Organic Rankine Cycle: An Effective Solution For Waste Heat RecoveryIn today's world, where energy consumption is increasing by the day, so are the concerns regarding the negative impact it has on the environment. The increasing emissions of carbon dioxide and fuel prices have pushed the researchers towards finding effective solutions to reduce the environment waste heat. One of the most promising solutions emerging is the Organic Rankine Cycle (ORC) system.The ORC system is a viable exhaust heat recovery technology that is widely used to recover low to medium-grade heat, rather than conventional steam Rankine cycle system. The system works by a closed-loop process, in which the organic fluid (e.g., refrigerant, hydrocarbon, etc.) is pumped into a heat exchanger where heat is transferred from the heat source (for example flue gas, exhaust gas, or hot water), causing the fluid to vaporize. The steam then passes through a turbine, converting thermal energy into mechanical work, which then drives a generator to produce electricity.The ORC system is versatile and can be designed to suit a wide range of applications, from small-scale energy recovery in industrial processes to large-scale electricity generation in power plants. The system is particularly suited for waste heat recovery applications, where the heat source temperatures are low to medium (100 - 350°C) as it operates effectively under such conditions.ORC systems come in various configurations and can be customized depending on the application requirements. The most common configurations include:1. Single-stage ORCThis is the most basic configuration of an ORC system, where the organic fluid is heated to its boiling point by the heat source and then passed through a turbine to produce electricity. This configuration is commonly used for low heat-sink temperatures and low power outputs.2. Two-stage ORCIn this configuration, the organic fluid is heated in two separate heat exchangers before being passed through a turbine. The two-stage configuration is ideal for applications where the heat source and heat sink temperatures are significantly different.3. Combined ORC systemsIn this configuration, the ORC system is combined with other energy recovery systems such as gas turbines, steam turbines, or cogeneration systems, to improve the overall efficiency of the energy recovery process.One of the most significant advantages of ORC systems is their ability to recover waste heat from different sources. The system can recover heat from various applications ranging from exhaust gases from combustors, engine exhaust, and flue gases from industrial processes to geothermal sources and solar thermal systems.Another promising application of ORC systems is in Total Heat Recovery Wheels (THRWs). These are advanced heat recovery systems that help in recovering both sensible and latent heat from the exhaust air stream and use it to precool or preheat the incoming fresh air. The technology changes the direction of the air flow using a specially designed wheel which traps the heat energy from the exhausted air, which is then exchanged with the incoming fresh air stream.In conclusion, the Organic Rankine Cycle (ORC) system provides an effective and sustainable solution to the challenge of waste heat recovery. The application of the system is versatile and can be customized to suit different requirements, depending on the application. Combined with other energy recovery systems, ORC systems can improve the overall efficiency of the energy recovery process and provide significant energy savings. The technology has great potential to contribute to environmental sustainability and should be considered as an integral part of future energy-efficient systems.
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