Abstract
Organic Rankine Cycle (ORC) is an effective way to recycle waste heat sources of a marine diesel engine. The aim of the present paper is to analyze and optimize the thermoeconomic performance of a Series Heat Exchangers ORC (SHEORC) for recovering energy from jacket water, scavenge air, and exhaust gas. The three sources are combined into three groups of jacket water (JW)→exhaust gas (EG), scavenge air (SA)→exhaust gas, and jacket water→scavenge air→exhaust gas. The influence of fluid mass flow rate, evaporation pressure, and heat source recovery proportion on the thermal performance and economic performance of SHEORC was studied. A single-objective optimization with power output as the objective and multi-objective optimization with exergy efficiency and levelized cost of energy (LCOE) as the objectives are carried out. The analysis results show that in jacket water→exhaust gas and jacket water→scavenge air→exhaust gas source combination, there is an optimal heat recovery proportion through which the SHEORC could obtain the best performance. The optimization results showed that R245ca has the best performance in thermoeconomic performance in all three source combinations. With scavenge air→exhaust, the power output, exergy efficiency, and LCOE are 354.19 kW, 59.02%, and 0.1150 $/kWh, respectively. Integrating the jacket water into the SA→EG group would not increase the power output, but would decrease the LCOE.
Highlights
The results showed that full recovery of the jacket water with a single Organic Rankine Cycle (ORC) loop could have a lower power output
In the calculation process, according to the amount of energy recovered in each heat exchanger, the calculation of the point temperature difference (PPTD) can be divided into 6 cases when the Series Heat Exchangers Organic Rankine Cycle (SHEORC) are utilizing three waste heat sources
The thermodynamic and economic model of SHEORC were implemented in MATLAB
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Diesel engines have very high thermal efficiency, nearly half of the energy in the HFO is still emitted into the environment through exhaust gas, jacket water, scavenging air, lubricating oil, and heat radiation [2] Utilizing these waste heat sources can cut down the cost of fuel consumption and reduce. Analyzed the thermal and economic performance of a single loop transcritical Rankine cycle to recover heat from the exhaust gas, jacket water and scavenging air. Yang [11] utilized heat from the exhaust gas, jacket water, scavenge air, and lubricating oil with the single loop transcritical Rankine cycle. These studies showed that utilizing multi-heat sources could significantly improve the thermal efficiency of the diesel engine. Thermoeconomic performance analysis and optimization of the SHEORC have been carried out to find the best combination and suitable working fluid
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