Study on Mixed Working Fluids with Different Compositions in Organic Rankine Cycle (ORC) Systems for Vehicle Diesel Engines

Abstract

Abstract:One way to increase the thermal efficiency of vehicle diesel engines is to recover waste heat by using an organic Rankine cycle (ORC) system. Tests were conducted to study the running performances of diesel engines in the whole operating range. The law of variation of the exhaust energy rate under various engine operating conditions was also analyzed. A diesel engine-ORC combined system was designed, and relevant evaluation indexes proposed. The variation of the running performances of the combined system under various engine operating conditions was investigated. R245fa and R152a were selected as the components of the mixed working fluid. Thereafter, six kinds of mixed working fluids with different compositions were presented. The effects of mixed working fluids with different compositions on the running performances of the combined system were revealed. Results show that the running performances of the combined system can be improved effectively when mass fraction R152a in the mixed working fluid is high and the engine operates with high power. For the mixed working fluid M1 (R245fa/R152a, 0.1/0.9, by mass fraction), the net power output of the combined system reaches the maximum of 34.61 kW. Output energy density of working fluid (OEDWF), waste heat recovery OPEN ACCESSEntropy 2014, 16 4770 efficiency (WHRE), and engine thermal efficiency increasing ratio (ETEIR) all reach their maximum values at 42.7 kJ/kg, 10.90%, and 11.29%, respectively.

Analysis of ORC (Organic Rankine Cycle) systems with pure hydrocarbons and mixtures of hydrocarbon and retardant for engine waste heat recovery

“…Aghahosseini et al [22] conducted both energy and exergy analyses for ORCs with different pure and zeotropic working fluids. Yang et al [23] evaluated ORC recovery system performance with six types of mixture working fluids with different compositions. The case study showed that the The temperature of the engine exhaust gas is high; therefore, working fluids with high critical temperatures are selected to maintain the ORC within the subcritical range.…”

A review of recent research on the use of zeotropic mixtures in power generation systems

“…Yang et al [56,57] analysed the use of zeotropic mixtures for WHR from the exhaust of a diesel engine. The heat source (i.e.…”

Performance Analysis of Organic Rankine Cycle with Internal Heat Regeneration: Comparative Study of Binary Mixtures and Pure Constituents in Warm Regions

“…Several studies have been conducted in recent decades on the exploitation of the potential of binary mixture organic fluids as working fluid in organic Rankine cycles [7]. Some researchers aimed to utilize waste heat [8,9], while some investigated it for renewable sources, like solar and geothermal sources [10,11]. Compared to cycles utilizing high-grade heat sources, organic Rankine cycles (ORCs) often exhibit lower efficiency due to the utilization of low-grade heat [12].…”