Heat loss is a major challenge in the process of power production when primary energy is converted into useful forms of energy. A study shows that around 72% of the global primary energy consumption is lost after such energy conversion and that 63% of the considered waste heat streams is generated at a temperature below 100°C. Thus, recovering waste heat, especially low-temperature waste heat, is the key to increasing the overall efficiency of power generation and industrial processes, and ultimately lowering the fuel demand. In order to make better use of the low-temperature heat, ITRI has developed the HiLLo-ORC (High-efficiency/Low-temperature/Low-cost Organic Rankine Cycle) system, a semi-hermetic expander technology that converts low-temperature waste heat into electricity in a cost-effective way.
ITRI’s HiLLo-ORC system is focused on the improvement of efficiency and cost—two crucial factors to be considered when using an ORC waste heat recovery system. Its feature design includes a semi-hermetic expander with a turbine-rotor subsystem, an optimized evaporator, a condenser, and a smart control system. The system enables a highly efficient operation without energy loss of the seal for separating the refrigerant and the waste heat flow. The refrigerant flows through the shell outside the rods to absorb the waste heat water or air in the evaporator. It is then evaporated at a low temperature below 100°C and becomes a high-pressure flow to drive the turbine to generate electricity with extreme efficiency. The closed loop allows the operation to work in an environment-friendly and economical manner. The semi-hermetic expander of the HiLLo-ORC system is a re-invention of the semi-hermetic compressor that has been commonly used in the refrigeration and air-conditioning industries. It is able to lower the cost of the system, providing a competitive return on investment (ROI).
A primary demo site of HiLLo-ORC.
ITRI has been dedicated to the commercialization of the HiLLo-ORC technology and is continuing to work with various sectors, such as the biomass, food processing, and solar energy industries for low-temperature waste heat recovery. With the support of Taiwan’s Bureau of Energy, four primary demo sites have been established, including a 125 kWe paper mill, a 200 kWe chemical plant, a 200 kWe steel refinery, and a 300 kWe geothermal farm. This technology was selected as a Top 100 for 2018 Create the Future Design Contest by NASA Tech Briefs magazine.