Abstract
ABSTRACT Organic Rankine cycle (ORC) has become a promising energy harvesting technique to recover thermal energy from low-grade heat sources. In this study, a lab-scale ORC system has been designed, constructed, and tested to investigate the potential of utilizing the heat from hot water, which is used to simulate the jacket water of internal combustion engines. The ORC system employs an oil-free scroll expander with R245fa as working fluid. A wide range of operating conditions has been studied by adjusting the pump frequency, the load and the mass flow rate of cooling water. Effect of the superheat degree at the expander inlet was investigated and the results showed that the ORC system presented better performance with superheat of 0. It is concluded that the system should be controlled to maintain the least possible superheat degree to obtain higher power output and better efficiency. The maximum electric power output and the maximum thermal efficiency are 0.61 kW and 4.09%, respectively, when the heat source is 96.8°C. The power consumed by the pump ranges from 0.07 to 0.18 kW, which accounts for 22 to 39% of the power output of ORC.
Highlights
Heat loss is one of the main challenges in power produc tion, whether from conventional or renewable sources
Li et al (2015) experimentally studied the effect of heat source temperature on a regenerative Organic Rankine cycle (ORC) perfor mance and the results indicated that the thermal efficiency and turbine isentropic efficiency of ORC with R123 are higher than that of the conventional Rankine cycle by approximately 5.9 and 24%, respectively
As shown in (Figure.1(a)), the ORC system consists of a evaporator, a condenser, a diaphragm pump driven by a motor, an oil-free scroll expander integrated with a single phase electric generator
Summary
Heat loss is one of the main challenges in power produc tion, whether from conventional or renewable sources. Yang et al (2016) conducted an experimental research and studied the ORC performance by adjusting the pump rotation speed and the heat sink temperature They found that the pressure drop in the expander had a significant effect on the ORC perfor mance, and the superheat influences the thermal efficiency more than the electrical output. Declaye (2013) studied the inlet pressure, outlet pressure and rotational speed on the expander performance in the ORC with R245fa as work ing fluid They found that the power to heat ratio varies from 1.9% to 11.8%. The effect of the heat source temperature, heat sink tempera ture, flow rate of working fluid, and load were taken into consideration, aiming to take into account the effect of figure out the potential of the system and the optimal operation condition that corresponded to maximum net power output
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