Is this even possible? (heat exchanger problem)

[yujean44]

I am currently dealing with a problem involving the heat transfer between two gases. Would it be possible to take JP-8 Fuel Exhaust (990C) and heat up water (starting at 140C, 9.8MPa) to produce 900 KW? The flow-rate of the water is 0.9kg/sec.

There is an extreme size-restriction on this heat exchanger, which is limited to 1.5m x 0.6m x 0.6m.

I read through this "Guide to Compact Heat Exchangers" (link below), and found that the Module 2.5 was the closest to the one I am trying to design, however the size-constraints and input-ranges specified are not within my range of desired inputs.


Thanks for all your help.

eugene


link to "Guide to Compact Heat Exchangers"

http://www.ept.ntnu.no/fag/tep32/Pensum/CompactHeatExchangers.pdf

 

[zdas04]

You've left out a few key pieces of information. What is the mass flow rate of your exhaust (no you can't generate that much power from a 3 hp Honda generator, but maybe you can from a Solar Turbine)? What is the specific heat of the exhaust? How far are you willing to cool the exhaust (this is a big one since if you cool it below the condensation temperature of the water vapor you can create some really nasty acids in the exhaust stack)? Is the 900kW output a steam load or a heat-extraction load?

David

 

[IRstuff]

Assume 80% eff for your engine and 20% eff for your generator, that puts your engine at 5.6 MW power output.

TTFN

FAQ731-376

 

[MortenA]

Eugene

If this is waste heat recovery from e.g. a gas turbine then these uints are sold as packaged units typically though the gas turbine vendor.

Best regards

Morteh

 

[danberry]

The power vs water flow are not unreal thermodynamically (I would say 500 kW is optimistic in those sizes) but we are talking about a hi-pressure boiler, a turbine-generator, a condenser, a heat sink, feedwater and condensate pumps, control valves etc, etc. That junk could maybe fit in a semi-trailer but certainly not in a coffin sized box.

Sorry

 

[yujean44]

Thank you all for your replies.

I am still curious ... Who are the leading Heat Exchanger makers for Mack Trucks, and other heavy trucks? Do those heavy trucks have this type of similar concept, using exhaust gas to heat up fluid?

The exhaust gas mass flow rate is about 9lbs/second. The allowed volume has almost doubled to about 10' x 2' x 1.5'


Thanks again,

Eugene

 

[gr2vessels]

Eugene,

Curiosity is an important thing for engineering, but I cannot imagine a heat recovery system installed on a truck, for intermittent operation, operating at aroung 1420 psi, to recover 900 kW from the 300-400 kW Mack engine. Obviously, I'm missing something. Besides a cabin heater and a few coolers for engine coolant, oil, power steering oil and the like, I don't know other heat exchangers installed on a truck, however why would you generate high pressure steam on a mobile plant and how you use it? And how you keep the steam hot, when you stop for refueling or for a quick toilet run?
cheers,
gr2vessels

 

[KMRDMECH]

The heat exchanger your are referring to on a truck is not used directly for power generation, but to transfer heat from the exhaust to the intake, thereby changing the power cycle.