Heat Transfer Coefficients Coils

Overview

Engineering reference data for Heat Transfer Coefficients Coils in thermodynamics.

Key Formulas

First Law

$\Delta U = Q - W$

Energy is conserved — heat added minus work done.

Ideal Gas Law

$PV = nRT$

Relates pressure, volume, and temperature of an ideal gas.

Heat Transfer

$Q = mc\Delta T$

Sensible heat transfer.

Carnot Efficiency

$\eta = 1 - T_C/T_H$

Maximum efficiency between two temperatures.

Variables

Symbol	Description	Unit
$U$	Internal energy	J
$Q$	Heat	J
$W$	Work	J
$P$	Pressure	Pa
$V$	Volume	m³
$T$	Temperature	K

Heat Transfer Coefficients for Submerged Coils

This section provides typical overall heat transfer coefficients (U) for steam，hot water，and other fluid coils submerged in liquids.

Example Calculation: Steam Coil in Oil

The heat transfer rate ($Q$) from a submerged coil can be calculated using the formula: $Q = U \cdot A \cdot \Delta T$

where:

• $U$ is the overall heat transfer coefficient (W/m²·°C)
• $A$ is the heat transfer surface area (m²)
• $\Delta T$ is the temperature difference between the coil surface and the bulk fluid (°C)

The surface area ($A$) of a cylindrical coil is: $A = \pi \cdot d_o \cdot L$

where:

• $d_o$ is the outside diameter of the coil (m)
• $L$ is the length of the coil (m)

Problem: A 50 mm nominal pipe coil ($d_o = 60.3\ \text{mm} = 0.0603\ \text{m}$) with length $L = 10\ \text{m}$ is submerged in oil. The coil carries steam at 120 °C, and the oil is at 50 °C.

Solution:

1. Calculate the surface area: $A = \pi \cdot 0.0603\ \text{m} \cdot 10\ \text{m} = 1.89\ \text{m}^2$
2. From the table, select $U = 170\ \text{W/m}^2\text{·°C}$ for "Steam to Light Oil, natural convection".
3. Calculate the heat transfer rate: $Q = (1.89\ \text{m}^2) \cdot (170\ \text{W/m}^2\text{·°C}) \cdot (120\ °C - 50\ °C) = 22,491\ \text{W}$

Interactive Charts

References

• Original Source