A study on efficiency and electric production in a basic and a recuperative organic rankine cycle

Abstract

Reusing waste heat is one of the techniques for increasing energy efficiency, which is a highly emphasized issue today. The organic Rankine cycle, also known as ORC, is increasingly recognized as a promising technique for converting low-temperature heat into electricity. ORCs are designed to operate without human intervention and require minimal maintenance. Although basic ORC is increasingly accepted by the industry, there is still a need to improve cost effectiveness. For the purpose of this review, calculations of the ORC system were made for the purpose of generating electricity by utilizing the recovery of heat energy at low temperatures for companies that discharge waste heat into the environment. EES program was used to investigate the relationship between efficiency rates as well as fluid properties to be used in the ORC system. Among the various fluids used in this system, cyclohexane, R123 and R290 were determined to have the highest efficiency rates. Estimated efficiencies for these fluids are 26%, 18.28% and 8% respectively. Condenser and turbine powers were calculated and compared to determine which fluid had the optimum efficiency rate and waste heat capacity. It has been noted that as the temperature of the condenser increases, the power output of the turbine decreases. The most effective fluids for turbine power generation are cyclohexane and R123.

Keywords

• Waste heat recovery
• Engineering Equation solver
• Thermodynamic analysis
• Organic rankine cycle

Temel ve reküperatif bir organik rankine çevriminde verim ve elektrik üretimi üzerine bir çalışma

Öz

Atık ısının yeniden kullanılması, günümüzde oldukça üzerinde durulan bir konu olan enerji verimliliğini artırma tekniklerinden biridir. ORC olarak da bilinen organik Rankine döngüsü, düşük sıcaklıklardaki ısıyı elektriğe dönüştürmek için umut verici bir teknik olarak giderek daha fazla tanınmaktadır. ORC'ler insan müdahalesi olmadan çalışacak ve minimum düzeyde bakım gerektirecek şekilde tasarlanmıştır. Temel ORC'nin endüstri tarafından giderek daha fazla kabul edilmesine rağmen, hala maliyet etkinliğinin arttırılmasına ihtiyaç vardır. Bu incelemenin amacı doğrultusunda atık ısıyı çevreye deşarj eden firmalar için düşük sıcaklıklarda ısı enerjisinin geri kazanılmasından yararlanılarak elektrik üretimi amacıyla ORC sisteminin hesaplamaları yapılmıştır. ORC sisteminde kullanılacak akışkan özelliklerinin yanı sıra verim oranları arasındaki ilişkiyi araştırmak için EES programı kullanıldı. Bu sistemde kullanılan çeşitli akışkanlar arasında sikloheksan, R123 ve R290'ın en yüksek verim oranlarına sahip olduğu belirlendi. Bu sıvılar için tahmini verimlilikler sırasıyla %26, %18.28 ve %8’dir. Hangi akışkanın optimum verim oranına ve atık ısı kapasitesine sahip olduğunu belirlemek için kondenser ve türbin güçlerini hesaplayıp karşılaştırılmıştır. Kondenserin sıcaklığı arttıkça türbinin güç çıkışının düştüğü kaydedilmiştir. Türbin güç üretimi için en etkili akışkanlar sikloheksan ve R123'tür.

Anahtar Kelimeler

• Atık ısı kazanımı
• Mühendislik denklem çözücü
• Termodinamik analiz
• Organik rankine çevrimi

Kaynakça

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