Theoretical and computational analyses of LNG evaporator

Theoretical and numerical analysis on the fluid flow and heat transfer inside a LNG evaporator is conducted in this work.Methane is used instead of LNG as the operating fluid.This is because;methane constitutes over 80％ of natural gas.The analytical calculations are performed using simple mass and energy balance equations.The analytical calculations are made to assess the pressure and temperature variations in the steam tube.Multiphase numerical simulations are performed by solving the governing equations (basic flow equations of continuity,momentum and energy equations) in a portion of the evaporator domain consisting of a single steam pipe.The flow equations are solved along with equations of species transport.Multiphase modeling is incorporated using VOF method.Liquid methane is the primary phase.It vaporizes into the secondary phase gaseous methane.Steam is another secondary phase which flows through the heating coils.Turbulence is modeled by a two equation turbulence model.Both the theoretical and numerical predictions are seen to match well with each other.Further parametric studies are planned based on the current research.     

Frosting of heat pump with heat recovery facility

This paper aims to prolong the heat pump frost time and reduce its growth with heat recovery facility, which should mix the exhausted indoor and outdoor air before entering the evaporator. An ideal mathematic model is developed for heat transfer, frost generation and airside pressure drop. The properties of the mixture would be obtained by solving the mass and energy conservation equations. A parametric analysis is performed to investigate the effects of air inlet temperature, relative humidity and air mass flow rate on total heat transfer coefficient, frost thickness and airside pressure drop, respectively. The results show that rationalizing the ratio of indoor and outdoor air could prolong frosting time and reduce the frost thickness greatly. The total heat transfer coefficient, frost thickness and airside pressure drop increase monotonically with time going, but are not proportional. Decreasing the mixture inlet air temperature and relative humidity could essentially reduce frost growth on the tube surfaces. This can also be observed when increasing the air mass flow rate.     

自动清洗式蒸发器自然循环推动力的冷模试验

自然循环自动清洗式蒸发器是解决蒸发器结垢问题的理想方案，关键之一是能否产生足够大的自然循环推动力。为此，作者进行了冷态的动力学模拟试验，结果表明经过加热室后相当于水溶液温度升高3℃以上，就能够形成10000Pa以上的自然循环推动力，使加热管内的自然循环流速达到1.0m/s以上，可靠地带动塑料纽带自转，实行连续地自动清洗。     

家用空调器采用微细尺度强化传热技术展望

基于对我国家用空调器产品现状的分析,探讨了执行新能效标准后空调换热器采用新型强化传热技术的潜在需求。制冷剂在微细管内凝结和沸腾传热的已有研究成果显示,家用空调器采用微细尺度强化传热技术,可以使换热器趋于紧凑、高效,从而使空调器满足新能效标准的要求。     

外热式自然循环蒸发器的计算

研究了外热式自然循环蒸发器的进料温度对循环速度、汽化段长度和传热膜系数的影响，并建立了数学模型，进行了模拟计算．计算结果表明，循环速度、汽化段长度和传热膜系数等参数随着进科温度的升高而增加．     

BP-PID Control Applied in Evaporator of Organic Rankine Cycle System

According to the problem that the selection of traditional PID control parameters is too complicated in evaporator of Organic Rankine Cycle system (ORC), an evaporator PID controller based on BP neural network optimization is designed. Based on the control theory, the model of ORC evaporator is set up. The BP algorithm is used to control the , and parameters of the evaporator PID controller, so that the evaporator temperature can reach the optimal state quickly and steadily. The MATLAB software is used to simulate the traditional PID controller and the BP neural network PID controller. The experimental results show that the , and parameters of the BP neural network PID controller are 0.5677, 0.2970, and 0.1353, respectively. Therefore, the evaporator PID controller based on BP neural network optimization not only satisfies the requirements of the system performance, but also has better control parameters than the traditional PID controller.     

液态纳米材料应用于空调器性能研究

本文研究了某种涂覆在空调器蒸发器和冷凝器翅片表面的液态纳米复合材料的性能,结果表明,这种纳米复合材料具有较强的综合性能,即优良的亲水性、基材表面自清洁功能、较强的附着力、耐流水冲刷和耐冷热冲击等物理性能,并能有效防止蒸发器和冷凝器发霉和产生水桥,同等条件下能保持两器的换热性能,能消除环境污染且材料本身对环境无污染。此外,对液态纳米材料未来的功能发展方向进行了预测。     

工业纯钛TA2焊接技术在刮板薄膜蒸发器上的应用

为了探索钛材TA2的焊接工艺技术,根据TA2材料的性能及焊接特点,从坡口的加工与处理、焊接操作方法和焊接保护工装等方面做了大量的试验。通过焊接工艺试验及分析,拟定了合理的焊接工艺参数和施焊过程中解决问题的措施。经过焊接工艺评定,最终确定了最佳的焊接工艺参数。试验和检测结果表明,采用该焊接工艺,焊缝的各项性能指标都符合设计要求,从而保证了产品的焊接质量。