本科毕业设计（论文）
能量损耗计算方法
The method of steam pipelines' energy loss calculating based on the measurement of
available energy
郑重声明
嘌呤霉素筛选浓度
本人呈交的毕业设计论文，是在导师的指导下，独立进行研究工作所取得的成果，所有数据、图片资料真实可靠。尽我所知，除文中已经注明引用的内容外，本学位论文的研究成果不包含他人享有著作权的内容。对本论文所涉及的研究工作做出贡献的其他个人和集体，均已在文中以明确的方式标明。本学位论文的知识产权归属于培养单位。学生签名：日期：
蒸汽管网的能量损耗计算方法
摘要：热电系统以蒸汽为媒介，通过热电厂与各用户的管网连接实现供热过程。供热量的计量主要有涡街流量计和差压式孔板流量计，目前广泛使用的是以标准孔板为节流装置的差压式流量计。用户端及热电厂的供热流量、温度压力状况一般可通过常用的测量仪器得到，但其测量精度受到多方面因素影响，主要表现为仪表量程的局限性或蒸汽的品质。对于这类问题，在一定程度上得到了解决。而作为供热单位的能量核算或用户所购买的蒸汽质量（品质），由于供热管网的热损失是一个复杂的过程变量，受多种因素影响，包括环境的扰动、网络的配置方案等，长期以来一直无法予以较为准确的分析。 为了研究蒸汽管网的散热损失，本文通过先建立单管段的数学模型，然后进行递推从而得到整个管网的运行工况。在建立单管段的数学模型时，需要做一些假设，简化某些条件，假定末端温度和末端压力，采用迭代算法，知道假定的和计算所得的误差在一定范围内。管道的传热有3个过程，蒸汽到保温层内壁，保温层内壁到保温层外壁，保温层外壁到外界空气，而管道钢材的热阻相对于保温层的热阻可以忽略不计。递推时，管段的末端温度可看作是后一段管段的进口温度，后一段管段进口压力则是前一段末端压力减去由于阻力件存在而造成的压力损失。本文采用Visual Basic6.0编程，通过对算法的程序化实现，可在界面上显示各管段的压力、温度、损失量，改变管网的参数进行比较可得到相对损失最小的管线。
水溶性酚醛树脂关键词：蒸汽管网；迭代；递推；热损失
中图分类号：TP2
The method of steam pipelines' energy loss calculating based on the
measurement of available energy
Abstract:The thermoelectric system with a medium of steam achieves heating system by connecting thermal power plants with each user’s pipe network. The metering of heating load consists mainly of differential pressure orifice flow meter, which is currently in widespread use with standard orifice plate for throttling device and vortex-shedding flowmeter. The conditions of heating flow and temperature stress of clients and thermal power plants are generally available through common measuring instruments，but its measuring accuracy can be influenced by various factors, mainly showed in the limitations of measuring instruments and the steam quality. To some extent, such problems have been solved. However, as an energy balance of heating units and steam quality(character) the users have bought, considering the thermosteresis of heat-supply pipelines is an intricate process variable on which various factors, including environmental disturbance and configu ration schemes, etc. have influence, they haven’t got any accurate analysis for the long term.
bimpTo research heat loss of steam pipelines, this paper shows operation conditions of the whole pipeline
s through a recursion after establishing individual pipe lines’ mathematical model for the first. During the process of establishing, in order to simplify certain conditions, it is necessary to make some assumptions to gain the error in a certain range between assumed results and calculated results by applying the iterative algorithm on the basis of presumed temperature and pressure of the pipelines’ ends. Pipeline has three processes of heat transfer, steam to its thermal insulation layer’s inner wall, from inner wall to outer wall of thermal insulation layer an d from thermal insulation layer’s outer wall to outside air. When recursing, the temperature and pressure of a pipe-section’s end can be considered as that of the next pipe-section’s inlet, whose parameter is not necessarily the same to the former one’s. T his paper simplifies the operation greatly by applying programme Visual Basic6.0 to show pressure, temperature, loss of each pipe section on the screen. It is possible to gain pipeline with the relatively least loss by the means of changing pipes’ paramete rs and compare them.
Keywords:Steam Network; Iteration; Recurrence; Heat loss
Classification: TP2
目次
目次 (1)
下变频器
1 前言 (1)
1.1 应用背景 (1)
1.2 研究现状及问题 (1)
1.3 研究意义 (2)
2 蒸汽管网能耗的概况 (3)
2.1 供热管网的热损失 (3)
2.2 能耗损失的表现形式 (3)
2.3 基于管网模拟技术的热损分析方法 (3)
3 研究思路 (4)
3.1 直管段数学模型的建立 (4)
3.2 管网模型的建立 (4)
3.3 软件编程的实现 (5)
4 具体研究过程 (6)
4.1 直管段的数学模型的建立 (6)
4.1.1 研究模型的假设 (6)
4.1.2 对流换热 (6)
4.1.3 圆筒壁的导热 (8)
4.1.4 流动经验公式的选取 (10)
4.1.5 压力损失计算 (12)芯片散热片
4.1.6 传热计算 (14)
4.2 管网模型的假设及管段的递推 (16)
4.2.1 模型的假设和简化 (16)
4.2.2 管段的递推 (19)本振频率
5 软件编程 (20)
5.1 VB 介绍 (20)
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