壳和管热交换器方程和计算-Enggcyclopediald乐动体育app

在本文中，我们将详细了解壳和管热交换器尺寸计算和设计。

Shell and tube heat exchangers are widely used and very popular in the process industry, due to their versatility. Different types of shell and tube exchangers can be easily configured by changing the shell and tube arrangement.

指数

Shell & tube heat exchanger design procedure

壳和管热交换器设计一世s an iterative process, which goes through the following steps.

Define process requirements for the new exchanger
Select a suitable外壳和管交换机的类型
Define design parameters such as - number of tube passes, tube size, shell ID etc.
Heat exchanger calculations和建模以获取输出 - 出口热/冷流体温度，传热速率，pressure drop on shell/tube sidesetc.
检查输出符合过程要求
- 如果输出按过程要求和成本在预算之内，则最终确定流程设计并准备热交换器规格表
- If the design does not match with either the process requirement or if it is over budget then go back to step 3, change the design parameters and repeat this process again.

tHere are a few equations that are very important for the calculations that we need to perform during heat exchanger design process.

Shell and tube heat exchanger equations

这是所有重要的清单壳和管热交换器方程式。

全面的Heat transfer equation

任何交换器中的总体传热均由以下等式控制 -

Equation-1

Q =总体传热率
U = Overall heat transfer coefficient
一个_全面的= Overall heat transfer surface ares
LMTD = Logarithmic Mean Temperature Difference

LMTD equation

tHe logarithmic mean temperature difference is an average quantification of the temperature difference between the shell and tube sides. It is calculated with the following equation.

Equation-2

在哪里，
ΔT₁→热交换器一端的热和冷液之间的温度差
ΔT₂→ the temperature difference between hot and cold fluids at the other end of the heat exchanger.

具有校正因子的LMTD

但是，LMTD仅适用于带有一个壳通道和一根管通道的热交换器。对于多数壳和管，热交换器中的流动模式既不是纯粹的共同流动，也不是纯粹的反流。因此，要考虑几何不规则性，对数平均温度差（LMTD）必须乘以平均温度差（MTD）校正因子（F_t）获得校正后的平均温度差（校正的MTD）。

Equation-3

这个correction factor calculatorw一世ll help you to quickly calculate the LMTD correction factor for a shell and tube exchanger with multiple shell or tube side passes.

根据所需的传热区域的管数

tHe number of tubes needed in shell & tube exchanger (N_t）可以根据总体传热面积的要求，使用以下方程计算。

Equation-4

在哪里，我们得到A_全面的（所需的总传热面积）来自传热速率方程（方程1）。
OD是选定管尺寸的外径
L is the total tube length

根据所选壳和管热交换器的几何形状，该方程非常直接。

管侧流体速度

tube side velocity is important for estimation of Reynolds number on the tubeside and then for getting the heat transfer coefficient for the tube side fluid. We can use the following equation for tube side velocity.

Equation-5

在哪里，m = mass flow rate on the tube side
n_p= Number of tube passes
n_t= Number of tubes
ρ = Tube side fluid density
ID = Tube internal diameter

Further, the雷诺的号码for the tube side fluid is calculated as,

Equation-6

在这里，μ是管侧流体的粘度

全面的Heat transfer coefficient equation

当我们在传热区域有一个手柄时（a_全面的）和温度差（LMTD），在传热方程（方程1）中唯一剩下的未知是总传热系数（U）。我们可以使用以下方程来获得壳和管交换器的总体传热系数。

Equation-7

在哪里，h_o= Shell side heat transfer coefficient
H_一世= Tube side heat transfer coefficient
r_做= shell side污垢因子
r_di=管侧污垢因子
OD and ID are respectively the outer and internal diameters for the selected tube size
一个oand Ai are outer and inner surface area values for the tubes
k_w一世s the resistance value for the tube wall

note, this overall heat transfer coefficient is calculated based on the outer tube surface area (Ao). So it must be multiplied by the Ao value for using in the overall heat transfer equation.

壳和管热交换器计算

We already saw that the壳和管热交换器的设计是一个迭代过程。通常，工程师更喜欢使用Heat exchanger design software创建热交换器模型。然后，您可以使用此模型模拟热交换器的性能，并验证它是否满足您的流程要求。

但是,如果你决定要手动执行他t exchanger sizing calculations,Here are some calculators and tutorials那可以帮助您。

热交换器计算器乐动体育网站怎样

note all of the following calculators are for demo. To access the actual working calculators, you will need to在Enggcyclopedia上创建ld乐动体育app登录。

这是一个shell & tube heat exchanger sizing calculator为了帮助您根据壳和管侧的进气/出口温度值计算所需的传热区域。这个calculator is for sizing the tubeside flow based on a fixed shell side flow。其他所需的输入是 - 流速，密度，粘度，壳和管侧流体的特定热值。
这是另一个calculator for shell side flow将帮助您计算所需的表面积以及外壳侧流，wHen you have fixed conditions on the tube side。其他所需的输入是 - 流速，密度，粘度，壳和管侧流体的特定热值。
这个快速LMTD计算器Helps to quickly getLMTD value用于交换器。
然后还有另一个LMTD校正因子的计算器。
除了这些,你还需要计算the pressure drop on the shell and tube sides for your process datasheet.这个calculator is for shell side pressure drop calculation。
You can use thiscalculator to determine tubeside pressure drop。

一个part from these calculators, you can always use aHeat exchanger design softwareto build a model of your heat exchanger design and then to simulate its performance.

tutorials for shell & tube exchanger calculations

Here are some step by step guided tutorials about how to use those calculators for shell & tube heat exchanger calculations. In these tutorials, we will make use of the shell & tube heat exchanger equations discussed above.

热交换器计算的提示和指针

壳侧挡板用于促进横流并增强两种流体之间的热传递。壳侧挡板之间的间距对传热程度有重要影响。您可以使用这些选择最佳外壳侧挡板间距的指南。It is generally recommended to consider baffle spacing between 0.3 to 0.6 times of shell ID, as per the TEMA standards.
Heat exchanger approach temperature一世s an important factor influencing the design of an exchanger. It is advisable to carefully consider the selected utility and corresponding approach temperature, before actually proceeding with the sizing calculations.

Shell & tube heat exchanger equations and calculations

Shell & tube heat exchanger design procedure