Effect of pinch point temperature difference on cost-effective performance of organic Rankine cycle

In this study, first and second law analyses of a new combined power cycle based on wet ethanol fuelled homogeneous charge compression ignition (HCCI) engine and an organic Rankine cycle are presented. A computational analysis is performed to evaluate first and second law efficiencies, with the latter providing good guidance for performance improvement. The effect of changing turbocharger pressure ratio, organic Rankine cycle (ORC) evaporator pinch point temperature, turbocharger compressor efficiency, and ambient temperature have been observed on cycle’s first law efficiency, second law efficiency, and exergy destruction in each of its component. A first law efficiency of 41.5% and second law efficiency of 36.9% were obtained for the operating conditions (T0 = 300 K, rp = 3, ηT = 80%). The first law efficiency and second law efficiency of the combined power cycle significantly vary with the change in the turbocharger pressure ratio, but the change in pinch point temperature, turbocharger efficiency, and ambient temperature shows small variations in these efficiencies. Second law analysis demonstrates well how the fuel exergy is used, lost, and reused in all of the cycle components. It was found that 78.9% of the total input exergy is lost: 2.0% to the environment in the flue and 76.9% due to irreversibilities in the components. The biggest exergy loss occurs in the HCCI engine which is 68.7%, and the second largest exergy loss occurs in catalytic converter, i.e., nearly 3.13%. Results clearly show that performance evaluation based on first law analysis alone is not adequate, and hence more meaningful evaluation must include second law analysis.

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Effect of Pinch Point Temperature Difference Assignment on the Thermal Performance of ORC System

Journal of Mechanical Engineering ◽

10.3901/jme.2017.08.158 ◽

2017 ◽

Vol 53 (8) ◽

pp. 158

Author(s):

Jiansheng WANG

Keyword(s):

Thermal Performance ◽

Temperature Difference ◽

Pinch Point ◽

Point Temperature

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Thermodynamic analysis of a wall mounted gas boiler with an organic Rankine cycle and hydrogen production unit

Energy & Environment ◽

10.1177/0958305x17724211 ◽

2017 ◽

Vol 28 (7) ◽

pp. 725-743 ◽

Cited By ~ 2

Author(s):

Anahita Moharamian ◽

Saeed Soltani ◽

Faramarz Ranjbar ◽

Mortaza Yari ◽

Marc A Rosen

Keyword(s):

Hydrogen Production ◽

Organic Rankine Cycle ◽

Rankine Cycle ◽

Inlet Pressure ◽

Pinch Point ◽

Working Fluids ◽

Turbine Inlet ◽

Energy And Exergy ◽

Cogeneration System ◽

Net Power Output

A novel cogeneration system based on a wall mounted gas boiler and an organic Rankine cycle with a hydrogen production unit is proposed and assessed based on energy and exergy analyses. The system is proposed in order to have cogenerational functionality and assessed for the first time. A theoretical research approach is used. The results indicate that the most appropriate organic working fluids for the organic Rankine cycle are HFE700 and isopentane. Utilizing these working fluids increases the energy efficiency of the integrated wall mounted gas boiler and organic Rankine cycle system by about 1% and the organic Rankine cycle net power output about 0.238 kW compared to when the systems are separate. Furthermore, increasing the turbine inlet pressure causes the net power output, the organic Rankine cycle energy and exergy efficiencies, and the cogeneration system exergy efficiency to rise. The organic Rankine cycle turbine inlet pressure has a negligible effect on the organic Rankine cycle mass flow rate. Increasing the pinch point temperature decreases the organic Rankine cycle turbine net output power. Finally, increasing the turbine inlet pressure causes the hydrogen production rate to increase; the highest and lowest hydrogen production rates are observed for the working fluids for HFE7000 and isobutane, respectively. Increasing the pinch point temperature decreases the hydrogen production rate. In the cogeneration system, the highest exergy destruction rate is exhibited by the wall mounted gas boiler, followed by the organic Rankine cycle evaporator, the organic Rankine cycle turbine, the organic Rankine cycle condenser, the proton exchange membrane electrolyzer, and the organic Rankine cycle pump, respectively.

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