Thermoeconomic Analysis of a Cogeneration System of Compression Ignition Engine and Absorption Refrigeration Machine

2002 ◽  
Author(s):  
Ricardo Wilson Cruz ◽  
Silvia Azucena Nebra
Keyword(s):  
Cold Storage ◽  
Second Law ◽  
Compression Ignition ◽  
Absorption Refrigeration ◽  
Absorption System ◽  
Compression Ignition Engine ◽  
Aqua Ammonia ◽  
Cogeneration System ◽  
Ammonia Absorption ◽  
Refrigeration Machine

This paper is a first attempt to evaluate a refrigeration with cogeneration system focusing on a 915 kW genset/90 ton aqua-ammonia absorption system capable of supplying refrigeration, e.g. for cold storage warehouses for food conservation in the Northern Brazilian autonomous grid. The first and second law joined formulation, i.e. exergy, is used in order to determine irreversibilities and to address the exergetic and monetary costs of the system.

Availability analysis on combustion of n-heptane and isooctane blends in a reactivity controlled compression ignition engine

2017 ◽  
Vol 232 (11) ◽  
pp. 1501-1515 ◽  
Author(s):  
Mostafa Mohebbi ◽  
Masoud Reyhanian ◽  
Iraj Ghofrani ◽  
Azhar Abdul Aziz ◽  
Vahid Hosseini
Keyword(s):  
Heat Transfer ◽  
Mass Fraction ◽  
Fossil Fuels ◽  
Utilization Efficiency ◽  
Second Law ◽  
Compression Ignition ◽  
Compression Ignition Engine ◽  
Reactivity Controlled Compression Ignition ◽  
Fuel Mass ◽  
Availability Analysis

Unfortunately, energy demands and destruction of the environment from uncontrolled manipulation of fossil fuels have increased. Climate change concerns have resulted in the rapid use of new, alternative combustion technologies. In this study, reactivity controlled compression ignition (RCCI) combustion, which can simply be exploited in internal combustion (IC) engines, is investigated. To introduce and identify extra insightful information, an exergy-based study was conducted to classify various irreversibility and loss sources. Multidimensional models were combined with the primary kinetics mechanism to investigate RCCI combustion, incorporating the second law of thermodynamics. The n-heptane, a highly reactive fuel, was supplied by direct injection into the cylinder, whereas premixed fuel was supplied through the intake port in an isooctane/ n-heptane RCCI engine. For five n-heptane increments (5%, 7.5%, 15%, 25%, and 40%) and six different exhaust gas recirculation (EGR) rates (0%, 10%, 20%, 30%, 40%, and 50%), accumulation of different exergy terms was calculated. The results show that as EGR introduction increases from 0% to 50%, the exergy destruction increases from 21.1% to 28.9%. Furthermore, the value of exhaust thermomechanical exergy decreases from 18.4% to 14.4% of the mixture fuel chemical exergy. Among the five different high reactive fuel mass regimes, the 40% n-heptane mass fraction has the major heat transfer exergy owing to its advanced CA50 that exerts a unique influence on cylinder charge temperature of heat transfer layer. The utilization efficiency of exhaust in RCCI is less affected by the variation of reactive fuel mass fraction by contrast; it will significantly influence heat transfer availability. This study revealed that with increasing reactive fuel ( n-heptane) from 7.5% to 40% the irreversibility decreased from 28.6% to 25.8% and the second law efficiency first increased from 43.2% to 44.6% at 15% n-heptane then decreased to 42.9% at 40% n-heptane.

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