Integrated Steam/Organic Rankine Cycle (ISORC) for Waste Heat Recovery in Distributed Generation and Combined Heat and Power Production

Author(s):  
Yaroslav Chudnovsky ◽  
Mikhail Gotovsky ◽  
Valentin Arefiev ◽  
Mark Greenman ◽  
Victor Fomin ◽  
...  

Energy efficiency improvement and waste heat utilization in power generation and energy intensive industrial applications are in the main focus of the researchers and engineers nowadays. A great deal of experience was gained by the industrial leaders such as ORMAT, Siemens, Caterpillar, Turboden, and others. However, the commercially and semi-commercially available systems for waste heat utilization have certain restrictions that limit the utilization cycle efficiency to approximately 18%. The paper presents an innovative concept of waste heat utilization system that allows reaching the utilization cycle efficiency up to 28–30% employing low-boiling media such as butane, propane, pentane and others. Applying such a concept to Distributed Generation systems the overall energy efficiency could be boost up to 58–60% and further up to 90% in case of CHP production.

Author(s):  
W Gu ◽  
Y Weng ◽  
Y Wang ◽  
B Zheng

This article describes and evaluates an organic Rankine cycle (ORC) for a waste heat recovery system by both theoretical and experimental studies. Theoretical analysis of several working fluids shows that cycle efficiency is very sensitive to evaporating pressure, but insensitive to expander inlet temperature. Second law analysis was carried out using R600a as a working fluid and a flow of hot air as a heat source, which is not isothermal, along the evaporator. The result discloses that the evaporator's internal and external entropy generation is the main source of total entropy generation. The effect of the heat source temperature, evaporating pressure, and evaporator size on the entropy generation rate is also presented. The obtained useful power is directly linked to the total entropy generation rate according to the Gouy—Stodola theorem. The ORC testing system was established and operated using R600a as a working fluid and hot water as a heat source. The maximum cycle efficiency of the testing system is 5.2 per cent, and the testing result also proves that cycle efficiency is insensitive to heat source temperature, but sensitive to evaporating pressure. The entropy result also shows that internal and external entropy of the evaporator is the main source of total entropy generation.


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