heat exchangers

Brad White

While it does depend in several variables, the plate heat exchanger (PHE) gets the nod for a lot of surface area in a small and relatively cost-effective package. They can also run with close "approaches" (entering hot fluid versus entering cold fluid temperatures), sometimes as little as 2-3 degrees. Depends on what you are doing with it.

Some pointers/caveats:

Brazed plate exchangers (the least expensive kind) are nearly impossible to clean. Back-flushing is all you can do so provide valves for the purpose if you risk fouling them. The tappings can also be used for acid washing if mineral build-up. By comparison, shell and tube types can be rodded out or the tubes replaced within the shell.

Plate and Frame exchangers (the big brother of the brazed plate) can be taken apart for cleaning, but these are more industrial application types.

Always put a 20 or even 80-mesh wye strainer into the PHE to protect it from clogging. Absent a good strainer, the PHE is a very effective strainer by itself. Ask me how I know. :)

Brazed-plate exchangers come in a variety of materials, usually different grades of stainless steel so if you are heating a pool or something corrosive, you have choices.

The plates are best piped in a counter-flow pattern which is why they are so darn effective. The hottest entering heating water sees the hottest leaving process water. The coolest leaving heating water sees the coolest entering process water. You can sometimes get hotter process water out than you have leaving heating water because of this, if the flow rates are right.

Dan_48

heat exchanger

Which type gives the best heat transfer. the shell and tube or plate type? Thanks in advance

ALH_4

HX's

Shell and tube have less head loss for higher flow rates. Plate exchangers are generally physically smaller for the same capacity. Heat transfer is a function of sizing and system design, so it is hard to answer that question. For most residential applications, a plate exchanger makes the most sense.

Dan_48

I am looking to split a wood boiler add on with glycol from the existing house hot water system. Cost and size are not issues. Just want the best heat exchange etc for this job. This wood boiler stuff is new to me.