蒸汽压缩-喷射耦合制冷循环系统设计与分析

论文总字数：37915字

摘 要

本课题所研究的蒸汽压缩-喷射耦合制冷循环系统相较于传统的蒸汽压缩制冷系统的改进方法是：通过气液分离器将节流过程中产生的闪蒸气分离开，并由喷射器引射。冷凝器中出来的液体分为两路：一路液体经升压泵加压后进入发生器中利用压缩机的排气显热将其加热至高压气体，作为喷射器的工作蒸汽；另一路液体经节流阀节流后进入蒸发器蒸发制冷。这种改进不仅可以解决节流后的闪蒸汽进入蒸发器占据换热面积从而影响蒸发传热的问题，且在产生相同制冷量的前提下时，可以减少压缩机的吸气量，降低压缩机的耗功。

本课题将这种新型的蒸汽压缩-喷射耦合制冷系统作为研究对象，对该系统的循环方式和系统性能进行研究，以及其核心部件-喷射器进行相关研究计算和分析，建立喷射系数计算模型，计算在不同蒸发温度下工作蒸汽所能达到的最大喷射压力和系统性能系数，并分析其变化规律和内在关系。此外根据系统计算结果选定工况，对系统中的重要部件-发生器进行设计计算和校核，掌握换热器设计方法，提高工程制图能力。另外，将本文的蒸汽压缩-喷射耦合制冷系统与传统蒸汽压缩制冷系统进行对比其耗功、制冷量和制冷系数，结果证明这种新型耦合系统确实具有一定的优势。计算结果显示：在该系统中，工作蒸汽的喷射压力随着蒸发温度的降低而提高，当蒸发温度从0℃到-30℃变化时，工作蒸汽的最大喷射压力可相应从1.8MPa到4.5MPa变化；并且通过热力计算结果证明：在相同工况条件下，该利用压缩排气工质的显热的蒸汽压缩-喷射耦合制冷循环的制冷量高于传统蒸汽压缩制冷循环，在蒸发温度为-30℃时，新系统相较于普通蒸汽压缩制冷循环制冷量相对提高达到0.304；而耗功量低于传统蒸汽压缩制冷循环，在-30℃的蒸发温度下，压缩机做功量只有普通蒸汽压缩制冷系统的0.767。因而，性能系数比较明显地高于传统蒸汽压缩制冷系统，在所选的工况范围内，性能系数的提高率可达到0.327。在系统理论计算分析设计的基础上，可为该制冷系统的实际生产应用提供相应参考。

关键字：喷射器，喷射系数，最大工作压力，COP，发生器

THE DESIGN AND ANALYSIS OF VAPOR COMPRESSION/EJECTION REFRIGERATION CYCLE

03112603 GuoShan

Supervised by professor DuKai

Abstract: Conventional vapor compression refrigeration system with its advantages of relatively simple and compact device, more stable running condition and easy maintenance, which make it in the area of air conditioning and refrigeration has been widely used. But with the energy crisis, the increasingly serious environmental problems, electric power consumption in air conditioning equipment is too much, and corruption problems using Freon and other refrigerants on the ozone layer, which threat the application of traditional vapor compression refrigeration system. If we can find little change assisted by some new energy-saving technologies but still maintain the basis of the original system which has been formed, this will be one of the more cost-effective energy conservation methods and energy-efficient refrigeration cycle way to ease the energy shortage currently in air conditioning and refrigeration industry.

The novel vapor compression - ejector refrigeration cycle system compared to conventional vapor compression refrigeration system has been improved by this procedure: the gas refrigerant generated in the throttling process and entrained by ejector later will be separated by gas-liquid separator. The liquid generated in the condenser is divided into two parts: one part of the liquid is boosted by a pump into the generator by utilizing the sensible heat of the compressor’s exhaust gas, then the liquid become high temperature and pressure gas as working steam in the ejector; the other part of the liquid come into evaporator after throttling. This improvement not only can solve the problem that the flash steam generated in the throttle occupied the area in the evaporator to affect the heat transfer, but also can reduce the intake and power consumption of the compressor in the basis of the same output of cooling capacity.

Our task is regarding the new vapor compression/ejection refrigeration system as the research object, the essay studied the loop mode and system performance, as well as its core part- ejector, calculate and analyze the research, and build the ejection coefficient calculation model, calculate the maximum ejection pressure and the coefficient of system performance at different evaporation temperatures, and to analyze the changes in the law of variation and internal relations. Select proper working conditions in accordance with the system calculation results. And an another important part in the system – generator, design model、calculate and check in order to improve the ability of engineering. In addition, this article will compare vapor compression /ejection refrigeration system to conventional vapor compression refrigeration system with its power consumption, cooling capacity and coefficient of performance. The results show that this new type of coupling system does have certain advantages. In this system, the ejection pressure of the working steam with decreasing evaporation temperature increased when the evaporation temperature from 0 ℃ to -30 ℃ with the maximum ejection pressure of working steam may correspond from 1.8MPa to 4.5MPa variation; ejection coefficient increases with the increasing steam pressure; and the thermodynamic calculation results show that under the same working conditions, vapor compression/ejection circle utilizing sensible heat compression have more cooling capacity than conventional vapor compression refrigeration cycle, when the evaporating temperature is -30 ℃, the new system compared to ordinary vapor compression refrigeration cycle is relatively improve by 0.304; and the amount of power consumption is less than conventional vapor compression refrigeration cycle’s, when the evaporating temperature is at -30 ℃, the compressor work load is only the ordinary vapor compression refrigeration system’s 0.767. The coefficient of performance is obviously much more than conventional vapor compression refrigeration system. With the proper selection within the range of operating conditions, the rate of increasing coefficient of performance is up to 0.327. Based on the theoretical analysis of the system design, the corresponding reference can be provided for the practical application of the refrigeration system.

Key words: ejector, ejection coefficient, the maximum working pressure, COP, generator

目录

目录 6

蒸汽压缩-喷射耦合制冷循环系统的设计与分析 8

1、 绪论 8

1.1 课题研究的背景 8

1.2 蒸汽压缩-喷射制冷系统的研究现状 8

1.3 喷射式制冷系统的研究现状 8

1.3.1 喷射器的特点 8

1.3.2 喷射式制冷剂的研究现状 9

1.3.3 喷射式制冷系统的最新发展 9

1.4 喷射式制冷系统的方法研究现状 10

1.5 本课题的研究内容 11

1.6 本课题的主要工作 11

2、 新型蒸汽压缩-喷射耦合制冷系统 13

2.1 系统流程简介 13

2.2 系统运行控制流程 14

2.3 新系统与传统蒸汽压缩制冷系统的对比及改进 15

2.3.1 普通蒸汽压缩制冷系统简介 15

2.3.2 新系统的改进及性能特点 15

3、 建立喷射系数计算模型以确定发生压力 17

3.1 喷射器的工作原理 17

3.2 选择喷射系数计算模型 17

3.3 喷射系数计算 18

3.4 计算方法 20

3.5 确定工作蒸汽的最高喷射压力 22

3.6 工况分析 22

4、 传统蒸汽压缩制冷系统与新系统的性能比较 24

4.1 系统性能热力计算 24

4.1.1 利用压缩排气显热的蒸汽压缩-喷射耦合制冷系统的热力计算 24

4.1.2 传统蒸汽压缩制冷系统的热力计算 25

4.2 两种系统的性能比较 25

4.3 系统性能分析的结论 26

5、 发生器设计 27

5.1 管壳式换热器设计计算说明书 27

5.1.1 设定工况基本参数 27

5.1.2 确定发生器热负荷及压缩排气量 27

5.1.3 管壳式换热器初步设计 28

5.1.4 换热器的允许压降校核计算 31

5.1.5 总传热系数的计算与校核 32

剩余内容已隐藏，请支付后下载全文，论文总字数：37915字