil Jackets

The physical models of the outer and inner half coil jackets were simplified to two types of coiled ducts.The mathematic models of incompressible fluid at the condition of laminar flow and heat transfer in the two types of jackets for cooling process reactor were set up and solved by the semi-implicit method for pressure linked equa-tions consistent （SIMPLEC） algorithm based on a control volume method.The flow and temperature fields were given and the effects of Dean and Prandtl numbers on flow and heat transfer were studied.The results show that flow in the inner half coil jacket is found to exhibit transition of secondary flow pattern from two vortices to four vortices when the Dean number increases,but that in the outer half coil jacket is not found.The critical Dean num-ber is about 96.The inner half coil jacket has stronger heat transfer ability than the outer half coil jacket and this superiority is more evident with larger Prandtl number.However,as the Dean number is greater than 105,the flow resistance enhances more severely in the inner jacket than the outer jacket.For both jackets,the centers of the heated wall are the poorest for heat transfer.

Theoretical and Experimental Study on Ground Coupled Heat Pump with Vertical Spiral Coil

The numeric al simulation study on the temperature distribution of underground field for the ground coupled heat pump (GCHP) with vertical spira l coil was carried out by using finite element. The distribution and recovery of undergroun d field temperature under different operation ratio and the optimal operation ratio were simulated.The performance parameters, i.e. inlet and outlet temperature of the ground spiral coil in heating and cooling modes were tested, the heat extracted or emitted by the heat pump to the ground was calculated, and the coefficients of performance (COP) of GCHP at heat ing and cooling modes were analyzed.

Experimental Verification to Estimate Ground Thermal Conductivity Using Spiral Coil Type Ground Heat Exchangers

This paper presents an experimental study on the evaluation of thermal response of a spiral coil type GHE （ground heat exchanger）. This GHE was installed on partially saturated landfill ground that was composed of silt and clay in the runway area of Incheon International airport. TRT （thermal response test） was conducted for more than 65 hours under continuous operation conditions. Ground thermal conductivity was derived based on line source theory, which has usually been found to be appropriate for line type GHEs such as U, W and 2U types. A reasonable method to derive ground thermal conductivity using the infinite line source theory for a spiral coil type GHE was introduced. Ground thermal conductivity from the TRT using spiral coil type GHE was compared with those from the analytical equivalent model of ground thermal conductivity.

Heat Transfer Behavior in a Square Duct with Tandem Wire Coil Element Insert

Effects of insertion of tandem wire coil elements used as turbulator on heat transfer and turbulent flow friction characteristics in a uniform heat-flux square duct are experimentally investigated in this work. The experiment is conducted for turbulent flow with the Reynolds number from 4000 to 25000. The wire coil element is inserted into the duct with a view to generating a swirl flow that assists to wash up the flow trapped in the duct corners and then increase the heat transfer rate of the test duct. Apart from the full-length coil, 1D and 2D length coil elements placed in tandem inside the duct with various free-space lengths are introduced to reduce the friction loss. The results obtained from these wire coil element inserts are also compared with those from the smooth duct. The experimental results reveal that the use of wire coil inserts for the full-length coil, 1D and 2D coil elements with a short free-space length leads to a considerable increase in heat transfer and friction loss over the smooth duct with no insert. The full-length wire coil provides higher heat transfer and friction factor than the tandem wire coil elements under the same operating conditions. Also, performance evaluation criteria to assess the real benefits in using the wire coil insert into the square duct are determined.

Thermal performances of non-equidistant helical-coil phase change accumulator for latent heat storage

Helical-coil is a common structure of heat exchanger unit in phase change heat accumulator and usually has the equal coil pitch between adjacent coils. Its thermal performances could be improved by improving the uniformity of the phase change material （PCM） temperature distribution. Thus, a novel non-equidistant helical-coil structure was proposed in this study. Its coil pitch decreased along the flow direction of heat transfer fluid, which made the heat exchange area in unit volume increase to match the decreasing temperature difference between the heat transfer fluid and PCM. The structure was optimized using numerical simulation. An experimental system was developed and the experiment results indicated that the proposed non-equidistant helical-coil heat accumulator was more effective than equidistant helical-coil for latent heat storage. The uniformity of the temperaalre distribution was also confirmed by simulation results.