System Design, Optimization and Applications

Depending on the application, the design of the optimal ORC system entails the selection of the working fluid, the choice of the cycle configuration and operating parameters and the selection of the components and materials. The engineering problem is multifaceted as a multitude of requirements must be taken into account. Several case studies are presented and cover a wide range of applications and adopted or proposed solutions. Current applications of ORC power systems include: Geothermal reservoirs, Biomass fuel, Solar radiation, Waste heat recovery from industrial processes, Waste heat recovery from gas turbines and recip engines for stationary power, Landfill gas, Municipal waste incineration.
Many new exciting applications are being studied, like heat recovery from automotive engines, micro-cogeneration for households, electricity generation in space and in remote areas, etc. For some of these applications the ORC concept competes with other technologies like the Stirling engine, fuel cells, micro and small gas turbines, closedBrayton cycle turbines, and the traditional steam power plant, though challenged by the small capacity. Comparisons with these technologies are also treated.

Operational Experience

Be it either a power plant that has been in operation for many years or a prototype, manufacturers and research institutions collect information on the operation of ORC systems that is of paramount importance also for their further development. For example, efficiency, reliability and maintenance needs are measured in various ways. Operation depends also on measurements of temperature, pressure, mass flow, composition, and electrical variables. These measurements are sometimes challenging. Experience with all aspects of operation and maintenance is exchanged, as well as test results and novel implementations.

Simulation and Design Tools

The design and operation of ORC system requires advanced software and simulation capabilities. The properties of working fluids must be measured and modeled, therefore thermophysical models of fluid properties are developed and constantly updated. The thermodynamic cycle is optimized using steady-sate simulation programs for energy systems. The turbines and expanders, which are often unconventional, if compared to air and steam machinery, are designed and optimized using sophisticated CFD tools, as well as heat exchangers and pumps. Dynamic simulation is used to study transient behavior and as an aid to control design. Modern software is also adopted for the control system. The development and use of these programs is illustrated and their performance evaluated.

Policy and Regulations

ORC is a quickly expanding technology for renewable energy and as such requires a rationale and long-term policy in order to prosper. Regulation is varied all over the world and often inconsistencies hamper extremely promising applications. For example, should heat recovery be treated as ‘green energy’ by the legislator? The session focuses on the the discussion on what are the most correct criteria to foster the widespread application of ORC technology in the many sectors in which it can play a major role for a sustainable future.