Designing and building a heat exchanger can be complex. Especially if it has to be compact, if it has to have a large cooling / heating capacity or if the efficiency plays a crucial role.

However, in many applications neither criterium is extremely critical.

This instructable will show you how to build a "classic" heat exchanger. Classic because you can find calculations and guidelines about them in almost any basic engineering book and it is darn simple to build.
The materials are cheap (PVC drainage pipe) and it can be easily enlarged or reduced to fit your cooling or heating capacity.

I used mine to protect the inlet of a vacuum pump by condensing liquid from an air stream.
https://www.instructables.com/id/Vacuum-infused-fruit-for-ice-cream/
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Step 1: What Do You Need?

The basis is a "one shell, one pass" type of exchanger. If you require more cooling / heating capacity you can lengthen the assembly, or choose to increase the number of passes (by widening the outer tube for which this procedure does not change).

* 1 outer pipe PVC, 32 mm. If you require more passes, choose a large size.
* 1 inner pipe (Aluminium OD 10 mm).
* 2 T-pieces (PVC, 32 mm))
* 4 pieces of PVC pipe (4 cm long). These are the connectors between the T-piece and the end caps.
* 4 end caps (PVC, 32 mm)
* 4 spacers (rings diameter 30 mm, 10 & 12 mm hole)
* 2 water pipes (Copper OD 12mm)
* 4 self made Rubber plugs (Alternatively: cork of a champagne bottle, styropor/styrofoam or polystyrene).
* PVC glue.

Step 2: The Inner & Outer Tube

Picture 1
Glue the 2 T-pieces directly onto the PVC pipe (in this stage pay attention to the configuration).

From now on, the procedure will describe only one half of the heat exchanger as the other one is identical.

Picture 2, 3 &4
Place the two spacers into both sides of the T-piece. Glue the PVC connectors in the T-piece and thus locking the spacers in place.

Picture 5
Insert the Aluminium pipe. This will nicely stay in place due to the spacers.

Step 3: Closing the Heat Exchanger

Picture 1
Fabricate the rubber plugs (or cork of a champagne bottle, styropor/ styrofoam or polystyrene). Ensure a very tight fit as they will act as a sealing plug.
Drill holes in the end caps.

Picture 2
Fit the rubber plug over the Aluminium pipe and push it (hard!) into the connector.
Apply glue to the end section of the PVC connector and apply a large blob of glue to the wall of the Aluminium pipe. Slide the cap, whilst rotating, over the connector. Once it is dry, you can start with the water connection.

Picture 3
Install the water pipe, install the plug, and glue in the similar way as described here above.