ENERGY AND EXERGY ANALYSIS OF COMPACT POWER GENERATION AND HYBRID SOLAR ENERGY-WASTE HEAT-BASED TRIPLE EFFECT EJECTOR-VAPOR ABSORPTION REFRIGERATION CYCLE

2013 ◽  
Vol 21 (04) ◽  
pp. 1350023 ◽  
Author(s):  
RAJ KUMAR ◽  
ANIL KUMAR

An NH 3– H 2 O ejector-absorption refrigeration cycle, and an R-152a ejector refrigeration cycle are employed with a renewable energy power generator to make a proposed compact power generation and triple effect ejector-absorption refrigeration cycle. The exergy analysis of the cycle leads to a possible performance improvement. Approximately 71.69% of the input exergy is destructed due to irreversibilities in different components. Around 7.976% is available as the useful exergy output. The exhaust exergy lost to the environment is 20.33%, which is lower than the exhaust energy loss of 47.95%, while the useful energy output is 27.88%. The refrigerants used are of zero ODP and negligible GWP, and the CO 2 emission of the exhaust gases is very small as compared to that of the fossil fuel run engine, hence, this cycle is favorable to the global environment. The results also show that the proposed cycle has significant higher energy and exergy efficiency than the earlier investigated 'triple effect refrigeration cycle' and 'the combined power and ejector-refrigeration cycle'.

Author(s):  
Guillermo Valencia ◽  
Armando Fontalvo ◽  
Yulineth Cardenas ◽  
Jorge Duarte ◽  
Cesar Isaza

One way to increase overall natural gas engine efficiency is to transform exhaust waste heat into useful energy by means of a bottoming cycle. Organic Rankine cycle (ORC) is a promising technology to convert medium and low grade waste heat into mechanical power and electricity. This paper presents an energy and exergy analysis of three ORC-Waste heat recovery configurations by using an intermediate thermal oil circuit: Simple ORC (SORC), ORC with Recuperator (RORC) and ORC with Double Pressure (DORC), and Cyclohexane, Toluene and Acetone have been proposed as working fluids. An energy and exergy thermodynamic model is proposed to evaluate each configuration performance, while available exhaust thermal energy variation under different engine loads was determined through an experimentally validated mathematical model. Additionally, the effect of evaportating pressure on net power output , absolute thermal efficiency increase, absolute specific fuel consumption decrease, overall energy conversion efficiency, and component exergy destruction is also investigated. Results evidence an improvement in operational performance for heat recovery through RORC with Toluene at an evaporation pressure of 3.4 MPa, achieving 146.25 kW of net power output, 11.58% of overall conversion efficiency, 28.4% of ORC thermal efficiency, and an specific fuel consumption reduction of 7.67% at a 1482 rpm engine speed, a 120.2 L/min natural gas Flow, 1.784 lambda, and 1758.77 kW mechanical engine power.


2019 ◽  
Vol 9 (23) ◽  
pp. 5028 ◽  
Author(s):  
Pektezel ◽  
Acar

This paper presents energy and exergy analysis of two vapor compression refrigeration cycles powered by organic Rankine cycle. Refrigeration cycle of combined system was designed with single and dual evaporators. R134a, R1234ze(E), R227ea, and R600a fluids were used as working fluids in combined systems. Influences of different parameters such as evaporator, condenser, boiler temperatures, and turbine and compressor isentropic efficiencies on COPsys and ƞex,sys were analyzed. Second law efficiency, degree of thermodynamic perfection, exergy destruction rate, and exergy destruction ratio were detected for each component in systems. R600a was determined as the most efficient working fluid for proposed systems. Both COPsys and ƞex,sys of combined ORC-single evaporator VCR cycle was detected to be higher than the system with dual evaporator.


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