Thermal Rating for Heat Exchangers

Nah, there is nobody "out there" who has experience with this, except for a few old farts. For the really old farts who still use the orange Crane catalog for HX design, K = about 90 or so on S&T HXs. For the young farts dealing with P&F HXs, K = 300-400, or maybe more. Ain't progress wonderful? (If this is not in your native language, you'll just have to get it translated.)

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Moonbeam...

Your phrase "figure out the thermal rating" is confusing to me.

Heat exchangers exist as part of a larger process chemical cycle. The cycle is designed to produce a certain amount of product per hour or day. The overall performance goal of the plant is summarized in a heat-mass balance documents. (Also called PFDs)

The various heat exchangers, as well as the columns, pumps, seperators are sized to meet this goal. Therefore, the desired HX thermal rating is part of the heat-mass balance goal. Typically, each heat exchanger is custom designed to best perform at one point.

Hope that this helps !!

Unless I'm missing something, thermal rating sounds to me pretty straightforward - the mass flow of what you're heating (or cooling) x specific heat x ΔT (in-out) = thermal power (kW).

The difficult bit is finding the heat transfer rate, kW/m² for a particular type of heat exchanger under the conditions you want to use it, and hence the surface area needed.

Cheers.......Codey

Two methods to design heat exchanger. LMTD Method and Effectiveness-NTU method. For most of process application the later one is preferred.

That's right, and that's what he needs to do to size his heat exchanger. But is that the "thermal rating"? Also it's a pretty complicated series of calculations. Unless there's some empirical back-up I'd want to include a good safety margin!

Codey