Regenerator Effectiveness
Calculate the effectiveness of a regenerator (heat recuperator), ε = (T_out − T_in) ÷ (T_hot − T_in), comparing the actual heating of the cold fluid with the maximum possible (if it reached the hot exhaust gas temperature). The result (between 0 and 1, or ×100%) measures heat-exchange effectiveness: a regenerator uses a gas turbine's exhaust heat to preheat the air before the combustor, cutting fuel use and raising the regenerative Brayton cycle efficiency. Typical effectiveness is 0.7–0.9. Enter the inlet, outlet and hot-gas temperatures.
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Regenerator effectiveness
In a gas turbine the exhaust gases leave very hot — while the compressed air enters the combustion chamber relatively cold. The regenerator (or recuperator) is a heat exchanger that exploits this gap: it uses the heat of the exhaust gas to preheat the air before combustion, so that less fuel is needed to reach the firing temperature — which raises the efficiency of the regenerative Brayton cycle. The effectiveness measures how well the regenerator does that job: ε = (T_out − T_in) ÷ (T_hot − T_in). The numerator is the actual heating of the air (how much it really warmed up); the denominator is the maximum possible heating, which would occur if the air came out as hot as the exhaust gas entering the regenerator. The ratio lies between 0 and 1: ε = 1 would mean an ideal exchanger (air preheated all the way to the gas temperature), impossible in practice. Real regenerators reach 0.7 to 0.9; higher values demand huge exchangers, with more pressure drop and more cost. Regeneration only pays off when the compressor pressure ratio is moderate, otherwise the compressed air already leaves the compressor too hot. Enter the inlet, outlet and hot-gas temperatures.
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