机械5

摘要 在工业、农业和食品生产中大量的物料往往需要进行干燥处理，制冷技术在干燥领域的应用主要有两种方法：除湿干燥和冷冻干燥。除湿木材干燥机是实际使用中最常用的一种木材干燥设备，它靠电加热使木材干燥室升温，因此其电能消耗很大。为了减轻能耗，应用热泵来对木材干燥窑进行加热。热泵实质上是一种热量提取装置，高温热泵干燥机组利用逆卡诺原理，从周围环境中吸取热量，并把它传递给被加热的对象，其工作原理与制冷机相同，都是按照逆卡诺循环工作的，所不同的只是工作温度范围不一样。此外，热泵干燥技术除了具有能源消耗之外，还有环境污染孝烘干品质高、适用范围广等优点，其优异的节能效果已被国内外的各种试验研究所证明。 本介绍了热泵干燥机的工作原理以及主要组成部件，并且总结了热泵干燥机在节能方面的优势。中的热泵干燥机系统采用双冷凝器结构，两个冷凝器的连接可以是串联也可以是并联，本设计的热泵干燥机中的冷凝器是属于并联连接，其主要部件有蒸发器，压缩机，冷凝器，风机等。一般干燥机由制冷系统和送风系统组成。其制冷系统中，由压缩机压缩出来的高温高压制冷剂气体进入冷凝器，将热量传给空气后，冷凝成常温高压液体，经毛细管节流后进入蒸发器，吸收通过蒸发器的空气中的热量，变成低温低压气体，然后进入压缩机压缩，如此往复循环。而对于送风系统，湿空气被吸入后，在蒸发器中被冷却到露点温度以下，析出冷凝水，此时绝对含湿量下降，然后再进入冷凝器，吸收制冷剂的热量而升温，此时相对湿度又降低，出来后的空气由风机送入干燥室。热泵干燥机用机组的部分冷凝热来提高机组的出风温度，虽可节省用电能加热的耗电量，但仍存在着制冷量和加热量相互抵消的问题，所以我们将热管技术运用于干燥机中，用热管换热器回收蒸发器出口空气的冷量，既能节省电加热的能耗，防止冷热抵消，又能提高出风温度。本描述的是一台2HP热泵干燥机的设计，其设计的主要内容是单级压缩制冷循环中蒸发器和冷凝器的设计，包括蒸发器，冷凝器的设计以及压缩机的选型，运用了工程热力学、传热学、流体力学、制冷技术及相关技术专业课程的知识。根据压缩机功率我们可以算出冷量循环，包括压缩机选型，冷、热负荷计算，风量分配等，然后根据给定条件可以查出空气循环中各点空气状态并进行除湿量的计算，在取得最大除湿量的基础上确定适合的风量分配，最后通过热力计算和换热器的结构设计计算确定蒸发器和冷凝器的结构，排管布置以及它们的尺寸。 关键词：热泵干燥机蒸发器冷凝器压缩机 The desig
n of the heat pump dryer ABSTRACT A large
number of materials i
n i
ndustry, agriculture a
nd food productio
n ofte
n
need to be dried. There are twoways of refrigeratio
n tech
nology applicatio
ns i
n dry areas, dehumidificatio
n dryi
ng a
nd freeze dryi
ng. The most practical ki
nd ofwood dryi
ng equipme
nt is called dehumidificatio
nwood dryi
ng machi
ne. Thewood dryi
ng kil
n is heated by electric,which cost electric e
nergy a lot. To this e
nd, the applicatio
n of heat pump heati
ng thewood dryi
ng kil
n comes to our co
nsideratio
n. The heat pump is esse
ntially a heat lifti
ng device. High temperature heat pump dryi
ng u
nits based o
n reverse Car
not pri
nciple, absorb heat from the surrou
ndi
ng e
nviro
nme
nt a
nd pass it to the heated object. This is the same pri
nciplewith refrigerator based o
n the reverse Car
not cycle.Their differe
nce is just the operati
ng temperature ra
nge. This thesis describes theworki
ng pri
nciple a
nd the mai
n compo
ne
nts of the heat pump dryer, a
nd summarizes the adva
ntages of e
nergy savi
ng. The heat pump dryer system iswith dual co
nde
nser. The two co
nde
nser co
n
nected i
n series ca
n also be co
n
nected i
n parallel.The heat pump dryer is desig
ned i
n this thesis are co
n
nected i
n parallel. Its mai
n compo
ne
nts are evaporator, compressor, co
nde
nser a
nd so o
n. The ge
neral dehumidifier refrigeratio
n systems have two parts,which are air supply systems, a
nd the refrigeratio
n system. The high-temperature high-pressure refrigera
nt gas is compressed by a compressor i
nto a co
nde
nser. The heat passed to the air at room temperature is co
nde
nsed i
nto high pressure liquid, a
nd the
n e
nters to the evaporator after throttli
ng absorbed by capillary tubes.It becomes the low-temperature a
nd low-pressure gas sucked i
nto the compressor for compressio
n, a
nd so forth cycle. For the blower system, thewet air sucked i
n the evaporator is cooled below the dew poi
nt temperature. The absolute moisture co
nte
nt decreases. A
nd the air re-e
nters the co
nde
nser to absorb the heat of the refrigera
nt. After that, the relative humidity decreases. At last, the air is blowed i
nto the room. The heat pump dryer’s outlet air temperature of the u
nit is i
ncreased by part of the heat of co
nde
nsatio
n u
nit. It ca
n save electric. But there are still problems of mutually offset betwee
n cooli
ng capacity a
nd processi
ng heat. Heat pipe tech
nology are used i
n the dryi
ng machi
ne to recycle the cooli
ng capacity of the evaporator outlet airwith the heat pipe heat excha
nger,which ca
n save the power co
nsumptio
n of electric heati
ng to preve
nt hot a
nd cold offset, but also improve the air temperature. This paper describes the decisio
n of a heat pump dryer. The mai
n poi
nt is the desig
ns of evaporator a
nd co
nde
nser i
n a si
ngle-stage compressio
n refrigeratio
n cycle, i
ncludi
ng the desig
ns of evaporator a
nd co
nde
nser a
nd the selectio
n of compressor. This desig
n i
nvolves the professio
nal courses of e
ngi
neeri
ng thermody
namics, heat tra
nsfer, fluid mecha
nics, cooli
ng tech
nology a
nd related tech
nical k
nowledge. Accordi
ng to the compressor power,we ca
n calculate the amou
nt of cold i
ncludi
ng the compressor selectio
n, cold, heat load calculatio
n, the airvolume distributio
n. A
nd the
n calculati
ng the amou
nt of dehumidificatio
n a
nd the status of each poi
nt of air i
n the air circulatio
n ca
n be isolated accordi
ng to the give
n co
nditio
ns. By thermody
namic calculatio
n, a
nd structural desig
n of the heat excha
nger, the structure of the evaporator a
nd co
nde
nser drai
n pipe i
nstallatio
n are determi
ned. Key Words: heat pump; evaporator;co
nde
nser; compressor 目录 摘要I ABSTRACT III 第一章概述1 1.1热泵干燥机简介1 1.2热泵干燥机的基本原理1 1.3评价干燥机工作效率的主要指标2 1.4热泵干燥机的特性2 1.4.1热泵干燥机的优点2 1.4.2热泵干燥机的缺点2 1.5国内外热泵干燥机的一些技术改进与改革3 第二章设计说明书5 2.1原始参数5 2.1.1压缩机的选型5 2.1.2湿空气的计算6 2.1.3计算单级压缩制冷循环7 2.2蒸发器、冷凝器的设计9 2.2.1蒸发器的设计10 2.2.2冷凝器的设计14 2.3计算结果汇总18 2.4风机的选择20 2.4.1风机参数20 2.4.2风机型号说明21 2.4.3产品简介21 2.4.4适用范围22 2.4.5用户使用维护须知22 2.4.6尺寸表22 结语24 参考文献25 致谢27