A considerable amount of heat recovered by recuperators
from turbine exhaust brings about a narrow temperature range through the heat source.
* Preheated combustion air-through recuperators
or regeneration pick up 6%-8% efficiency, for a 24-month or 60-month ROI.
For more than a decade, ORNL had been working with industrial partners to design recuperators
(counter-flow heat exchangers for waste heat recovery) for turbines that can endure high-temperature, wet operating conditions.
It would, however, produce 10 MW of electricity (enough for 8,000 homes), require about 40 MW of recuperators
, a 26 MW C[O.sub.2] heater, and 15 MW of heat rejection.
Overall thermal efficiency is 25%-achieved through high pressure ratios instead of the heavy (and expensive) recuperators
found on most micro gas turbines.
In addition, the scope of the contract includes replacement of the gas turbine skids and auxiliaries, replacing and installing heat recuperators
, installing new control logic functions into the existing controls systems, site installation activities and a full-string test for the first upgraded unit.
The feed stream is preheated in the low temperature (State 2r) and the high temperature (State 3r) recuperators
before entering the evaporator.
Analogical experiments were fulfilled with different recuperators
with different requirements for the airflow rate capacity.
Lightweight and compact gas turbines that employ recuperators
to pre-heat combustion air, microturbines operate on the same principle as gas turbines.
Effectiveness of heat recuperators
follow simple correlations with two independent dimensionless parameters for air-to-air exchangers (Kays and London 1984).