An exhaust jet condenser is a direct-contact condenser: exhaust steam and cold injection water enter a chamber separately, mix, and leave together as warm water while an air pump or ejector removes non-condensable gases. Use the steady heat and mass balance to estimate the required injection-water flow for entered steam conditions and water temperatures.
Exhaust Jet Condenser Interactive Calculator
Trace the separate steam and water inlets, direct-contact spray, mixed discharge and air-removal path while calculating an ideal injection-water balance.
Equation Used
- Complete condensation and uniform outlet temperature.
- Negligible heat loss and kinetic-energy terms in the balance.
- Constant liquid-water heat capacity.
- No nozzle sizing, noncondensables, pump performance, pressure drop or equipment rating.
Steady adiabatic balance with constant liquid-water heat capacity. Entered steam enthalpy must come from appropriate steam data. Saturation pressure is an ideal equilibrium reference; air leakage, pressure drops, nozzle performance and pump capacity are omitted.
Direct-contact condensation
Cold injection water enters as a sheet or spray and contacts exhaust steam inside the condenser shell. Steam condenses into that water, so the condensate and injection water form one mixed discharge. An air pump or ejector removes the mixture and non-condensable gases.
This distinguishes a jet condenser from a surface condenser, where cooling water remains separated by tube walls.
Where direct contact fits
Jet condensers are mechanically simple where abundant suitable cooling water is available and mixing condensate with injection water is acceptable. They are not appropriate when clean condensate must remain isolated for reuse.
Steady mass and energy balance
For one kilogram of incoming steam, let r be injection-water mass, hs steam enthalpy, cp liquid-water heat capacity, Tin injection temperature and Tout mixed-discharge temperature. Adiabatic balance gives hs+r cp Tin=(1+r)cp Tout, so r=(hs-cp Tout)/(cp(Tout-Tin)).
The calculator multiplies r by steam flow for injection flow and adds both mass streams for mixed discharge.
Reading the result
The ratio increases as inlet water warms or the selected outlet temperature approaches inlet temperature. Outlet saturation pressure is an equilibrium reference from the water-temperature relation; actual condenser pressure also includes air partial pressure and losses.
Scope and limitations
The balance does not size the spray nozzle, shell, discharge or air pump and does not predict heat-transfer rate, entrainment, air leakage, cavitation or attainable vacuum. Those require detailed design data.
Questions
Do the two water streams remain separate?
No. Direct contact mixes injection water and condensed steam.
Why is an air pump shown?
Condensation removes steam volume but not leaked air or other non-condensable gases.
Is calculated vacuum guaranteed?
No. The saturation value is only an ideal equilibrium reference.
References
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