Spreyleme Yöntemi ile Soğutulan Yarı Kapalı Bir Gaz Çevriminin Modellenmesi ve Performansının İncelenmesi

Öz

Güç üretiminin yanısıra soğutma ve temiz su eldesi sağlayan yeni nesil PoWER çevriminin performansı günümüzde incelemeye tabi olmaktadır. Bu çevrim temel olarak yüksek basnıçta geri beslemeli olarak çalışan HPRTE çevrimi ve buhar absorpsiyonlu soğutma çevrimi olan VARS çevriminin birleşimi olarak tasarlanmıştır. HPRTE sisteminde yakılan gazın bir kısmı sisteme geri kazanılarak verimden kazanç sağlanmakta ve faydalı atık ısı VARS elemanları tarafından kullanılmaktadır. Bu gaz çevrimin termal verimi yüksek basınç kompresörü girişinde akışkan sıcaklığı suyun donma sıcaklığı altına düşürülerek yükseltilebilir. Etilen glikol ve su karışımı gaz ortamına direkt olarak spreyleme yapılabilir. Bu sayede hem kurutma hem de soğutma işlemi yapılmış olur. Etilen glikol düşük buharlaşma basıncı olduğu için modellemede göz önüne alınmıştır. Çevrimlerin simülasyonu bilgisayar modeli ile yapılmakta olup soğutmanın sadece VARS tarafından ve VARS ile beraber spreyleme ile ortak yapıldığı durumları kıyaslamak için tasarlanmıştır. Geri beslemeli gaz çevriminde iki büyüklükte gaz motoru olduğu durum düşünülmüştür. Etilen glikol konsantrasyonunun yüzde 60 bileşende olduğu spreyleme yöntemi ile soğutmada orta ölçekte gaz motoru taşıyan sistemde termal verimin yüzde 2.2 oranında, küçük ölçekte gaz motoru taşıyan sistemde yüzde 2.7 oranında arttığı hesaplanmıştır.

Anahtar Kelimeler

• gaz türbinleri
• etilen glikol
• kurutma
• yarı kapalı
• termal verim

Modelling and Performance Investigation of Semi-Closed Gas Turbine Cycle with Spray Cooling

Abstract

The performance of a novel system, Power, Water Extraction, and Refrigeration cycle (PoWER), has been under investigation recently which is a combination of high-pressure regenerative turbine engine cycle (HPRTE) and a vapor absorption refrigeration system cycle (VARS). After the burned gas expand in the turbine, some portion is mixed with the pressurized fresh air and taken back into the cycle. Some of the waste heat is used by VARS through several heat exchangers. By this way external cooling load can be efficiently obtained. The efficiency of the semi-closed gas cycle can be further improved by achieving below-freezing temperatures of pure water at the high-pressure compressor inlet. Solution of ethylene glycol and water can be directly sprayed into the gas stream to both dry and to lower the temperature of the gas flow simultaneously. The computer model of the PoWER cycle with simple VARS model by considering second-law thermal efficiency and glycol cycle are used to compare the thermal efficiencies of the system when cooling is only accomplished by VARS and cooling is accomplished with both VARS and spraying aqueous glycol solution into the gas stream. Ethylene glycol is used as desiccant since it has very low vapor pressure and has a relatively low freezing point. Two systems with gas engines in different scales are investigated for this purpose. By enabling spray cooling the overall thermal efficiency of the system with medium size engine can be increased by 2.2%, whereas the efficiency of the system with the small size engine can be increased by 2.7% by using glycol-water solution with 60% ethylene glycol concentration.

Keywords

• Gas turbine
• Ethylene glycol
• drying
• semi-closed
• thermal efficiency

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