Abstract
Two-stage Gas turbine unite (GTU) inlet air cooling by absorption lithium-bromide chiller (ACh) to the temperature 15 °C and by refrigerant ejector chiller (ECh) to 10 °C through utilizing the turbine exhaust gas heat for changeable ambient air temperatures and corresponding heat loads on the air coolers for the south Ukraine climatic conditions is analysed. An excessive refrigeration capacity of combined absorption-ejector chiller (AECh) exceeding the current heat loads and generated at decreased heat loads on the air coolers at the inlet of GTU can be used for covering increased heat loads to reduce the refrigeration capacity of AECh. The GTU inlet air cooling system with an ambient air precooling booster stage and a base two-stage cooling air to the temperature 10 °C by AECh is proposed. The AECh excessive cooling capacity generated during decreased heat loads on the GTU inlet air coolers is conserved in the thermal accumulator and used for GTU inlet air precooling in a booster stage of air cooler during increased heat loads. There is AECh cooling capacity reduction by 50% due to the use of a booster stage for precooling GTU inlet ambient air at the expense of an excessive cooling capacity accumulated in the thermal storage.
Highlights
Gas turbine unit (GTU) inlet air cooling by waste heat recovery refrigeration machine (HRRM) which transforms the exhaust gas heat into the cold is one of the main trends in increasing GTU efficiency
The heat load on the air cooler (AC) at the GTU inlet changes significantly according to the current ambient air temperature tamb and relative humidity φamb that leads to adequate change of absorption-ejector chiller (AECh) cooling capacity
The project specific cooling capacity q0, on the one hand, should cover the GTU inlet air cooling need for as long time as possible during the year, which would have the greatest effect in the fuel saving
Summary
Gas turbine unit (GTU) inlet air cooling by waste heat recovery refrigeration machine (HRRM) which transforms the exhaust gas heat into the cold is one of the main trends in increasing GTU efficiency. Gas turbine inlet air can be cooled to the temperature ta2 ≈ 15 oС by transformation of waste heat into the cold with a high efficiency in the most widespread absorption lithium-bromide chiller (ACh). Deeper air cooling to the temperature ta2 = 10 oС and below is possible in refrigerant ejector chiller (ECh). It is rational to use two-stage air cooling at the GTU inlet: to ta2 = 15...20 oС in the ACh and to ta2 = 7...10 oC in the ECh, that is in the combined absorption-ejector chiller (AECh) [4, 5]. The heat load on the air cooler (AC) at the GTU inlet changes significantly according to the current ambient air temperature tamb and relative humidity φamb that leads to adequate change of AECh cooling capacity. It is expedient to cover the deficit of cooling capacity at high loads, thereby reducing the ACh installed cooling capacity and it cost
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