机电专业培训-chilledwater

日期：冷冻水系统Chilled

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System讲者：鲍中林Chilled

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System单机容量系统定压Topics

to

Be

DiscussedUnit

CapacityPressurization一次泵系统二次泵系统分配压力分区压差放在哪里?冷却水负荷控制Primary

Pump

SystemPrimary/secondary

Pump

SystemDistribution

PiPressure

PartitionWhere

is

the

⊿P

placed?Cooling

waterLoadControlChilled

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SystemA

simplified

system

diagramChillerCoilCoilCoilChilled

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System单机容量Unit

CapacityChilled

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System确定单机容量考虑的因素至少两台机组考虑负荷连续变化考虑最小负荷N×A+1×BN×A+1×BChilled

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System总冷量2500Ton1000Ton×2+500Ton×12500Ton500Ton500Ton500Ton1000Ton1000Ton1000Ton1000Ton1000Ton1000Ton2000Ton1500Ton1000Ton500Ton100Ton负荷组合举例Chilled

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System系统定压PressurizationChilled

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System为什么要定压?为系统安全运行提供压力参考点温度波动介质Chilled

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System定压原则系统充满水运行时不出现负压尽量降低系统部件承压Chilled

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System压力线分析ChillerCoilCoilCoil压力线Chilled

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System当忽略系统高程时ChillerCoilCoilCoil压力最低点ExpansionChilled

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SystemExpansionCoilCoilCoilCoil高层建筑压力分析(1)HP1P

=

H-

P1HP=H-PHChillerP

=

H-

P1-

PcPcChilled

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SystemChillerExpansionCoilCoilCoilCoilHP1P

=

HHP

=

H-

PcPcP=H+

P1

-PH高层建筑压力分析(2)Chilled

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SystemChillerExpansionCoilCoilCoilCoilHP1P

=

H+

Pc

HP

=

HPcP=H+

P1+

Pc

–PH=H-

P2-

Pch高层建筑压力分析(3)P2PchChilled

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SystemChillerExpansionCoilCoilCoilCoilChilled

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System一次泵系统Primary

Pump

SystemChilled

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SystemCoilCoilCoilChillerChillerChillerP一次泵系统Chilled

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System一次泵系统基本特性末端盘管变流量冷冻机定流量水泵定速运行旁通管平差(由调节阀控制)Decoupling供回水压差稳定Chilled

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SystemQH水泵扬程特性系统阻力特性100m3/h145m3/h

250m3/h

300m3/h泵的并联运行（当系统内没有可变阻力元件时）Chilled

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SystemCoilCoilCoilChillerChillerChillerP一次泵系统压力分析P1P2P3(I)P3(II)P1=ConstantChilled

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System一次泵系统泵的运行分析QH300m3/h215m3/h115m3/h水泵扬程特性系统阻力特性P3P2P1Chilled

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System二次泵系统Primary/secondary

Pump

SystemChilled

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SystemCoilCoilCoilChillerChillerChillerP二次泵系统INVChilled

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System二次泵系统基本特性末端盘管变流量冷冻机定流量一次泵定速运行二次泵变速运行旁通管平差(无阀门控制)Decoupling供回水压差稳定Chilled

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System为什么要用二次泵系统?节能Chilled

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SystemCoilCoilCoilChillerChillerChillerP二次泵系统INV100L/s,15m100L/s,25mChilled

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System0.6

100050%流量运行时一次泵系统水泵的电耗分析100%流量运行时一次泵系统Q

gH

100kg/s

9.8m/s2

40m

65kWη1000

0.6

1000二次泵系统100kg

/

s

9.8m/s2

15m

100kg

/

s

9.8m/s2

25m

65kW0.6

1000Q

g

H

100kg

/

s

9.8m/s2

40m

65kW0.6

1000

1000二次泵系统100kg

/

s

9.8m/s2

15m

50kg

/

s

9.8m/s2

25m

45kW0.6

1000

0.6

1000Chilled

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System离心式水泵变速的大致规律当系统阻力特性保持不变时流量∝转速扬程∝转速2Chilled

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SystemQH水泵工频特性系统阻力特性水泵变频特性泵的变速运行100%90%80%70%Chilled

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SystemQH泵的扬程特性系统阻力特性变频泵的运行分析(一)两台泵工频运行第三台泵70%工频水泵组合特性！Chilled

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SystemQH泵的工频特性系统阻力特性变频泵的运行分析(二)三台泵均运行在70%工频泵的变频特性Chilled

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SystemCoilCoilCoilChillerChillerChillerP二次泵系统INVP≈0P=ConstantChilled

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SystemQH泵的工频特性系统阻力特性二次泵的运行过程分析三台泵运行频率约77%工频泵的变频特性定压差线Chilled

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System分配Distribution

PiChilled

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System典型的异程系统AHUAHUAHUAHUAHUAHUChilled

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System(a)水平管路同程AHUAHUAHUAHUAHUAHUChilled

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System(b)垂直管路同程AHUAHUAHUAHUAHUAHUChilled

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System(c)水平与垂直管路均同程AHUAHUAHUAHUAHUAHUChilled

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System同程管路的压力线AHUAHUAHUAHU⊿P1⊿P2⊿P3⊿P4Chilled

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System同程设计的基本要求等比摩阻盘管阻力相近Chilled

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System压力分区Pressure

PartitionChilled

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System板式热交换器水系统压力分区AHUAHU高区AHUAHUChiller低区Chilled

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System压差放在哪里?Where

is

the

⊿P

placed?Chilled

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System压力无关Pressure

IndependentChilled

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SystemCoilCoilCoilP压差探测点(1)INVCoilCoilCoilChilled

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SystemCoilCoilCoilP压差探测点(2)INVCoilCoilCoilChilled

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SystemCoilCoilCoilP负荷变化时的压力变化INVCoilCoilCoil满负荷部分负荷前端定压差Chilled

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SystemCoilCoilCoil负荷变化时的压力变化CoilCoilCoil满负荷部分负荷末端定压差PINVP1P2(I)P2(II)P1Chilled

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SystemQH泵的工频特性系统阻力特性前端定压水泵运行过程分析水泵运行频率约77%工频泵的变频特性定压差线Chilled

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SystemQH泵的工频特性系统阻力特性末端定压水泵运行过程分析水泵运行频率约65%工频泵的变频特性定压差线P2P1=CChilled

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SystemQH泵的工频特性系统阻力特性泵的变频特性末端定压水泵运行过程分析定压差线P2P1=C假定水泵没有进行转速调节...Chilled

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System压差定位的比较末端定压降低水泵电耗改善调节阀调节性能适合于各回路负荷相似的场合不适合负荷变化混杂的系统控制线路较长前端定压水泵电耗较高调节阀调节性能较差适合于负荷变化混杂的系统控制线路较短Chilled

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System思考：同程系统会怎样?Chilled

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System冷却水Cooling

waterChilled

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System冷却塔排热量=冷冻机制冷量+冷冻机耗电量考虑裕量10%Chiller电能输入吸收热量排出热量Chilled

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System冷却水系统ChillerChillerChillerCTCTCTChilled

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SystemCTCT水位水位CT水位冷却塔水位的不平衡Chilled

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System冷却塔水位的不平衡CTCT水位水位CT水位Chilled

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System冷却水系统CTCTCTChillerChillerChillerChilled

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System冷却水系统CTCTCTTChillerChillerChillerChilled

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System冷却水系统CTCTCTTChillerChillerChillerChilled

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System冷却水系统设计要点冷却塔运行台数与冷冻机对应考虑水位不平衡防低温旁通(>14~19°C)冬季防冻措施注意校核水泵超载Chilled

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System负荷控制Load

ControlChilled

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System方案(1)根据旁通管流量控制Chilled

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SystemCoilCoilCoilChillerChillerChillerTrTs×FTeTsChilled

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System加机条件旁通流量<10%单台冷冻机设计流量，且持续一定时间(10~20分钟)减机条件旁通流量>120%单台冷冻机设计流量，且持续一定时间(10~20分钟)Chilled

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System方案(1)的问题它假定末端盘管供回水温差与冷冻机工作温差完全匹配它假定冷冻水流量与负荷成正比关系其实…Chilled

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System100%

FlowLoad典型的热交换器的流量特性是这样的：50%100%设计负荷80%20%40%Chilled

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System实际上…在设计负荷下，末端盘管供回水温差大于设计温差，也大于冷冻机设计温差冷冻水流量与负荷并不成比例关系，而且流量下降的速度比负荷下降来得快对于调节型末端而言(区别于开关型，如FCU)，负荷越低则温差越大，因为负荷=流量×温差Chilled

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System方案(2)根据一次侧温差计算负荷，决定冷冻机运行台数负荷=流量×温差Chilled

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System加机条件计算负荷/

冷冻机容量>95%，或(冷冻水供水温度-设定温度)>1°C，且持续一定时间(10~20分钟)减机条件(

冷冻机容