It is explored from the literature study that engine-ORC system could operate with the maximum thermal efficiency range about 10–25%. The evaporator for the engine-ORC needs to be designed by keeping a view of variable exhaust gas heat source (variable temperature and mass flow rate profiles). Research challenges associated with engine-ORC technology such as selection of organic working fluid, type of evaporator/condenser, back pressure due to additional ORC components in the exhaust line are discussed. A review on the potential of waste heat recovery from exhaust gas, water jackets and intake charge air of CI engines was carried out.
The study deals with the utilization of organic Rankine cycle (ORC) to recover waste heat from compression ignition (CI) engines and produce additional power output. At all values of electrode spacing in this study, thermocell in vertical direction performs better than that of horizontal direction. Convection of electrolyte is unfavorable to cell performance and the critical electrode spacing where convection begins to affect heat transfer is predicted to be the optimized spacing. The power of thermocell rises significantly as the electrode spacing increases, from about 0.75mW in both directions to 1.75 mW in horizontal direction and 2.75 mW in vertical direction. Results indicate the ratio of electrolyte thermal resistance to total thermal resistance plays a crucial role in cell performance while electric resistance has relatively less influence. In this study, we establish an one-dimensional model of a Fe(CN)63-/4- concentric annulus thermocell and evaluate the influence of electrode spacing and cell direction on the cell performance. Thermogalvanic cell also named as thermocell is a new type of technology converting low-grade thermal energy to electricity. It was concluded that when using siloxane MDM as the working fluid, the requirements for the process sealing to withstand low vacuum conditions as well as the effective removal of non-condensable gases during the operation can be identified as one of the major challenges in achieving the targeted power output from this type of ORC systems. The system under study was identified to be capable of efficiently recovering the waste heat of the exhaust gases, and the potential of using high molecular weight and high critical temperature fluids as the working fluids in high-temperature, small-scale ORC applications was confirmed. The high pressure MDM vapor was expanded through an expansion valve thus, no power was extracted from the experimental setup and the main focus was on studying the performance of the process heat exchangers. The experiments were conducted with the aim of studying and analyzing the capability of the ORC process of recovering heat from the diesel engine exhaust. Based on the working fluid selection study, siloxane MDM was evaluated as the most suitable fluid for the experimental system.
In this paper, the working fluid selection and experimental results of a small-scale ORC unit utilizing exhaust heat of a diesel engine are presented and discussed.
In recent years, the use of small-scale organic Rankine cycles (ORC) in exhaust gas heat recovery of reciprocating engines has been intensively studied.
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