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## What is double pipe heat exchanger?

DOUBLE PIPE HEAT EXCHANGER. A double pipe exchanger consists of one or more pipes or tubes inside a pipe shell. Basically two straight pipe lengths are connected at one end to form a U or “hair-pin.” Longitudinal fins may be used on the outside of the inner tube.

How do you calculate the temperature difference between a double pipe heat exchanger?

Wall temperature is calculated as following. Viscosity is calculated for both streams at wall temperature and heat transfer coefficient is multiplied by viscosity correction factor. Overall heat transfer coefficient (U) is calculated as following. Calculate Area and length of double pipe exchanger as following.

How do you calculate heat exchanger?

4.0 – HEAT EXCHANGERS CALCULATIONS:

1. The main basic Heat Exchanger equation is: Q = U x A x ΔTm =
2. The log mean temperature difference ΔTm is: ΔTm =
3. (T1 – t2) – (T2 – t1) = °F.
4. T1 = Inlet tube side fluid temperature; t2 = Outlet shell side fluid temperature;
5. ln (T1 – t2) (T2 – t1)

### How do you calculate pressure drop in a double pipe heat exchanger?

Background on Pressure Drop Calculation for Pipe Flow

1. hL = frictional head loss, ft-lb/lb.
2. L = pipe length, ft.
3. D = pipe diameter, ft.
4. V = average flow velocity of fluid (= Q/A), ft/sec.
5. g = acceleration due to gravity = 32.2 ft/sec2.

What is the main disadvantage of double pipe heat exchanger over the shell & tube heat exchanger?

The disadvantage of the double-pipe heat exchanger is that it covers a large area. At the same time, the metal consumption per unit heat transfer area is much, about 5 times that of the shell-and-tube heat exchanger. There are many pipe joints, which are easy to leak and large flow resistance.

Where are double pipe heat exchangers used?

Double-pipe heat exchangers are used in many industries because of their low design and maintenance costs, flexibility, and low installation costs . They are mainly used for sensible heating or cooling of process fluids in applications of small heat transfer areas of up to 50 m2 .

#### How can you increase the efficiency of a double pipe heat exchanger?

In the present work, the thermal performance of a conventional heat exchanger is improved by inserting porous substrates at both sides of the inner tube wall. The porous substrates improve the convective heat transfer coefficient between the tube wall and the fluid.

How do you calculate pressure drop in a heat exchanger?

Total volumetric flow = 50000 kg/hr ÷ 988.0 kg/m3 = 50.61 m3/hr Volumetric flow in each 1″ tube = 50.61 ÷ 25 = 2.02 m3/hr Pressure loss per unit length of the tube is then calculated using EnggCyclopedia’s pressure drop calculators for pipes and tubes. This calculator is based on Darcy-Weisbach equation.

How does a double pipe heat exchanger work?

In this part there will be looked at a double-pipe heat exchanger with parallel flow. This means that the hot fluid and the cold fluid flow in the same directions. There are also counter flow heat exchangers. In this situation the hot fluid and the cold fluid flow in opposite directions.

## How to calculate double pipe heat transfer coefficient?

Calculate equivalent diameter (D e) and flow area (A f) for both streams. Calculate velocity (V), Reynolds No. (Re) and Prandtl No. (Pr) number for each stream. For first iteration a Length of double pipe exchanger is assumed and heat transfer coefficient is calculated.

How is the heat given in a heat exchanger?

For heating (), the heat flow from the pipe wall in a length is where is the pipe diameter. The heat given to the fluid (the change in enthalpy) is given by where is the density of the fluid, is the mean velocity of the fluid, is the specific heat of the fluid and is the mass flow rate of the fluid.

What is viscosity correction factor for double pipe exchanger?

For first iteration a Length of double pipe exchanger is assumed and heat transfer coefficient is calculated. Viscosity correction factor (μ / μ w) 0.14 due to wall temperature is considered 1. For Laminar Flow (Re <= 2300), Seider Tate equation is used.