SIMULTANEOUS HEAT AND MOISTURE TRANSFER IN CHEDDAR CHEESE DURING COOLING. II. MRI TEMPERATURE MAPPING

ABSTRACT

Non-destructive Magnetic Resonance Imaging (MRI) techniques were developed to monitor simultaneous heat and moisture transfer in cheese cooling. The FLASH imaging sequence was used to achieve fast data acquisition for temperature images. MRI results of temperature distributions in cheese blocks during cooing are very closed to those from numerical simulation.     

Debottlenecking procedure of effluent thermal treatment system

In this study pinch technology has been improved for wastewater temperature reduction. Having considered design grouping rules on the basis of pinch technology, a new debottlenecking procedure for thermal treatment of the wastewater network, has been introduced. In the presented procedure, better thermal treatment of effluent network using the new method can be used to avoid investment in new cooling tower capacity and to improve the performance of the tower in a systematic way. Related coding in Visual Sudio.Net 2003, C++, has been developed for the illustrative example to get optimal values in the cooling water design method computations.     

Technology of Drying and Thermoaeroseparation

ABSTRACT

The DINC (Direct-Indirect Evaporative Cooling) cycle was proposed in 1986 by Texas A6H researchers. The idea wae to combine the benefits of direct and indirect evaporative cooling with desiccant dehumidifying using a rotating aolid silica-gel dehumidifier. Recent parametric studies completed for the Texas Energy Ramarch In Applications Program have-devoloped a computer desrgn for s nomlnal 3-con system that would minimize the energy conuvmption (both thermal and electric) while mslntainina a sensible heat ratio of 75% or less. That “optimum design” for the original 1986 DINC cycle wae modified to improve ite energy efficiecy. The modifications deecribed in this paper were: (1) staging the desiccant regeneration air and (2) recirculation of the primary air to the secondary aide of the indirect evaporative cooler. Computer simulations were run to study the effect of the modifications on the performance of the system. American Refrigeration Institute (ARI) standard conditions (Ambient sir at 35°C. 40% R.H. and Room air at 26.7°C. 50% R.H.) were used for all the modifications. Results were sleo compared to the familiar Pennington (ventilation) cycle.

The atudy indicated that recirculating the indirect evaporative cooler air only degenerated the performance. However, staging a portion of the regeneration air could improve the thermal Coefficient of Performance by 25% over the non-staged DINC cycle. Compared to a aimilar staged-regeneration Pennington Cycle it is a 16% improvement in thermal COP and the sensible heat ratio was 70%.     

大型冷却模块结构在鞍钢1号高炉的应用

鞍钢１号高炉在１９９８年年修中引进和应用了大型冷却模块结构技术，对大型冷却模块的设计，备件制备，施工等作了介绍，并分析了采用该技术的经济效益。     

整流机组的综合保护

介绍了大功率硅整流机组的保护功能及其原理,为整流机组配置完善的保护系统是安全生产的可靠保证。     

Constructal design of distributed cooling on the landscape

Here we constructal design to determine the area size (or number of users N) to be allocated to a central refrigeration plant, and to configure the distribution network for the distributed cooling system. The main objective is to maximize the net cooling capacity delivered to every user, and to minimize the pumping power required for transporting the chilled water. Two types of distribution networks are investigated: radial and tree‐shaped networks. First, when ducts with a single diameter are used, the net cooling capacity delivered to every user is almost the same, while the pumping power requirement for the tree network is greater than that for the radial network. Multi‐diameter tree networks are investigated next. The pumping power requirement for multi‐diameter tree‐shaped network is less than for radial network when N is greater than 19 if the flow is laminar, and when N is greater than 80 if the flow is turbulent. The global performance of the area‐based cooling system can be improved by increasing the freedom to morph the configuration. Copyright © 2010 John Wiley & Sons, Ltd.     

Numerical study of electrode geometry effects on resistance spot welding

Abstract

This work numerically investigates the geometrical effects of the electrode containing a coolant hole on transport variables during resistance spot welding. The model accounts for transient magneto-fluid mechanics, heat and species transport, bulk resistance in workpiece, and film and constriction resistances at contact interfaces. The computed results show that electrode cooling due to the coolant hole influences transport processes during not only freezing and cooling periods but also heating and melting periods. Electrode cooling can be interpreted by thermal resistance, depending on the shapes of the electrode and coolant hole within the growing thermal diffusion layer. Major factors affecting electrode cooling are different in distinct time stages. In most cases, enhanced electrode cooling due to the coolant hole decreases the electrode temperature and nugget growth rate. A decrease in the electrode face radius strongly increases nugget growth rate and workpiece temperature and decreases electrode temperature, whereas its effect on cooling rate is insignificant. The optimum design and sensitivity analysis of the electrode shapes subject to required cooling rate, nugget growth rate and welding time are revealed.     

浅谈直接空冷凝汽器的热态清洗

直接空冷凝汽器(简称ACC)的热态清洗是ACC系统试车前的重要环节,本文介绍了热态清洗的有关准备工作和热态清洗的程序,并提出了热态清洗的注意事项。     

湿式冷却塔自烟现象分析与解决方案

湿式冷却塔在一定气象条件下运行时，会出现“白烟现象”。该现象的发生对建筑景观、周边道路交通安全将会产生一定的影响，且易使人产生火灾的错觉。本文对湿式冷却塔“白烟现象”的发生条件及发生原因进行了分析，提出相应的解决方案，并针对各解决方案的优缺点进行了对比分析。     

水钢2号高炉炉底钻孔安装水冷管实践

水钢炼铁厂２号高炉第三代炉役投产后炉底温度持续升高，虽然采取了加入钒钛矿等措施，但炉底温度的上升仍未得到控制。采取在炉底钻孔安装冷却水管的措施后，炉底温度才趋于稳定。