Effect of Vacuum on Engine Exhaust
Effect of Vacuum on Engine Exhaust
(OP)
I'm working on an "Evaporation Pond" project. The goal of the project is to dispose of about 15 gpm of water produced in conjunction with natural-gas production.
The higher the temperature of the stream, the more effective the evaporation will be.
The transfer pump is powered by a natuarally-aspirated 90 Hp industrial engine. I can install an "eductor" to let the water I'm pumping suck on the engine exhaust-stack and create a 10-15 inHg vacuum on the engine exhaust (and thereby raising the temperature of the water 10-15F).
My question (finally) is: Will there be any adverse affects of pulling a medium vacuum on the engine?
The higher the temperature of the stream, the more effective the evaporation will be.
The transfer pump is powered by a natuarally-aspirated 90 Hp industrial engine. I can install an "eductor" to let the water I'm pumping suck on the engine exhaust-stack and create a 10-15 inHg vacuum on the engine exhaust (and thereby raising the temperature of the water 10-15F).
My question (finally) is: Will there be any adverse affects of pulling a medium vacuum on the engine?
David Simpson, PE
MuleShoe Engineering
www.muleshoe-eng.com





RE: Effect of Vacuum on Engine Exhaust
RE: Effect of Vacuum on Engine Exhaust
Of course, before posting either comment, I should have asked whether the engine is 2 or 4 stroke, and whether it runs gasoline or natural gas as fuel...
RE: Effect of Vacuum on Engine Exhaust
David Simpson, PE
MuleShoe Engineering
www.muleshoe-eng.com
RE: Effect of Vacuum on Engine Exhaust
With a 90 hp natural gas engine your waste coolant heat and exhaust heat will be about the same -- close to 4000 BTU/min. 15 gallons of water a minute is equal to about 120 lbs of water. 4000 BTU a minute will raise the temperature of this amount of water about twenty deg F (assuming a 100% efficient heat exchanger. You might want to consider a liquid/liquid intecooler to recover the coolant system heat, since this would essentially double your recovery to 8000 BTU/min.
I would recommend getting a custom cam that minimizes the exhaust and intake valve overlap. Otherwise the exhaust manifold suction will be sucking some of the fuel/air mixture when both the intake and exhaust valves are open.
RE: Effect of Vacuum on Engine Exhaust
RE: Effect of Vacuum on Engine Exhaust
David