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如何计算冷干机的热负荷?

来源:杭州优联超滤设备有限公司  日期:2017-12-18 09:34:26  点击:618  属于:公司新闻
在冷干机中,换热器(蒸发器和预冷器)负荷可通过计算热流体进出口焓差来求得: Δh=1.01Δt+(2501+1.84Δt)Δd (KJ/kg干空气) ①
在冷干机中,换热器(蒸发器和预冷器)负荷可通过计算热流体进出口焓差来求得:
In a cold dryer, the load of the heat exchanger (evaporator and precooler) can be calculated by calculating the enthalpy difference between the inlet and outlet of the thermal fluid.
 
Δh=1.01Δt+(2501+1.84Δt)Δd (KJ/kg干空气) ①
Delta h=1.01 Delta t+ (2501+1.84 delta T) Delta D (KJ/kg dry air)
 
式中Δt──作为热流体的压缩空气进出口温度差,℃
In the form of delta T - the temperature difference between the inlet and outlet of the compressed air as a thermal fluid, C
 
Δt=t’-t”
Delta t=t '-t
t’──压缩空气进入换热器时的温度
T '-- the temperature of compressed air entering the heat exchanger
 
t”──压缩空气离开换热器时的温度
T "- the temperature of compressed air leaving the heat exchanger
 
1.01──干空气的平均定压比热,KJ/kg.℃
1.01 - average constant pressure and specific heat of dry air, KJ/kg. C
 
1.84──水蒸气的平均定压比热,KJ/kg.℃
1.84 - the average constant pressure of water vapor, KJ/kg. C
 
2501──水的汽化潜热,KJ/kg
2501 - latent heat of vaporization of water, KJ/kg
 
Δd ──换热器中产生的凝结水量,kg
Delta D - condensation water produced in the heat exchanger, kg
 
Δd=d’-d”
Delta d=d '-d
 
式中,d’、d”分别表示对应温度t’和t”时压缩空气中的饱和含水量,kg。
In the formula, d 'and D respectively indicate the saturated water content in the compressed air, kg, when the temperature T' and T are corresponding to the temperature.
 
换热器的热负荷为
The heat load of the heat exchanger is
 
Q=qmΔh (W) ②
Q=qm delta H (W) 2
 
式中,qm──空气的质量流量,kg/s
In the formula, QM - the mass flow of air, kg/s
 
公式①和②是计算压缩空气降温过程热负荷的基本公式,它由下述三部分组成:
The formula 1 and 2 are the basic formulas for calculating the heat load of the compressed air cooling process. It consists of the following three parts:
 
1)1kg干空气从t’降到t”放出的热量1.01Δt;
1) the heat of 1kg dry air from t 'to t' is 1.01 delta T;
 
2)(d’-d”)kg的水蒸气从t’降到t”放出的热量;
2) the heat released from the water vapor from t 'to t in (d' -d ") kg.
 
3)(d’-d”)kg的水蒸气凝结成液态水放出的凝聚热(在数值上等于汽化潜热)。
3) (d '-d ") the condensation heat of the water vapour of kg condenses into liquid water (in numerical value equals vaporization latent heat).
 
其中1),2)两项是随温度变化的热量,称为显热,第3)项由凝结水量的多少决定,它不参与系统的换热,因此是潜热。
Among them, 1), 2) two is the heat that changes with the temperature. It is called sensible heat. Third) is determined by the amount of condensation water. It does not participate in the heat exchange of the system, so it is latent heat.
 
在蒸发器里,冷媒蒸发过程放出的冷量(或吸收的热量),一部分用于压缩空气的降温,另一部分用于支付水蒸气凝结所需的潜热;
In evaporator, the cooling capacity (or absorbed heat) released by the refrigerant evaporation process is used for cooling the compressed air, and the other part is used to cover the latent heat required for steam condensation.
 
在预冷器里,低温干燥空气升温过程吸收的热量(或放出的冷量)一部分用于压缩空气进气的降温,另一部分用来支付热气流中部分水蒸气凝结所需的潜热。
In the pre cooler, the amount of heat absorbed (or released) during the heating process of low temperature and dry air is partly used for cooling the compressed air intake, and the other part is used to cover the latent heat required for condensation of some steam in the hot gas flow.
 
结合上图,通过单位质量流量(kg/s)压缩空气时,预冷器热负荷可以写成
Combined with the above picture, the heat load of the precooler can be written when the unit mass flow (kg/s) is compressed into the air.
 
Q’=[1.01Δt1-2+(2501+1.84Δt1-2)*(d1-d2)] (W)
Q '=[1.01 Delta t1-2+ (2501+1.84 delta T1-2) * (d1-d2)] (W)
 
式中,Δt1-2=t1-t2
In the formula, Delta t1-2=t1-t2
 
通过单位质量流量(kg/s)压缩空气时,蒸发器热负荷可写成如下表达式
When the air is compressed by a unit mass flow (kg/s), the heat load of the evaporator can be written as the following expression
 
Q0=[1.01Δt2-3+(2501+1.84Δt2-3)*(d2-d3)] (W)
Q0=[1.01 Delta t2-3+ (2501+1.84 Delta T2-3) * (d2-d3)] (W)
 
式中,Δt2-3=t2-t3
In the formula, Delta t2-3=t2-t3