区域供冷系统经济供冷参数研究

发布时间：2019-03-02 11:40

【摘要】：区域供冷系统因为其系统运行能效高,维护管理方便等优点引起了人们的极大关注。近年来,中国也开始引入这种供冷系统,随着区域供冷系统在中国的发展,在工程实践中也突显了很多问题,如系统初投资较大,运行维护成本较高,系统制冷机组综合能效低。因而给区域供冷系统的推广带来了阻碍,若要从根本解决这个问题,就需以综合经济效益去考虑,而影响系统经济性的主要影响因素为系统的一些关键参数包括供冷半径、冷冻水供回水温差、冷冻水流速等,本文从系统经济性角度出发,研究这些参数对系统经济性的影响,并得出经济供冷参数值。首先,本文介绍了区域供冷系统的类型及其组成,根据系统类型确定系统各组成部分的初投资,并介绍了区域供冷系统冷源的类型,分析了制冷机组容量的确定方法。并简要分析了区域供冷系统关键参数对系统各项费用的影响。然后,介绍了系统参数对主要运行设备(如制冷机组和水泵)运行性能的影响,从传热原理分析各参数如供回水温度,冷却水进出口温度等对制冷机组能效比的影响,并以此计算制冷机组的运行费用。根据水泵的性能曲线,分析了水泵的几种运行模式及不同模式下的性能表现,计算不同工况下的水泵的运行费用。其次,介绍了输配管网造成的冷量损失,着重介绍了由管网与土壤传热产生的冷量损失和水泵运行产生的冷冻水温升冷量损失,并计算了由冷量损失造成的冷冻水温升,分析其对系统投资的影响。最后,本文针对区域供冷系统最优供冷半径和经济流速问题,根据区域供冷系统用户分布的特点简化了系统供冷区域的负荷分布及管网分布,采用全寿命周期费用方法,以经济最优为目标,建立了区域供冷系统经济供冷参数的目标函数,结合工程实例为目标函数的一些参数赋值,并分析电力价格、管道流速、供回水温差以及用户负荷密度等因素对区域供冷系统经济效益的影响,并计算了不同工况下的区域供冷系统的经济供冷参数如经济供冷半径和经济流速。研究结果表明经济供冷半径随电价的增大而减小,随负荷密度的增大而增大;经济流速随供冷半径增大而增大,随供回水温差增大而减小;在确定的供冷半径下,供回水温差越大,区域供冷系统的经济性越好。研究成果为区域供冷系统的设计提供了理论依据与技术指导,具有重要意义。
[Abstract]:Regional cooling system has attracted great attention because of its advantages of high energy efficiency and convenient maintenance and management. In recent years, China has also begun to introduce this cooling system. With the development of regional cooling system in China, many problems have also been highlighted in engineering practice, such as the large initial investment of the system and the high cost of operation and maintenance. The overall energy efficiency of the system refrigeration unit is low. Therefore, it hinders the popularization of regional cooling system. In order to solve this problem fundamentally, it is necessary to consider the comprehensive economic benefit, and some key parameters of the system, such as cooling radius, are the main influencing factors affecting the economic efficiency of the system. In this paper, the effects of these parameters on the economic efficiency of the system are studied from the point of view of system economy, and the economic cooling parameters are obtained. Firstly, this paper introduces the type and composition of the regional cooling system, determines the initial investment of each component of the system according to the system type, introduces the type of the cold source of the regional cooling system, and analyzes the determination method of the capacity of the refrigeration unit. The influence of the key parameters of the regional cooling system on the cost of the system is briefly analyzed. Then, the influence of the system parameters on the operation performance of the main operating equipment, such as refrigeration unit and pump, is introduced. The influence of the parameters such as the temperature of supply and return water, the temperature of cooling water inlet and outlet on the energy efficiency ratio of the refrigeration unit is analyzed from the principle of heat transfer. The operating cost of the refrigeration unit is calculated by this method. According to the performance curve of the pump, several operation modes of the pump and its performance under different modes are analyzed, and the running cost of the pump under different working conditions is calculated. Secondly, the cooling loss caused by the transmission and distribution network is introduced, the cooling loss caused by the heat transfer between the pipe network and soil and the cooling loss caused by the operation of the water pump are emphatically introduced, and the cooling water temperature rise caused by the cooling loss is calculated. Analysis of its impact on the system investment. Finally, aiming at the problem of optimal cooling radius and economical velocity of regional cooling system, according to the characteristics of user distribution of regional cooling system, the load distribution and pipe network distribution are simplified in this paper, and the whole life cycle cost method is adopted. Taking economic optimization as the goal, the objective function of economic cooling parameters of regional cooling system is established, and some parameters of the objective function are assigned with engineering examples, and the electricity price and pipeline velocity are analyzed. The effects of the temperature difference between supply and return water and user load density on the economic benefit of regional cooling system are studied. The economic cooling parameters such as economic cooling radius and economic velocity are calculated under different working conditions. The results show that the economic cooling radius decreases with the increase of electricity price and increases with the increase of load density, and the economic velocity increases with the increase of cooling radius and decreases with the increase of the temperature difference between supply and return water. Under the given cooling radius, the greater the temperature difference between the supply and return water, the better the economy of the regional cooling system. The research results provide theoretical basis and technical guidance for the design of regional cooling system, which is of great significance.
【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU831

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